5.2 Embryo Flashcards Preview

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Flashcards in 5.2 Embryo Deck (87):
1

Forgut

pharynx to duodenum
celiac artery

2

Midgut

duodenum to txvrs colon
SMA

3

Hindgut

distal txvrs colon to rectum
IMA

4

Devt defects of anterior abd wall

defect of --- leads to ---
rostral fold closure- sternal defects
lateral fold closure- omphalocele, gastroschisis
caudal fold closure- bladder exstrophy

5

Gastroschisis

Failure of lateral body folds to fuse --> extrusion of abd contents through abd folds
NOT covered by sac
Defect is lateral to umbilicus, usu on R side
But the "better" one- liver doesn't protrude, other anomalies in only 10-15%
See incrsd AFP
Rx surgical closure

6

Omphalocele

persistence of herniation of abd contents into umb cord, covered by peritoneum
IS covered by sac (peritoneum + amnion)
But "worse"- liver is often protruding
Other anomalies v common (50%)- GI, GU, CV, CNS, MS
See elevated AFP lvls
Rx surgical closure

7

Duodenal atresia

failure to recanalize
trisomy 21 (down)

8

Jejunal, ileal, colonic atresia

due to vascular accident
apple peal atresia

9

When does normal umbilical herniation occur and regress in utero?

6th week- midgut herniates thru umbilical ring --> rapid growth of midgut (duod to txvrs colon)
10th wk- returns to abd cavity and rotates around SMA

10

Pathology of normal umb herniation

malrotation of midgut
omphalocele
intestinal atresia or stenosis
vovulus (twisting of gut) +/- incarceration (not enough blood, kinked off)

11

Tracheoesophageal fistula (TE)

Abn connection bt esophagus and trachea
Most common subtype: blind upper esophagus w lower esophagus connected to trachea.
Results in cyanosis, choking/vom w feeding, air bubble in stomach on CXR, failure to pass NG tube into stomach, pneumonitis, polyhydramnios (bc fetus can't swallow amniotic fluid)

12

Congenital pyloric stenosis

Hypertrophy of pylorus causes obstruction
Palpable olive mass in epigastric region and nonbilious (bc no bile since before gall bladder) projectile vom at 2wks old.
Rx surgical incision
Occurs in 1/600 live births, often 1st born males
Will have hypochloremic metabolic alkalosis from the vom. (also hypoK+)

13

What is marker bt midgut and hindgut?

Splenic flexure (where txvrs colon hits spleen)

14

What is bladder exstrophy?

Failure of caudal fold closure
Inside of bladder is exposed to outside world
(turned inside out, and outside abd)

15

If you are alkalotic or acidotic, what will happen to your Cl- and K+ levels

Alkalotic means decreased HCl, so hypochloremic. When you are alkalotic, the H+/K+ countertxptr tries to compensate by dumping H+ into the blood, which means K+ will be brought into cells, at you will be hypokalemic (d/t decreased K+ in blood bc more inside cells)

Acidosis is the opp- too much HCl, so hyperchloremia; plus H+/K+ cotxprt compensates by taking H+ out of blood into cells, which dumps K+ into blood- so hyperkalemia.

In both cases, the hypo/hyperkalemia takes a few weeks of alk/acidosis before it is measurable.

16

Pancreas embryology

Derived from foregut
Ventral and dorsal pancreatic buds become pancreatic head.
Ventral bud becomes uncinate process (lower half of head) and main pancreatic duct.
Dorsal bud becomes everything else- body, tail, isthmus, accessory pancreatic duct

17

Annular pancreas

ventral pancreatic bud abnormally encircles 2nd part of duod and forms a ring of pancreatic tsu; can cause duodenal narrowing.
2/3 pts asympt
Sympt onset can occur at any age, dep on severity of duod constriction

18

Children px of annular pancreas

gastric outlet obstruction- bilious vom (has bile, bc after the GB), feeding intolerance, abd distention

19

Adult px of annular pancreas

20-50yo
Abd pain, post-prandial fullness and nausea, peptic ulceration, pancreatitis
Rarely, biliary obstruction

20

Infants w annular pancreas assoc w...

maternal polyhydramnios,
Down syndrome
esophageal and duodenal atresia
imperforate anus
Meckel's diverticulum

21

Pancreas divisum

ventral and dorsal parts fail to fus at 8 weeks

22

Spleen embryology

arises from dorsal mesentery (it's mesodermal!) but is supplied by an artery of the foregut, the celiac artery.

