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Microanatomy > SM01 Mini4 > Flashcards

SM01 Mini4 Flashcards

1
Q

functions of blood

A
  1. transports O2, CO2, hormones, nutrients, & waste
  2. stabilizes pH & electrolyte concentrations of interstitial fluids
  3. regulation of blody temperature
  4. migration pathway for WBCs
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2
Q

What are the three formed elements of blood?

A
  1. erythrocytes (RBC)
  2. leukocytes (WBC)
  3. platelets
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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)

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4
Q

serum

A

plasma lacking fibrinogen

collected without anticoagulation

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5
Q

blood clot

A

fibrin strings connecting trapped blood cells

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6
Q

Wright stain

A

mixture of methylene blue & eosin

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7
Q

methylene blue

A

basic/positively charged dye

stains acidic/negatively charged cellular structures blue

ex. DNA, RNA, specific granules of basophils

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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

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9
Q

azures

A

stain reddish blue when methylene blue is oxidized

ex. lysosomes

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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

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11
Q

hematocrit

A

percentage (v/v) of packed RBCs in given sample of blood after centrifugation

higher in males than females

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12
Q

erythropoietin

A

hormone

secreted by kidneys in adults; liver in fetus

stimulates RBC production to match O2 demand

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13
Q

What is the life span of an erythrocyte?

A

120 days

then phagocytosed in spleen, liver, or bone marrow→ hemoglobin recycled

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14
Q

Rouleaux

A

stacking of erythrocytes seen in capillaries

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15
Q

Why do erythrocytes have a biconcave shape?

A

to maximize their surface area to volume ratio→ maximize O2 exchange

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16
Q

anisocytosis

A

RBCs of unequal size

microcyte: less than 6um
macrocyte: greater than 9um

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17
Q

How do RBCs pass easily thru smaller blood vessels?

A

increased flexibility via spectrin

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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

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19
Q

dendritic cells

A

differentiate from monocytes in tissue

best anitgen-presenting cells in body

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20
Q

granulocytes

A

have specific granules

differentiated by Wright stain rxns

neutrophils, eosinophils, & basophils

non-dividing terminal cells w/life span of days

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21
Q

agranulocytes

A

no specific granules

but do have nonspecific azurophilic granules (lysosomes)

lymphocytes & monocytes

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22
Q

Why do neutrophils have a mulitlobed nucleus?

A

aides in moving between tissues as they are more flexible

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23
Q

What are the main components of pus?

A

dead neutrophils & dead bacteria

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24
Q

function of neutrophils

A

first line defense of bacterial infection

sense chemical gradients near them

active phagocytosis of bacteria

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25
Q

neutrohils microscopy

A

identified by 3-5 lobed nucleus

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26
Q

Why do neutrophils use glycosis for ATP generation?

A

allows them to survive in anaerobic environment→ kill bacteria & clean up debris in poorly oxygenated regions (inflammed or necrotic

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27
Q

what is the life span of neutrophils?

A

6-7 hours in blood

1-4 days in connective tissue

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28
Q

chemoattractors

A

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

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29
Q

chemotaxis

A

crawling along s soluble concentration gradient towards source of attractant

cell driven by lamellipodi

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30
Q

what does mitochondria release during necrosis that causes inflammation?

A

N-methylated oligopeptides

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31
Q

cytokine

A

non-antibody protein released by spefic cell type as part of body’s immune response

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32
Q

chemokine

A

cytokine that can induce chemotaxis of a leukocyte during inflammation

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33
Q

classic symptoms of inflammation

A

swelling, redness, heat, & pain

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34
Q

What is the purpose of acute inflammation?

A

ease travel of leukocytes & plasma proteins to injury site

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35
Q

chronology of acute inflammation

A
  • increase blood flow via vasodilation
  • loosening of capillary endothelial cell tight junctions
  • emigration of leukocytes form microcirculation
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36
Q

diapedesis

A

passage of WBCs thru intact capillary walls into surrounding tissue

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37
Q

myeloperoxidase

A

in lysosomes of neutrophils

generates highly reactive hypochlorite & chloramines

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38
Q

neutrophil oxidative burst

A

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

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39
Q

chronic granulomatous disease

A

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

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40
Q

granuloma

A

localized nodular inflammation found in tissue

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41
Q

Where is collagenase in neutrophils & why do they have it?

A

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

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42
Q

neutrophil extracellular traps

A

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

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43
Q

eosinophil microscopy

A

bilobed nucleus

large, pink specific granules

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44
Q

functions of eosinphils

A

parasitic infections (generally multicellular)

phagocytosing antigen-antibody complexes

control mechanisms in allergy & asthma

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45
Q

parasite

A

organism that grows, feeds, & is sheltered on or in a different organism while not contributing to survival of host

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46
Q

eosinophil killing

A

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

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47
Q

internum

A

thick band seen on specific granules of eosinophils

produced by major basic protein

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48
Q

eosinophilia

A

increase # of eosinophils in blood

causes: parasitic infection OR allergic rxn

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49
Q

basophil microscopy

A

S-shaped nucleus

nucleus commonly masked by large dark blue specific granules

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50
Q

What do specific granules of basophils contain?

A

heparin & histamine

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51
Q

difference between basophils & mast cells

A

basophils- in blood

mast cells- in CT

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52
Q

functions of basophils

A

release of mediators: histamine, serotonin, prostaglandin, & leukotrienes

increases blood flow to area & adds to infammatory process

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53
Q

lymphocytes

A

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

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54
Q

What is the life span of a lymphocyte

A

few days- years

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55
Q

lymphocyte microscopy

A

1.5 size of erythrocyte

dense, round nucleus that takes up most of the cell

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56
Q

Monocyte functions

A
  • phagocytosis
  • destroy dead & defunct cells & antigen/foreign particulate matter
  • immune response
  • **precursor of macrophages (differentiate in CT)
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57
Q

monocyte microscopy

A

largest blood cell: 12-20um (3x erythrocyte)

large, kidney-shaped nucleus

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58
Q

macrophage

A

differentiates from monocyte when it enters CT

connective tissue surrounding it will determine exact final differentiation

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59
Q

platelets

A

aka thrombocytes

pieces derived from megakaryocyte

life span= 10 days

no nucleus, but do have lysosomes, mitochondria, ER, Golgi, 3 types granules, & *extensive cytoskeleton*

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60
Q

megakaryote

A

giant precursor cell of platelets

never leaves bone marrow, but reaches appendages out into the blood stream

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61
Q

function of platelets

A
  • 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
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62
Q

von Willebrand factor

A

promotes adhesion of platelets to endothelial cells

produced by platelets & endothelial cells

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63
Q

platelet factor IV

A

stimulates blood coagulation

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64
Q

where is post-natal blood made and how does it change with age?

A

red bone marrow

of bones reduced w/age for relatively constant area of red bone marrow

in cancellous bone

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65
Q

how does the body respond to severe blood loss (to replace blood)?

A

transition of yellow bone marrow to red bone marrow

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66
Q

hematopoiesis

A

process of blood cell formation

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67
Q

yellow bone marrow

A

yellow due to adipose cells

seeded w/some hematopoietic cells

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68
Q

hematopoietic stem cell

A

multipotent cell

gives rise to all 3 formed elements in blood

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69
Q

mesenchymal stem cell

A

pluripotent

can differentiate into osteoblast, chondroblast, mycocyte, & others

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70
Q

how is the stem cell population kept constant?

A

only one daughter cell differentiates

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71
Q

totipotent

A

cell can differentiate into anything

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72
Q

pluripotent

A

blastocyst inner cell mass

can become all cell types except extra-embryonic

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73
Q

where is fetal blood made?

