SM01 Mini4 Flashcards
(555 cards)
1
Q
functions of blood
A
- transports O2, CO2, hormones, nutrients, & waste
- stabilizes pH & electrolyte concentrations of interstitial fluids
- regulation of blody temperature
- migration pathway for WBCs
2
Q
What are the three formed elements of blood?
A
- erythrocytes (RBC)
- leukocytes (WBC)
- platelets
3
Q
plasma
A
mostly water & plasma proteins (albumin, fibrinogen, immunoglobulins)
but also lipids, hormones, vitamins & salts
must be collected in blood tube with anticoagulant (heparin, EDTA, sodium citrate)
4
Q
serum
A
plasma lacking fibrinogen
collected without anticoagulation
5
Q
blood clot
A
fibrin strings connecting trapped blood cells
6
Q
Wright stain
A
mixture of methylene blue & eosin
7
Q
methylene blue
A
basic/positively charged dye
stains acidic/negatively charged cellular structures blue
ex. DNA, RNA, specific granules of basophils
8
Q
eosin
A
acidic/negatively charged dye
stains basic/positively charged structures pink/red
ex. hemoglobin (not +, but stretches of + aa) & specific granules of eosinphils
9
Q
azures
A
stain reddish blue when methylene blue is oxidized
ex. lysosomes
10
Q
erythrocyte
A
RBC
function: transport of O2 & CO2
no nucleus or organelles
only has: plasma membrane, cytoskeleton, hemoglobin, & glycolysis enzymes
increase in # at higher altitude (decreased binding of O2)
8um diameter
11
Q
hematocrit
A
percentage (v/v) of packed RBCs in given sample of blood after centrifugation
higher in males than females
12
Q
erythropoietin
A
hormone
secreted by kidneys in adults; liver in fetus
stimulates RBC production to match O2 demand
13
Q
What is the life span of an erythrocyte?
A
120 days
then phagocytosed in spleen, liver, or bone marrow→ hemoglobin recycled
14
Q
Rouleaux
A
stacking of erythrocytes seen in capillaries
15
Q
Why do erythrocytes have a biconcave shape?
A
to maximize their surface area to volume ratio→ maximize O2 exchange
16
Q
anisocytosis
A
RBCs of unequal size
microcyte: less than 6um
macrocyte: greater than 9um
17
Q
How do RBCs pass easily thru smaller blood vessels?
A
increased flexibility via spectrin
18
Q
hereditary spherocytosis
A
somatic dominant inheritance
cause: defective spectrin or ankyrin
result: abnormal spectrin lattice binding or complete absence→ spherical RBCs instead of biconcave
RBCs are more fragile, break down rapidly & transport less O2
19
Q
dendritic cells
A
differentiate from monocytes in tissue
best anitgen-presenting cells in body
20
Q
granulocytes
A
have specific granules
differentiated by Wright stain rxns
neutrophils, eosinophils, & basophils
non-dividing terminal cells w/life span of days
21
Q
agranulocytes
A
no specific granules
but do have nonspecific azurophilic granules (lysosomes)
lymphocytes & monocytes
22
Q
Why do neutrophils have a mulitlobed nucleus?
A
aides in moving between tissues as they are more flexible
23
Q
What are the main components of pus?
A
dead neutrophils & dead bacteria
24
Q
function of neutrophils
A
first line defense of bacterial infection
sense chemical gradients near them
active phagocytosis of bacteria
25
neutrohils microscopy
identified by 3-5 lobed nucleus
26
Why do neutrophils use glycosis for ATP generation?
allows them to survive in anaerobic environment→ kill bacteria & clean up debris in poorly oxygenated regions (inflammed or necrotic
27
what is the life span of neutrophils?
6-7 hours in blood
1-4 days in connective tissue
28
chemoattractors
mediators of processes, including immune responses, inflammation, wound healing, & embryogenesis
attract cell type to their area of need
ex. C5a of complement system, intermediate lipid metabolites (arachidonic acids & leukotriene B4), N-formylated oligopeptides, & chemokines
29
chemotaxis
crawling along s soluble concentration gradient towards source of attractant
cell driven by lamellipodi
30
what does mitochondria release during necrosis that causes inflammation?
N-methylated oligopeptides
31
cytokine
non-antibody protein released by spefic cell type as part of body's immune response
32
chemokine
cytokine that can induce chemotaxis of a leukocyte during inflammation
33
classic symptoms of inflammation
swelling, redness, heat, & pain
34
What is the purpose of acute inflammation?
ease travel of leukocytes & plasma proteins to injury site
35
chronology of acute inflammation
* increase blood flow via vasodilation
* loosening of capillary endothelial cell tight junctions
* emigration of leukocytes form microcirculation
36
diapedesis
passage of WBCs thru intact capillary walls into surrounding tissue
37
myeloperoxidase
in lysosomes of neutrophils
generates highly reactive hypochlorite & chloramines
38
neutrophil oxidative burst
azurophilic granules (lysosomes) & specific granules of neutrophils fuse w/phagosome
hypochloride from myeloperoxidase & superoxide denatures proteins & membranes of microorganisms→ kills them
toxicity of these rxns leads to neutrohil death
39
chronic granulomatous disease
inherited disorder of phagocytic cells
cause: defect in NADPH oxidase enzyme of phagocytes→ inability to produces superoxide anions O2- for denaturing/killing targets
result: recurrent life-threatening bacterial & fungal infections
granulomas develop due to chronic inflammation
cannot activate NETs
40
granuloma
localized nodular inflammation found in tissue
41
Where is collagenase in neutrophils & why do they have it?
in both specific granules & azurophilic
neutrophils will release collagenase in CT when they cannot reach their target→ collagenase breaks down collagen of CT→ neutrophil can pass thru
42
neutrophil extracellular traps
formed during cell death of neutrophils
creates network of chromatin & granule proteins that can bind & kill microorganisms
dependant on generation of reactive oxygen species by NADPH oxidase
more bacteria killed this way than by phagocytosis
43
eosinophil microscopy
bilobed nucleus
large, pink specific granules
44
functions of eosinphils
parasitic infections (generally multicellular)
phagocytosing antigen-antibody complexes
control mechanisms in allergy & asthma
45
parasite
organism that grows, feeds, & is sheltered on or in a different organism while not contributing to survival of host
46
eosinophil killing
can phagocytose or secret granules when target is too large for phagocytosis
agent: major basic protein
a lot of self-damage when secreted as it targets eukaryotes
47
internum
thick band seen on specific granules of eosinophils
produced by major basic protein
48
eosinophilia
increase # of eosinophils in blood
causes: parasitic infection OR allergic rxn
49
basophil microscopy
S-shaped nucleus
nucleus commonly masked by large dark blue specific granules
50
What do specific granules of basophils contain?
heparin & histamine
51
difference between basophils & mast cells
basophils- in blood
mast cells- in CT
52
functions of basophils
release of mediators: histamine, serotonin, prostaglandin, & leukotrienes
increases blood flow to area & adds to infammatory process
53
lymphocytes
subdivided: T, B, null (NK, stem, etc)
2nd most populace WBC behind neutrophils
more often in lymph than blood
only leukocyte that can return from tissue back to blood
54
What is the life span of a lymphocyte
few days- years
55
lymphocyte microscopy
1.5 size of erythrocyte
dense, round nucleus that takes up most of the cell
56
Monocyte functions
* phagocytosis
* destroy dead & defunct cells & antigen/foreign particulate matter
* immune response
* \*\*precursor of macrophages (differentiate in CT)
57
monocyte microscopy
largest blood cell: 12-20um (3x erythrocyte)
large, kidney-shaped nucleus
58
macrophage
differentiates from monocyte when it enters CT
connective tissue surrounding it will determine exact final differentiation
59
platelets
aka thrombocytes
pieces derived from megakaryocyte
life span= 10 days
no nucleus, but do have lysosomes, mitochondria, ER, Golgi, 3 types granules, & \*extensive cytoskeleton\*
60
megakaryote
giant precursor cell of platelets
never leaves bone marrow, but reaches appendages out into the blood stream
61
function of platelets
* prevent excessive internal or external bleeding after injury
* activated on exposure to collagen
* secrete platelet-derived growth factor & transforming growth factor beta→ promotes invasion of fibroblasts
62
von Willebrand factor
promotes adhesion of platelets to endothelial cells
produced by platelets & endothelial cells
63
platelet factor IV
stimulates blood coagulation
64
where is post-natal blood made and how does it change with age?
red bone marrow
of bones reduced w/age for relatively constant area of red bone marrow
in cancellous bone
65
how does the body respond to severe blood loss (to replace blood)?
transition of yellow bone marrow to red bone marrow
66
hematopoiesis
process of blood cell formation
67
yellow bone marrow
yellow due to adipose cells
seeded w/some hematopoietic cells
68
hematopoietic stem cell
multipotent cell
gives rise to all 3 formed elements in blood
69
mesenchymal stem cell
pluripotent
can differentiate into osteoblast, chondroblast, mycocyte, & others
70
how is the stem cell population kept constant?
only one daughter cell differentiates
71
totipotent
cell can differentiate into anything
72
pluripotent
blastocyst inner cell mass
can become all cell types except extra-embryonic
73
where is fetal blood made?