23

Kidney embryology

1. Pronephros at week4, then degenerates
2. Mesonephros- functions as interim kidney during 1st trimester; later contributes to male genital system
3. Metanephros- permanent. starts appearing during 5th wk of gestation, nephrogenesis continues through wks 32-36

24

Ureteric bud

Derived from caudal end of mesonephros
gives rise to ureter, pelvises, and (by branching) the calyces and collecting ducts
fully canalized by week10
Abberant devt results in congenital malformation of the lower urinary tract

25

Metanephric mesenchyme

Ureteric bud interacts with this tsu
interaction induces differentiation and formation of glomerulus and renal tubules to DCT
Abberant interaction bt MM and Ureteric bud results in congenital malformation of kidneys

26

Uteropelvic jn w kidney

Last to canalize, most common site of obstruction (hydronephrosis) in fetus.

27

Potter's syndrome

Bilateral renal agenesis
Leads to oligohydramnios (little amniotic fluid, bc fetus can't pee), which leads to limb deformities, facial deformities, pulmonary hypoplasia
Caused by malformation of ureteric bud
POTTER:
Pulm hypoplasia
Oligohydramnios
Twisted skin
Twisted face
Extremities defects
Renal agenesis

28

Liver diverticulum gives rise to...

Liver
Gall bladder
Bile duct system
Ventral pancreatic bud (!!)

29

What tsu gives rise to pancreas? To the spleen?

Endoderm - pancreas (from foregut)
Mesoderm - spleen

30

GI problems in Down Syndrome

Annular pancreas
Duodenal atresia

31

Horseshoe kidney

Gets stuck under IMA
Inferior poles of both kidneys fuse, ascend during fetal devt but not as high as regular kidneys bc blocked by IMA.
Kidney fn normal
Complete fusion - cake kidney

32

Female genital embryol

Default devt
Mesonephric duct degenerates and Paramesonephric (Mullerian) duct develops into fallopian tubes, uterus, upper 1/3 of vag
(lower 2/3 of vag is from urogenital sinus, so even if you have Mullerian duct problems can still have a vag)

33

Male genital embryol

SRY gene on Y chromosome codes for testis-determining factor.
Mullerian inhibiting substance is secreted by Sertoli cells of testis, and suppresses devt of Mullerian (paramespnephric) duct.
Leydig cells secrete increased androgens, leading to devt of mesonephric ducts (wolffian ducts) into seminal vesicles, epididymis, ejaculatory duct, and ductus deferens (everything except prostate).

34

Default genitals

Female
Mesonephric (wolffian) duct has to be induced to remain.
Otherwise, will get paramesonephric duct and be female.

35

Bicornate uterus

Incomplete fusion of paramesonephric ducts causes 2 uteruses.
Assoc w urinary tract abn and infertility

36

What does the genital tubercle become?

M: glans penis / F: glans clit
M: corpus cavernosum and spongiosum / F: vestibular bulbs

37

What does the urogenital sinus become?

M: bulbourethral gland of cowper / F: greater vestibular glands of bartholin
M: prostate gland / F: Urethral and paraurethral glands of skene

38

What do the urogenital folds become?

M: Ventral shaft of penis (penile urethra)
F: Labia minora

39

What does the labioscrotal swelling become?

M: scrotum
F: labia majora

40

Glans penis in F

Glans clitoris

41

Corpus cavernosum and spongiosum in F

Vestibular bulbs

42

Bulbourethral glands of cowper in F

Greater vestibular glands of bartholin

43

Prostate gland in F

urethral and paraurethral glands of skene

44

Ventral shaft of penis (ventral urethra) in F

Labia minora

45

Scrotum in F

Labia majora

46

What is the M and F remnant of the gubernaculum

M: anchors testes w/in scrotum
F: ovarian ligmt and round ligmt of uterus

47

What is the M and F remnant of the processus vaginalis (evagination of the peritoneum?

