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Microanatomy > SM01 Mini3 > Flashcards

SM01 Mini3 Flashcards

1
Q

primary cardiogenic field

A

horse-shoe shaped zone of heart precursor cells of splanchnic mesoderm (subdivision of lateral plate mesoderm) cranially & laterally to neural plate (if it were on the mesoderm, but it’s really on the ectoderm above)

W3

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2
Q

heart tube

A

two endothelial lined tubes left & right that fuse lateral body folding

W3

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3
Q

definitive heart tube

A

single heart tube after fusion of earlier endothelial tubes (through apoptosis of medial cells)

they do NOT fuse at the cranial or caudal extremes

created after lateral body folding, begins cranially and continues caudally

W3

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4
Q

cranio-caudal folding effect on heart

A

repositions heart tube into presumptive thoracic cavity, caudal to brain & oral cavity

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5
Q

primitive heart tube layers

A
  1. inner: endocardial layer
  2. middle: cardiac jelly
  3. outer: myocardial layer (muscle)

D22-25 (W4), presence of heart beat

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6
Q

epicardium is derived from

A

mesodermal cell that migrate from near the developing liver

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7
Q

cardiac jelly

A

extracellular matrix proteins

unknown function, but required, b/c if it doesn’t form, a spontaneous abortion will occur

middle layer of primitive heart tube

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8
Q

vitelline veins

A

paired right & left veins that carry deoxygenated blood from the yolk sac to caudal end of primitive heart tube

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9
Q

cardinal veins

A

paired right & left veins that carry deoxygenated blood from body of embryo to caudal end of primitive heart tube

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10
Q

umbilical veins

A

paired left & right veins that carry oxygenated body from placenta to the caudal end of primitve heart tube

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11
Q

primitive heart outflow tract

A

truncus arteriosus (which becomes the aorta & pulmonary thrunk) connects to right & left aortic archs (3 branches/side at this stage)

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12
Q

transverse pericardial sinus

A

forms from the degeneration of dorsal mesocardium

postnatally: located posteriorly to aorta and pulmonary trunk & anterior to superior vena cava

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13
Q

dorsal mesocardium

A

initial attachment of heart to posterior thoarcic wall during the development of pericardial cavity

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14
Q

5 dilations of primitive heart tube cranial to caudal

A
  1. truncus arteriosus
  2. bulbus cordis
  3. primitive ventricle
  4. primitive artrium
  5. right & left horns of sinus venosus

blood flows caudally to cranially

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15
Q

heart tube folding

A

D23 too long to be accomodated in available space

caudal primitive atrium shifts back then up & to the left, dorsocranially & left

cranial primitive ventricle moves ventrocaudally & to the right

D25-28 (end of W4)

blubus cordis & truncus arteriosus are medial & anterior in resulting structure

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16
Q

dextrocardia

A

when heart is on right instead of left due to abnormal looping

w/situs inversus→ normal or asymptomatic life

in isolation→ accompanied by severe cardiac abnormalities, ex. single ventricle or ventricular septal defect

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17
Q

formation of right atrium

A

trabeculated part: from right side of primitive atrium

sinus venarum (smooth portion): from right horn of sinus venosus

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18
Q

sinus venarum

A

smooth part of right atrium on posterior wall near opening of superior vena cava

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19
Q

left horn of sinus venosus derivatives

A

oblique vein of the left atrium & coronary sinus

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20
Q

crista terminalis

A

internal ridge demarcating the juntion of smooth portion & trabeculated portion of atria

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21
Q

formation of left atrium

A

trabeculated portion: left side of primitive atrium

smooth portion: from reincorporated pulmonary vein

single pulmonary vein develops out of posterior wall of left atria→ branches into four & connect to lungs→ proximal portions reincorporate into left atria forming smooth portion of left atria

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22
Q

3 fetal shunt systems

A

open prenatally, close postnatally

  1. ductus venosus (to liver)
  2. foramen ovale (between atria)
  3. ductus arteriosus (to lungs)
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23
Q

circulation through fetal system

A

placenta→ umbilical vein→ ductus venosus→ inferior vena cava→ right atria (also receives from superior vena cava)→ right ventricle & thru foramen ovale to left atria (also receives from pulmonary veins)→ left ventricle→ aortic arch & pulmonary trunk (to aortic arch via ductus arteriosus)→ descending aorta→ internal iliac arteries→ umbilical arteries→ placenta

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24
Q

septum primum

A

thin membranous septum starts at superior medial wall of primitive atrium & grows toward the endocardial cushion

as it nears the endocardial cushion, apoptosis occurs in some superior central cells opening the ostium secudum to keep the shunt system in place

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25
Q

ostium primum

A

opening between growing septum primum & endocardial cushion

allow shunting of blood from right to left atria

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26
Q

ostium secundum

A

opening of septum primum in superior central portion

allow shunting of blood from right to left atria

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27
Q

endocardial cushions

A

form in atrioventricular region

dorsal & ventral fuse to partition AV region into left & right canals

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28
Q

septum secundum

A

thick muscular septum

grows cranial to caudally like septum secundum and just to its right

past ostium secundum, it grows outward a little bit to leave an opening creating the foramen ovales

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29
Q

foramen ovale

A

opening in caudal portion of septum secundum

prenatally: allows oxygenated blood to bypass lungs to left atrium
postnatally: higher pressure in left atrium prevents backflow of blood into right atrium & septum primum adheres to septum secundum

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30
Q

valve of foramen ovale

A

higher pressure in right atrium v. left atrium pushes septum primum into left atrium, acting as a primitive valve to foramen ovale shunt system

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31
Q

types of atrial septal defects

A

10% of congenital heart defects

females more frequent than males

  1. probe patent foramen ovale
  2. ostium secunudum defect
  3. endocardial cushion defect w/ostium primum defect
  4. sinus venosus defect
  5. common atria
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32
Q

probe patent foramen ovale

A

failure of septum primum to adhere to septum secundum after birth

usually small & insignificant

increased risk of migraine

25% of all people

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33
Q

ostium secundum defects

A
  1. reabsorption of septum primum in abnormal location
  2. excessive reabsorption of septum primum
  3. defect development of septum secundum
  4. combination of excessive reabsorption of septum primum & large foramen ovale
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34
Q

endocardial cushion defect w/ostium primum defect

A

septum primum doesn’t fuse w/endocardial cushions→ patent ostium primum

septum secundum never reaches EC either

associated w/mitral valve cleft

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35
Q

mitral valve cleft

A

slit-like or elongated hole usually involving anterior leaflet

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36
Q

sinus venosus defect

A

occurs in septum near superior vena cava

causes: incomplete absorption of sinus venosus into right atrium or abnormal development of septum secundum
consequences: pulmonary veins may be attached to right atrium instead of left

requires surgical repair

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37
Q

common atrium

A

aka cor tricolare biventriculare

three chambered heart= one atrium, two ventricles

very rare

failure to develop septum primum or septum secundum

associated w/heterotaxy (abnormal distribution of organs in the thorax & abdomen)

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38
Q

results of premature closure of foramen ovale

A

hypertrophy of right heart

under-development of left heart

death shortly after birth

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39
Q

derivatives of truncus arteriosus

A

proximal aorta & pulmonary trunk

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40
Q

derivatives of bulbus cordis

A

caudally: smooth right ventricle & smooth left ventricle
cranially: (aka conus cordis) proximal aorta & pulmonary trunk w/truncus arteriosus

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41
Q

derivatives of primitive ventricle

A

trabeculated portions of left & right ventricles

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42
Q

derivatives of primitive atria

A

trabeculated portions of left & right atria

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43
Q

derivatives of sinus venosus

A

right: smooth part of right atrium (sinus venarum)
left: coronary sinus & oblique vein of left atrium

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44
Q

interventricular spectum formation

A

not as complex as atrial→ don’t need shunting→ complete before birth

muscular & membranous components that fuse

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45
Q

formation of muscular interventricular septum

A

grows from expanding myocardium of ventricles (end of W4) toward endothelial cushions

stops at W7 before fusion with endothelial cushions, creating interventricular foramen

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46
Q

interventricular foramen

A

opening of the ventricular septum formed W7 when the muscular interventricular septum does not fuse with the endothelial cushions

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47
Q

Membranous interventricular septum

A

forms from right endothelial cushions extension toward muscular interventricular septum & tissue from teh airticopulmonary septum growing down from the outflow tract

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48
Q

ventricular spectal defects

A

most close spontaneously during the first year of life

more frequent in females than males

membranous: most prevalent & often associated with aorticopulmonary septal defects
muscular: single or swiss chesse defects & can fill spontaneously

cor triloculare biatriatum/common ventricle

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49
Q

partitioning of outflow tract

A

neural crest cells migrate & invade truncal (on truncus arteriosus) & bulbar (on conus cordis-cranial remenant of bulbus cordis) ridges→ grow & twist in sprial fashion→ fuse to form aorticopulmonary septum