5+5
blood precursors from yold sac mesoderm
5W→ fetal liver
5M→ bone marrow
74
red bone marrow
colored red due to presence & formation of blood
75
bone marrow stroma
"land"
where blood cells develop
formed by reticular cells and the web of reticular fibers they create (much like fibroblasts)
also contains type I collagen, fibronectin, laminin, & proteoglycans
76
bone marrow sinusoids
blood vessels where mature blood cells enter blood stream
lined by endothelial cells w/discontinuous basal lamina
77
what do reticular cells secrete in the stroma?
reticular fibers (type III collagen)
cytokines that stimulate development of progenitor cells into blood cells
78
why is it important that the basal lamina of endothelium of bone marrow sinusoids be discontinuous?
it's how the newly formed blood cells enter, between the endothelial cells
79
stages of lymphocyte development
hematopoietic stem cell→ lymphoid stem cell (CFU-L)→ T or B lymphocyte
80
CFU
colony forming unit
81
GEMM
granulocyte, erythrocyte, monocyte, megakaryocyte
should ahve one more M for Mast cells
82
What blood cell does not differentiate in bone marrow?
T lymphocytes migrate to & differentiate in the thymus
83
erythropoiesis
formation of RBCs
get smaller
nucleus condenses & eventually extrudes
loss of organelles
gain of hemoglobin
released into bloodstream as proerythroblast, takes 7 days to make one
84
what are the derivatives of the mesonepheric ducts?
males: vas deferens, seminal vesicle, & epididymis as induced by testosterone & eferent ductules
female: degenerate due to absence of testosterone
85
what is the testis-determining factor?
SRY protein
coded for by SRY gene
on Y chromosome
86
what embryonic layer are the gonads derived from?
intermediate mesoderm
87
genital ridges
formed by proliferation of coelomic epithelium & condensation of mesenchyme from mesonephric ridge
88
where do primordal stem cells originate?
epiblast of yolk sac wall
89
where do primordial stem cells migrate to? what happens when they fail?
genital ridge during W4-W5
invade sex cords W6
if they don't→ gonads don't develop
90
how are primitive sex cords formed?
epithelium proliferates & penetrates underlying mesenchyme in medulla of indifferent gonads
91
what do the primitive sex cords become?
male: testis cords (horseshoe shaped)→ seminiferous tubues containing primodial germ cells (outer portion) & rete testis tubular network (inner portion)
female: form irregular clusters w/oogonia as medullary cords, then degenerate
92
when does the tunica albuginea form?
coincides w/testis cord formation
93
origin & funtion of Leydig cells
mesenchyme between testis cords
testosterone secretion W8 as stimulated by hCG (human chorionic gonadotropin)
94
when does lumenization of the testis cords occur?
during puberty
95
location & function of sertoli cells
secretion of mullerian inhibiting substance (aka anti-mullerian hormone)
found in testis
96
what effect does mullerian inhibiting substance have?
suppresses development of paramesonephric ducts in males
97
where & when do the paranephric ducts form?
D44-48
longitudinal invaginations of surface epithelium later to mesonephric ducts
98
where do the paranephric ducts terminate & open?
on urogenital sinus between ends of mesonephric ducts
cranial opening into coelomic cavity
99
what forms the paradidymis?
caudal mesonephric tubules as they degerate
location: caudal end of epididymal connection to testis
100
what forms the appendix epididymis?
cranial mesonephric duct
location: cranial to efferent ductules & distal from testis relative to appendix testis
101
what are the derivatives of the paranephric ducts?
males: appendix testis (cranially) & prostatic utricle (distally)
females: uterine tubes, uterus, & upper vagina
102
what female structure is the prostatic utricle homologous with?
uterus & upper vagina
103
cortical cords
2nd generation of medullary cords in ovary development
w/oogonia
form in W7
104
what happens to the coritcal cords in M3?
split into isolated cell clusters
proliferate into primary oocyte surrounded by follicular cells
105
primordial follicle
primary oocyte surrounded by follicular cells
106
epoophoron
vestigial epigenital mesonephric ductules in females
homologous w/efferent ductules
107
paroophoron
vestigial caudal mesonephric ductules in females
homologous w/paradidymis
108
Gartner's cyst
vestigial distal mesonephric duct in females
homologous to seminal vesicle
109
function & origin or estrogenic hormones in fetus
from mother & placenta
must be present for full development of female genital tract
110
how is the uterus formed?
fusion of lower portion of paramesonephric ducts & degeneration of septum
111
how is the vagina formed?
upper 1/3: fusion of distal paramesonephric ducts
lower part: posterior wall of urogenital sinus
112
sinovaginal bulbs
* induced to form by paramesonephric contact to urogenital sinus
* collection of endodermal cells from urogenital sinus
* proliferates into solid plate
* canalizes M5 into lower portion of vagina
113
unterine & vaginal formation abnormalities
* uterine duplication w/vaginal duplication
* uterine duplication w/o vaginal duplication
* uterine duplication w/o vaginal duplication only superiorly→ Y-shape
* septally separated uterus (unknown cause)
* one-sided: one paramesonephric dict fails to develop
* cervical atresia
114
proerythroblast
large cell
basophilic cytoplasm
visible nucleoli
NOT morphologically distinguishable from other committed precursor cells or myeloid stem cell
115
basophilic erythroblast
strongly basophilic cytoplasm→ caused by large # of ribosomes involved in synthesis of hemoglobin
NO visible nucleoli
116
polychromatophilic erythroblast
less polyribosomes→ less basophilic→ less blue
more hemoglobin in cytoplasm→ more acidophilic→ more pink
polychromatic b/c both colors present
117
orthochromatophilic erythroblast
nucleus condensation
loose basophilia→ uniform acidophilia
118
reticulocyte
AFTER expelling nucleus
still has a few polyribosomes→ agreggate to form reticular network
leaves bone marrow & passes to blood stream
lasts 2-3 days
119
what is the difference between reticulocytes & erythrocytes?
loss of polyribosomes & mitochondria
120
nurse cell
macrophage that erythrocytes develop on
phagocytose discarded nuclei of erythroblasts
121
what is distinguishable when a blood smear is stained w/cresyl blue?
reticular network of polyribosomes in reticular cells
122
what is the action of erythropoietin?
stimulates colony forming unit-erythrocyte differentiation
123
where is erythropoietin produced/secreted from?
endothelial cells of peritubular capillary network of kidneys
hepatocytes
124
granulopoiesis
development of granulocytes- eosinophils, basophils, & neutrophils
125
myeloblast
looks like lymphocytes, but has 3-5 nucleoli
1st stage of granulocytes after committed precursor
126
promyelocyte
azurophilic
very large
appearance of non-specific granules
2nd stage of granulocytes after committed precursor
127
myelocyte
oval or flat nucleus
specific granules
last stage cell division is possible
3rd stage of granulocytes after committed precursor
128
metamyelocyte
accumulation of specific granules
indented nucleus in C or V shape
4th stage of granulocytes after committed precursor
129
band/stab cell
rarely seen for basophils or eosinophils, mostly immature neutrophils
5th stage of granulocytes after committed precursor
130
what is an increased number of band cells in blood stream indicative of?
bacterial infection
131
what cell type is stored in bone marrow?
neutrophils (5:1 in blood stream)
132
what two WBCs share the same progenitor?
monocytes & neutrophils
133
promonocyte
bluish cytoplasm due to numerous azurophilic non-specific granules (lysosomes)
2nd stage after committed precursor
monoblast is between progenitor & this stage
134
monocyte
1010 made daily
1-2 days in circulation
then enter connective tissue where they differentiate into macrophages
135
leukemias
malignant clones of leukocyte precursors
found in lymphoid tissue & bone marrow
large release of immature cells into blood
result: lack of some cell types & excessive production of others
pt. usually anemic & prone to infection
136
megakaryocytopoiesis
nucleus becomes highly polyploid- 30X DNA, chromosomes replicate, but cells don't divide
invaginations of plasma membrane form demarcation membranes w/platelet granules in each
platelets break off into bone marrow sinuses
137
what is contained in platelet granules?