M: forms tunica vaginalis
F: obliterated

48

Klinefelter's

Male XXY
Testicular atrophy, eunuchoid body shape, tall long extremities, gynecomastia, female hair distribution
May present w devt delay
Presence of inactivated X-chr (barr body)
Common cause of hypogonadism seen in infertility workup.

49

Hormones of Kleinfelter

Dysgenesis of seminiferous tubules leads to decrsd inhibin, so incrsd FSH

Abn leydig cell fn leads to decreased testosterone, which leads to increased LH, and then to increased estrogen

50

Turner's Syndrome

Female 45XO
Short stature (<5ft if untreated), ovarian dysgenesis (streak ovary), shield chest, bicuspid aortic valve, neck webbing (+cystic hygroma), preductal (infantile) coarc of aorta
Most common cause of primary amenorrhea
No barr body

51

Hormones of Turner's

Decreased estrogen leads to increased LH and FSH.

52

Double Y males

Male, XYY
Phenotypically normal, v tall, severe acne
Antisocial bhvr in 1-2%
Normal fertility

53

Testosterone increased, LH increased

Defective androgen receptor

Normal: Increased LH increases Testosterone.
But here, body doesn't recognize testosterone do to receptor problem- so it feeds back to elevate LH, which causes even more testosterone production.

54

Testosterone increased, LH decreased

Testosterone-secreting tumor
Exogenous steroids

Increased testosterone from outside causes neg fdback on Leydig so decreased LH (so Leydig won't make as much testosterone)

55

Testosterone decreased, LH increased

Primary hypogonadism

Lots of LH, trying to get Leydig cells to secrete testosterone, but they are hypogonads, so can't make it.

56

Testosterone decreased, LH decreased

Hypogonadotropic hypogonadism

LH is low so testosterone is low.

57

What is pseudohermaphroditism

Disagreement bt phenotypic sex (external genitalia) and gonadal sex (internal genitalia)
Name pt female if ovaries, male if testes.

58

Female pseudohermaphrodite

XX
Ovaries present, but external genitalia virilized or ambiguous.
Due to excessive and inappropriate exposure to androgenic steroids during early gestation
eg congenital adrenal hyperplasia (21beta hydroxylase def, 17beta hydroxylase def)
eg exog admin of androgens during pregnancy

59

Male pseudohermaphrodite

XY
Testes present, but external genitalia are female or ambiguous.
Most common form is androgen insensitivity syndrome (aka testicular feminization)

60

Androgen insensitivity syndrome

46XY
Defect in androgen receptor results in normal-appearing female; female external genitalia w rudimentary vagina (lower 2/3 of vag comes from urogenital sinus, not mullerian, so will have this)
Uterus and uterine tubes generally absent
Presents w no sexual hair
Develops testes (often found in labia majora- removed to prevent malignancy)
Increased testosterone, increased estrogen, increased LH
aka testicular feminization
Causes Male pseudohermaphrodite

61

True hermaphrodite

46XX or 47XXY
Both ovary and testicular tsu are present, ambiguous genitalia.
V rare

62

5alpha reductase deficiency

Inability of males to convert testosterone to DHT (more potent form of testosterone)
Ambiguous genitalia until puberty, when increased testosterone causes masculinization/increased growth of external genitalia. Even tho can't convert it to DHT, have so much testosterone that it doesn't matter. (Penis at 12)
Internal genitalia are normal.
Testosterone/estrogen lvls normal
LH normal or increased.

63

Where are barr bodies found?

In neutrophils- extra drumstick globule on nucleus in 3% of neutrophils.
Shows X-inactivation
Seen in all females
Also in XXY Kleinfelter's (males).
Not seen in Turner's (females bc there is no inactivated X chr)

64

What is the downstream effect of increased LH in males?