A

5+5

blood precursors from yold sac mesoderm

5W→ fetal liver

5M→ bone marrow

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74
Q

red bone marrow

A

colored red due to presence & formation of blood

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75
Q

bone marrow stroma

A

“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

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76
Q

bone marrow sinusoids

A

blood vessels where mature blood cells enter blood stream

lined by endothelial cells w/discontinuous basal lamina

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77
Q

what do reticular cells secrete in the stroma?

A

reticular fibers (type III collagen)

cytokines that stimulate development of progenitor cells into blood cells

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78
Q

why is it important that the basal lamina of endothelium of bone marrow sinusoids be discontinuous?

A

it’s how the newly formed blood cells enter, between the endothelial cells

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79
Q

stages of lymphocyte development

A

hematopoietic stem cell→ lymphoid stem cell (CFU-L)→ T or B lymphocyte

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80
Q

CFU

A

colony forming unit

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81
Q

GEMM

A

granulocyte, erythrocyte, monocyte, megakaryocyte

should ahve one more M for Mast cells

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82
Q

What blood cell does not differentiate in bone marrow?

A

T lymphocytes migrate to & differentiate in the thymus

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83
Q

erythropoiesis

A

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

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84
Q

what are the derivatives of the mesonepheric ducts?

A

males: vas deferens, seminal vesicle, & epididymis as induced by testosterone & eferent ductules
female: degenerate due to absence of testosterone

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85
Q

what is the testis-determining factor?

A

SRY protein

coded for by SRY gene

on Y chromosome

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86
Q

what embryonic layer are the gonads derived from?

A

intermediate mesoderm

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87
Q

genital ridges

A

formed by proliferation of coelomic epithelium & condensation of mesenchyme from mesonephric ridge

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88
Q

where do primordal stem cells originate?

A

epiblast of yolk sac wall

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89
Q

where do primordial stem cells migrate to? what happens when they fail?

A

genital ridge during W4-W5

invade sex cords W6

if they don’t→ gonads don’t develop

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90
Q

how are primitive sex cords formed?

A

epithelium proliferates & penetrates underlying mesenchyme in medulla of indifferent gonads

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91
Q

what do the primitive sex cords become?

A

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

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92
Q

when does the tunica albuginea form?

A

coincides w/testis cord formation

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93
Q

origin & funtion of Leydig cells

A

mesenchyme between testis cords

testosterone secretion W8 as stimulated by hCG (human chorionic gonadotropin)

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94
Q

when does lumenization of the testis cords occur?

A

during puberty

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95
Q

location & function of sertoli cells

A

secretion of mullerian inhibiting substance (aka anti-mullerian hormone)

found in testis

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96
Q

what effect does mullerian inhibiting substance have?

A

suppresses development of paramesonephric ducts in males

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97
Q

where & when do the paranephric ducts form?

A

D44-48

longitudinal invaginations of surface epithelium later to mesonephric ducts

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98
Q

where do the paranephric ducts terminate & open?

A

on urogenital sinus between ends of mesonephric ducts

cranial opening into coelomic cavity

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99
Q

what forms the paradidymis?

A

caudal mesonephric tubules as they degerate

location: caudal end of epididymal connection to testis

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100
Q

what forms the appendix epididymis?

A

cranial mesonephric duct

location: cranial to efferent ductules & distal from testis relative to appendix testis

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101
Q

what are the derivatives of the paranephric ducts?

A

males: appendix testis (cranially) & prostatic utricle (distally)
females: uterine tubes, uterus, & upper vagina

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102
Q

what female structure is the prostatic utricle homologous with?

A

uterus & upper vagina

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103
Q

cortical cords

A

2nd generation of medullary cords in ovary development

w/oogonia

form in W7

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104
Q

what happens to the coritcal cords in M3?

A

split into isolated cell clusters

proliferate into primary oocyte surrounded by follicular cells

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105
Q

primordial follicle

A

primary oocyte surrounded by follicular cells

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106
Q

epoophoron

A

vestigial epigenital mesonephric ductules in females

homologous w/efferent ductules

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107
Q

paroophoron

A

vestigial caudal mesonephric ductules in females

homologous w/paradidymis

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108
Q

Gartner’s cyst

A

vestigial distal mesonephric duct in females

homologous to seminal vesicle

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109
Q

function & origin or estrogenic hormones in fetus

A

from mother & placenta

must be present for full development of female genital tract

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110
Q

how is the uterus formed?

A

fusion of lower portion of paramesonephric ducts & degeneration of septum

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111
Q

how is the vagina formed?

A

upper 1/3: fusion of distal paramesonephric ducts

lower part: posterior wall of urogenital sinus

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112
Q

sinovaginal bulbs

A
  • 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
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113
Q

unterine & vaginal formation abnormalities

A
  • 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
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114
Q

proerythroblast

A

large cell

basophilic cytoplasm

visible nucleoli

NOT morphologically distinguishable from other committed precursor cells or myeloid stem cell

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115
Q

basophilic erythroblast

A

strongly basophilic cytoplasm→ caused by large # of ribosomes involved in synthesis of hemoglobin

NO visible nucleoli

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116
Q

polychromatophilic erythroblast

A

less polyribosomes→ less basophilic→ less blue

more hemoglobin in cytoplasm→ more acidophilic→ more pink

polychromatic b/c both colors present

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117
Q

orthochromatophilic erythroblast

A

nucleus condensation

loose basophilia→ uniform acidophilia

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118
Q

reticulocyte

A

AFTER expelling nucleus

still has a few polyribosomes→ agreggate to form reticular network

leaves bone marrow & passes to blood stream

lasts 2-3 days

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119
Q

what is the difference between reticulocytes & erythrocytes?

A

loss of polyribosomes & mitochondria

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120
Q

nurse cell

A

macrophage that erythrocytes develop on

phagocytose discarded nuclei of erythroblasts

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121
Q

what is distinguishable when a blood smear is stained w/cresyl blue?

A

reticular network of polyribosomes in reticular cells

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122
Q

what is the action of erythropoietin?

A

stimulates colony forming unit-erythrocyte differentiation

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123
Q

where is erythropoietin produced/secreted from?

A

endothelial cells of peritubular capillary network of kidneys

hepatocytes

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124
Q

granulopoiesis

A

development of granulocytes- eosinophils, basophils, & neutrophils

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125
Q

myeloblast

A

looks like lymphocytes, but has 3-5 nucleoli

1st stage of granulocytes after committed precursor

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126
Q

promyelocyte

A

azurophilic

very large

appearance of non-specific granules

2nd stage of granulocytes after committed precursor

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127
Q

myelocyte

A

oval or flat nucleus

specific granules

last stage cell division is possible

3rd stage of granulocytes after committed precursor

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128
Q

metamyelocyte

A

accumulation of specific granules

indented nucleus in C or V shape

4th stage of granulocytes after committed precursor

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129
Q

band/stab cell

A

rarely seen for basophils or eosinophils, mostly immature neutrophils

5th stage of granulocytes after committed precursor

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130
Q

what is an increased number of band cells in blood stream indicative of?

A

bacterial infection

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131
Q

what cell type is stored in bone marrow?

A

neutrophils (5:1 in blood stream)

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132
Q

what two WBCs share the same progenitor?

A

monocytes & neutrophils

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133
Q

promonocyte

A

bluish cytoplasm due to numerous azurophilic non-specific granules (lysosomes)

2nd stage after committed precursor

monoblast is between progenitor & this stage

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134
Q

monocyte

A

1010 made daily

1-2 days in circulation

then enter connective tissue where they differentiate into macrophages

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135
Q

leukemias

A

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

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136
Q

megakaryocytopoiesis

A

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

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137
Q

what is contained in platelet granules?

A

platelet-derived growth factor, fibroblast growth factor, von Willebrand’s factor, & platelet factor IV

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138
Q

what is the function of von Willebrand’s factor?

A

promotes platelet adhesion to endothelial cells

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139
Q

how do erythrocytes enter sinusoids?