platelet-derived growth factor, fibroblast growth factor, von Willebrand's factor, & platelet factor IV
138
what is the function of von Willebrand's factor?
promotes platelet adhesion to endothelial cells
139
how do erythrocytes enter sinusoids?
not sufficient motility like leukocytes
use pressure gradient: veins are smaller tha arteries in bone marrow, resulting in suciton of RBCs into capillary
140
which WBCs can divide after differentiation and which cannot?
divide: monocytes & lymphocytes
unable to divide: eosinophils, basophils, & neutrophils (granulocytes)
141
how are the testes attached cranially & caudally during descent?
cranially: as mesonephros degenerates urogenital mesentary attachment is limited to the cranial suspensory ligament
caudally: caudal genital/inguinal ligament→ gubernaculum
142
1st phase of testis decent
enlargment of testis
regression of mesonephros
cranial ligament regresses & releases testis (diaphragmatic connection)
143
2nd phase of testis descent
descent to level of inguinal ring by W12
144
3rd phase of testis descent
transinguinal descent
testes pass thru inguinal canal by W28
into scrotum by W33-38
guided by testosterone & gubernaculum (attached to scrotal floor
145
vaginal process
testis slides behind this extension of the peritoneal cavity
becomes tunica vaginalis
canal connecting it to peritoneum is obliterate at birth or shortly after
146
what happens when obliteration of vaingal process to peritoneum is incomplete or weak?
prone to indirect inguinal hernia
irregular can leave small cyst→ hydrocele of testis
147
descent of ovaries
cranial genital ligament→ suspensory ligament of ovary
caudal genital ligament→ ligament of ovary proper & round ligament of uterus
ovaries suspended in peritoneal fold→ broad ligament of uterus (remnant of gubernaculum)
settle just below rim of true pelvis
148
What are the connections of the round ligament?
uterus & labia majora
149
indifferent stage of external genitalia
W3-W7
mesenchymal cells from primitive streak around cloaca
form pair of genital folds extending to proctoderm (anus)
folds unite cranially to form genital tuberacle
genital swellings form laterally to folds
cloaca breaks down in W7→ opening of urogenital sinus between folds
150
adults structures from genital tubercle
males: glans penis
females: clitoris
151
adults structures from genital folds
males: shaft of penis
females: labia minora, urethral & vaginal orifices
152
adult structures from genital swellings
males: scrotum
females: labia majora
153
what hormone influences growth of male external genitalia?
dihydrotestosterone
154
male urethra formation
lateral folding & midline fusion of genital folds
endodermal in origin from urogenital sinus
155
penile raphe
epithelial seam alond penile shaft & scrotum where urethra fused
156
vestibule
opening to urethra & vagina in females
remnant of urogenital groove
157
hypospadias
most common male external genitalia malformation
ventral opening of urethra anywhere that isn't at the glans
158
true hermaphrodite
have ovotestes (ovaries & testicular tissue in same gonad)
or in opposite gonad (one ovary & one testicle)- this type has NEVER been seen in humans
usually 46 XX w/hypertropied clitoris
159
female pseudohermaphrodite
has ovaries
ambiguous or male external genitalia
caused by fetal exposure to excessive andrgens→ clitoral enlargement & labial fusion
congential adrenal hyperplasia: excessive production of androgens by fetal adrenal glands
160
male pseudohermaphrodite
has testes
ambiguous or female external genitalia
cause: inadequate production or testosterone and/or MIF by fetal testies
161
androgen sensitivity syndrome
aka testicular feminization
genetic males 46 XY
have testes
normal females external phenotype
cause: lack of androgen receptors or failure of response to dihydrotestosterone
MIF functional so uterus & upper vagina NOT present
not diagnosed until seeking tx for amenorrhea
162
lymphoid follicle
aka lymphoid nodule
small spherical nodules arrangement of immune cells in connective tissue & inside organs
UNencapsulated
reticular fiber frame by reticular cells NOT ERCs
163
what is teh definitive difference between 1º & 2º lymphoid follicles?
if they have a germinal centrer→ 2º
2º are usually larger, but a large follicle can NOT be labeled 2º w/o germinal center
164
immunocompetence
ability of body to produce normal immune response w/exposure to antigen
165
naive lymphocyte
immunocompetent, but has yet to be exposed to antigen
166
structure of thymus
bilateral organ superior to heart
thin connective tissue capsule w/trabeculae that divides organ into lobules
167
how are thymic lobules established?
via trabeculae of connective tissue
168
why do the thymic lobules cortices stain darker?
they are richer in lymphocytes than medulla
169
after reaching immunocompetence in cortex, how do T cells enter the bloodstream?
migrate to medulla→ bloodstream
170
why is the thymic medulla lighter staining than the cortex?
less cells
95% precursor T cells die via apoptosis during + & - selction process in cortex
171
functions of epithelial reticular cells in thymus
* framework
* form cytoreticulum: ERCs connected together by desmosomes
* in cortex & medulla
* produce & secrete thymic hormones
* promote lymphocyte proliferation & maturation
* form blood-thymus barrier
172
why is it important to have a blood-thymus border?
to exclude antigen from developing thymocytes
antigen contact at this stage results in thymocyte apoptosis
173
what characteristics make ERCs like epithelial cells?
connected by desmosomes
contain keratin intermediate filaments
have basal lamina
174
what makes ERCs NOT like epithelial cells?
grow in reticular pattern
175
what is the embryonic origin of the thymus?
lymphocytes are mesoderm
epithelial reticular cells are endoderm
176
what 3 structures make up the blood-thymus barrier?
1. thymic cortical epithelial cells joined by desmosomes
2. dual basal laminae: 1 by above & 2nd by endothelial cells
3. capillary endothelial cells linked by tight junctions
177
what back up mechanism is in place if antigen gets thru blood-thymus barrier?
macrophages hover nearby
178
Hassal's corpuscles
aka thymic corpuscles
round globular mass of ERC cells
function: suggested that they secrete factors that aid thymocyte development
179
function of fibroblasts in thymus?
external framework only
capsule & trabecule, not part of network
180
what cell types are found in the thymus?
lymphocytes
epithelial reticular cells
fibroblasts
macrophages
181
thymic involution
shrinking of thymus with age
replaced by adipose tissue
starts transition during puberty
182
DiGeorge Syndrome
rare congential disorder
failure of thymus to develop properly
cause: faulty developmement of 3rd & 4th pharyngeal pouches (chromosome 22)
result: poor T cell production→ increased susceptibility to viral, fungal, & bacterial infections
183
MALT
mucosa-associated lymphatic tissue
diffuse lymphatic tissue
foudn in digestive, repsiratory, & genitounrinary tracts
184
Peyer's patches
aggregates lymphatic nodules in teh wall of the ileum
185
what cells make up a 1º lymphatic follicle?
naive & memory B cells
186
why does the germinal center of a 2º follicle stain lighter than its cortex or 1º follicle?
proliferation of B cells after antigen presentation & larger B cell size due to antibody production
187
what is a plasma cell?
a mature B cell that secretes antibodies
larger cytoplasm volume cause them to stain lighter
188
what is the name of the darker stainging rim of a 2º follicle?
mantle zone
189
what is the characteristic appearance of folliculra dentritic cells?
multiple long, thin hairlike projections that run between B cells in GC
190
follicular dendritic cell function
capture & retain antigens for long time (weeks-years)
NOT APCs
of mesenchymal origin
191
what are dendritic cells derived from?
monocytes
192
what is the most important/best APC?
dendritic cells
193
what cells are antigen presenting cells?
dendritic cells
macrophages
B cells
thymic epithelial reticular cells
194
what are HEVs and where are they found?
high endothelial venules
specialized blood vessels where naive lymphocytes enter 2º lymphoid tissues, except spleen
195
how do HEVs differ from regular endothelial cells of veins?
they are simple cuboidal/columnar cells instead of squamous
express addressins that atrract T & B cells
196
lymphocyte homing
adhesion of circulating lymphocytes in blood to cells of HEVs w/in lymphoid organs
197
circulatory path of lymphocytes
blood→ HEVs→ 2º lymphoid organ→ lymph→ blood
198
M cells
aka microfold cells
isolate lymphoid nodules from lumina of tract
transfer antigen from lumen to nodule via transcytosis→ NOT APCs
deep invagination of basal surface filled w/dendritic cells & macrophages, B+T cells present further from lumina
immune response generated in lamina propria
present in GI & bronchial MALT
199
what is the functional importance of the appendix?
filled w/lymphocytes & lymphoid follicles
store normal gut bacteria
200
what is the ring of waldheyer?
masses of lymphoid tissue that form a ring in posterior mouth
1st line of defenseagainst ingested or inhaled foreign pathogens
201
palatine tonsils
lateral walls of oral pharynx
dense lymphoid tissue, forms band of lymphatic nodules
non-keratinaized, stratified, squamous epitelium w/multiple invaginations called crypts
partial capsule of dense connective tissue
efferent lymph vessels only
202
lingual tonsils
@ base of tongue
numerous nodules surrounding single crypt
lined by non-keratinized, stratified, squamous epithelium
thin, partial capsule of dense connective tissue separates from underlying tissue
203
pharyngeal tonsils
aka adenoids
roof of nasopharynx
nodules w/o crypts
typical respiratory epithelium (pseudostraitified ciliated columnar w/goblet cells)
thin partial capsule of dense connective tissue
204
lymph
clear fluid that circulates around body tissue
plasma that leaks from capillaries to surround & bathe tissues drains into lymphatic vessels
flows in one direction: to heart
filtered thru lymph nodes along way
205
what is the size of a lymph node?
pea-grape
206
what cells are found in the paracortex of a lymph node?
