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NSF > Histology > Flashcards

Histology Flashcards

done to 24

1
Q

4 tissue types

A

epithelial, connective, muscle, nervous

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2
Q

define histology

A

study microscopic structure of tissue

branch of anatomy

essential for understanding function, abnormalities + pathological change

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3
Q

avg cell mem thickness

A

7.5nm

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4
Q

nucleus + nucleolus diameter

A

4µm 1µm

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5
Q

length mitochondrion + width cilium

A

0.5 - 4µm 250nm

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6
Q

resolution LM + EM

A

w/in 0.2µm 0.5nm

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7
Q

plasmalemma

A

pm bounding cell, esp directly inside plant cell wall

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8
Q

steps tissue processing

A
  1. fixation
  2. embedding
  3. sectioning
  4. mounting
  5. de-waxing
  6. staining
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9
Q

describe fixation process

A
  • dehydration by dipping incresing conc alcohol sols up to 100% to replace water in cells w alcohol
  • clearing w organic solvent, e.g. xylene, - dissolve alcohol (+ lipids :()

bc wax + water not miscible

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10
Q

why fixation

A

prevent rotting - bac/fungal attack; autodigestion by enzs leaking out lysosomes

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11
Q

how fixation works

A

binding sites form cross-links bet 2 prots so stay in place (or 2 locations on prot for shape)

spare sites bind (+ deactivate) microbes - prevents digestion

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12
Q

embedding process

A

poor on wax (LM) / resin (EM) to provide scaffolding for support in sectioning

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13
Q

problems w tissue processing

A
  • heating + dehydration can damage/alter tissue structure, e.g. shrinkage/tearing
  • hardening tissue by freezing but icicles, then melt = holes
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14
Q

sectioning process

A

using sharp microtome, wanting 1 cell thick (5-7µm), LM or 1 organelle (100nm), EM - best if makes continuous ribbon

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15
Q

process mounting

A

slide slide under ribbon floating in water

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16
Q

de-waxing process

A

reverse fixation
* xylene dissolves wax
* 100% alcohol to remove xylene
* decreasing alcohol conc sols to water

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17
Q

why de-waxing

A
  1. not natural part tissue so needs removal before viewing
  2. most conventional stains waterbased so need for stain penetrate
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18
Q

routine LM stain

A

Haemotoxylin + Eosin (H+E)

every prot in cyt -> pink so cyt pink

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19
Q

why staining necessary

A

cells pretty much colourless

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20
Q

why nucleus visible

A

histone prots fixed in place + NAs coiled around (forming chromatin)

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21
Q

histochemical stains

A

specific - used highlight certain parts cell, e.g. enzs or chemical components

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22
Q

trichrome

A
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23
Q

how stains work EM

A

stained w heavy metals
* heterochromatin has affinity bc area e- density = takes it up = dark + e- beams deflected off
* euchromatin e- lucent = e- beams pass through
* vesicles e- dense

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24
Q

common EM stain

A

Osmium tetroxide (OsO4) - stain + fixative

stabilises lipids so e- dense + black = visible = specialised stain

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25
Q

description + purpose myelin sheath

A

concentric layers myelin (lipid) around axon to:
1. protect
2. insulate
3. make more efficient at conducting

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26
Q

When to change light intensity on LM

A

increased mag = smallr specimen field = more light required

and vice versa

= turn up lamp + widen diaphragm

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27
Q

epithelial tissues

A

form barrier bet other body tissues + internal/external environ across which all exchanges take place, defending underlying tissues

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28
Q

features common to all epithelia

A
  • cellular = no connective tissue fibres holding cells together
  • avascular = no blood vessels
  • self-regen from stem cells lying w/in epithelium
  • sepped underlying tissues by basal lamina
  • supported underlying layer connective tissue cont bvs (metabolic support)
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29
Q