A

not sufficient motility like leukocytes

use pressure gradient: veins are smaller tha arteries in bone marrow, resulting in suciton of RBCs into capillary

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140
Q

which WBCs can divide after differentiation and which cannot?

A

divide: monocytes & lymphocytes

unable to divide: eosinophils, basophils, & neutrophils (granulocytes)

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141
Q

how are the testes attached cranially & caudally during descent?

A

cranially: as mesonephros degenerates urogenital mesentary attachment is limited to the cranial suspensory ligament
caudally: caudal genital/inguinal ligament→ gubernaculum

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142
Q

1st phase of testis decent

A

enlargment of testis

regression of mesonephros

cranial ligament regresses & releases testis (diaphragmatic connection)

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143
Q

2nd phase of testis descent

A

descent to level of inguinal ring by W12

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144
Q

3rd phase of testis descent

A

transinguinal descent

testes pass thru inguinal canal by W28

into scrotum by W33-38

guided by testosterone & gubernaculum (attached to scrotal floor

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145
Q

vaginal process

A

testis slides behind this extension of the peritoneal cavity

becomes tunica vaginalis

canal connecting it to peritoneum is obliterate at birth or shortly after

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146
Q

what happens when obliteration of vaingal process to peritoneum is incomplete or weak?

A

prone to indirect inguinal hernia

irregular can leave small cyst→ hydrocele of testis

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147
Q

descent of ovaries

A

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

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148
Q

What are the connections of the round ligament?

A

uterus & labia majora

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149
Q

indifferent stage of external genitalia

A

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

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150
Q

adults structures from genital tubercle

A

males: glans penis
females: clitoris

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151
Q

adults structures from genital folds

A

males: shaft of penis
females: labia minora, urethral & vaginal orifices

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152
Q

adult structures from genital swellings

A

males: scrotum
females: labia majora

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153
Q

what hormone influences growth of male external genitalia?

A

dihydrotestosterone

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154
Q

male urethra formation

A

lateral folding & midline fusion of genital folds

endodermal in origin from urogenital sinus

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155
Q

penile raphe

A

epithelial seam alond penile shaft & scrotum where urethra fused

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156
Q

vestibule

A

opening to urethra & vagina in females

remnant of urogenital groove

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157
Q

hypospadias

A

most common male external genitalia malformation

ventral opening of urethra anywhere that isn’t at the glans

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158
Q

true hermaphrodite

A

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

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159
Q

female pseudohermaphrodite

A

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

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160
Q

male pseudohermaphrodite

A

has testes

ambiguous or female external genitalia

cause: inadequate production or testosterone and/or MIF by fetal testies

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161
Q

androgen sensitivity syndrome

A

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

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162
Q

lymphoid follicle

A

aka lymphoid nodule

small spherical nodules arrangement of immune cells in connective tissue & inside organs

UNencapsulated

reticular fiber frame by reticular cells NOT ERCs

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163
Q

what is teh definitive difference between 1º & 2º lymphoid follicles?

A

if they have a germinal centrer→ 2º

2º are usually larger, but a large follicle can NOT be labeled 2º w/o germinal center

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164
Q

immunocompetence

A

ability of body to produce normal immune response w/exposure to antigen

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165
Q

naive lymphocyte

A

immunocompetent, but has yet to be exposed to antigen

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166
Q

structure of thymus

A

bilateral organ superior to heart

thin connective tissue capsule w/trabeculae that divides organ into lobules

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167
Q

how are thymic lobules established?

A

via trabeculae of connective tissue

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168
Q

why do the thymic lobules cortices stain darker?

A

they are richer in lymphocytes than medulla

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169
Q

after reaching immunocompetence in cortex, how do T cells enter the bloodstream?

A

migrate to medulla→ bloodstream

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170
Q

why is the thymic medulla lighter staining than the cortex?

A

less cells

95% precursor T cells die via apoptosis during + & - selction process in cortex

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171
Q

functions of epithelial reticular cells in thymus

A
  • framework
    • form cytoreticulum: ERCs connected together by desmosomes
    • in cortex & medulla
  • produce & secrete thymic hormones
    • promote lymphocyte proliferation & maturation
  • form blood-thymus barrier
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172
Q

why is it important to have a blood-thymus border?

A

to exclude antigen from developing thymocytes

antigen contact at this stage results in thymocyte apoptosis

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173
Q

what characteristics make ERCs like epithelial cells?

A

connected by desmosomes

contain keratin intermediate filaments

have basal lamina

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174
Q

what makes ERCs NOT like epithelial cells?

A

grow in reticular pattern

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175
Q

what is the embryonic origin of the thymus?

A

lymphocytes are mesoderm

epithelial reticular cells are endoderm

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176
Q

what 3 structures make up the blood-thymus barrier?

A
  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
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177
Q

what back up mechanism is in place if antigen gets thru blood-thymus barrier?

A

macrophages hover nearby

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178
Q

Hassal’s corpuscles

A

aka thymic corpuscles

round globular mass of ERC cells

function: suggested that they secrete factors that aid thymocyte development

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179
Q

function of fibroblasts in thymus?

A

external framework only

capsule & trabecule, not part of network

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180
Q

what cell types are found in the thymus?

A

lymphocytes

epithelial reticular cells

fibroblasts

macrophages

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181
Q

thymic involution

A

shrinking of thymus with age

replaced by adipose tissue

starts transition during puberty

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182
Q

DiGeorge Syndrome

A

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

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183
Q

MALT

A

mucosa-associated lymphatic tissue

diffuse lymphatic tissue

foudn in digestive, repsiratory, & genitounrinary tracts

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184
Q

Peyer’s patches

A

aggregates lymphatic nodules in teh wall of the ileum

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185
Q

what cells make up a 1º lymphatic follicle?

A

naive & memory B cells

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186
Q

why does the germinal center of a 2º follicle stain lighter than its cortex or 1º follicle?

A

proliferation of B cells after antigen presentation & larger B cell size due to antibody production

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187
Q

what is a plasma cell?

A

a mature B cell that secretes antibodies

larger cytoplasm volume cause them to stain lighter

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188
Q

what is the name of the darker stainging rim of a 2º follicle?

A

mantle zone

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189
Q

what is the characteristic appearance of folliculra dentritic cells?

A

multiple long, thin hairlike projections that run between B cells in GC

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190
Q

follicular dendritic cell function

A

capture & retain antigens for long time (weeks-years)

NOT APCs

of mesenchymal origin

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191
Q

what are dendritic cells derived from?

A

monocytes

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192
Q

what is the most important/best APC?

A

dendritic cells

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193
Q

what cells are antigen presenting cells?

A

dendritic cells

macrophages

B cells

thymic epithelial reticular cells

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194
Q

what are HEVs and where are they found?

A

high endothelial venules

specialized blood vessels where naive lymphocytes enter 2º lymphoid tissues, except spleen

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195
Q

how do HEVs differ from regular endothelial cells of veins?

A

they are simple cuboidal/columnar cells instead of squamous

express addressins that atrract T & B cells

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196
Q

lymphocyte homing

A

adhesion of circulating lymphocytes in blood to cells of HEVs w/in lymphoid organs

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197
Q

circulatory path of lymphocytes

A

blood→ HEVs→ 2º lymphoid organ→ lymph→ blood

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198
Q

M cells

A

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

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199
Q

what is the functional importance of the appendix?

A

filled w/lymphocytes & lymphoid follicles

store normal gut bacteria

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200
Q

what is the ring of waldheyer?

A

masses of lymphoid tissue that form a ring in posterior mouth

1st line of defenseagainst ingested or inhaled foreign pathogens

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201
Q

palatine tonsils

A

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

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202
Q

lingual tonsils

A

@ 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

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203
Q

pharyngeal tonsils

A

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

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204
Q

lymph

A

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

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205
Q

what is the size of a lymph node?