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50
Q

aorticopulmonary septum

A

derived from neural crest cells

partitions the outflow tract to form aorta (ventral &sac) & pulmonary trunk

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51
Q

aortic sac

A

derived from truncus arteriosus

formed by aorticopulmonary septum

gives rise to right & left horns→ brachiocephalic artery, ascending aorta & proximal segment of aortic arch

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52
Q

persistent truncus arteriosus

A

always seen w/ventricular septal defect

failure of truncus arteriosus to partition→ common outflow from both ventricles→ oartially deoxygenated blood circulates (cyanosis)→ death in first 2 years

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53
Q

transposition of great vessels

A

caused by aorticopulmonary partition not spiraling when formed→ pulmonary arteries connect to left ventricle & aorta connects to right ventricle→ oxygenated blood goes back to lungs & blood from body goes around again w/o getting oxygenated

3:1 males to females

risk factors: intrauterine rubella & other viral illnesses

cyanosis in 2/3 day postnatal

incompatible w/life unless shunt system still available

treatment: prostagladin to keep ductus arteriosus open

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54
Q

tetralogy of Fallot

A

displacement of septum due to four defects:

  1. pulmonary stenosis (narrosing of blood vessel)
  2. membranous interventricular septal defect
  3. overriding aorta (displacement to the right)
  4. right ventricular hypertrophy (from working harder to get blood through stenosed pulmonary artery)

less blood reaches lungs, poor oxygenation of body, cyanosis

can be corrected surgically

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55
Q

lung bud formation

A

aka repsiratory diverticulum

W4- appears D22 & grows ventrocaudally

outcropping of endoderm from foregut

surrounding splanchnic mesoderm will form the connective tissue & musculature of the lungs

separates from esophagus by tracheo-esophageal ridges

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56
Q

tracheo-esophageal ridge

A

separates esophagus dorsally & trachea and lung buds ventrally

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57
Q

tracheo-esophageal fistulas

A

TEF

more common in males

most associated with esophageal atresia

cause: incomplete division of foregut into esophageal & respiratory portions

can cause polyhydraminos

NOT usually isolated congenital abnormality

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58
Q

tracheo-esophageal fistula w/esophageal atresia

A

upper portion of esophagus ends & lower portion branches off of posterior trachea (fistula- abnormal or surgical passage)

rapid abdomen distention- air in stomach

aspiration of food (milk) into lungs or ejected

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59
Q

tracheo-esophageal fistula between trachea & esophagus

A

aka H-type

connecting tube from esophagus to posterior traches

4% of cases

food (milk) may be driven into lungs

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60
Q

VACTERL syndrome

A

Vertebrate defects

Anal atresia

Cardiac defects

Tracheo-esophageal fistulas

Esophageal atresia

Renal abnormalities

Limb defects

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61
Q

VATER syndrome

A

Vertebrate defects

Anal atresia

Tracheo-esophageal fistulas

Esophageal atresia

Renal abnormalities

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62
Q

W5 lung formation features

A

formation of left & right lung buds during partitioning by tracheo-esophageal ridge

main & secondary bronchi (3 on tight & 2 on left)

right is straighter (more vertical) & has larger lumen than left→ more foreign objects get lodged in it

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63
Q

formation of vasculature

A

W3

sets of paired vessels

arteries: aortic arches, dorsal aorta, vitelline & umbilical arteries
veins: cardinal, vitelline, & umbilical veins

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64
Q

when vascular connection is made between placenta & embryo

A

W4

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65
Q

where blood vessels begin

A

embryo & yolk sac

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66
Q

Aortic arches

A

five paired arteries (L+R): 1, 2, 3, 4, 6 (cranial to caudal)

5’s only purpose is to kickstart the growth of 6 & degenerate

dorsally connect to dorsal aortae

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67
Q

descending aorta formation

A

fusion of right & left dorsal aorta at T4-L4

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68
Q

adult derivative of first aortic arch

A

mostly degenerates

remenants: maxillary arteries

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69
Q

adult derivatives of second aortic arch

A

most degenerates

dorsal end forms hyoid artery which later forms the stapedial arteries, which is a transient connect between external & internal carotid arteries

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70
Q

persistent stapedial artery

A

manifests as pulsatile mass in middle ear cavity

sometimes causes pulsatile tinnitus

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71
Q

adult derivatives of third aortic arch

A

right & left common carotid arteries

proximal portion of internal carotid branches

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72
Q

adult derivatives of fourth aortic arch

A

left: arch of aorta
right: proximal right subclavian artery

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73
Q

formation of right subclavian artery

A

proximally: fourth aortic arch
distally: 7th intersegmental artery

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74
Q

adult derivatives of sixth aortic arch

A

right: right pulmonary artery & grows toward lungs
left: forms ductus arteriosus (part of shunt system)→ closes after birth & becomes ligamentum arteriosum

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75
Q

recurrent laryngeal nerves

A

branch off of vagus nerves (runs anterior to arches & just medial to R subclavian & descendin aorta on L)

R: loops under & posterior to 4th aortic arch

L: loops under & posterior to 6th aortic arch (ductus arteriosus)

innervates larynx

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76
Q

coarctation of aorta

A

constriction or narrowing of aorta

subdivided by location: pre or postductal

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77
Q

postductal coarctations of aorta

A

restriction occurs below ductus arteriosus

w/ & w/o ductus arteriosus closure, most are closed

most common type of coarctation

collateral circulation thru: subclavian arteries→ internal thoracic→ anterior intercostal arteries→ posterior intercostal arteries (3rd-9th)→ thoracic aorta

dilated tortuous arteries: increased blood flow & palpable pulses (in posterior intercostal spaces)→ rib notching

blood pressure is lower in lower body & lower limbs & higher in upper limbs

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78
Q

preductal coarctation of aorta

A

restriction of aorta before the ductus arteriosus

w/ & w/o patent ductus arteriosus

patent ductus arteriosus allows blood flow to inferior body, but is deoxygenated

collateral circulation through subclavian arteries does NOT work, reason unknown

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79
Q

double aortic arch

A

persistent portion of right dorsal aorta cranial to T4

results in vascular ring that can constrict the esophagus & trachea or be asymptomatic

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80
Q

vitelline arteries

A

paired (R+L) vessels of yolk sac where they anastamose in a vascular plexus→ migrate into embryo as yolk sac regresses→ separate from descending aorta→ reattaches to descending aorta as 3 trunks

celiac, superior & inferior mesenteric arteries

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81
Q

celiac trunk

A

found at T12

supplies forgut structures (liver & spleen)

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82
Q

superior mesenteric trunk

A

found at L1

supplies mudgut structures

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83
Q

inferior mesenteric trunk

A

found at L3

supplies inferior mesenteric structures

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84
Q

umbilical arteries

A

carry deoxygenated blood & waste from fetus to placenta

initially connectes to dorsal aortae in sacrum→ loose connection (W5)→ connect to proximal segment of internal iliac arteries

thus proximal portion of umbilical arteries form distal segment of internal iliac arteries & superior vesicle arteries; distal degenerates

close a few minutes after birth do to smooth muscle contraction in vessel walls

perment fibrous closure in 2-3 months

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85
Q

vitelline veins

A

drain blood from yolk sac to heart

initially a pair that drain into sinus horns

cranial L: left hepatocardiac channel→ regresses w/left sinus horn, leaving the left hepatic vein caudally

cranial R: right hepatocardiac channel→ hepatic portion of inferior vena cava & right hepatic vein

central R+L: hepatic sinusoids & ductus venosus (venous plexus in liver)

caudal portions of both: form plexus around duodenum→ portal vein (connects hepatic sinusoids in liver & passes thru septum transversum) & splenic, superior mesenteric, and inferior mesenteric veins

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86
Q

umibilical veins

A

returns oxygenated blood from placenta to embryo

R: completely obliterated in 2nd month

L: known as definitive umbilical vein, drains into ductus venosus then inferior vena cava

after birth: intraabdominal portion becomes ligamentum teres hepatic or round ligament of the liver

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87
Q

common cardinal veins

A

drains blood from body to heart of embryo

receives drainage from anterior & posterior cardinal veins

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88
Q

ductus venosus

A

fetal shunt to bypass liver sinusoids prenatally

shunt connects hepatocardiac channel w/left umbilical vein

adult derivative: ligamentum venosum

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89
Q

left brachiocephalic vein formation

A

W8

develops form anastomoses of L+R anterior cardinal veins, when caudal left anterior cardinal vein degenerates

functions to shunt systemic blood from L to R

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90
Q

posterior cardinal veins

A

important for drainage of mesonephroi

majority degenerate

remaining portion forms Root of azygos vein (Right posterior cardinal vein) & common iliac veins