T cells
207
what cells are found in the medullary cords of lymph nodes?
plasma cells
208
where are B cells concentrated in lymph nodes?
cortical follicles
209
flow of lymph thru a lymph node
afferent lymphatic vessel→ subcapsular sinuses→ peritrabecular sinuses→ medullary sinuses→ efferent lymphatic vessels
210
what substructure are HEVs found?
paracortex
(of lymph nodes, tonsils, Peyer's patches, appendix)
211
functions of spleen
remove aged/damaged RBCs from circulation
mount immune response to antigen in circulating blood
212
structural features of spleen
enclosed by dense connective tissue capsule w/trabeculae
hilum w/neurovasculature
NO afferent lymph vessels
\*\*terminal arterial capillaries
213
red pulp
75% of spleen mass
where blood is filtered
sinusoids & splenic cords
214
white pulp
production site of lymphocytes which migrate to red pulp to enter circulation
mostly B cells
215
what are sheathed capillaries of the spleen sheathed by?
macrophages
216
PALS
**p**eri**a**rteriolar **l**ymphoid **s**heath
central splenic arteries surrounded by T cells w/nodules of B cells
217
role of the marginal zone
between PALS & red pulp
trap particulate antigen from circulation & present it to lymphocytes
218
stave cell
special elongated endothelial cells in spleen
oriented parallel to sinusoid's blood flow
wrapped in reticular fibers
219
how much of circulating blood is found in the spleen?
1/3
220
effects of splenectomy
modest increase of circulating WBCs & platelets
diminished responsiveness to vaccines
\*\*increased susceptibility to infecion by bacteria & protozoa
221
What are the components that make up the pharyngeal arches?
1. neural crest cells: a+v+n, skeletal component (cartilage)
2. mesenchymal core (will become musculature)
3. ectoderm (outside)
4. endoderm (inside)
222
what is a rhombomere?
segmentation of the neural tube in the hindbrain
223
what is the function of rhombomeres in pharyngeal development?
molecular cues to neural crest cells to migrate in formation of face, skull, thyroid, tongue, parathyroid, & thymus
224
When does the 1st pharyngeal arch apprear?
approximately D27
225
what indentation can be found just dorsal to the 2nd pharyngeal cleft?
otic pit forming the inner ear
226
what is the difference between a pharyngeal pouch and pharyngeal cleft?
clefts are found on the outside of the embryo; made of ectoderm
pouches are found on the inside of the embryo; made of endoderm
227
How many pharyneal arches are there?
6, but like the aortic arches only 5 form permenant structures (1, 2, 3, 4, & 6)
228
what is another name for pharyngeal arches evolutionarily speaking?
branchial arches
229
what nerve innervates the 1st pharyngeal arch?
CN V
230
what pharyngeal arch is innervated by CN X (vagus)?
4 by pharyngeal branch & 6 by recurrent laryngeal branch
231
what pharyngeal arch is innervated by CN IX (glossopharyngeal)?
3rd
232
what nerve innervates the 2nd pharyngeal arch?
CN VII (facial n)
233
what forms the malleus, incus & stapes of the inner ear?
1st 2 are formed by the 1st pharyngeal arch
stapes is formed by the 2nd paryngeal arch
234
What is Meckel's cartilage?
forms from the 1st pharyngeal arch
gives rise to the sphenomandibular ligament (among others)
235
what does the 1st pharyngeal cleft give rise to?
external auditory meatus
236
what does the 2nd pharyngeal cleft give rise to?
merges w/3rd & 4th pharyngeal clefts to form cervical sinus
237
what does the 3rd pharyngeal cleft give rise to?
merges w/2nd & 4th pharyngeal clefts to form cervical sinus
238
what does the 4th pharyngeal cleft give rise to?
merges w/2nd & 3rd pharyngeal clefts to form cervical sinus
239
what does the 1st pharyngeal pouch give rise to?
primitive tympanic cavity & auditory tube
240
what does the 2nd pharyngeal pouch give rise to?
palatine tonsil
241
what does the 3rd pharyngeal pouch give rise to?
inferior parathyroid glands
thymus
242
what does the 4th pharyngeal pouch give rise to?
superior parathyroid glands
ultimobranchial body (C cells of thyroid)
243
what muscles does the 1st pharyngeal arch give rise to?
muscles of mastication
244
what muscles does the 2nd pharyngeal arch give rise to?
muscles of facial expression
245
what muscles does the 3rd pharyngeal arch give rise to?
stylopharyngeus m.
246
what muscles does the 4th pharyngeal arch give rise to?
pharyngeal & laryngeal musculature
247
an external branchial fistula is a failure of what to form?
when the 2nd pharyngeal cleft fails to grow caudally to merge w/3rd & 4th arches
2nd & 3rd clefts are in contact w/surface & tonsils by a narrow canal
248
where are branchial fistulas & cysts normally found?
anterior to the sternocleidomastoid
249
what causes the formation of a lateral cervical cyst?
failure of the cervical sinus to obliterate
250
what malformation(s) of the 1st pharyngeal arch are seen?
Treacher Collins Syndrome
Pierre Robin Sequence
Goldenhar Syndrome
251
what are the key features of Treacher Collins Syndrome?
abnormalities of ears, palate, maxilla, & mandible
sunken cheeks & smaller lower jaw & chin
downward slanting eyes
252
what causes Treacher Collins Syndrome?
aka mandibulofacial disostosis
autosomal dominant mutation on Ch5
failed migration of neural crest cells in first branchial arch
253
key features of Pierre Robin Sequence
micrognathia (small mandible)
tongue displaces superiorly & falls to back of throat which my cause breathing problems
254
key features of Goldenhar Syndrome
aka hemifacial microsomia
\*one side of face affected\*
temporomandibular joint, mastication muscles, mandible, & ear often underdeveloped
255
Cause of DiGeorge Syndrome
specific deltion on ch22→ abnormal neural crest cell migration→ underdevelopment of 3rd & 4th pharyngeal arches
256
Characteristics of DiGeorge Syndrome
* **C**ardiac & aortic malformations: tetrology of Fallot or truncus arteriosus
* F**A**cial malformations: micrognathia, ear anomalies, & telecanthus (increased space between eyes)
* **T**hymus: fail or under development
* **C**left palate
* **H**ypotcalcemia: @ birth due to underdevelopment of parathyroid glands
257
When does the tongue appear during development?
W4-5
258
how does the 1st pharyngeal arch contribute to tongue formation?
two lateral lingual swellings & one medial
259
how does the 2nd pharyngeal arch contribute to tongue formation?
root of the tongue
260
how does the 3rd pharyngeal arch contribute to tongue formation?
root of the tongue
261
how does the 4th pharyngeal arch contribute to tongue formation?
root of the tongue & epiglottis formtation
262
what causes a bifid tongue?
failure of L+R lateral lingual swellings to fuse
263
what causes ankyloglossia?
aka tongue-tie
impaired development of alveolo-lingual sulcus (separates longue & floor of mouth)
264
thyroid gland formation
forms from the foramen cecum of the tongue & travels caudally via thyroglossal duct
265
where are thyroglossal duct cysts found?
along the midline of the neck (or paramedian)
caused from the persistence of thyroglossal duct
266
what forms the nose?
fusion of medial & lateral nasal processes
267
how is the upper lip formed?
fusion of medial nasal process & maxillary process
268
how is the philtrum formed?
fusion of the R+L medial nasal processes
269
what causes a mandibular facial cleft?
failure of R+L mandibles to fuse
270
what causes a cleft lip?