A

pea-grape

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206
Q

what cells are found in the paracortex of a lymph node?

A

T cells

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207
Q

what cells are found in the medullary cords of lymph nodes?

A

plasma cells

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208
Q

where are B cells concentrated in lymph nodes?

A

cortical follicles

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209
Q

flow of lymph thru a lymph node

A

afferent lymphatic vessel→ subcapsular sinuses→ peritrabecular sinuses→ medullary sinuses→ efferent lymphatic vessels

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210
Q

what substructure are HEVs found?

A

paracortex

(of lymph nodes, tonsils, Peyer’s patches, appendix)

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211
Q

functions of spleen

A

remove aged/damaged RBCs from circulation

mount immune response to antigen in circulating blood

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212
Q

structural features of spleen

A

enclosed by dense connective tissue capsule w/trabeculae

hilum w/neurovasculature

NO afferent lymph vessels

**terminal arterial capillaries

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213
Q

red pulp

A

75% of spleen mass

where blood is filtered

sinusoids & splenic cords

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214
Q

white pulp

A

production site of lymphocytes which migrate to red pulp to enter circulation

mostly B cells

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215
Q

what are sheathed capillaries of the spleen sheathed by?

A

macrophages

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216
Q

PALS

A

periarteriolar lymphoid sheath

central splenic arteries surrounded by T cells w/nodules of B cells

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217
Q

role of the marginal zone

A

between PALS & red pulp

trap particulate antigen from circulation & present it to lymphocytes

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218
Q

stave cell

A

special elongated endothelial cells in spleen

oriented parallel to sinusoid’s blood flow

wrapped in reticular fibers

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219
Q

how much of circulating blood is found in the spleen?

A

1/3

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220
Q

effects of splenectomy

A

modest increase of circulating WBCs & platelets

diminished responsiveness to vaccines

**increased susceptibility to infecion by bacteria & protozoa

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221
Q

What are the components that make up the pharyngeal arches?

A
  1. neural crest cells: a+v+n, skeletal component (cartilage)
  2. mesenchymal core (will become musculature)
  3. ectoderm (outside)
  4. endoderm (inside)
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222
Q

what is a rhombomere?

A

segmentation of the neural tube in the hindbrain

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223
Q

what is the function of rhombomeres in pharyngeal development?

A

molecular cues to neural crest cells to migrate in formation of face, skull, thyroid, tongue, parathyroid, & thymus

224
Q

When does the 1st pharyngeal arch apprear?

A

approximately D27

225
Q

what indentation can be found just dorsal to the 2nd pharyngeal cleft?

A

otic pit forming the inner ear

226
Q

what is the difference between a pharyngeal pouch and pharyngeal cleft?

A

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
Q

How many pharyneal arches are there?

A

6, but like the aortic arches only 5 form permenant structures (1, 2, 3, 4, & 6)

228
Q

what is another name for pharyngeal arches evolutionarily speaking?

A

branchial arches

229
Q

what nerve innervates the 1st pharyngeal arch?

230
Q

what pharyngeal arch is innervated by CN X (vagus)?

A

4 by pharyngeal branch & 6 by recurrent laryngeal branch

231
Q

what pharyngeal arch is innervated by CN IX (glossopharyngeal)?

232
Q

what nerve innervates the 2nd pharyngeal arch?

A

CN VII (facial n)

233
Q

what forms the malleus, incus & stapes of the inner ear?

A

1st 2 are formed by the 1st pharyngeal arch

stapes is formed by the 2nd paryngeal arch

234
Q

What is Meckel’s cartilage?

A

forms from the 1st pharyngeal arch

gives rise to the sphenomandibular ligament (among others)

235
Q

what does the 1st pharyngeal cleft give rise to?

A

external auditory meatus

236
Q

what does the 2nd pharyngeal cleft give rise to?

A

merges w/3rd & 4th pharyngeal clefts to form cervical sinus

237
Q

what does the 3rd pharyngeal cleft give rise to?

A

merges w/2nd & 4th pharyngeal clefts to form cervical sinus

238
Q

what does the 4th pharyngeal cleft give rise to?

A

merges w/2nd & 3rd pharyngeal clefts to form cervical sinus

239
Q

what does the 1st pharyngeal pouch give rise to?

A

primitive tympanic cavity & auditory tube

240
Q

what does the 2nd pharyngeal pouch give rise to?

A

palatine tonsil

241
Q

what does the 3rd pharyngeal pouch give rise to?

A

inferior parathyroid glands

thymus

242
Q

what does the 4th pharyngeal pouch give rise to?

A

superior parathyroid glands

ultimobranchial body (C cells of thyroid)

243
Q

what muscles does the 1st pharyngeal arch give rise to?

A

muscles of mastication

244
Q

what muscles does the 2nd pharyngeal arch give rise to?

A

muscles of facial expression

245
Q

what muscles does the 3rd pharyngeal arch give rise to?

A

stylopharyngeus m.

246
Q

what muscles does the 4th pharyngeal arch give rise to?

A

pharyngeal & laryngeal musculature

247
Q

an external branchial fistula is a failure of what to form?

A

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
Q

where are branchial fistulas & cysts normally found?

A

anterior to the sternocleidomastoid

249
Q

what causes the formation of a lateral cervical cyst?

A

failure of the cervical sinus to obliterate

250
Q

what malformation(s) of the 1st pharyngeal arch are seen?

A

Treacher Collins Syndrome

Pierre Robin Sequence

Goldenhar Syndrome

251
Q

what are the key features of Treacher Collins Syndrome?

A

abnormalities of ears, palate, maxilla, & mandible

sunken cheeks & smaller lower jaw & chin

downward slanting eyes

252
Q

what causes Treacher Collins Syndrome?

A

aka mandibulofacial disostosis

autosomal dominant mutation on Ch5

failed migration of neural crest cells in first branchial arch

253
Q

key features of Pierre Robin Sequence

A

micrognathia (small mandible)

tongue displaces superiorly & falls to back of throat which my cause breathing problems

254
Q

key features of Goldenhar Syndrome

A

aka hemifacial microsomia

*one side of face affected*

temporomandibular joint, mastication muscles, mandible, & ear often underdeveloped

255
Q

Cause of DiGeorge Syndrome

A

specific deltion on ch22→ abnormal neural crest cell migration→ underdevelopment of 3rd & 4th pharyngeal arches

256
Q

Characteristics of DiGeorge Syndrome

A
  • Cardiac & aortic malformations: tetrology of Fallot or truncus arteriosus
  • FAcial malformations: micrognathia, ear anomalies, & telecanthus (increased space between eyes)
  • Thymus: fail or under development
  • Cleft palate
  • Hypotcalcemia: @ birth due to underdevelopment of parathyroid glands
257
Q

When does the tongue appear during development?

258
Q

how does the 1st pharyngeal arch contribute to tongue formation?

A

two lateral lingual swellings & one medial

259
Q

how does the 2nd pharyngeal arch contribute to tongue formation?

A

root of the tongue

260
Q

how does the 3rd pharyngeal arch contribute to tongue formation?

A

root of the tongue

261
Q

how does the 4th pharyngeal arch contribute to tongue formation?

A

root of the tongue & epiglottis formtation

262
Q

what causes a bifid tongue?

A

failure of L+R lateral lingual swellings to fuse

263
Q

what causes ankyloglossia?

A

aka tongue-tie

impaired development of alveolo-lingual sulcus (separates longue & floor of mouth)

264
Q

thyroid gland formation

A

forms from the foramen cecum of the tongue & travels caudally via thyroglossal duct

265
Q

where are thyroglossal duct cysts found?

A

along the midline of the neck (or paramedian)

caused from the persistence of thyroglossal duct

266
Q

what forms the nose?

A

fusion of medial & lateral nasal processes

267
Q

how is the upper lip formed?