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91
Q

supracardinal veins

A

formed during late embryonic period to take over the role of posterior cardinal artery

disrupted in the region of the kidneys

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92
Q

subcardinal veins

A

formed during late embryonic period to take over the role of posterior cardinal artery

anastamose with supracardinal veins to for azygos & hemiazygos veins

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93
Q

pseudoglandular period

A

W5-17

formation of lung division thru terminal bronchioles, but not including respiratory bronchioles

repiration not yet possible

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94
Q

canalicular period

A

W16-25 (28)

terminal bronchioles give rise to repiratory bronchioles

alveolar ducts form

mesodermal tissue becomes highly vascularized

low chance of survival, but respiration is possible toward the end

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95
Q

terminal sac period

A

W24-birth

terminal sacs develop & surfactant produced

epithelium thins & capillaries come into contact forming blood-air barrier

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96
Q

alveolar period

A

birth to 8yrs-old

increasing number of alveoli & respiratory bronchioles

95% formed during this period

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97
Q

type I pneumocytes

A

differentiates from epithelium

cells across which gaseous exchange takes place

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98
Q

type II pnuemocytes

A

differentiates from epithelium

secretes surfactant, forms filmover internal wall of terminal sacs to decrease surface tension to facilitate inflation

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99
Q

atelectasis

A

partial or complete collapse of lung

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100
Q

Respiratory distress syndrome

A

prime cause: premature birth (W23-30)

signs: labored breathing, increased RR, mechanical ventilation needed, damage to alveolar lining (fluid & serum proteins leak into alveolus), & continued injury may lead to detachment of alveolar lining (causing hyaline membrane dz)

treat w/glucocorticoid to accelerate fetal lung development and surfactant production & artifical surfactant therapy

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101
Q

surfactant B deficiency

A

causes respiratory distress syndrome

autosomal recessive inheritance pattern

fatal dz

NO treatment

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102
Q

unilateral pulmonary agenesis

A

failure of one lung to develop

presentation: repiratory distress in 1st year, usually w/lower respiratory tract infection

60% have concurrent congenital abnormalities: cardiac lesions, diaphragmatic hernias, & skeletal anomalies (vetebral or costal)

higher frequency of anomallies seen with R lung agenesis

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103
Q

bilateral pulmonary agenesis

A

absence of lungs

extremely rare & always lethal

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104
Q

pulmonary hypoplasia

A

failure to obtain adequate size, but has all components

severity determines amt of compromise

may be associated w/congenital diaphragmatic hernia (abdominal organs in thorax via whole in diaphragm)

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105
Q

congenital cysts of lung

A

formed by dilation of terminal or larger bronchi

usually drain poorly causing frequent infections

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106
Q

diaphragm formation

A

divides thoracic & abdominal cavities

from: septum transversum, pleuroperitoneal membranes, dorsal mesentary of esophagus, & muscular ingrowth of somites at cervical levels C3-C5

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107
Q

septum transverseum

A

derived from mesoderm

begins to divide intraembryonic cavity into thoracic & abdominal cavities

pericardial canals: open channels left on either side from incomplete formation of septum trnasversum (the lungs grow in these)

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108
Q

congenital diaphragmatic hernia

A

1/2,000 births

when pleuroperitoneal folds fail to form properly, more often on L (called foramen of Bochdalek

results: small bowel enters thorax→ hinders pulmonary formation causing pulmonary hypoplasia

degree determines severity

can be surgically repaired

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109
Q

formation of IVC

A

Inferior vena cava

  1. hepatic: derived from hepatocardiac channel (from right vitelline vein)
  2. prerenal (suprarenal): derived from right subcardinal vein
  3. renal: derived from supracardinal anastomoses of right subcardinal vein
  4. postrenal (infrarenal): derived form right supracardinal vein
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110
Q

absence of inferior vena cava

A

failure of hepatic segment formation, et al form attachesd to azygos

blood will drain via azygos & hemizygos veins

usually associated w/heart malformations

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111
Q

double IVC

A

inferior portion of left supracardinal vein persists

left IVC typically ends at left renal vein, cross aorta, & joins R IVC

no complications

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112
Q

SVC formation

A

from an anastomoses of right common cardinal vein & right anterior cardinal vein

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113
Q

double SVC

A

cause: persistence of left anteriof cardinal vein & failure of left brachiocephalic to form
results: left SVC drains venous blood from left & drains into coronary sinus, which dilates to accommodate increased blood flow

no ill effects

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114
Q

left SVC in isolation

A

cause: failure of degeneration of left anterior cardinal vein→ anastomoses of left common cardinal vein & left anterior cardinal vein→ L SCV formation AND degeneration of right common cardinal & caudal portion of right anterior cardinal veins

no left brachiocephalic vein formed

results: blood drains to L SVC→ coronary sinus→ right atrium

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115
Q

left brachiocephalic formation

A

from anastomoses of left & right anterior cardinal veins

when caudal part of left anterior cardinal vein degenerates

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116
Q

changes in circulation after birth

A
  • alveoli expand
  • pulmonary vessels open & resistance reduces
  • placental blood flow ceases
  • above events initiate closure of shunts
  • high oxygen saturated blood enters ductus arteriosus→ increase in localized O2 tension→ constriction of ductus arteriosus
    • immediately after birth
    • complete obliteration intima in 1-3 months
  • foramen ovale closure due to pressure changes in atria
    • fusion (permenant closure) takes about 1yr
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117
Q

patent ductus arteriosus

A

most common among preterm babies

can close spontaneously

treatment: in preterm, use of NSIDS or indomethacin to help close by blocking prostagladin E1 (which is keeping it open)→ will NOT work in full term babies or adults

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118
Q

formation of primitive gut tube

A

creeated by lateral folding in W3+4

all 3 layers in concentric tubes around lume

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119
Q

foregut

A

cranial portion of primitve gut tube

blood supply: celiac trunk @ T12

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120
Q

midgut

A

portion of primitive ut tube attached to the yolk sac

blood supply: superior mesenteric @ L1

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121
Q

hindgut

A

caudal portion of primitive gut tube

blood supply: inferior mesenteric @ L3

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122
Q

vitelline duct

A

opening/passageway from midgut to yolk sac

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123
Q

formation of vitelline duct

A

end of W4

constriction of midgut connection to yolk sac as craniocaudal folding takes place

incorporated into proximal umbilical cord

*formed at the same time as allantois*

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124
Q

ileal diverticulum

A

aka Meckel’s diverticulum

persistence of vitelline duct postnatally

may become inflammed & mimic appendicitis

2% pop

2” length

w/in 2’ of ileocecal valve

found under age of 2

males 2x over females

(other persistence of vitelline duct: enterocyst or vitelline fistula)

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125
Q

derivatives of foregut

A

pharynx, esophagus, stomach, superior 1/2 of duodenum

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126
Q

derivatives of midgut

A

inferior 1/2 of duodenum, jejunum, ileum, cecum, ascending colon, R 2/3 transverse colon

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127
Q

derivatives of hindgut

A

L 1/3 transverse colon, descending colon, sigmoid colon, rectum, & upper portion of anal canal

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128
Q

stomodeum

A

mouth opening created by the rupture of the buccopharyngeal (oropharyngeal) membrane

W4

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129
Q

cloacal membrane rupture

A

W7

creats opening for anus & urethra

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130
Q

layers of gut tube

A

lumen outward

  1. mucosa (epithelium [endodermic origin], lamina propria, & muscularis mucosae)
  2. submucosa
  3. muscularis
  4. serosa/adventitia

derived from splanchnic mesoderm

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131
Q

formation of esophagus

A

W3 w/formation of esphagotracheal septum

cranially: pharynx
caudally: esophagus

W4-7: elongation

histological changes: simple columnar→ stratified columnar→ multilayered ciliated→ straified squamous non-kartinated epithelium

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132
Q

short esophagus

A

cause: failure to elongate in proportion to neck & thorax development
result: congenital hiatal hernia (part of stomach displaced into thorax)

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133
Q

esophageal stenosis

A

caused: incomplete recanalization of lumen

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134
Q

Barret’s Esophagus

A

CELLO (columnar epithelium lined lower oesophagus)