failure of R+L medial nasal processes OR maxillary processes to fuse
271
features of hyaline cartilage
chondrocytes embedded in collagen type II in amorphous ground substance
4 types GAG linked to hyaluronic acid to form proteoglycans
chrondronectin (glycoprotein)
272
functions of cartilage
support for soft tissue
shock absorption
gliding surface for joints
template for growth of long bones epiphyseal plates
273
features of cartilage
hard consistency due to collagen & proteoglycans
avascular, no lymphatics, no nerves
surrounded by perichondrium \*\*\*except articular cartilage & fibrocartilage\*\*
274
locations of cartilage
ends of lone bone & ventral end of ribs
joint surfaces
respiratory system & external ear
epiphyseal plates for growth of long bones
275
EM features of chondrocyte
large rER & extensive Golgi→ synthesis of collagens & GS
numerous dark particles containing proteoglycans
276
where are chondrocytes found?
singly or in isogenous groups (clusters) in lacunae
277
what determines chondrocyte function? and their effect?
growth hormone, thyroxine, & testosterone
increase synthesis of sulfated GAGs
278
what decreses GAG synthesis in chrondrocytes?
cortisol, cortisone, & estradiol
279
How does growth hormone control cartilage growth?
via somatomedin C (an insulin-like growth factor) from the liver
280
interstitial growth
chondrocytes w/in matrix divide forming isogenous groups
cells separate as they synthesize new matrix substances pushing away from each other
occurs early in development, in articular cartilage \*\*b/c no perichondrium\*\*, & in epiphyseal plates of long bones
281
appositional growth
new chondrocytes divide & form from growing zone just beneath the perichondrium- chondrogenic cells
282
differences among chondrogenic, chondroblast, & chondrocyte
chondrogenic cell: precursor cell
chondroblast: commited but immature chondrocyte
chondrocyte: mature cartilage cell, surrounded by matrix
283
features of elastic cartilage
chondrocytes embedded in collagen type II in amorphous ground substance
4 types GAG linked to hyaluronic acid to form proteoglycans
chrondronectin (glycoprotein)
IDENTICAL TO HYALINE CARTILAGE + ELASTIC FIBERS
284
locations of elastic cartilage
pinna of ear, external & internal auditory tubes, epiglottis, & larynx
285
features of fibrocartilage
NO perichondrium→ only interstitial growth
combination of dense connective tissue & hyaline cartilage
predominantly collagen type I→ stain pink
scant GS
\*\*support & tensile strength
286
locations of fibrocartilage
intervertebral discs, symphysis pubis, menisci of knee joints
287
what type of collagen is predominant in annulus fibrosus?
type I
288
what type of collagen is predominant in nucleus pulposus?
type II
derived from notochord
289
functions of bone
1. provide mechanical support for internal organs
2. permit locomotion via tendons
3. protection of vital organs
4. metabolic reservoir of Ca2+ & other mineral salts
290
osteoid matrix
non-mineralized organic matrix of bone
291
what are the main inorganic components of bone matrix?
calcium & phosphorus in the form of hydroxyapatite crystals
292
what are the organic components of bone matrix?
collagen type I→ acidophilic→ stains red/pink
GS: GAGs, proteoglycans, proteoglycan aggregates
glycoproteins
293
bone cell types
osteogenic (osteoprogenitor)
osteoblast
osteocyte
osteocyst
294
what do osteogenic cells derive from?
mesenchyme cells
295
what are osteoclasts derived from?
monocytes
296
where are osteogenic cells found?
inner cell layer of periosteum
lining Haversian canals
endosteum
297
appearance of osteogenic cells
flat cell w/pale-staining oval nucleus & sparse cytoplasm
298
what are matrix vesicles?
vesicles secreted from osteoblasts into ostoid matrix
contain Ca2+, PO42-, alkyline phosphatase, etc.
contributes to formation of hydroxyapatite crystallization
299
what is the differences between osteoblasts & osteocytes?
osteocytes are trapped in lacunae of calcified matrix
300
cannaliculi
cytoplasmic projections of osteocytes that form gap junctions w/adjacent osteocytes
301
osteocyte appearance
flat, almond shape
reduced rER & Golgi
302
function of osteocytes
maintanence of bone matrix via maintaining blood clacium levels
303
what three states are osteocytes found in?
1. quiescent: little rER; surrounded by mature calcified matrix
2. formative: lots of rER; deposition of osteoid in pericellular space w/in lacuna
3. resorptive: well developed rER, Golgi, & lysosomes; cells removes matrix
304
osteocytic osteolysis
mechanism of Ca2+ resorption by osteocytes in resorptive state to maintain blood Ca2+ levels
305
appearance of osteoclasts
very large cells
5-50 nuclei due to cellular fusion
extensive brached acidophilic cytoplasm→ red
306
from what are osteoclasts derived from?
monocytes
307
where are osteoclasts found?
in Howship's lacunae: shallow depressions on bone surface
308
what are the phases of bone resorption and where do they occur?
both occur at the ruffled border (infoldings of osteoclast plasma membrane formed by microfilaments)
1. dissolutiono of Ca2+ salts by organic acids from plasma membrane
2. lysosomal enzymes released from osteoclast to degrade matrix collagen
309
mechanism of bone resorption
1. H+ dissociated from bicarbonate
2. active transport of H+ into subosteoclastic compartment
3. reduced pH actson inorganic matrix
4. released matrix minerals enter capillaries via transport thru osteoclast
5. lysosomal enzymes released on decalcified bone
6. organic fragmetns taken up & further degraded by osteoclast
310
what is the effect of parathyroid hormone?
@ low levels: osteoblast & bone formation
@ high levels: stimulates osteoblast release of RANKL
311
what is RANKL and its effect?
**r**eceptor **a**ctivator of **N**F-**k**appaB **L**
released by osteoblasts upon stimulation with high levels of parathyroid hormone
binds to RANK on osteoclasts→ maturation & differentiation (increases # & activity of osteoclasts)→ bone resorption
312
Where is calitonin secreted from? and its function?
C-cells of thyroid
acts directly on osteoclasts for bone resorption
313
Function of somatotropin in bone development and where is it secreted from?
pituitary growth hormone
stimulates liver→ produces & secrets somatomedins (insulin-like growth factor)→ stimulates bone growth at epiphyseal plates
314
effect of somatotropin deficiency
dwarfism
315
effect of excess somatotropin
gigantism (giantism)
316
2 methods of bone classification
gross observation
OR
microscopic observation
317
characteristics of spongy bone
numerous interconnecting cavities & trabeculae (osseous projections)
irregular arrangement of lamelle in matrix
318
types of bone per gross obervation
spongy bone & compact bone
319
where can primary bone be found in adults?
tooth sockets, suture lines of skull, & insertion sites of tendons
320
primary bone
first bone to form in both fetal development & during bone repair
abundant osteocytes + haphazardly organized collagen fibers + low [mineral]= weak bone
remodeled & replaced by 2º bone
321
secondary bone
replaces primary bone
composed of parallel or concentric lamellae of collagen
calcified matrix
322
Sharpey's Fibers
strong collagenous fibers connecting periosteum to bone
323
osteon
functional unit of compact bone
concentric circles of osteocytes around Haversian canal (contains blood vessel)
bounded by cement line
324
layers of bone from exterior inward
* periosteum
* Sharpey's fibers
* compact bone
* outer circumferential lamellae
* osteons/interstitial lamellae
* inner circumferential lamellae
* endosteum
* spongy bone & marrow
325
which circumferential lamellae is thicker?
outer is thicker than inner
326
how does intermembranous ossification occur?
aka direct bone formation
mesenchymal cells condense→ osteogenic cell formation→ differentiation into osteoblasts→ creation of osteoid tissue & trabeculae→ primary bone formation→ remodeling→ lamellar compact bone formation
327
where intermembranous ossification seen?
ex. clavicle & skull bones
328
how does endochondral ossification occur?
hyaline cartilage is model for bone formation
* 2 phases:
* hypertrophy of cartilage & destruction of chondrocytes
* osteogenic bud penetrates empty space left by degenerating chondrocytes & osteogenic cells form osteoblasts
329
subperiosteal bone collar formation
* @ midregion of perichondrium: vascularization & of chondrogenic cells to osteogenic cells
* differentiation into osteoblasts→ now called periosteum
* intramembranous bone formation
this structure blocks nutrients from reaching inner cartilage→ degeneration→ calcification→ formation of lacunae for marrow spaces
330
where does the osteogenic bud form? and how does bone grow?
osteogenic bud invades via midregion bone collar
bone formation occurs in both directions
331
how does bone growth occur at the epiphysis of bones?
secondary ossification centers form in the center and expand outward
332
layers at epiphyseal plate
bone & calcified cartilage
* resting zone (reserve cartilage)
* proliferating zone (increase cell #)
* maturing & hypertrophic zone (increase cellular size)
* calcified cartilage zone (cellular death & release of Ca2+)
* ossification resorption zone
333
where do hormones affect bone growth?