2 types epithelia

A
  1. simple = single layer cells
  2. stratified = multiple cell layers
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30
Q

purpose basal lamina in epithelia

A

attachment structure to allow attachment ep cells to connective tissue

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31
Q

how epithelial cells held together

A

cell junctions
1. occluding = tight + selectively permeable, act as barrier
2. anchoring for strength
3. communicating for movement bet cells = gap junction

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32
Q

basolateral surface

A

surface that adjoins underlying tiss

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33
Q

type anchoring cell junctions

A

desmosomes for cell-cell attachment
hemidesmosomes attach cell to basement mem

multiprot complexes to facilitate adhesion

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34
Q

where simple epithelia found + why

A

found only internal protected surfaces bc too delicate constitute defensive barrier against mechanical damage (as single layer)

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35
Q

types simple epithelia

A
  1. squamous
  2. cuboidal
  3. columnar
  4. pseudostratified
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36
Q

types stratified epithelia

A
  1. squamous
    * squamous
    * keratinised
    * parakeratotic
  2. transitional
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37
Q

structure + function simple squamous epithelium

A
  • nucleus flattened + cytoplasm indistinct (0.1μm < res LM + not visible)
  • slick surface for flow fluids
  • insufficient cyt for organelles involved secretion
  • rapid transport due short diff dist, e.g. lungs)
  • large SA
  • low friction = cover internal organs as move against each other, e.g. lining pleural cavity
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38
Q

endothelium

A

epithelium internal lining blood vessels - simple squamous

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39
Q

structure + function simple cuboidal epithelium

A
  • cube-shaped cells w central, round nucleus
  • not involved synthesis except form walls thyroid follicles + involved formation thyroid hormone
  • often lining secretory part exocrine glands; duct walls
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40
Q

structure + function simple columnar epithelium

A
  • rectangle w oval nuclei
  • nuclei lying same level towards base cells
  • more cyt than squamous/cuboidal = engage more cellular activity
  • specialised absorption + secretion, e.g. lining intestine - diff functions = diff morphology
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41
Q

how simple columnar epithelium specialised secretion

A

no apical specialisations but goblet cells can sweel w mucus (lubricant)

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42
Q

how simple columnar epithelium specialised absorption

A

microvilli (finger-like protrusions) surface increase SA for increased Roabsorption

visible as finger-like protrusions under EM, like brush border under LM

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43
Q

how simple columnar epithelium specialised move mats over epithelial surface

A

cilia, e.g. airways

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44
Q

structure + function pseudostratified columnar epithelium

A
  • single layer cells all in contact w basal lamina but not all reaching free surface
  • nuclei at diff levels in lower half of cells
  • resulting from apical specialisations bc all cells slightly diff
  • e.g. ciliated + goblet together in airways
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45
Q

structure + function stratified squamous epithelium

A
  • basal layers cuboidal, upper layers squamous
  • defence against mech damage as can withstand shearing forces coarse food, e.g. oral cavity, oesophagus
  • desmosomes for integrity
  • rete pegs for attachment
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46
Q

how are stratified epithelia classified (named)

A

superficial layer gives rise to naming

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47
Q

rete pegs

A

peg-like downgrowths from lowest layer cells into underlying connective tissue to attach

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48
Q

structure + function keratinised stratified squamous epithelium

A
  • constant renewal as dealing w damage like microtears from eating
  • as cells move up through layers become squamous + accumulate granules keratohyalin (stains dark blue H+E)
  • abruptly adjacent layer more superficial no cellular detail + keratohyalin replaced red-staining keratin
  • rete pegs to anchor
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49
Q

cornification

A

formation layer dead cells w/o cellular detail filled w keratin

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50
Q

keratin

A
  • physically strong, chemically inert, semi-waterproof
  • forms epidermis + protects mech damage, chem damage, dessication
  • allows retain shape
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51
Q

epidermis

A

epithelial layer of skin

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52
Q

structure + function parakeratotic stratified squamous epithelium

A
  • stratified squamous but superficial cell layer has cellular detail + keratinisation
  • allows absortion products fermentation, e.g. shortchain fatty acids
  • ruminant forestomach only in GI tract
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53
Q

structure + function transitional epithelium

A
  • some cells so big 2 nuclei
  • as cells move up from base get fatter + rounder
  • no keratin or rete pegs (not subjected shearing forces etc)
  • urinary sys only as stretch when bladder fills - can accomodate variable vol fluid w/o rupturing
  • stretch laterally w balloon shape
squamous shape at tips when stretched
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54
Q

oblique section demonstrated

A
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55
Q

single secretory cells found?