LH stim's leydig cells to make testosterone.
So increased LH will mean increased testosterone.

65

Cryptorchidism

Undecended testis (one or both)
Lack of spermatogenesis d/t increased body temp
Assoc w high risk of germ cell tumors
Prematurity increases risk of crytorchidism
Rx if before puberty: orchioplexy (bring it into scrotum and suture it there)

66

SIDS

Usu at 2-4 mo old
Usu when infant is sleeping
Occlude breathing but don't stir to change their O2 supply.
Maternal risk factors: low SES, age <20, drugs/tobacco during pregnancy
Infant risk factors: low birth weight, female, preemie, prior sibling w SIDS
Prevent: back to sleep, pacifier when sleeping, fan in room

67

ACA

Lesion causes MMS
medial medullary syndrome:
Triad of 3 things:
1. Dmg to medullary pyramid (and thus corticospinal fibers of pyrimidal tract) --> limb weakness/contralat hemiparesis in lower extremities
2. Dmg to Medial lemniscus - decreased contralat proprioception, vibration, touch
3. Dmg to hypoglossal nerve - ipsilateral musc weakness, so deviation of tongue to ipsilateral side on protrusion

68

PICA

Lesion causes LMS
lateral medullary syndrome aka wallenberg's
Contralateral P/T loss
Ipsilateral dysphagia
Hoarseness, decreased gag reflex
Vertigo, diplopia, nystagmus
Vom
Ipsilateral Horner's
Ipsilateral facial P/T loss
Trigeminal nucleus (spinal tract and nucleus) loss
Ipsilateral ataxia

69

AICA

Lesion causes LIPS
Lateral Inferior Pontine Synd
Ipsilateral facial paralysis
Ipsilateral loss of cochlear nucleus, vestibular nucleus (nystagmus)
Ipsilateral facial P/T
Ipsilateral dystaxia (MCP, ICP- middle, inf cerebral peduncle)

70

PCA

Lesion:
Contralateral homonomous hemianopia w macular sparing
Supplies the occipital cortex

71

MCA

Contralateral face and arm paralysis and sensory loss
Aphasia (dominant sphere)
Left-sided neglect

72

ACA

Supplies medial surface of the brain, leg/foot area of motor and sensory cortexes

73

A-Comm

Most common site of circle of Willis aneurysm
Lesions can cause visual defects

74

P-Comm

Common area of aneurysm
Causes CN III palsy

75

Lateral striate

Divisions of MCA
Supply Internal Capsule, Caudate, Putamen, Globus Pallidus
"Arteries of stroke"
Infarct of post limb of the IC causes pure motor hemiparesis

76

Watershed zones

Bt ACA and MCA
Bt PCA and MCA
Dmgd in severe hypotension, leading to upper leg/arm weakness and defects in higher-order visual processing

77

Basilar artery

Lesion causes "locked-in syndrome"
CN III is usu intact

78

Stroke of anterior circle of Willis

General sensory and motor dysfn, aphasia

79

Stroke of posterior circle of willis

Cranial nerve defects (vertigo, visual)
Coma
Cerebellar deficits (ataxia)
Dominant hemisphere- ataxia
Non-dom: neglect

80

Berry aneurysm

Occur at bifurcations of Circle of Willis
Most common site is A-Comm
Rupture (most common complication) leads to hemorrhagic stroke/subarachnoid hemorrhage.

Assoc w:
APKD
Ehlers-Danlos, Marfans
Advanced age
HTN
Smoking
Higher risk in blacks

81

Charcot-Bouchard microanerysms

Assoc w chronic HTN
affects sml vessles (eg in basal gang, thalamus)

82

What infarct causes lateral inferior pontine syndrome?

AICA

83

What infarct affects occipital lobe/vision?

PCA

84

What infarct causes wallenberg's syndrome

PICA
aka lateral medullary syndrome

85

Most common site for berry aneurysm

A-Comm
also P-Comm

86

Goes to medial part of brain --> Leg, foot

ACA

87

Supplies Broca's and Wernicke's areas

MCA