A

fusion of medial nasal process & maxillary process

268
Q

how is the philtrum formed?

A

fusion of the R+L medial nasal processes

269
Q

what causes a mandibular facial cleft?

A

failure of R+L mandibles to fuse

270
Q

what causes a cleft lip?

A

failure of R+L medial nasal processes OR maxillary processes to fuse

271
Q

features of hyaline cartilage

A

chondrocytes embedded in collagen type II in amorphous ground substance

4 types GAG linked to hyaluronic acid to form proteoglycans

chrondronectin (glycoprotein)

272
Q

functions of cartilage

A

support for soft tissue

shock absorption

gliding surface for joints

template for growth of long bones epiphyseal plates

273
Q

features of cartilage

A

hard consistency due to collagen & proteoglycans

avascular, no lymphatics, no nerves

surrounded by perichondrium ***except articular cartilage & fibrocartilage**

274
Q

locations of cartilage

A

ends of lone bone & ventral end of ribs

joint surfaces

respiratory system & external ear

epiphyseal plates for growth of long bones

275
Q

EM features of chondrocyte

A

large rER & extensive Golgi→ synthesis of collagens & GS

numerous dark particles containing proteoglycans

276
Q

where are chondrocytes found?

A

singly or in isogenous groups (clusters) in lacunae

277
Q

what determines chondrocyte function? and their effect?

A

growth hormone, thyroxine, & testosterone

increase synthesis of sulfated GAGs

278
Q

what decreses GAG synthesis in chrondrocytes?

A

cortisol, cortisone, & estradiol

279
Q

How does growth hormone control cartilage growth?

A

via somatomedin C (an insulin-like growth factor) from the liver

280
Q

interstitial growth

A

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
Q

appositional growth

A

new chondrocytes divide & form from growing zone just beneath the perichondrium- chondrogenic cells

282
Q

differences among chondrogenic, chondroblast, & chondrocyte

A

chondrogenic cell: precursor cell

chondroblast: commited but immature chondrocyte
chondrocyte: mature cartilage cell, surrounded by matrix

283
Q

features of elastic cartilage

A

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
Q

locations of elastic cartilage

A

pinna of ear, external & internal auditory tubes, epiglottis, & larynx

285
Q

features of fibrocartilage

A

NO perichondrium→ only interstitial growth

combination of dense connective tissue & hyaline cartilage

predominantly collagen type I→ stain pink

scant GS

**support & tensile strength

286
Q

locations of fibrocartilage

A

intervertebral discs, symphysis pubis, menisci of knee joints

287
Q

what type of collagen is predominant in annulus fibrosus?

288
Q

what type of collagen is predominant in nucleus pulposus?

A

type II

derived from notochord

289
Q

functions of bone

A
  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
Q

osteoid matrix

A

non-mineralized organic matrix of bone

291
Q

what are the main inorganic components of bone matrix?

A

calcium & phosphorus in the form of hydroxyapatite crystals

292
Q

what are the organic components of bone matrix?

A

collagen type I→ acidophilic→ stains red/pink

GS: GAGs, proteoglycans, proteoglycan aggregates

glycoproteins

293
Q

bone cell types

A

osteogenic (osteoprogenitor)

osteoblast

osteocyte

osteocyst

294
Q

what do osteogenic cells derive from?

A

mesenchyme cells

295
Q

what are osteoclasts derived from?

296
Q

where are osteogenic cells found?

A

inner cell layer of periosteum

lining Haversian canals

endosteum

297
Q

appearance of osteogenic cells

A

flat cell w/pale-staining oval nucleus & sparse cytoplasm

298
Q

what are matrix vesicles?

A

vesicles secreted from osteoblasts into ostoid matrix

contain Ca2+, PO42-, alkyline phosphatase, etc.

contributes to formation of hydroxyapatite crystallization

299
Q

what is the differences between osteoblasts & osteocytes?

A

osteocytes are trapped in lacunae of calcified matrix

300
Q

cannaliculi

A

cytoplasmic projections of osteocytes that form gap junctions w/adjacent osteocytes

301
Q

osteocyte appearance

A

flat, almond shape

reduced rER & Golgi

302
Q

function of osteocytes

A

maintanence of bone matrix via maintaining blood clacium levels

303
Q

what three states are osteocytes found in?

A
  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
Q

osteocytic osteolysis

A

mechanism of Ca2+ resorption by osteocytes in resorptive state to maintain blood Ca2+ levels

305
Q

appearance of osteoclasts

A

very large cells

5-50 nuclei due to cellular fusion

extensive brached acidophilic cytoplasm→ red

306
Q

from what are osteoclasts derived from?

307
Q

where are osteoclasts found?

A

in Howship’s lacunae: shallow depressions on bone surface

308
Q

what are the phases of bone resorption and where do they occur?

A

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
Q

mechanism of bone resorption

A
  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
Q

what is the effect of parathyroid hormone?

A

@ low levels: osteoblast & bone formation

@ high levels: stimulates osteoblast release of RANKL

311
Q

what is RANKL and its effect?

A

receptor activator of NF-kappaB 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
Q

Where is calitonin secreted from? and its function?

A

C-cells of thyroid

acts directly on osteoclasts for bone resorption

313
Q

Function of somatotropin in bone development and where is it secreted from?

A

pituitary growth hormone

stimulates liver→ produces & secrets somatomedins (insulin-like growth factor)→ stimulates bone growth at epiphyseal plates

314
Q

effect of somatotropin deficiency

315
Q

effect of excess somatotropin

A

gigantism (giantism)

316
Q

2 methods of bone classification

A

gross observation

OR

microscopic observation

317
Q

characteristics of spongy bone

A

numerous interconnecting cavities & trabeculae (osseous projections)

irregular arrangement of lamelle in matrix

318
Q

types of bone per gross obervation

A

spongy bone & compact bone

319
Q

where can primary bone be found in adults?

A

tooth sockets, suture lines of skull, & insertion sites of tendons

320
Q

primary bone

A

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
Q

secondary bone

A

replaces primary bone

composed of parallel or concentric lamellae of collagen

calcified matrix

322
Q

Sharpey’s Fibers

A

strong collagenous fibers connecting periosteum to bone

323
Q

osteon

A

functional unit of compact bone

concentric circles of osteocytes around Haversian canal (contains blood vessel)

bounded by cement line

324
Q

layers of bone from exterior inward

A
  • periosteum
    • Sharpey’s fibers
  • compact bone
    • outer circumferential lamellae
    • osteons/interstitial lamellae
    • inner circumferential lamellae
  • endosteum
  • spongy bone & marrow
325
Q

which circumferential lamellae is thicker?

A

outer is thicker than inner

326
Q

how does intermembranous ossification occur?

A

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
Q

where intermembranous ossification seen?

A

ex. clavicle & skull bones

328
Q

how does endochondral ossification occur?

A

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
Q

subperiosteal bone collar formation

A
  • @ 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
Q

where does the osteogenic bud form? and how does bone grow?

A

osteogenic bud invades via midregion bone collar

bone formation occurs in both directions

331
Q

how does bone growth occur at the epiphysis of bones?

A

secondary ossification centers form in the center and expand outward

332
Q

layers at epiphyseal plate

A

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
Q

where do hormones affect bone growth?

A

cartilaginous proliferating zone of epiphyseal plate

334
Q

how long is the epiphyseal plate present?