cartilaginous proliferating zone of epiphyseal plate
334
how long is the epiphyseal plate present?
as long as # of proliferating zone cells \>/= # of resorption zone cells
usually until the end of puberty
335
role of vitamin D in bone formation
necessary for Ca2+ absorption in small intestines
336
effect of vitamin D deficiency
* children: Rickets
* poor calcification of bones
* deformed leg bones
* adults: osteomalacia
* newly formed bone not properly calcified
* bigger problem in pregnancy
337
role of vitamin C in bone formation
necessary for collagen formation
338
effect of vitamin C deficiency
scurvy
poor collagen production
reduction in bone matrix formation & development
healing problems
bleeding gum
339
role of vitamin A in bone formation
lack→ inhibits proper bone formation & growth
excess→ early ossification of epiphyseal plates
340
acromegaly
cause: excess GH in adults
effect: abnormal increase in bone formation w/o normal resorption→ thickening of bones of hands & face
341
osteopetrosis
genetic disorder of osteoclasts
no ruffle border→ can't resorb bone
342
osteoporosis
low bone density; thin trabeculae & wide Haversian canals
cause: increased bone resoption & decreased bone formation or both
effect: fragile bone
343
achondroplasia
defect of endochondral ossification
reduced chondrocyte proliferation at epiphyseal plate
\*\*cause of most common form of inherited dwarfism
344
somites are divided into
sclerotomes & dermomyotomes
345
where are sclerotomes found?
ventral medial portion of somite
346
where is the epaxial dermomyotome located & what does it form?
dorsal portion of somite
differentiates into erector spinae muscles & skin of back
347
where is the hypaxial dermomyotome and what does it form?
vetrolateral portion of somite
skin & muscles of limbs & thorax
348
formation of mature myotubes?
muscle cell progenitor→ myoblast→ fusion of myoblasts→ nascent myotube→ sarcomere assembly→ mature muscle fiber cell (myotube)
349
syncytium
fusion of two muscle precursor cells
350
satellite cells
resident population of muscle precursor cells in adults
351
where are nuclei found in skeletal muscle?
in the perphery
352
what cell type is found between muscle cells?
fibroblasts
353
functions of muscle
produce movement by acting on bones, pumping blod, or propelling
maintain posture
stabilize joints
generate heat during metabolic processes
354
muscle cell
muscle fiber
355
cytoplasm of a muscle cell
sarcoplasm
356
muscle cell membrane
sarcolemma
357
sarcoplasmic reticulum
sER of muscle fiber
358
classification of skeletal muscle
striated & voluntary
359
classification of smooth muscle
non-striated & involuntary
360
classification of cardiac muscle
striated & involuntary
361
what muscle(s) are derived from ectoderm?
muscles of pupil
362
endomysium
tissue sheath covering a single muscle fiber, small diameter blood vessels, & finest neuronal branches
363
perimysium
tissue sheath surround a group of muscle fibers w/larger blood vessels & nerves
364
epimysium
dense connective tissue sheath that surround a collection of fasicles w/major blood vessels & nerves
around whole muscle
365
how is epimysium attached to bones?
direct: fused to periosteum or pericondrium
OR
indirect: epimysium extens as tendon or aponeurosis before attaching to periosteum, perichondrium, or fascia of otehr muscles
366
where are satellite cells found?
between sarcolemma & external lamina
367
what is the external lamina?
basal lamina of muscles fibers
368
what is a myofibril?
bundle of myofilament (contracile proteins- actin & myosin)
made of repeating units of sarcomeres
369
sarcomere
contractile unit of myofibril
begins & ends @ Z-line (Zwischenscheibe)
370
what are thick filaments made of?
myosin
371
what are thin proteins made of?
actin
372
Anisotropic band
aka A band
length of myosin filament
373
isotropic band
aka I band
runs between sarcomeres
Z-line/disc (Zwischenscheibe) runs in middle of I band
from end of one myosin filament to the beginning of the next
shortens during contraction
374
Zwischenscheibe
A-line/disc
connection point of sarcomere to sarcolemma
found between end of one titan (elastic) filament and the start of the next
(titan filaments are attached to the ends of myosin filaments)
dark line in the middle of the lighter I-band
375
Hell
H zone
center section of A band where myosin & no actin is found when sarcomere is relaxed
lighter area of A band
376
Mitte
aka M line
center of movement in sarcomere
thick filaments (myosin) is connected via accessory proteins
connected to sarcolemma
377
what protein integrates the sarcolemma with the Z-line?
desmin
378
what blocks myosin from binding actin in resting sarcomeres?
tropomysin
379
rigor mortis
stiffening of muscle after death
caused by calcium release→ myosin binds actin
no ATP to release the bound myosin
380
rule of Nysten
rigor mortis starts 1hr after death & reaches maximum 12hrs after death depending on temperature
381
where does the triad sit? what components make up the triad?
@ A/I band junction
terminal cisterna of sarcoplasmic reticulum, T tubule of sarcolemma, terminal cisterna of sarcoplasmic reticulum
382
motor unit
lower motor neuron & muscle fibers it innervates
383
how many muscle fibers are innervate/lower motor neuron in mimetic muscles? in postural muscles (back or thigh)?
face: \<100fibers/neuron
postural \>1000/neuron
384
type I muscle fibers
aka slow, red, or oxidative fibers
many mitochondria & abundant myoglobin
derive energy primarily form aerobic oxidative phosphorylation of fatty acids
adapted for slow, continuous contractions over prolonged periods
ex. postural muscles of back
385
type IIa muscle fibers
aka fast or intermediate oxidative-glytolytic fibers
many mitochondria & myoglobin, but less than type I
also contains glycogen
utilize both oxidative & anaerobic (glycolytic) metabolism
adapted for rapid contractions & short bursts
386
type IIb muscle fibers
aka fast, white, or glycolytic fibers
fewer mitochondria, less myoglobin, abundant glycogen
pale color
uses glycolysis for energy
adapted for rapid contraction, but fatigue quickly
typically small muscles w/relatively large # NMJs
ex. muscles of eyes & digits
387
muscle spindles
stretch detectors among muscle fasicles
composed of intrafusal fibers
sensory nerve fibers penetrate muscle spindles & wrap around individual intrafusal fibers
388
intrafusal fibers
connective tissue capsule surrounding fluid-filled space
contains few thin, non-striated muscle fibers, densely filled w/nuclei
389
where does cardiac muscle derive from?
splanchnic mesoderm of primitive heart tube
390
histological appearance of cardiac muscle
* one or two centrally located nuclei
* glycogen storage
* numerous mitochondria (40% of cytoplasmic V)
* lipofusin granules appear yellowish
* cells connected at intercalated discs
* often branch after intercalated disc
391
why are desmosomes & fascia adherens present at intercalated discs?
to prevent cardiac muscle cells from pulling apart under constant contractile activity
\*in transverse regions of intercalated discs
392
why are gap junctions present in intercalated discs?
provide ionic continuity between adjacent cells→ allow cardiac muscle to act as multinucleated syncytium→ contraction signals passing in wave from cell to cell
\*in longitudinal portions of intercalated discs
393
What components make up a diad? where is it found?
@ Z line/disc
terminal cisterna of sarcoplasmic reticulum & T-tubule of sarcolemma
394
origin, target & effect of ANF
ANF= atrial natriuretic factor
origin: granules of cardiac muscle, mostly R atrium but L too
target: kidney→ induce loss of sodium & water
effect: lower blood pressure
395
what initiates, regulates, & coordinates the heart beat?
cardiac conducting cells= specialized & modified cardiac muscle cells
exhibit inherent & spontaneous rhythmic contraction
SA & AV nodes & fibers: Bundle of His & Purkinje
396
what innervates cardiac muscle?
motor: cardiac conducting cells (AV, SA, His, & Purkinje)
parasympathetic & sympathetic fibers modify heart rate at nodes only
397
why can't cardiac muscle regenerate?
it lacks satellite cells
398
what is responsible for regeneration of smooth muscle?
pericytes (from walls of small blood vessels)
399
histological appearance of smooth muscle
small, spindle shape w/one central nucleus
lack of connective tissue→ NO epimysium
NO striation→ NO sarcomeres
arranged into sheets of opposing fibers forming circular & longitudinal layers
400
where is calcium stored in smooth muscle?
sarcoplasmic reticulum, but since less developed compared to other muscle types, also caveolae of cell membrane
401
Since smooth muscle does not have sarcomeres, what do muscle filaments attach to?
anchored to sarcolemmma & surrounding tissue via dense bodies
402
How is smooth muscle innervated?