  • congenital: cells did not complete histological evolution→ tendency toward GERD
  • acquired: abnormal change in cells, possibly caused by chronic acid exposure or reflux esophagitis
    • premalignant condition
    • 1-5% develop cancer
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135
Q

formation of stomach

A

end of W4/beginning W5, fusiform dilation of foregut

attached to anterior & posterior walls via ventral & dorsal mesentery respectively

dorsal grows more to create greater curvature

L+R vagus nerve run on either side

makes 90º turn counter-clockwise: greater curvature is L, lesser curvature is R, R vagus n. becomes posterior vagus n., L vagus n. becomes anterior vagus n., & dorsal mesentery is L as greater omentum

anteropsterior axis rotation: pyloris up & cephalic portion down

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136
Q

histologenesis of stomach

A

rugae & gastic pits of epithelium form during late embryonic period

cell differentiation during early fetal period

HCl production just before birth

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137
Q

congenital pyloric stenosis

A

cause: incomplete recanalization of pyloric lumen during development
symptoms: projectile vomitting during 2nd week, formation of pyloric mass, infrequent stool, dehydration & loss of subcutaneous fat

male 4x more than female

1:200 live births

Tx: surgery

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138
Q

derivatives of embryonic ventral mesentery

A

lesser omentum (hepatoduodenal & hepatogastric ligaments), falciform ligament of liver, coronary ligament of liver, & triangular ligament of liver

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139
Q

derivatives of embryonic dorsal mesentery

A

greater omentum (gastrorenal, gastrosplenic, gastrocolic, & splenorenal ligaments), mesentery of small intestine, mesoappendix, transverse mesocolon, & sigmoid mesocolon

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140
Q

Formation of omental bursa

A

aka lesser peritoneal sac

space behind stomach formed when the dorsal mesogastrium is pulled to the L during longitudinal rotation

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141
Q

Greater Sac

A

peritoneal cavity opening on left & anterior of stomach & mesentery after longitudinal rotation

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142
Q

epiploic foramen of Winslow

A

opening if the lesser omentum (between stomach & liver) connection the greater & lesser sacs

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143
Q

formation of greater omentum

A

dorsal mesogastrium extends to forma double layer sac over small intestine & transverse colon

2 layers fuse to form greater omentum, hanging from greater curvature of the stomach to protect the small intestine & transverse colon

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144
Q

formation of the duodenum

A

derivative of foregut & midgut

duodenum & head of pancreas are pressed dorsally aginst body wall after stomach rotation (retroperitoneal)

dorsal mesoduodenum fuses w/peritoneum

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145
Q

lesser omentum is formed from

A

ventral mesogastrium

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146
Q

development of midgut

A

expands to U-shpaed midgut loop in W5

cranial limb→ distal duodenum, jejunum, & upper ileum

caudal limb→ rest of ileum & rest of midgut

rapid growth of liver→ forces physiological herniation of midgut into umbilical cord in W6 & rotates 90º counterclockwise around superior mesenteric artery→ W10 abd expansion allows return to abd cavity→ +180º counter-clockwise rotation during regression & **viteline duct looses connection to intestines*→ mesenteries of ascending & descending colon fixed to peritoneum of posterior wall (retroperitoneal)

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147
Q

histological development of small intestine

A

M2, epithelium proliferates to obliterate lumen→ recanalization as multi-layered epithelium→ rearrangement of tissue to yield villi & crypts w/stem cells (simple columnar epitelium)

cell types formed by end of 2nd trimester (M6)

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148
Q

omphalocoele

A

failure of intestinal loop to return to abd cavity following physiological herniation

seen by fetal US

variation in size

has shiny coverings

frequently associated w/: fetal liver herniation w/small abd size & pulmonary hypoplasia (small lungs)

other risks: other birth defects, intestinal malrotation, & urinary anomalies

tx: bag covering & slowly push intestines inside until abd defect can be sewn shut, takes time

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149
Q

gastrochisis

A

aka cleft stomach

no shiny covering, but otherwise looks similar to omphalocoele (but rarer)

no known cause

1: 3000 births
tx: bag covering & slowly push intestines inside until abd defect can be sewn shut, takes time

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150
Q

congenital umbilical hernia

A

more common in premature births

2x male over female

intestines return to abd cavity, but ventral abd wall doesn’t close umbilical ring

protruding bowel still covered by skin

some resolve spontaneously by 2yrs-old

sx by 4yrs-old if symptomatic

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151
Q

non-rotation of midgut

A

results in small intestine on R & large intestine on L

usually asymptomatic

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152
Q

Mixed rotation of midgut

A

failure to complete last 90º rotation

results in cecum inferior to pylorus fixed to posterior abd wall by peritoneal bands

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153
Q

volvulus

A

twisting of intestines

impedes intestinal contents & compromises blood supply

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154
Q

cloaca

A

endodermal lined pouch at terminal end of hindgut

partitioned by urorectal septum into rectum, upper anal canal, & urogenital sinus

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155
Q

proctoderm

A

surface ectoderm

joined with cloaca to form cloacal membrane

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156
Q

cloacal membrane

A

joining of proctoderm & cloaca

partitioned to form anal membrane & urogenital membrane

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157
Q

perineal body

A

where urorectal septum fused with cloacal membrane

158
Q

development of anal canal

A

upper: from hindgut
lower: from proctoderm

pectinate line marks the junction of upper & lower ana canals (site of former anal membrane)

159
Q

intestinal stenosis

A

narrowed intestinal lumen from incomplete recanalization

causes considerable backup→ excessive GI distention & excessive vomitting

160
Q

intestinal atresia

A

complete failure of recanalization

most commonly found in the duodenum

causes considerable backup→ excessive GI distention & excessive vomitting

161
Q

duplication of intestines

A

rare congenital maleformation

dual wall formation

caused by abnormal recanalization

162
Q

Meconium

A

dark green substance that is 1st bowel movement

if occurs before birth, fetal distress

if it doesn’t occur, anal opening may not be patent

bile gives it a green coloring

163
Q

Formation of liver

A

hepatic diverticulum (liver bud): ventral outgrowth @W3

cranial portion becomes liver

grows to extend into septum transversum

hepatic cords form & intermingle w/vitelline vv to give the hepatic sinusoids

hepatic cord differentiate into parenchyma & form lining of biliary ducts

connective tissue, haemopoietic tissue, & Kupffer cells derived from mesoderm of septum transversum

later grows to protrude into ventral mesentery→ mesentery modified into falciform ligament & lesser omentum

L+R lobe formation

164
Q

formation of biliary appartus

A

caudal portion of hepatic divertivulum becomes bile duct

outgrowth from bile duct becomes gallbladder & cystic duct

cystic duct divides bile duct into hepatic duct & common bile duct

bile duct passes drosal to duodenum

165
Q

falciform ligament

A

attaches liver to body wall

166
Q

BARE area of liver

A

area of liver that makes contact with diaphragm

NO visceral peritoneum

167
Q

coronary ligament

A

reflective fold of peritoneum around margins of bare area

168
Q

L+R triangular ligaments

A

joining of anterior & posterior layers of coronary ligament to these on R+L

169
Q

functions of developing liver

A

haematopoiesis

2nd biggest blood producer after yolk sac

begins W6

accounts for large size drung W7-9

peaks at end of T2 (M6) & declines before birth

bile production: begins W12 & stored in intestines

170
Q

development of gallbladder

A

outgrowth from bile duct

endodermal derivatives: epithelial lining and mucosal glands of gallbaldder & epithelial lining of extrahepatic duct

mesodermal derivatives: lamina propria, muscularis externa, & adventitia of gallbladder

intense miotic activity that fills lumen then recanalized

*duplication of gallbladder occurs & is asymptomatic

171
Q

biliary atresia

A
  • intrahepatic is very rare (1:100,000)
  • extrahepatic 1:10,000
    • atresia of hepatic or bile duct
    • causes: incomplete recanalization or in utero infection
    • symptoms: jaundice
    • tx: sx or liver transplant
172
Q

formation of pancreas

A

from foregut

small ventral & larger dorsal pancreatic buds

both are derivatives of endoderm

ventral bud is rotates dorsally with duodenum to be posterior to dorsal bud

fusion of buds W6

ventral forms uncinate process

dorsal bud becomes head, body & tail

connective tissue & blood vessels from surrounding mesoderm

fuses to dorsal body wall (retroperitoneal)