A

as long as # of proliferating zone cells >/= # of resorption zone cells

usually until the end of puberty

335
Q

role of vitamin D in bone formation

A

necessary for Ca2+ absorption in small intestines

336
Q

effect of vitamin D deficiency

A
  • children: Rickets
    • poor calcification of bones
    • deformed leg bones
  • adults: osteomalacia
    • newly formed bone not properly calcified
    • bigger problem in pregnancy
337
Q

role of vitamin C in bone formation

A

necessary for collagen formation

338
Q

effect of vitamin C deficiency

A

scurvy

poor collagen production

reduction in bone matrix formation & development

healing problems

bleeding gum

339
Q

role of vitamin A in bone formation

A

lack→ inhibits proper bone formation & growth

excess→ early ossification of epiphyseal plates

340
Q

acromegaly

A

cause: excess GH in adults
effect: abnormal increase in bone formation w/o normal resorption→ thickening of bones of hands & face

341
Q

osteopetrosis

A

genetic disorder of osteoclasts

no ruffle border→ can’t resorb bone

342
Q

osteoporosis

A

low bone density; thin trabeculae & wide Haversian canals

cause: increased bone resoption & decreased bone formation or both
effect: fragile bone

343
Q

achondroplasia

A

defect of endochondral ossification

reduced chondrocyte proliferation at epiphyseal plate

**cause of most common form of inherited dwarfism

344
Q

somites are divided into

A

sclerotomes & dermomyotomes

345
Q

where are sclerotomes found?

A

ventral medial portion of somite

346
Q

where is the epaxial dermomyotome located & what does it form?

A

dorsal portion of somite

differentiates into erector spinae muscles & skin of back

347
Q

where is the hypaxial dermomyotome and what does it form?

A

vetrolateral portion of somite

skin & muscles of limbs & thorax

348
Q

formation of mature myotubes?

A

muscle cell progenitor→ myoblast→ fusion of myoblasts→ nascent myotube→ sarcomere assembly→ mature muscle fiber cell (myotube)

349
Q

syncytium

A

fusion of two muscle precursor cells

350
Q

satellite cells

A

resident population of muscle precursor cells in adults

351
Q

where are nuclei found in skeletal muscle?

A

in the perphery

352
Q

what cell type is found between muscle cells?

A

fibroblasts

353
Q

functions of muscle

A

produce movement by acting on bones, pumping blod, or propelling

maintain posture

stabilize joints

generate heat during metabolic processes

354
Q

muscle cell

A

muscle fiber

355
Q

cytoplasm of a muscle cell

A

sarcoplasm

356
Q

muscle cell membrane

A

sarcolemma

357
Q

sarcoplasmic reticulum

A

sER of muscle fiber

358
Q

classification of skeletal muscle

A

striated & voluntary

359
Q

classification of smooth muscle

A

non-striated & involuntary

360
Q

classification of cardiac muscle

A

striated & involuntary

361
Q

what muscle(s) are derived from ectoderm?

A

muscles of pupil

362
Q

endomysium

A

tissue sheath covering a single muscle fiber, small diameter blood vessels, & finest neuronal branches

363
Q

perimysium

A

tissue sheath surround a group of muscle fibers w/larger blood vessels & nerves

364
Q

epimysium

A

dense connective tissue sheath that surround a collection of fasicles w/major blood vessels & nerves

around whole muscle

365
Q

how is epimysium attached to bones?

A

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
Q

where are satellite cells found?

A

between sarcolemma & external lamina

367
Q

what is the external lamina?

A

basal lamina of muscles fibers

368
Q

what is a myofibril?

A

bundle of myofilament (contracile proteins- actin & myosin)

made of repeating units of sarcomeres

369
Q

sarcomere

A

contractile unit of myofibril

begins & ends @ Z-line (Zwischenscheibe)

370
Q

what are thick filaments made of?

371
Q

what are thin proteins made of?

372
Q

Anisotropic band

A

aka A band

length of myosin filament

373
Q

isotropic band

A

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
Q

Zwischenscheibe

A

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
Q

Hell

A

H zone

center section of A band where myosin & no actin is found when sarcomere is relaxed

lighter area of A band

376
Q

Mitte

A

aka M line

center of movement in sarcomere

thick filaments (myosin) is connected via accessory proteins

connected to sarcolemma

377
Q

what protein integrates the sarcolemma with the Z-line?

378
Q

what blocks myosin from binding actin in resting sarcomeres?

A

tropomysin

379
Q

rigor mortis

A

stiffening of muscle after death

caused by calcium release→ myosin binds actin

no ATP to release the bound myosin

380
Q

rule of Nysten

A

rigor mortis starts 1hr after death & reaches maximum 12hrs after death depending on temperature

381
Q

where does the triad sit? what components make up the triad?

A

@ A/I band junction

terminal cisterna of sarcoplasmic reticulum, T tubule of sarcolemma, terminal cisterna of sarcoplasmic reticulum

382
Q

motor unit

A

lower motor neuron & muscle fibers it innervates

383
Q

how many muscle fibers are innervate/lower motor neuron in mimetic muscles? in postural muscles (back or thigh)?

A

face: <100fibers/neuron

postural >1000/neuron

384
Q

type I muscle fibers

A

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
Q

type IIa muscle fibers

A

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
Q

type IIb muscle fibers

A

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
Q

muscle spindles

A

stretch detectors among muscle fasicles

composed of intrafusal fibers

sensory nerve fibers penetrate muscle spindles & wrap around individual intrafusal fibers

388
Q

intrafusal fibers

A

connective tissue capsule surrounding fluid-filled space

contains few thin, non-striated muscle fibers, densely filled w/nuclei

389
Q

where does cardiac muscle derive from?

A

splanchnic mesoderm of primitive heart tube

390
Q

histological appearance of cardiac muscle

A
  • 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
Q

why are desmosomes & fascia adherens present at intercalated discs?

A

to prevent cardiac muscle cells from pulling apart under constant contractile activity

*in transverse regions of intercalated discs

392
Q

why are gap junctions present in intercalated discs?

A

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
Q

What components make up a diad? where is it found?

A

@ Z line/disc

terminal cisterna of sarcoplasmic reticulum & T-tubule of sarcolemma

394
Q

origin, target & effect of ANF

A

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
Q

what initiates, regulates, & coordinates the heart beat?

A

cardiac conducting cells= specialized & modified cardiac muscle cells

exhibit inherent & spontaneous rhythmic contraction

SA & AV nodes & fibers: Bundle of His & Purkinje

396
Q

what innervates cardiac muscle?

A

motor: cardiac conducting cells (AV, SA, His, & Purkinje)

parasympathetic & sympathetic fibers modify heart rate at nodes only

397
Q

why can’t cardiac muscle regenerate?

A

it lacks satellite cells

398
Q

what is responsible for regeneration of smooth muscle?

A

pericytes (from walls of small blood vessels)

399
Q

histological appearance of smooth muscle

A

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
Q

where is calcium stored in smooth muscle?

A

sarcoplasmic reticulum, but since less developed compared to other muscle types, also caveolae of cell membrane

401
Q

Since smooth muscle does not have sarcomeres, what do muscle filaments attach to?

A

anchored to sarcolemmma & surrounding tissue via dense bodies

402
Q

How is smooth muscle innervated?

A

NO NMJs

autonomic nerve fibers release neurotransmitters into wide synaptic cleft

403
Q

Smooth muscle does not have troponin, so how is tropomyosin moved aside for myosin binding?

A

calmodulin

404
Q

what filaments in smooth muscle do pathologists use to determine tumor type?

A

desmin & vimentin

405
Q

what does contracted smooth muscle look like?

406
Q

single-unit smmoth muscle

A

most common of smooth muscle types

contracts rhythmically as a unit

electrically coupled via gap junctions & exhibits spontaneous action potentials

ex. GI tract

407
Q

multi-unit smooth muscle

A

structurally independent cells, has motor units, capable of graded potentials

ex. large airways, large arteries, iris of eye, arrector pili of hair follicles

408
Q

what are myocardial endocrine cells?

A

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
Q

When do the limbs form?

A

upper limbs buds form end of W4 & lower beginning W5

toes & fingers formed by end of W8

410
Q

what are the limb buds derived from?

A

lateral plate mesoderm core covered by ectoderm

ectoderm forms skin

lateral plate mesoderm forms bones & connective tissue

411
Q

what are the muscles derived from?