NO NMJs
autonomic nerve fibers release neurotransmitters into wide synaptic cleft
403
Smooth muscle does not have troponin, so how is tropomyosin moved aside for myosin binding?
calmodulin
404
what filaments in smooth muscle do pathologists use to determine tumor type?
desmin & vimentin
405
what does contracted smooth muscle look like?
waves
406
single-unit smmoth muscle
most common of smooth muscle types
contracts rhythmically as a unit
electrically coupled via gap junctions & exhibits spontaneous action potentials
ex. GI tract
407
multi-unit smooth muscle
structurally independent cells, has motor units, capable of graded potentials
ex. large airways, large arteries, iris of eye, arrector pili of hair follicles
408
what are myocardial endocrine cells?
in atria, more in R than L
produce & store atrial natriuretic factor in granules
released & targeted to kidney to induce loss of sodium & water to lower blood pressure
409
When do the limbs form?
upper limbs buds form end of W4 & lower beginning W5
toes & fingers formed by end of W8
410
what are the limb buds derived from?
lateral plate mesoderm core covered by ectoderm
ectoderm forms skin
lateral plate mesoderm forms bones & connective tissue
411
what are the muscles derived from?
somites & somitomeres formed form paraxial mesoderm
412
difference between somites & somitomeres
somitomeres are in the head region
somites are all the others caudal to the occiput
413
what is cardiac muscle derived from?
splanchnic mesoderm surrounding primitiva heart tube
414
what is smooth muscle derived from?
splanchnic mesoderm, except for muscels of the pupil which are derived form the neuroectoderm
415
where does the dermomyotome come from?
dorsolateral ascpect of the somite
416
what does the dermomyotome differentiate into?
dermis of the skin
& myotome→ gives rise to skeletal muscle
417
what is the ventromedial aspect of the somites referred to and what does it become?
sclerotome
cells surround the neural tube & become the vertebral column
418
What makes up the intervertebral discs?
mesenchymal tissue composes the annulus fibrosus
notocord forms nucleus pulposus
419
how are vertebra formed?
caudal half of sclerotome grows & fuses with cephalic half of adjacent sclerotome
each on is 50% caudal half of one somite & 50% cranial half of next somite
420
cause of scoliosis
2 successive vertebrae fuse asymmetrically or half of a vertebra is missing
421
cleft vertebra
aka spina bifida
imperfect fusion or non-union of vertebral arches
422
spina bifida occulta
incomplete vertebral arches, but intact spinal cord
423
epimere
dorsal division of myotome
gives rise to muscles of the back that are innervated by dorsal rami of spinal nerves
424
hypomere
ventral division of myotome
gives rise to lateral & ventral muscels of thorax & abdomen & limb muscles
all muscles innervates by ventral rami of spinal nerves
425
what hypomere regions do teh limb skeletal muscles arise from?
upper: C5-C8
lower: L3-L5
426
what muscles are in the posterior condensation of the limbs?
upper: extensors & supinators
lower: extensors & abductors
427
what muscles are in the anterior condensation of the limbs?
upper: flexsors & pronators
lower: flexsors & adductors
428
what ventral rami innervate the limb buds?
upper: C5-T1
lower: L4-S3
429
when and in what direction do the limbs rotate?
W6-8
upper: laterally→ flexors are anterior
lower: medially→ flexors are posterior
\*\*this is why dermotomes spiral around limbs
430
how are the digits formed?
lateral plate mesoderm secretes FGF7 & FGF10→ induction of overlying ectodermal growth→ formation of apical ectodermal ridge (AER)→ AER promotes mesodermal growth→divisin of cells in proximo-distal progress zone→ bone morphogenic protein (BMP) controls interdigital cell death
431
syndactylyl
fused digits
432
Amelia
complete absence of a limb
cause: early loss of FGF signaling
433
Meromelia
partial absence of limb
cause: later of partial loss of FGF signaling
434
phocomelia
aka flipper limb
digits develop prematurely
proximal elements of limb absent
435
micromelia
all segements are present but abnormally short
436
polydactylyl
extra digits
437
brachydactyly
short digits
438
ectrodactylyl
absence of a digit
439
split hand/foot
aka lobster claw deformity
abnormal cleft between 2nd & 4th metacarpal/metatarsal
absence of 3rd phalanx & its meta-
\*more commonly found in the foot\*
440
amniotic band syndrome
fetus is entangles in strands of fibrous & string-like amniotic bands
bands restrict blood flow & fetal growth & development
441
what forms the axial skeleton?
paraxial mesoderm
442
what forms the bones of the limbs?
somatic layer of lateral plate mesoderm
443
what are the circoid & thyroid cartilages?
lateral plate mesoderm
444
what forms the posterior skull bones?
paraxial mesoderm
445
what forms the anterior bones of the skull?
neural crest cells
446
when does the posterior fontanelle close?
1-2 months
447
when does the anterior fontanelle close?
7-19 months
448
scaphocephaly
long & narrow skull
cause: early closure of sagittal suture
associated w/protuberance of frontal bones
449
acrocephaly
aka tower skull
pointed or conical shape
cause: remature closure of coronal suture
450
what are the functions of skin?
protect body from injury, desication, & infection
regulate body temperature
absorb UV light for vitamin D synthesis
contains receptors for touch, temperature, & pain stimuli from external environment
451
what are the layers of skin?
epidermis & dermis
hypodermis/subcutaneous fat layer is NOT considered part of skin
452
what embroynic layer is the epidermis derived from?
ectoderm
453
what embryonic layer is dermis derived from?
mesoderm
454
what is the cellular composition of epidermis?
keritinized squamous cell epithelium
455
where do hair, nails, sesbacous & sweat glands come from?
they are all derived from epidermis
456
what is the composition of dermis?
dense connective tissue
457
where is thick vs. thin skin found?
thick skin is on the palmar aspect of the hand & plantar aspect of the foot only----NO hairs
thin skin is everywhere else, usually has hairs
458
what forms the fingerprints?
the interdigitation of the epidermal pegs (invaginations of epidermis) into the dermal papillae (projections of dermis)
interdigitation occurs everywhere, but this is one location where we can see it on the surface
459
If the upper portion of the back has the thickest skin, why is it not considered thick skin?
because thick/thin classification is a misnomer
they are classified only on the thickness of the epidermal layer of skin
460
what are the layers of thick epidermis?
superficial to deep
1. stratum corneum
2. stratum lucidum
3. stratum granulosum
4. stratum spinosum
5. stratum basale
461
what layer of epidermis is only observable in thick skin and not thin skin?
stratum lucidum
462
how long does it take for the skin to be completely replaced?
15-30 days dependent on location (temperature, humidity) & care (location, etc)
463
what protein increased in amount as keratinocytes rise thru the epidermal layers?
keratin intermediate filaments
464
what characterizes the stratum basale layer of epidermis?
CONTAINS STEM CELLS- very high mitotic activity
SINGLE layer of cells
bound to basal lamina via hemidesmosomes & to each other & the stratum spinosum via desmosomes
contain keratin intermediate filaments
465
what characterizes the stratum spinosum layer of epidermis?
polyhedral-shaped keratinocyte→ desmosomes give them this shape→ aka prickle cells
few layers
lower layers are also mitoticaly active
466
what is the stratum germanitivum?
old name= malpighian layer
layers of cell division
stratum basale + stratum spinosum
467
what are tonofilaments?
old name for keratin intermediate filaments
468
what characterizes the stratum granulosum of epidermis?
LAST LAYER with nuclei
2-5 layers of flattened keratinocytes
cytoplasm filled w/**basophilic keratinohyalin granules**- binds keratin filaments together
granules are not membrane bound
469
what "waterproofs" the skin?
lipid containing sheets expelled from lamellar granules form stratum granulosum & stratum spinosum
also functionally considered to be intracellular cement in stratum granulosum
470
what characterizes teh stratum lucidum of epidermis?
clear layer superficial to stratum granulosum
only observable in thick skin
keratinocytes have no nucleus & no organelles, but do have keratin filaments
471
what characterizes the stratum corneum?