A

scattered in simple epithelia = individual exo/endocrine cells, e.g. goblet cells

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56
Q

gland defn

A

grp cells main function synth + secretion mat w extracellular function, excl neurotransmission
* e.g. prots (enzs, hormones), mucous, steroids, lipids)

aggregates secretory cells into downgrowths epithelium

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57
Q

embryological origin endocrine glands

A
  1. derived mesodermal layer + don’t retain connection w epithelium, e.g. thyroid
  2. neuronal
    * neuronal w morphology retained, e.g. hypothalamic neurons release hormones into blood from axon terminals
    * endocrine = adrenal medulla, releasing NTs into blood w phenotype altered
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58
Q

classification glands based on function

A
  • apical secretion = into free epithelial surface = exocrine w connection epithelial via drainage duct
  • basal secretion = into underlying connective tissue = endocrine w/o connection epithelium
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59
Q

exocrine vs endocrine glands

A
  • exocrine ducts, endo ductless
  • exocrine prots etc, endo hormones
  • apical vs basal secretion
  • exo secrete through duct sys directly to site where used, endo secrete into blood to be carried to target organs
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60
Q

classification exocrine glands based shape

A
  1. simple
  2. compound
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61
Q

simple exocrine gland structure + function

A
  • single duct, unbranched
  • secretory units tubular or alveolar (= acinar)
  • secretory unit drains directly onto epithelial surface
  • rare as punctures protective epithelial layer lots = poor design
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62
Q

examples simple exocrine glands

A
  • sebaceous w no duct, secretory unit opens directly into hair follicle - acinar
  • sweat - each secretory unit own duct to drain onto epidermis - coiled
diff sized lumens RHS as caught diff angles in section
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63
Q

compound exocrine gland structure + function

A

multiple ducts from many secretory units join form large single duct, opens epithelial surface
* epithelial barrier only weakened 1 pt
* allows put secretory units somewhere convenient, e.g. parotid salivary ventral outer ear, ducts through cheek wall
* tubular, alveolar, or tubuloacinar (mix)

easier to see connections bet ducts + sys as whole if sectioned longitudinally
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64
Q

classification exocrine glands based secretion type

A
  1. serous - alveolar units
  2. mucous - tubular units
  3. seromucous (mix)
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65
Q

serous glands structure + function

A
  • most prots secreted enzs
  • some other purposes, e.g. nutritive prots from mammary gland (also lipids)
  • alveolar = pyramid shaped cells - strong-staining as intracellular storage lots secretory prots
much more watery secretion
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66
Q

mucous gland structure + function

A
  • secretes proteoglycans (mucous) = lubricant
  • tubular units made columnar epithelial cells - pale-staining due large intracellular mucous store
  • mucous store = cell swollen = nucleus flattened towards base
mucous v sticky
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67
Q

mixed seromucous gland

A

gland w tubular + alveolar units OR serous demilunes = mucous units capped crescent-shaped serous cells (along edges)

e.g. mandibular salivary gland

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68
Q

classification exocrine glands based mode of release

A
  1. merocrine
  2. apocrine
  3. holocrine
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69
Q

merocrine gland descr

A

vesicle releases secretory products into duct via exocyt

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70
Q

apocrine gland descr

A

mem-bound vesicle pinched off (w some cytoplasm) + deposited on epithelial surface

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71
Q

holocrine gland descr

A

entire cell sheds into duct then dying cell pm ruptures, releases secretory products
* formation replacement cells