A

somites & somitomeres formed form paraxial mesoderm

412
Q

difference between somites & somitomeres

A

somitomeres are in the head region

somites are all the others caudal to the occiput

413
Q

what is cardiac muscle derived from?

A

splanchnic mesoderm surrounding primitiva heart tube

414
Q

what is smooth muscle derived from?

A

splanchnic mesoderm, except for muscels of the pupil which are derived form the neuroectoderm

415
Q

where does the dermomyotome come from?

A

dorsolateral ascpect of the somite

416
Q

what does the dermomyotome differentiate into?

A

dermis of the skin

& myotome→ gives rise to skeletal muscle

417
Q

what is the ventromedial aspect of the somites referred to and what does it become?

A

sclerotome

cells surround the neural tube & become the vertebral column

418
Q

What makes up the intervertebral discs?

A

mesenchymal tissue composes the annulus fibrosus

notocord forms nucleus pulposus

419
Q

how are vertebra formed?

A

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
Q

cause of scoliosis

A

2 successive vertebrae fuse asymmetrically or half of a vertebra is missing

421
Q

cleft vertebra

A

aka spina bifida

imperfect fusion or non-union of vertebral arches

422
Q

spina bifida occulta

A

incomplete vertebral arches, but intact spinal cord

423
Q

epimere

A

dorsal division of myotome

gives rise to muscles of the back that are innervated by dorsal rami of spinal nerves

424
Q

hypomere

A

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
Q

what hypomere regions do teh limb skeletal muscles arise from?

A

upper: C5-C8
lower: L3-L5

426
Q

what muscles are in the posterior condensation of the limbs?

A

upper: extensors & supinators
lower: extensors & abductors

427
Q

what muscles are in the anterior condensation of the limbs?

A

upper: flexsors & pronators
lower: flexsors & adductors

428
Q

what ventral rami innervate the limb buds?

A

upper: C5-T1
lower: L4-S3

429
Q

when and in what direction do the limbs rotate?

A

W6-8

upper: laterally→ flexors are anterior
lower: medially→ flexors are posterior

**this is why dermotomes spiral around limbs

430
Q

how are the digits formed?

A

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
Q

syndactylyl

A

fused digits

432
Q

Amelia

A

complete absence of a limb

cause: early loss of FGF signaling

433
Q

Meromelia

A

partial absence of limb

cause: later of partial loss of FGF signaling

434
Q

phocomelia

A

aka flipper limb

digits develop prematurely

proximal elements of limb absent

435
Q

micromelia

A

all segements are present but abnormally short

436
Q

polydactylyl

A

extra digits

437
Q

brachydactyly

A

short digits

438
Q

ectrodactylyl

A

absence of a digit

439
Q

split hand/foot

A

aka lobster claw deformity

abnormal cleft between 2nd & 4th metacarpal/metatarsal

absence of 3rd phalanx & its meta-

*more commonly found in the foot*

440
Q

amniotic band syndrome

A

fetus is entangles in strands of fibrous & string-like amniotic bands

bands restrict blood flow & fetal growth & development

441
Q

what forms the axial skeleton?

A

paraxial mesoderm

442
Q

what forms the bones of the limbs?

A

somatic layer of lateral plate mesoderm

443
Q

what are the circoid & thyroid cartilages?

A

lateral plate mesoderm

444
Q

what forms the posterior skull bones?

A

paraxial mesoderm

445
Q

what forms the anterior bones of the skull?

A

neural crest cells

446
Q

when does the posterior fontanelle close?

A

1-2 months

447
Q

when does the anterior fontanelle close?

A

7-19 months

448
Q

scaphocephaly

A

long & narrow skull

cause: early closure of sagittal suture

associated w/protuberance of frontal bones

449
Q

acrocephaly

A

aka tower skull

pointed or conical shape

cause: remature closure of coronal suture

450
Q

what are the functions of skin?

A

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
Q

what are the layers of skin?

A

epidermis & dermis

hypodermis/subcutaneous fat layer is NOT considered part of skin

452
Q

what embroynic layer is the epidermis derived from?

453
Q

what embryonic layer is dermis derived from?

454
Q

what is the cellular composition of epidermis?

A

keritinized squamous cell epithelium

455
Q

where do hair, nails, sesbacous & sweat glands come from?

A

they are all derived from epidermis

456
Q

what is the composition of dermis?

A

dense connective tissue

457
Q

where is thick vs. thin skin found?

A

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
Q

what forms the fingerprints?

A

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
Q

If the upper portion of the back has the thickest skin, why is it not considered thick skin?

A

because thick/thin classification is a misnomer

they are classified only on the thickness of the epidermal layer of skin

460
Q

what are the layers of thick epidermis?

A

superficial to deep

  1. stratum corneum
  2. stratum lucidum
  3. stratum granulosum
  4. stratum spinosum
  5. stratum basale
461
Q

what layer of epidermis is only observable in thick skin and not thin skin?

A

stratum lucidum

462
Q

how long does it take for the skin to be completely replaced?

A

15-30 days dependent on location (temperature, humidity) & care (location, etc)

463
Q

what protein increased in amount as keratinocytes rise thru the epidermal layers?

A

keratin intermediate filaments

464
Q

what characterizes the stratum basale layer of epidermis?

A

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
Q

what characterizes the stratum spinosum layer of epidermis?

A

polyhedral-shaped keratinocyte→ desmosomes give them this shape→ aka prickle cells

few layers

lower layers are also mitoticaly active

466
Q

what is the stratum germanitivum?

A

old name= malpighian layer

layers of cell division

stratum basale + stratum spinosum

467
Q

what are tonofilaments?

A

old name for keratin intermediate filaments

468
Q

what characterizes the stratum granulosum of epidermis?

A

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
Q

what “waterproofs” the skin?

A

lipid containing sheets expelled from lamellar granules form stratum granulosum & stratum spinosum

also functionally considered to be intracellular cement in stratum granulosum

470
Q

what characterizes teh stratum lucidum of epidermis?

A

clear layer superficial to stratum granulosum

only observable in thick skin

keratinocytes have no nucleus & no organelles, but do have keratin filaments

471
Q

what characterizes the stratum corneum?

A

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
Q

what layers of epidermis display desmosomes?

A

stratum basale

stratum spinosum

stratum granulosum

473
Q

what layer of the epidermis is waterproof?

A

stratum granulosum

474
Q

what layers of the epidermis do not have nuclei?

A

stratum lucidum & stratum corneum

475
Q

what layers of epidermis are mitotically active?

A

stratum basale & lower layers of stratum spinosum

476
Q

What does thick skin lack compared to thin skin?

A

hair follicles & sebaceous glands

477
Q

what causes a callous & why?

A

thickening of stratum corneum

due to pressure, skin grows more quickly to protect itself

most often foudn in thick skin

478
Q

what is the cause & treatment of a wart?

A

cause: papillomavirus
effect: epidermal hyperplasia
tx: salicyclic acid→ dissolves keratins

479
Q

besides keratinocytes, what other cell types are found in the epidermis?

A

melanocytes, Langerhan’s cells, & Merkel cells

480
Q

what is the function & appearance of melanocytes?

A

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
Q

what determines the color of skin, hair, & eyes?

482
Q

what do melanocytes synthesize melanin from?

A

tyrosine

via tyrosinase (activated by UV light→ why skin darkens with sun exposure)

483
Q

why is no melanin found in cells of the stratum corneum?

A

because when melanin granules are received by keratinocytes they fuse with lysosome that begin degrading the melanin

484
Q

reasons for darker skin coloring

A
  • melanocytes produce more melanin- NOT increase # of melanocytes
  • slower melanin degradation
485
Q

where is melanin found in keratinocytes?

A

between the sun & the nucleus to shield the DNA from radiation

486
Q

what are the types of melanin & where are they found?