173
Q

Duct of Wirsung

A

aka main pancreatic duct

formed from distal portion of dorsal pancreatic duct & ALL of ventral pancreatic duct

enters duodenum at ampulla of vater

174
Q

Duct of Santorini

A

aka accessory pancreatic duct

formed from proximal portion of dorsal pancreatic duct

may be obliterated during development

175
Q

Ampulla of Vater

A

aka major duodenal papilla

where main pancreatic & bile ducts enter duodenum

176
Q

histogenesis of pancreas

A
  • exocrine acini
    • exocrine cells
    • no secretory products during fetal life
    • derived from endoderm of pancreatic bud
  • Islets of Langerhan
    • endocrine
    • pale staining area
    • unknown origin: endoderm or neural crest
    • develop in M3
    • alpha cells first: glucagon W15
    • beta cells second: insulin M5
    • then D cells (somatostatin)
    • F cells last
177
Q

ectopic pancreatic tissue

A

pancreatic tissue found elsewhere in the body

from distal esophagus to primary intestinal loop

most frequently found in duodenum or stomach mucosa

178
Q

annular pancreas

A

cause: bifid pancreatic bud

encircles duodenum from both sides

partial or total constriction of duodenum

blockages can occur if pancreas becomes inflammed or malignant

179
Q

histology

A

study of tissue of body & how they are organized to form organs

includes cells & extrcellular matrix

180
Q

types of tissue

A
  1. nervous
  2. connective
  3. epithelial
  4. muscle

most organs are composed of all 4

181
Q

how sample is studied via light microscope

A
  1. fixed
  2. embedded
  3. sectioned
  4. stained
  5. observed
182
Q

how sample is studied via electron microscope

A
  1. fixed
  2. embedded
  3. sectioned
  4. coasted with Osmium oxygenate (OsO4)
  5. observed under beam of electrons
183
Q

hematoxylin

A

dyes blue

binds to nucleic acids

thus we see nucleus and acidic regions of cytoplasm (RNA)

also binds cartilage matrix

often used with Eosin

184
Q

Eosin

A

dyes pink, orange, or red

visualize: collagen fibers, basic regions of cytoplasm, & muscle

often used w/hematoxylin

185
Q

PAS

A

periodic acid-Schiff

dyes magenta

visualize: glycogen & carbohydrate-rich molecules, i.e. glycocalyx

186
Q

characteristics of epithelia

A
  • flat continuous sheets of cells
  • line body surfaces & cavities
  • cover every exposed surface
  • make up skin & all passageways that communicate w/ outside world: digestive, reproductive, urinary, & repiratory
  • avascular: nutrients delivery via diffusion
  • anchored by basal lamina
  • little to no free intercellular space
  • does have nerve supply
  • structural/functional polarity
  • continuously wear out & replaced via mitosis
  • derived from all 3 germ layers
187
Q

functions of epithelia

A
  • protective barrier
  • secretion: hormones, enzymes, mucus, etc
  • absorption: from lumen
  • transport: esp. across
  • detection of sensation: ex. taste buds
188
Q

endothelium

A

epithelium of blood vessels

single layer of mesodermal origin

189
Q

connective tissue

A

supportive tissue distributed throughout body

very few cells & abundent intercellular substances

190
Q

basal lamina

A

layer of extracellular matrix secreted by epithelial cells

lies at interface of epithelia & connective tissue

composition vareis between cell types

functions: anchor for overlying epithelium, influence cell polarity and organize proteins in adjacent plasma membrane, & acts as filter

also found surrounding, muscle, adipose, & Schwann cells

two layers: lamina lucida & lamina densa

only seen on electron microscope

191
Q

reticular lamina

A

aka lamina reticularis

secreted by underlying connective tissue cells

connected to basal lamina via collagen type VII anchoring fibrils & reticular fibrils

192
Q

basement membrane

A

fusion of basal lamina & reticular lamina

can be seen w/light microscope

193
Q

lamina lucida

A

secreted by epithelia

part of basal lamina

contains membrane proteins (integrins) projecting from epithelial membrane w/laminin receptors

194
Q

lamina densa

A

secreted by epithelia

part of basal lamina

meshwork of collagen type IV coated by perlacan, laminin, & entactin

195
Q

Perlecan

A

protein w/negatively charged side chains

found in lamina densa of basal lamina

does NOT allow large negative particles to past through basal lamina (important in kidneys)

196
Q

apical domain

A

face of epitelium toward the lumen

possible modifications: microvili w/associated glycocalyx, cilia, or stereocilia

197
Q

lateral domain

A

sides of epithelia that connect to each other

198
Q

basal domain

A

surface of epithelium in contact w/basal lamina

199
Q

microvilli

A

/cell directly correlates to cell’s absorptive capacity

finger-like projections

function to increase surface area for absorption, secretion, cellular adhesion, and/or mechanotransduction

actin microfilament core anchored by terminal web

1-2microm long & 50-100nm diameter

200
Q

terminal web

A

network of actin filaments just below plasma membrane

anchors microvilli actin via spectrin

septrin also binds web to cell membrane

201
Q

brush border

A

distinctive border of vertical striations at apical surface of cell made of microvilli

seen in kidneys & intestines

called striated border in intestines

202
Q

cilia

A

mictrotubules in 9+2 pattern w/basal bodies & associated motor proteins

beat in rhythmic waves

found in lungs, repiratory tract, & middle ear

lots of mitochondria near basal bodies

203
Q

kartagener syndrome

A

aka immotile cilia syndrome

inherited

cilia function ineffectively due to lack of dynein

males are sterile (non-functional flagella)

mucus collects in airways & sinuses promoting infection

204
Q

stereocilia

A

actin core, but much larger than microvilli (120microm long & 100-150nm diameter)

passive movement only: vibration in inner ear (mechanoreceptors) & fluid in genital system

in light microscope will recognize either by being told location or presence of sperm

205
Q

squamous cell

A

wider than they are tall

flat

squame= scale

206
Q

cuboidal cell

A

height & width are the same

207
Q

columnar cell

A

cells are taller than they are wide

208
Q

simple cell type

A

single layer

generally found where absorption & filtration occur

ex. kidney tubule (simple cuboidal)

209
Q

stratified epithelium

A

more than one layer

found where body linings have to withstand mechanical or chemical insult

layers may be lost w/o exposeing subepithelial layers

ex. skin, vagina, & esophagus

classified according to most superficial layer

210
Q

simple squamous epithelium

A

flat, plate-like w/plump nucleus

locations: blood and lymph vessel lining, certain body cavities, line alveoli of lungs, & parietal layer of Bowman’s capsule in kidney
functions: sites for fluid, metabolite, or gas exchange-favored by thinness

211
Q

mesothelium

A

layer of flat cells of mesodermal origin that lines embryonic body cavity

gives rise to squamous cells of peritoneum, pericardium, & pleura

212
Q

simple cuboidal epithelium

A

nucleus is spherical & central

location: kidney tubules, covering of ovaries, & ducts of glands
functions: protection, secretions, & absorption

213
Q

simple columnar epithelium

A

ovoid nucleus

locations: stomach, small intestine, gallbladder and other organs
function: protection, secretion, & adsorption

214
Q

Goblet cells

A

present among columnar epithelial cells

dialated apical cytoplasm

contains ligh-stained mucus material

215
Q

pseudostratified columnar epithelium

A

nuclei appear to lie in 2 or more layers, but all cells touch basal lamina

some cells do not touch surface

croweded cells w/various shapes

functions: protection, secretion, & absorption

only 2 locations: trachea & epididymis

216
Q

stratified squamous epithelium

A

thoughest epithelium the body makes

ketatinized: contains keratin, waterproof, most apical layers are dead w/o nucleus or cytoplasm, ex. skin

non-kertinized: esophagus & vagina

217
Q

keratin

A

tough, fibrous, insoluble protein that forms hair & nails

218
Q

stratified cuboidal epithelium

A

very rare

in large secretory ducts of sweat & salivary glands

more robust than simple cuboidal

219
Q

stratified columnar epithelium

A

rare

found in male urethra & in large ducts of some glands

220
Q

transitional epithelium

A

aka urothelium

lines bladder, ureter, & upper urethra

protect against hypertonic & cytotoxic effects of urine

characterized by superficial layer of dome-like cells that flatten as bladder fills

neitehr squamous nor columnar

221
Q

cutaneous membrane

A

cover entire body as skin

composed of many layers to protect from: invading pathogens, light, heat, & injury

222
Q

mucous membrane

A

aka mucosa

lies in cavities that open directly to exterior environment: GI, repiratory, reproductive, & urinary tracts

function: prevent entry of pathogens & microbes

consists of: surface epithelium, supporting CT (lamina propria), basal lamina, & sometimes muscularis (smooth muscle)

secrete mucus to keep membrane moist (not required, but common characteristic)

223
Q

serous membrane

A

aka serosa

line cavities of body that do NOT open directly to external environment

2 layers: parietal & visceral

secrete lubricating serous fluid to reduce friction w/movement

224
Q

epithelia derived from ectoderm

A

epidermis & glands on skin

225
Q

epithelia derived from mesoderm

A

endothelium of blood vessels & serous membranes lining body cavities

226
Q

epithelia derived from endoderm

A

lining of airways and digestive systems & glands

227
Q

anchoring junctions

A

zomula adherens

desmosomes/macula adherens

demi-desmosomes

228
Q

occluding junctions

A

tight-junctions/zonula occludens

229
Q

channel forming junctions

A

gap junctions

230
Q

tight junctions

A

aka zonula occludens

separate & maintain apical domain from basolateral domain→ block diffusion of membrane proteins between domains

claudin & occluden proteins form strands to bind adjacent cells together, forming a belt all the way around

function: prevent ion passage between cells, efficiency increases w/# of strands

*ONLY in epithelial cells*

231
Q

paracellular pathway

A

movement of a substance between cells

232
Q

transcellular pathway

A

movement of substance through cells

233
Q

what modifcaiton is found in basal domain of fluid & ion transporting cells?