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72
Q

endocrine gland structure

A

each gland own morphology
sometimes cells aggregated around caps, e.g. islets Langerhans in pancreas prod insulin + glucagon

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73
Q

thyroid gland structure

A

prods T3 (triiodothyronine) + T4 (thyroxine) to regulate basic metabolic rate
* lipophilic hormones so formed + diff out into target cells enseguida

cells organised follicles (= hollow balls cuboidal epith)

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74
Q

how does thyroid gland ensure healthy animal never runs out T3/T4

A
  • heavily iodinated precursor prot thyroglobulin (TGB) synthed + secreted (exocrine) apical cells for storage in follicle
  • thyroid hormones needed = cuboidal epith cells take up TGB + breakdown by phagocytosis, releasing active T3/T4 to diff out into cap beds for distrib in body = endocrine

central cavity follicles filled sticky colloid fluid (hormones synthed)

once proded loads TGB enters storage phase
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75
Q

adrenal gland structure

A

2 main parts w diff functions
1. adrenal medulla
2. adrenal cortex

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76
Q

adrenal medulla structure + function

A

centre gland derived sympathetic neurons (but lost neuronal phenotype) = neuroendocrine
* neurohormones (mostly adrenaline, tiny noradrenaline (catecholamines)) secreted blood
* cells under nervous control from symp ns
* granular cyt w many vesicles

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77
Q

adrenal cortex structure + function

A

gland conts cells for synth + release hormones w 3 areas
1. zona glomerulosa
2. zona fasciculata
3. zona reticulata

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78
Q

zona glomerulosa

A
  • secretes mineralocorticoids - aldosterone
  • signals from kidneys - reabsorb Na+ for water + electrolyte balance
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79
Q

zona fasciculata

A
  • secretes glucocorticoids, e.g. cortisol, increasing in response to stress
  • signals from hypothalamus + pituitary
  • pale-staining as prod steroids from lipid
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80
Q

zona reticulata

A
  • secretes sex steroids (androgens, sex hormones)
  • signals from hypothalamus + pituitary
81
Q

myogenesis

A

process all muscle cell types from in embryogenesis

82
Q

myocyte

A

= mucle cell = muscle fibre = myofibre
* characteristically long + fibre-like, arranged parallel direction contraction

83
Q

basic structure sk musc

A

muscle cells surrounded CT (endomysium), aggregated form fascicle surrounded CT (perimysium), aggregated form muscle surrounded CT (epimysium)

at end CT condenses allow connection to bone (e.g. tendon)

CT for insulation

84
Q

general features sk myocytes

A
  • synctium = cells fused so long + multinucleate
  • nuclei at periphery
  • parallel unbranching fibres
  • striated
  • 10-110μm diameter, 30-50cm length
  • cell mem = sarcolemma + modified SER = sarcoplasmic reticulum (SR) + cyt = sarcoplasm
85
Q

motor unit

A

motor neuron + select muscle fibres it transmits to
* contraction each fibre all-or-nothing but graded response depending no. recruited fibres
* allow selective contraction to control strength + extent contraction

86
Q

what causes striations sk musc

A

dark-stained A(nisotropic) bands + light I(sotropic) bands
* A have thick myosin (+ actin) = heavily proteinated = no light through, but I only actin

87
Q

sarcomere

= contractile unit

A

dist bet 2 z-discs/z-lines @ centre I band

88
Q

myofibrils

A

parallel arrangements thread-like elongated structures running whole length sarcoplasm myocyte
* have 2 myofilament types
1. thick myosin
2. thin actin

89
Q

structure myosin filament in sk musc

A

made myosin prots, each w 2 globular heads + tail
* heads have binding sites actin + ATP + some ATPase activity

90
Q

structure actin filaments

A

globular actin prots end-to-end
* form longitudinal strands that twist round each other
* in groove bet 2 strands = prots tropomyosin + troponin