A
  • eumelanin
    • black/brown hue
    • more common form
    • hair, areola, skin
  • pheomelanin
    • pink/red hue
    • redhair, lips, nipples, glans penis, & vagina
487
Q

what causes a freckle?

A

hyperpigmentation in localized spot due to sun exposure

488
Q

what is the difference between a mole & a nevus?

A

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
Q

what causes albinism?

A

2 different autosomal recessive genes on different chromosomes:

  • absence of tyrosinase activity OR
  • cellular inability to uptake tyrosine
490
Q

Why must albinos avoid the sun?

A

because they aren’t just fair they do NOT produce melanin

they will acquire DNA damage→ skin cancer

491
Q

what is a suspected autoimmune disorder that attacks melanocytes?

492
Q

Why did people evolve to become paler as they migrated north?

A

less sun→ vitamin D deficiency

light skin has less melanin blocking UV rays need to make vitamin D

493
Q

what are Langerhans cells & their function?

A

DC cells that have migrated into epidermis

function: APC

494
Q

Where are Merkel cells found & what is their function?

A

small # in stratum basale

connect to keratinocytes via desmosomes

store & relase neurocrine-like substance

function: touch receptor

495
Q

what are the layers of the dermis?

A

papillary & reticular

496
Q

what are the main components of dermis? why?

A

collagen type I & elastic fibers

b/c they give skin resilience & elasticity

497
Q

what causes wrinkling?

A

extensive cross-linking of collagen fibers

loss of elastic fibers

degeneration of collagen or elastic fibers by sun exposure

498
Q

how does skin receive nutrients?

A

dermal papillae contain capillaries

epidermis via diffusion from underlying capillaries in dermis

499
Q

what is the difference between a bruise & a contusion?

A

bruise: capillary damage that allows blood to seep into surrounding tissues
contusion: bruise caused by trauma

500
Q

what causes a blister?

A

epidermis separates from dermis

pool of lymph & bodily fluid accumulates in the space created

usually found in thick skin

501
Q

what is a hemangioma?

A

most common type of birthmark, often at birth & disappears

many new blood vessels grouped together in one place on the skin

502
Q

what type(s) of nerve receptors are found in skin?

A
  1. free nerve endings
  2. Meissner’s corpuscles
  3. Pacinian corpuscles
  4. Merkel cells w/associated nerve
  5. Ruffini’s corpuscle
503
Q

corpuscle

A

rounded globular mass of cells

504
Q

what types of receptor/information do free nerve endings transmit?

A

fine touch, heat, cold, pain, & itching

505
Q

where do free nerve endings terminate?

A

stratum granulosum

506
Q

what type of nerve receptor is sensitive to hair movement?

A

free nerve endings

507
Q

what part of the body are Merkel cells most abundant?

A

where sensory perception is most acute

ex. finger tips

508
Q

Where are Pacinian corpuscles found in skin?

A

deep dermis & hypodermis

509
Q

what function do Pacinian corpuscles fulfill?

A

deep pressure sensation & vibrations

510
Q

how are Pacinian corpuscles activated?

A

pressure/vibrations→ displaces capsule lamellae→ opens mechanically-gated ion channels

multilayered capsule surrounds terminal of afferent axon

511
Q

what skin receptor contains mechanically gated ion channels?

A

Meissner’s corpuscles

Pacinian corpuscles

Ruffini’s corpuscles

512
Q

where are Meissner’s corpuscles found in skin & body?

A

in dermal papillae, just below epidermal basal lamina

areas sensitive to tactile stimulation: lips, external genitalia, & nipple

513
Q

in what layer of skin are Ruffini’s corpuscles found?

A

deep dermis

514
Q

what type of information do Ruffini’s corpuscles transmit?

515
Q

what is specialized about the structure of Ruffini’s corpuscles?

A

elongated, spindle-shaped capsule

oriented parallel to stretch lines of skin

516
Q

what type of neurons correspond to skin receptors?

A

pseudounipolar axons

517
Q

what is the function of the Glassy membrane?

A

thickened basement membrane separating dermis from epithelium of hair follicle

518
Q

where does hair obtain its color from?

A

melanocytes in epidermis over dermal papilla of hair bulb

519
Q

how does hair grow?

A

via proliferation of matrix cells at hair bulb

(homologous to proliferation at stratum basale

520
Q

how do hairs move?

A

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
Q

what causes cutis anserina?

A

coloquially: goosebumps

cold & strong emotions: fear, awe, admiration, & arousal

522
Q

what type(s) of glands are found in the skin?

A

eccrine, apocrine, & sebaceous

523
Q

what is the product & function of eccrine glands?

A

sweat

thermoregulation

524
Q

what type of secretion is utilized by eccrine glands?

A

merocrine (simple exocytosis)

525
Q

how do eccrine glands develop?

A

invaginations of epithelium of dermal ridge

grows down into dermis

526
Q

where are glands found in the skin?

A

dermis only

527
Q

where are eccrine glands found in the body?

A

everywhere

528
Q

where are apocrine glands found in the body?

A

armpits, areolae, anal region

529
Q

where are sebaceous glands found in the body?

A

everywhere except palms & soles of feet

msot abundant on face & scalp

530
Q

what controls eccrine glands?

A

postganglionic sympathetic fibers

531
Q

explain histology of eccrine glands

A

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
Q

where do the ducts of the skin glands open to?

A

eccrine→ skin

apocrine→ hair follicle

sebaceous→ hair follicle

533
Q

when do the skin glands start working/producing their secretions?

A

eccrine→ birth

apocrine→ puberty

sebaceous→ puberty

534
Q

what gland displays merocrine secretion?

A

apocrine & eccrine

535
Q

what gland displays holocrine secretion?

536
Q

which gland has the largest lumen & why?

A

apocrine

b/c product is stored in the lumen of the duct

537
Q

why does apocrine secretion smell bad?

A

metabolism of secretory product by surface bacteria

538
Q

what is the product of sebaceous glands & its function?

A

sebum

prevents water loss from skin

lubricates hair

possible antibacterial & antifungal properties

539
Q

what causes acne?

A

chronic inflammation of obstructed sebaceous glands

540
Q

where do sebaceous glands open directly to the skin?

A

glans penis, glans clitoris, & lips

541
Q

what is the analogous the stratum corneum at the nail bed?

A

nail plate

542
Q

where does nail growth occur?

A

the nail root NOT the nail bed

543
Q

why do stitches prevent scarring?

A

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
Q

what happens when the wound healing response doesn’t revert beck to resting?

A

formation of keloids (fibrous growths)

caused by continuous collagen production

545
Q

who gets keloids?

A

usually a genetic predisposition

more common among darker pigmented races

546
Q

what causes stretch marks?

A

tearing of the dermis

547
Q

what causes cellulite?

A

formation of fibrous septae cause dimpling

decreasing fat is the only method for reducing cellulite

only found in women

548
Q

what skin layers are injured in a first degree burn?

A

aka scald

any to all layers above the stratum basale

549
Q

what skin layers are injured in a second degree burn?

A

all epidermal layers are destroyed

BUT keratinocytes from hair follicles can replenish epidermis

can involve upper layers of dermis

550
Q

what type of burn results in blistering?

A

second degree burn

551
Q

what skin layers are injured in a third degree burn?

A

all of epidermis & dermis w/some invasion into subcutaneous fat

only replaced by skin graft

NO pain (burned away the receptors)

552
Q

what causes sunburn?

A

acute inflammatory reaction to ultraviolet radiation

553
Q

if skin is constantly lost due to desquamation, how do tatoos work?

A

pigment droplets are trapped between epidermis & dermis

554
Q

how are tatoos removed?

A

laser light breaks pigment droplets up into pieces small enough for macrophage or more likely Langerhans cells to phagocytose

Microanatomy (9 decks)

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