A

lots of mitochondria (for active transport) & infoldings of basal membrane

234
Q

zonula adherens

A

aka adherens junction

type of anchoring junction

function: joins actin bundle in one cell to another actin bundle in adjeacent cell via cadherin proteins extracellularly

forms adhesion belt around epitelial cells→ reinforces zonula occludens belt

235
Q

desmosome

A

aka macula adherens

type of anchoring junction

joins intermediate filaments in one cell to those in adjacent cell via cadherin transmembrane proteins

found on lateral domains

functions: resist shearing forces

in epithelia & muscles tissue

major cell-to-cell junction, very strong

NO gap on EM

236
Q

gap junction

A

aka communicating junctions

function: form channels to allow small, water soluble molecules to pass cell to cell & electrical charge from neuron to neuron→ allow many tissues to act in a coordinated manner
ex. cAMP, cGMP, <5000MW

occur along LATERAL membranes in epithelia or between cells of any type

formed by abutting pairs of connexons (6 subunit, transmembrane protein)

“no gap” on EM

high [Ca2+] & low pH (sign of necrosis) close conenction to prevent death of one cell from killing those its connected to

237
Q

hemidesmosome

A

function: anchors intermediate filaments in cell to basal membrane via integrin proteins binding lamini & type IV collage

occur in epithelia to give strong, stable adhesion to basal membrane

238
Q

adhesion plaques

A

type of anchoring junction

function: joins actin bundle in one cell to extracellular matrix

239
Q

Pemphigus

A

rare group of blistering autoimmune dz

autoantibodies attack desmosomes→ cells & tissue layers detach doem each other

most common type: pemphigus vulgaris

240
Q

integrin

A

transmembrane protein found in hemidesmosomes

binds laminin & type IV collagen in basal lamina

241
Q

exocrine gland

A

secretes product into lumen from apical domain

formed by down growth of epithelium during embryonic development

connecting stalks→ duct

ex. acinar cells secrete pancreatic enzymes

242
Q

endocrine gland

A

product secrets across basal lamina & picked up by blood vessel in connective tissue

formed by down growth of epithelium during embryonic development

connecting stalks→ lost

ex. insulin from islets of Langerhans in pancreas

243
Q

Goblet cell

A

only important unicellular gland

mass of secretory vescicles contianing mucinogen at apical region give them their goblet shape

located in epithelia of intestines & conduction portions of respiratory tract

244
Q

mucinogens

A

large gylcoproteins that swell into mucin with hydration

main component of mucus

245
Q

merocrine glands

A

cells secrete product by exocytosis

246
Q

apocrine gland

A

secretes product by budding off portion of plasma membrane

ONLY seen in lactating mammary glands

247
Q

holocrine gland

A

porduct is screted by entire cell disintegration

ex. sebaceous glands of skin & nose

248
Q

serous gland

A

secretes proteins, often enzymes

249
Q

mucous gland

A

secretes mucus

paler than serous on EM

250
Q

functions of connective tissue

A

structural support

medium for exchange: waste, nutrients, & gases

defense & protection by phagocytic, immune, & mast cells

251
Q

characteristics of loose CT

A

lots of cell & ground substance w/less fibers (collagen type I, elastin, & reticular fibers [aka collagen type III])

locations: beneath epithelia (as lamina propria), around glandular cells & small blood vessels

initial site of inflammation & allergic reaction

252
Q

characteristics of dense CT

A

mostly fibers (collagen type I), less cells & ground substance

fibers in bundle arrangmentin various directions→ more strength to withstand stress

locations: dermis of skin & submucosa of intestines

253
Q

ground substance

A

gel-like to viscous consistency

extracellular fluid found in connective tissue

where diffusion of waste, gases, & nutrients takes place

254
Q

differentiating characteristic of dense regular CT & its locations

A

tendinocytes: collagen bundles & rows of fibroblasts are oriented in parallel fibers
locations: tendons, aponeuroses, & ligaments

255
Q

epitendineum

A

connective tissue capsule around tendon

also contains small blood vessels & nerves

256
Q

endotendineum

A

extension of connective tissue capsule around tendon to subdivide tendon into fascicles

257
Q

elastic ligaments

A

contain more elastin fibers than collagen fibers

found in spinal column

258
Q

aponeurosis

A

broad flat tendon

fibers arranged in multiple layers @ 90º angles from adjacent layer

arrangement also seen in cornea

259
Q

fibroblast

A

connective tissue cell that produces: collagen, reticular, & elastic fibers

260
Q

collagen fibers & their microscopic appearance

A

every third aa is Gly

characteristic aa= hydroxyproline & hydroxylysine

most abundant type

flexible w/high tensile strength

made of fibrils

light microscope: stain w/eosin, aniline blue, or light green dye

EM: see collagen fibrils that appear as bundle of thread (10-300nm each)

261
Q

fibril

A

subunit of collagen

made by stackign together of tropocollagen units in overlapping arrangement that creates lacunar regions

lysine & hydroxylysine are cross-linked in adjacent tropocollagens

262
Q

lacunar region

A

area where tropocollagen fibers do not completely overlap

high # of free radicals→ binds Os→ EM dark bands

263
Q

tropocollagen

A

280nm long & 1.5nm wide

triple helix of 3 alpha polypeptide chains

string together and make overlapping strains to form fibrils

264
Q

location of collagen type I

A

loose & dense connective tissue

bone

dentine

265
Q

location of collagen type II

A

hyaline & elastic cartilage

266
Q

location of collagen type III

A

aka reticular fibers

267
Q

location of collagen type IV

A

basal lamina of epithelia

268
Q

procollagen peptidase

A

membrane bound protein that cleaves nonhelical registration peptides on tropocollagen extracellularly

tropocollagen is soluble until this cleavage then becomes insoluble

269
Q

reticular fibers

A

aka collagen type III

produced by fibroblasts

form fibrils & fibers, but NOT bundles

higher hexose content (6-12% v. 1%)→ stains w/periodic acid Schiff for light microscope

provides support for tissue & organs

locations: around nerves, small blood vessels, and muscle cells & in hemopoientic organs (red bone marros) & in lymphatic tissue (spleen & lymph node, NOT thymus) & in endocrine organs & in liver

270
Q

Ehlers-Danlos syndrome

A

hyperelasticity of skin & hypermibility of joints

type IV: genetic defect for deficiency of lysyl hydroxylase enzyme→ no hydroxylysine production→abnormal reticular fibers→ ruptures in arteries & large intestines

271
Q

elastic fibers

A

produced by fibroblasts, chondrocytes, & smooth muscle cells

composed of elastin core & sheath of fibrillin microbibrils

272
Q

elastin

A

protein rich in Gly & Pro, poor in hydroxyproline, and no hydroxylysine

characteristic aa: desmosine & isodesmosine- both formed from rxn of 4 lysine residues

5x more extensible than rubber

273
Q

fibrillin

A

organizing center for elastic fibers

forms first & elastin deposited on it

damaged by UV sun exposure→decreased skin elasticity→ wrinkles

274
Q

lamellae

A

elastin sheet found in the aorta

275
Q

Marfan Syndrome

A

cause: mutation of fibrillin gene→ lack of resistance in tissues with elastic fibers

changes in skeleton, eyes, & cardiovascular system (mitral valve prolapse & dilation of aorta)

weak periosteum of bones

detached lens & myopia (short-sighted) of eyes

276
Q

functions of nervous system

A
  • sensory input
  • integration of data
  • control of muscles & glands
  • homeostasis
  • mental activity
277
Q

homeostasis

A

process that maintains stability of the body’s internal environment in response to changes in external conditions

ex. regulation of temperature & pH

278
Q

neuron

A
  • structural & functional unit of nervous system
  • functions:
    • accepts, integrates, & sends impulses
    • communicates w/other neurons
    • excites tissue, ie muscle
  • cannot divide/permanently in G0
  • parts: soma, dendrites, & axon
279
Q

grey matter

A

mostly cell bodies of CNS

found on inside of spinal cord & outside of brain

contains microglia in brain

280
Q

whtie matter

A

white due to myelin of axons

found on the inside of the brain & outside of the spinal cord

281
Q

nerve fiber

A

axon of a neuron in the PNS

282
Q

nerve

A

bundle of many nerve fibers & their sheaths

283
Q

ganglion

A

gathering of neuron cell bodies in PNS

typically site of synapses

284
Q

what are cell bodies called in teh CNS?