91
Q

contraction sk

A
  1. influx Ca2+ from SR binds troponin on actin myofilament
  2. conformational change troponin = tropomyosin unbinds actin
  3. myosin binding sites exposed = actin-myosin interaction
  4. E released at same time + myosin head pulls attached actin towards centre sarcomere
  5. sarcomere shortened + muscle cell contracted
  6. myosin head binds new ATP, detaches actin, lengthens, repeat
92
Q

muscle spindle

A

stretch-responsive sensory receptor - receives input to stretch + immediately contracts + sends feedback CNS

modified muscle fibre

93
Q

transverse tubules (t-tubules)

A

invaginations of sarcolemma to carry depolarisation (a pot) from motor nerve into myocyte rapidly to effect on terminal cisternae
* sac-like regions on SR for Ca2+ storage

ensure simultaneous contraction myofibrils in each cardiac muscle cell

94
Q

structure cardiac myocytes

A
  • joined at ends by intercalated discs
  • not syncytium
  • cells may branch
  • central nuclei
  • striated
  • more + larger mitochondria due more aerobic resp
95
Q

how can cardiac muscle maintain contractions over long time

A

t tubs more developed + release more Ca2+

96
Q

intercalated discs

A

transmit contraction force bet cells
* low elec resistance so muscle impulse cell-cell fast
* acts like functional syncytium so cells contract all together

bet cardiac muscle cells

97
Q

Purkinje fibres

A

specialised myocytes to conduct a pots more quickly + efficiently
* allow synchronised, spontaneous contraction = consistent heart rhythm
* lots glycogen

pale staining w H&E as fewer myofibrils

98
Q

smooth muscle cell structure

A
  • tapered ends = nucleus often not visible TS
  • visceral = no striations
  • unbranched
  • no t-tubules
  • gap junctions bet cells - communicate, coordinate, less precision
  • v little SR
  • elongated nuclei
99
Q

regeneration smooth myocytes

A

pericytes = undiffed cells
1. hyperplasia (increase cell nos)
2. hypertrophy (increase cell size)

100
Q

criteria to be lymphoid organ

A

need partial or complete connective tissue capsule surrounding organ

otherwise accessory lymphoid tissue

101
Q

primary vs secondary lymphoid organs

A
  1. where lymphocytes receive immunocompetence (bone marrow (B) + thymus (T)) = site maturation
  2. receive lymphocytes, e.g. lymph nodes, spleen, tonsils
102
Q

non-specific, innate immune defences

A
  1. skin + mucous mems - protective surfaces/secretions
  2. internal defences - inflammation, phagocytosis

specific is acquired or adaptive

103
Q

basic lymphocyte development

A

precursor B + T cells derived stem cells, mature + stimmed by foreign invaders
* diff into cells that effect immune response (effector cells) or remember antigen for quicker response next time (memory cells)

104
Q

secondary lymphoid tissue

A
  • tonsils
  • Peyer’s patches = gut associated lymphoid tissue (GALT)
  • mucosal associated lymphoid tissue (MALT)
  • broncheal associated lymphoid tissue

….

105
Q

thymus, LP under LM

A
  • v purple = lymphoid organ
  • lymphocytes small round purple cells w v little cyt
  • lobules w CT sepping them w/in organ
106
Q

Hassall’s corpuscles

A

in medulla THYMUS ONLY - epithelial cells concentrically surrounding cell debris

look like roses

107
Q

lymph nodes

role + paradox

A
  • filter lymph fluid through cortex + medulla + return to blood = physical barrier
  • immunosurveillance w lymphocytes + phagocytes
  • barriers to spread infection + tumours by containing + destroying antigens/microbes
  • also facilitate spread through lymphatic circulation
bvs enter + leave at hilus (= indentation concave surface) but pigs + ruminants from convex surface
108
Q

clinical importance lymph nodes

A

enlarge when activated by infection so swelling indicates disease

109
Q

germinal centres lymph node

A

at centre nodules (follicles) in cortex - where B + T cells proliferated + activated