15-20 layers of flattened dead squames (non-viable, scale-like structures)
filled w/keratin
outermost layer
site of desquamation
usually thinner in thin skin than thick
472
what layers of epidermis display desmosomes?
stratum basale
stratum spinosum
stratum granulosum
473
what layer of the epidermis is waterproof?
stratum granulosum
474
what layers of the epidermis do not have nuclei?
stratum lucidum & stratum corneum
475
what layers of epidermis are mitotically active?
stratum basale & lower layers of stratum spinosum
476
What does thick skin lack compared to thin skin?
hair follicles & sebaceous glands
477
what causes a callous & why?
thickening of stratum corneum
due to pressure, skin grows more quickly to protect itself
most often foudn in thick skin
478
what is the cause & treatment of a wart?
cause: papillomavirus
effect: epidermal hyperplasia
tx: salicyclic acid→ dissolves keratins
479
besides keratinocytes, what other cell types are found in the epidermis?
melanocytes, Langerhan's cells, & Merkel cells
480
what is the function & appearance of melanocytes?
sit in stratum basale with processes between keratinocytes into stratum spinosum→ dendritic appearance
synthesize & release melanin pigment→ protects DNA of dividing cells from UV radiation from sun
481
what determines the color of skin, hair, & eyes?
melanin
482
what do melanocytes synthesize melanin from?
tyrosine
via tyrosinase (activated by UV light→ why skin darkens with sun exposure)
483
why is no melanin found in cells of the stratum corneum?
because when melanin granules are received by keratinocytes they fuse with lysosome that begin degrading the melanin
484
reasons for darker skin coloring
* melanocytes produce more melanin- NOT increase # of melanocytes
* slower melanin degradation
485
where is melanin found in keratinocytes?
between the sun & the nucleus to shield the DNA from radiation
486
what are the types of melanin & where are they found?
* eumelanin
* black/brown hue
* more common form
* hair, areola, skin
* pheomelanin
* pink/red hue
* redhair, lips, nipples, glans penis, & vagina
487
what causes a freckle?
hyperpigmentation in localized spot due to sun exposure
488
what is the difference between a mole & a nevus?
a mole is a group of melanocytes in the skin & considered a type of nevus
a nevus is any pigmented spot on the skin
489
what causes albinism?
2 different autosomal recessive genes on different chromosomes:
* absence of tyrosinase activity OR
* cellular inability to uptake tyrosine
490
Why must albinos avoid the sun?
because they aren't just fair they do NOT produce melanin
they will acquire DNA damage→ skin cancer
491
what is a suspected autoimmune disorder that attacks melanocytes?
vitiligo
492
Why did people evolve to become paler as they migrated north?
less sun→ vitamin D deficiency
light skin has less melanin blocking UV rays need to make vitamin D
493
what are Langerhans cells & their function?
DC cells that have migrated into epidermis
function: APC
494
Where are Merkel cells found & what is their function?
small # in stratum basale
connect to keratinocytes via desmosomes
store & relase neurocrine-like substance
function: touch receptor
495
what are the layers of the dermis?
papillary & reticular
496
what are the main components of dermis? why?
collagen type I & elastic fibers
b/c they give skin resilience & elasticity
497
what causes wrinkling?
extensive cross-linking of collagen fibers
loss of elastic fibers
degeneration of collagen or elastic fibers by sun exposure
498
how does skin receive nutrients?
dermal papillae contain capillaries
epidermis via diffusion from underlying capillaries in dermis
499
what is the difference between a bruise & a contusion?
bruise: capillary damage that allows blood to seep into surrounding tissues
contusion: bruise caused by trauma
500
what causes a blister?
epidermis separates from dermis
pool of lymph & bodily fluid accumulates in the space created
usually found in thick skin
501
what is a hemangioma?
most common type of birthmark, often at birth & disappears
many new blood vessels grouped together in one place on the skin
502
what type(s) of nerve receptors are found in skin?
1. free nerve endings
2. Meissner's corpuscles
3. Pacinian corpuscles
4. Merkel cells w/associated nerve
5. Ruffini's corpuscle
503
corpuscle
rounded globular mass of cells
504
what types of receptor/information do free nerve endings transmit?
fine touch, heat, cold, pain, & itching
505
where do free nerve endings terminate?
stratum granulosum
506
what type of nerve receptor is sensitive to hair movement?
free nerve endings
507
what part of the body are Merkel cells most abundant?
where sensory perception is most acute
ex. finger tips
508
Where are Pacinian corpuscles found in skin?
deep dermis & hypodermis
509
what function do Pacinian corpuscles fulfill?
deep pressure sensation & vibrations
510
how are Pacinian corpuscles activated?
pressure/vibrations→ displaces capsule lamellae→ opens mechanically-gated ion channels
multilayered capsule surrounds terminal of afferent axon
511
what skin receptor contains mechanically gated ion channels?
Meissner's corpuscles
Pacinian corpuscles
Ruffini's corpuscles
512
where are Meissner's corpuscles found in skin & body?
in dermal papillae, just below epidermal basal lamina
areas sensitive to tactile stimulation: lips, external genitalia, & nipple
513
in what layer of skin are Ruffini's corpuscles found?
deep dermis
514
what type of information do Ruffini's corpuscles transmit?
stretch
515
what is specialized about the structure of Ruffini's corpuscles?
elongated, spindle-shaped capsule
oriented parallel to stretch lines of skin
516
what type of neurons correspond to skin receptors?
pseudounipolar axons
517
what is the function of the Glassy membrane?
thickened basement membrane separating dermis from epithelium of hair follicle
518
where does hair obtain its color from?
melanocytes in epidermis over dermal papilla of hair bulb
519
how does hair grow?
via proliferation of matrix cells at hair bulb
(homologous to proliferation at stratum basale
520
how do hairs move?
contraction of arrector pili muscles make hair stand up
arrector pili originate in connective tissue of hair follicle & insert into papillary layer of dermis
521
what causes cutis anserina?
coloquially: goosebumps
cold & strong emotions: fear, awe, admiration, & arousal
522
what type(s) of glands are found in the skin?
eccrine, apocrine, & sebaceous
523
what is the product & function of eccrine glands?
sweat
thermoregulation
524
what type of secretion is utilized by eccrine glands?
merocrine (simple exocytosis)
525
how do eccrine glands develop?
invaginations of epithelium of dermal ridge
grows down into dermis
526
where are glands found in the skin?
dermis only
527
where are eccrine glands found in the body?
everywhere
528
where are apocrine glands found in the body?
armpits, areolae, anal region
529
where are sebaceous glands found in the body?
everywhere except palms & soles of feet
msot abundant on face & scalp
530
what controls eccrine glands?
postganglionic sympathetic fibers
531
explain histology of eccrine glands
dark cells contain lumen form duct to surface of skin
clear cells produce & secrete sweat
myoepithelial cells (beneth clear cells) contract & aid in expressing gland's secretions into duct
532
where do the ducts of the skin glands open to?
eccrine→ skin
apocrine→ hair follicle
sebaceous→ hair follicle
533
when do the skin glands start working/producing their secretions?
eccrine→ birth
apocrine→ puberty
sebaceous→ puberty
534
what gland displays merocrine secretion?
apocrine & eccrine
535
what gland displays holocrine secretion?
sebaceous
536
which gland has the largest lumen & why?
apocrine
b/c product is stored in the lumen of the duct
537
why does apocrine secretion smell bad?
metabolism of secretory product by surface bacteria
538
what is the product of sebaceous glands & its function?
sebum
prevents water loss from skin
lubricates hair
possible antibacterial & antifungal properties
539
what causes acne?
chronic inflammation of obstructed sebaceous glands
540
where do sebaceous glands open directly to the skin?
glans penis, glans clitoris, & lips
541
what is the analogous the stratum corneum at the nail bed?
nail plate
542
where does nail growth occur?
the nail root NOT the nail bed
543
why do stitches prevent scarring?
scarring is when fibroblasts fill a cut with colagen
so sutures allow the skin to knit back together & form new epidermis
to reform epidermal layer of keratinocytes
544
what happens when the wound healing response doesn't revert beck to resting?
formation of keloids (fibrous growths)
caused by continuous collagen production
545
who gets keloids?
usually a genetic predisposition
more common among darker pigmented races
546
what causes stretch marks?
tearing of the dermis
547
what causes cellulite?
formation of fibrous septae cause dimpling
decreasing fat is the only method for reducing cellulite
only found in women
548
what skin layers are injured in a first degree burn?
aka scald
any to all layers above the stratum basale
549
what skin layers are injured in a second degree burn?
all epidermal layers are destroyed
BUT keratinocytes from hair follicles can replenish epidermis
can involve upper layers of dermis
550
what type of burn results in blistering?
second degree burn
551
what skin layers are injured in a third degree burn?
all of epidermis & dermis w/some invasion into subcutaneous fat
only replaced by skin graft
NO pain (burned away the receptors)
552
what causes sunburn?
acute inflammatory reaction to ultraviolet radiation
553
if skin is constantly lost due to desquamation, how do tatoos work?
pigment droplets are trapped between epidermis & dermis
554
how are tatoos removed?
laser light breaks pigment droplets up into pieces small enough for macrophage or more likely Langerhans cells to phagocytose
555