A

nuclei

285
Q

where are sensory neuronal bodies found?

A

in sensory ganglion

286
Q

where are interneurons found?

A

CNS

make up 99% of CNS

287
Q

where are motor neuronal bodies found?

A

CNS

288
Q

what shape do most neurons have?

A

multipolar

one axon w/two or more dendrites

289
Q

bipolar neuron

A

one dendrite & one axon

found in sensory neurons of retina, olfactory mucosa, & inner ear only

290
Q

unipolar neuron

A

aka pseudopolar

no dendrite

single bifurcated process- longer branch goes to periphery & shorter to CNS

found as spinal ganglia (sensory found in spinal nerves) & most cranial ganglia

291
Q

anaxonic neuron

A

in CNS only

many dendrites & no axon

does NOT produce action potentials

function: regulates elelctrical changes in adjacent neurons

292
Q

glial cells

A

4 types in CNS & 2 types in PNS

no crossover of types, therefore 6 types total

functions: provide nutrition, support, & protection to neurons

5-10X more abundant in brain that neurons

293
Q

neuropil

A

intercellular network surrounding cells of CNS composed of cellular processes from neurons & glial cells

294
Q

what organelles extend into neuronal processes?

A

individulal cisternae of sER

mitochondria

lysosomes

peroxisomes

295
Q

why do nuclei of neuron stain pale?

A

almost all euchromatin & little to no heterochromatin→ intense synthetic acivity in neurons

296
Q

Nissl bodies

A

aggregation of RER rubules & polyribosomes

prominent cytoplasmic dark staining structures of neuron cytoplasm w/H&E

appear blue as opposed to lipfuscin granules that will appear brown via light microscope

297
Q

dendrites

A

thousand/neuron of CNS

receives signal at synapse from other neurons

branch extensively in a near constant diameter

often covered w/dendritic spines- increase surface area for synaptic contact

298
Q

why are dendritic spines important?

A

they are key for neural plasticity for adaptation, learning & memory

299
Q

when are less dendritic spines found?

A

increasing age

poor nutrition

300
Q

axolemma

A

plasma membrane of an axon

301
Q

axoplasm

A

cytoplasm of axon

302
Q

axon hillock

A

pyramis region of the soma at the base of an axon

303
Q

initial segment of an axon

A

unmyelinated

where action potentials begin

just distal to axon hillock

304
Q

node of Ranvier

A

gaps in myelin sheath along an axon

location where ions can flow in or out of axolemma

305
Q

myelin

A

lipoprotein material organized into sheath surrounding an axon

function: increase axolemma resistance→ increase speed of action potential propagation down an axon

produced by oligodendrocytes in CNS & Schwann cells in PNS

306
Q

What types of glial cells are found in the CNS?

A
  1. oligodendrocytes
  2. astrocytes
  3. microglia
  4. ependymal cells
307
Q

What type of glial cells are found in PNS?

A

Schwann cells & satellite cells

308
Q

oligodendrocyte

A

small round condensed nucleus

few short processes

produces myelin sheths around axons of the CNS

predominant glial cell in white matter

one can myelinate several axons

309
Q

Multiple Sclerosis

A

1/1,000 in US & europe

autoimmune demyelinating disorder of unknown cause

lesions on myelin sheath of CNS from immune response

symptoms: weakness, tingling, numbness, & blurred vision→ deficit dependent on area of affected CNS

310
Q

bouton

A

dilation at the terminal end of axonal branch

presynaptic plate

311
Q

what are collaterals and where are they found?

A

branches of interneurons & some motor neurons that end at synapses influencing many other neurons

312
Q

terminal arborization

A

branching of an axon at its distal end

313
Q

synapse

A

junction between two nerve cells or nerve cell & excitable muscle

minute gap across which neurotransmitters pass via diffusion

314
Q

axosomatic synapse

A

common type of synapse

axon synapses on cell body

315
Q

axodendritic synapse

A

common type of synapse

axon synapses on dendrite of next neuron

316
Q

axoaxonic

A

axon synapses on another axon

infrequent type

used to modulate synaptic activity

317
Q

neurofilaments

A

cell-type specific intermediate filament

abundant in cell body & processes

318
Q

why are microtubules important in axons?

A

axonal transport in both directions

anterograde: mitochondria, cytoskeletl polymers, vesicles w/neurotransmitters
retrograde: used synaptic vesicles & condition of axon terminals **injury response signaling**

319
Q

dynein

A

retrograde

+ to -

microtubular motor protein

320
Q

kinesin

A

anterograde

  • to +

microtubular motor protein

321
Q

neurotrophic

A

relating to growth, differentiation, & survival of neuron

322
Q

How and by what is retrograde axonal transport used against us?

A

viral infection

ex. herpes simplex, rabies, & polio

*delay in rabies symptoms correlates to time needed for pathogen to reach somas

323
Q

functions of actin in neurons

A
  • growth, guidance & branching
  • morphogenesis of dendrites & dendritic spines
  • synapse formation & stability
  • axon & dentrite retraction
324
Q

filopodia

A

slender cytoplasmic projections made ofactin bundles containing +/- receptors

325
Q

lamellipodium

A

sheet-like foot on leading edge of cell pushed forward by actin polymerization

326
Q

astrocytes

A

aka astroglia

largest glial cell in size & # in CNS

fucntions: regulate synaptic transmission & neurovascular coupling (form blood-brain barrier)

processes contact thousands of synapses & have end-feet on arterioles & capillaries

also absorb excess neurotransmitters

express glial fibrillary acidic protein

formation of glial limiting membrane

networked together via gap junctions

327
Q

glial fibrilary acidic protein

A

GFAP

astrocyte cell-type specific intermediate filament protein

used for detecting astrocytomas

328
Q

cerebrum

A

aka cortex

largest part of brain

associated with higher brain functions

329
Q

cerebellum

A

10% brain volume/50% total # neurons

controls balance & posture

330
Q

glial limiting membrane

A

aka glia limitans

innermost meningeal layer at external surface of CNS

made of astrocyte processes

331
Q

microglia

A

macrophages of CNS

descend from monocytes

evenly distributed thorughout white & grey matter

constantly migrate thru neuropil→ appear amoeboid

function: if damaged cell or microorganism found, proliferate & differentiate into phagocytotic & antigen presenting cells

332
Q

ependymal cells

A

epithelial-like: line neural tube & ventricles of brain, but NO basal lamina

some have cilia to move CSF around

have elongated basal ends that anchor them to neuropil

333
Q

CSF

A

cerebrospinal fluid

produced in choroid plexus by modified ependymal cells

fucntions: bath and nourish brain and spinal cord & shock absorption

334
Q

gliosis

A

nonspecific reactive change of glial cells in response to CNS damage

proliferation or hypertrophy of several types of glial cells

prominent in my dz states: MS & post-stroke

often interferes w/neuronal regeneration

335
Q

astrocytoma

A

most common type of glioma

vary in growth rate

release excessive glutamate→ damages adjacent neurons via excitotoxic action

336
Q

epineurium

A

dense irregular fibrous connective tissue that forms external coat of nerves

continues downward to fill space between fascicles

337
Q

perineurium

A

layers of flattened epithelial cells forming sleeve around fascicle of nerve (bundle of nerve fibers)

cells are joined by tight junctions

function: blood nerve barrier→ blocks passage of most macromolecules protecting nerve fibers & helps maintain their internal environment

338
Q

endoneurium

A

sparse layer of loose connective tissue that surrounds individual nerve fibers

merges w/Schwann cells

339
Q

Schwann cell

A

aka neurolemmocyte

producer of myelin in PNS

if unmyelinated, one Schwann cell will protect & separate several small axons

several Schwann cells myelinate one axon→ reason its easier to regenerate myeling in PNS than CNS

340
Q

Schmidt-Lanterman clefs

A

aka myelin clefts

cytoplasm in spaces between Schwann cell membranes

341
Q

neuromuscular junction

A

motor neuron branches to form synapse on individual muscle fibers

342
Q

satellite glial cells

A

principal PNS glial cell

cover surface of neuronal cell bodies in ganglia

function: supply nutrients, protect & cushion soma

343
Q

PNS neural regeneration

A

peripheral have good capacity for regeneration & return of function

  • axon distal to injury degenerates
  • 2W later: decrease # of Nissl bodies in soma, nucleus moves peripherally, & macrophages remove debris
  • 3W later: Scwann cells proliferate forming tube, multiple axons sprout from proximal unharmed axon, sprouts seek Schwann tube, one axon finds tube & others degenerate
  • 3M later: axon lengthens w/in Schwann tube, guided & promoted by factors released by Schwann cells fibroblasts and macrophages, 4mm/day, & re-establishes synaptic contact

reasons unsuccessful: blockage of Schwann cells by scar tissue & if sensory fibers grow to motor end plate

344
Q

glycoaminoglycans

A

GAGs

long straight chiain poysaccharides of repeating units: N-acetylglucosamine or N-acetylglactosamine & uronic acid sugar

sugars are usually sulfated→ negatively charged→ stain w/basic dyes

attract cations which atract water creates gel-like & resistent to compressive forces

345
Q

proteoglycan

A

core protein w/GAGs attached

present in all ground substance & surface of some cell types

346
Q

syndecan

A

transmembrane proteoglycan that links cells to extracellular matrix molecules

347
Q

decorin

A

proteoglycan w/only one GAG

348
Q

aggrecan

A

proteoglycan w/more than 200 GAGs

GAGs are chondroitin sulfate & keratin sulfate

349
Q

versican

A

proteoglycan w/identical GAGs (chondroitin sulfate)

350
Q

proteoglycan aggregates

A

aggregcan noncovalently bonded to hyaluronic acid via linker proteins

abundant in gound substance of cartilage

351
Q

multiadhesive glycoproteins

A

function: stabilize extracellular matrix by binding to cell surface, collagen, proteoglycans, & GAGs
ex. fibronectin, laminin, chondronectin, & osteonectin

352
Q

hyaluronidase

A

enzyme secreted by staphylococcus aureus

chops hyaluronic acid into smaller pieces converting it from gel-like to solid in extracellular matrix

breakdown on ground substance causes rapid spread of microorganism thru CT spaces

353
Q

principal cell

A
354
Q

myofibroblast

A

modified fibroblast w/features of smooth muscel cell

abundant in areas of wound healing to contract wound

also seen in periodontal ligament

355
Q

macrophage

A
356
Q

plasma cell

A

derived from B-lymphocytes

few in CT, but numerous in inflammatory sites & sites penetrated by bacteria

large ovoid cell w/ extesive rER

nucleus has alternating patches of heter- & euchromatin

function: produce antibodies

357
Q

mast cell

A

derived from bone marrow

oval to round shape in CT w/small spherical nucleus

metachromatic (changes color w/basic dye) granules due to high levels of heparin (GAG)

function: storage of chemical mediators of inflammatory repsonse

358
Q

allergic response

A

aka immediate hypersensitivity rxn

  1. initial exposure to antigen
  2. IgE production by plasma cell & IgE binds receptor on mast cell
  3. 2nd exposure, antigen/antibody rxn occurs at mast cell surface
  4. discharge of mast cells granules containing primary mediators & secondary mediators (leukotrienes)
359
Q

inflammatory mediators released by mast cells

A

heparin: anti-coagulant
histamine: dilates and increases permeability in postcapillary venules, increases mucus, & causes bronchiospasm

eosinophil & neutrophil chemotacic factors: attract eosinophils (inactivate histamine & destroy ag/ab complex) & neurtophils (destroy parasite) to inflammatory site

leukotrienes: increase permeability & smooth muscle contraction
prostaglandins: increase mucus secretion

360
Q

mesenchyme cells

A

multipotent

stellate in shape

pericytes: mesenchyme cell in close association w/small vessels→ can differentiate into smooth muscle or endothelial cell during blood vessel formation or repair

361
Q

adipose

A

fat cell

arise form embryonic mesechyme cell

brown: multilocular (many fat droplets), dark in color due to # of mitochondria, diminishes during 1st decade of life
white: unilocular, single large fat droplet w/nucleus at periphery

functions of white: energy reserves, insulation, padding of vital organs, & have receptors for insulin, GH norepi & glucocorticords for uptake and release of fatty acids & triglycerides

362
Q

what structure gives rise to the bladder?

A

urogenital sinus

363
Q

what is meant by the 3 kidney system?

A

embryologically: pronephros, mesonephros, & metanephros

364
Q

what are the parts of the nephron?

A

glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, & distal convoluted tubule

365
Q

what are the derivatives of the cloaca?

A

urogenital sinus & anorectal canal

366
Q

trigone region of the urinary bladder & it’s origin

A

smooth triangular region of internal bladder formed by 2 ureteral orifices & urethral orifice

embryonic origin: mesodermal→ replaced by endodermal epithelium

367
Q

renal agenesis

A

failure of one or both kidneys to form

cause: failure of ureteric bud to develop or early degeneration or ureters→ bud fails to contact & induce metanephric blastema development
unilateral: other kidney will hypertrophy to conpensate, 1:1000, more often male
bilateral: incompatible w/life, die in first few days, 1:3000, often seen w/oligohydraminos

368
Q

ecoptic kidney

A

one or more kidney in abnormal position

369
Q

horseshoe kidney

A

anterior poles of kidneys fuse

usually in lumbar region→ hindered from ascending in the abdomen by the inferior mesenteric artery

370
Q

duplications of ureter

A

cause: early splitting of ureteric bud
complete: 2 ureters to one kidney
partial: 2 ureters @ kidney that later merge

ectopic ureteral: one normal, second has abnormal openings to vagina, bladder, and/or urethra

371
Q

urachal fistula

A

persistent allantois

allows urine to leak out of umbilicus

372
Q

urachal cyst

A

only a small portion allantois persists

NOT connected to umbilicus or bladder

can trap embryonic urine that can be prone to infection

373
Q

urachal sinus

A

patent allantois in superior portion only

connected to umbilicus

NOT connected to bladder

374
Q

exstrophy of bladder

A

ventral body wall defect

bladder mucosa opens broadly onto abdominal wall

often seen w/epispadias in males

375
Q

extrophy of cloaca

A

more severe that exstrophy of bladder

also includes urorectal septum developmental defects & anal canal malformations

376
Q

urogenital ridge

A

bilateral ridges on either side of descending aorta that give rise to parts of urinary & genital systems

from intermediate mesoderm

377
Q

nephrogenic cord

A

part of the urogenital ridge that forms the urinary system

378
Q

gonadal ridge

A

part of urogenital ridge that forms the genital system

379
Q

pronephros

A

rudimentary & non-functional kidney

most cranial

from intermediate mesoderm

appears early W4 & disappears by the end of W4

7-10 cells clusters in cervical region

pronephric duct runs caudally to cloaca & persist, used by the next set of kidneys

380
Q

mesonephros

A

large elongated excretory organs

appear late W4 caudal to pronephros

function as interim kidneys for 4 weeks

glomeruli w/mesonephric tubules that open to mesonephric ducts to cloaca (aka Wolffian Duct)

disappear by W8

MALE→ few caudal tubules & duct persist in formation of genital system

FEMALE→ disappear

381
Q

metanephros

A

permanent kidney

begins formation in W5

function starts in W12

from metanephric diverticulum (ureteric bud) & metanephric mass of intermediate mesoderm (metanephric blastema)

urine passes to amniotic cavity→ swallowed→ recycled in kidney, BUT waste excreted by placenta

382
Q

metanephric mass

A

aka metanephric blastema

derived form caudal part of nephrogenic cord

383
Q

metanephric diverticulum

A

aka ureteric bud

outgrowth of mesonephric duct near entrance to cloaca

gives rise to ureter, renal pelvis, major & minor calyces, & 1-3 million collecting tubules

elongates to penetrate metanephric mass

major calyx forms two minor calyces

384
Q

uriniferous tubule

A

nephron (from metanephric mass) & its collecting tubule (from ureteric bud)

385
Q

positional changes of kidneys during development

A

start in pelvis

move cranially due to caudal growth of embryo

90º clockwise rotation

finish as retroperitoneal

386
Q

pelvic kidney

A

when kidney fails to relocate/ascend

387
Q

urorectal septum

A

mesodermal layer

divides cloaca (endoderm) during W4-W7

into urogenital sinus & anorectal canal

tip forms perineal body

388
Q

urogenital sinus

A

derived from cloaca

divides into 3 parts:

upper: forms bladder & continuous w/allantois
middle: narrow, male: prostatic & membranous urethra, female: entire urethra
caudal: males: phallic urethra & degenerates in females

389
Q

urachus

A

thick, fibrous cord

forms from the allantois as its lumen is obliterated

connects umbilicus to apex of bladder

forms median umbilical ligament in adult

390
Q

epispadias

A

very rare

malformation of the penis- urethra open on upper aspect (dorsum) of the penis

females: urethra develops too far anteriorly.

391
Q

mesonephric ducts

A

males: become ejaculatory ducts as they move closer together & enter prostatic part of urethra as kidneys ascend
females: degenerate

Microanatomy (9 decks)

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