110
Q

trabecula

A

CT going into lymph node (+ others, not thymus) from external capsule for structural support

111
Q

why is stained medulla paler than cortex in lymph node

A

lymphocytes v little cyt = mostly nucleus = v purple
epithelial cells more cyt = paler
medulla has higher prop epithelial cells than cortex

112
Q

spleen function

A

filter blood - involved immunosurveillance in left abdomen

113
Q

spleen basic structure

A
  • red pulp - mostly rbcs
  • white pulp - wbcs (B, T, macrophages) (purple in stain)
114
Q

tonsil structure

A
  • no capsule
  • lined oral epithelium
  • follicles w B-cell germinal centres when stimmed antigens (all the time)
115
Q

cellular els of blood + purposes

A
  1. erythrocytes for gas exchange to transport O2 + CO2 bet lungs + peripheral tissues
  2. leukocytes for defence against infectious + injurious agents
  3. platelets/thrombocytes to stop bleeding (= haemostasis
116
Q

plasma

A

sol of blood in which cells dispersed made water + plasma prots

117
Q

plasma prots + purpose

A
  1. albumin
  2. globulins = immunoglobulins, fibrinogen, clotting factors + complement

provide oncotic press = osmotic press exerted by prots in sol, preventing movement water from 1 sol into other
* water no move plasma across semipermeable mem (vascular endothelium) into interstitial fluid or vice versa

118
Q

functions plasma

A
  1. transport nutrients, hormones, waste products, heat
  2. homeostasis - maintain blood fluidity, pH, water content
119
Q

serum

A

plasma but w/o clotting factors (inc fibrinogen)

120
Q

where are cell components blood proded

rbcs, wbcs + platelets

A

haematopoietic tissues
* haematopoietic islands in yolk sac embryo
* bone marrow - major
* extra marrow sites - liver, spleen, kidney (fish + amphibians)

121
Q

haematopoietic cells

A

multipotent, primitive + can develop any type blood cell

122
Q

types bone marrow

A
  1. red marrow = mostly haematopoietic cells, mostly in long, flat bones - spine, hips, sternum
  2. yellow marrow = mostly fat cells, can be converted haematopoietic lines
123
Q

maturation erythrocytes

A

lose organelles inc nucleus -> anucleate, biconcave discs = erythropoiesis
* in bone marrow, final stage whilst circulating in blood

anucleate = no nucleus

stain pink due Hb

124
Q

general variations in rbc size + shape bet species

w photos

A
  • cat + equine = Rouleaux formations = dysproteinaemia = coin stacks
  • camelids = elongated
  • central pale area more obvious dogs, goats; less in cats, horses
  • non-mammalian = nucleus, ellipsoid, large
125
Q

variation colour rbc

beyond normal small amount

A

polychromasia

126
Q

variation in rbc size

beyond small normal amount

A

anisocytosis

127
Q

variation in shape rbc

beyond normal small amount

A

poikilocytosis

128
Q

prominent central pallor rbc

A

hypochromia = hypochromasia, possibly indicating reduced Hb conc

129
Q

role carbonic anhydrase in gas exchange

A

facilitates transport O2 + CO2

130
Q

how can rbc carry O2

A

adult Hb has 2α + 2β chains, each w Fe-cont haem grp that can bind 1O2 mol

131
Q

how is structure foetal Hb diff from adult + why

A

2γ chains instead of β, giving higher affinity O2, enabling placental O2 transfer

132
Q

what happens as erythrocytes age

A
  • more rigid, less deformable = more prone damage whilst circulating
  • changes in p mem, recognised by macrophages so removed = engulfed into cyt + lysed

lifespan varies, 2-5 months in domestic animals

133
Q

what happens when macrophage engulfs aged erythrocyte

A

in cyt:
1. broken down + Hb released into cyt
2. Hb broken down to haem, iron + globin
3. globin broken down to aas, reused for production new Hb chains
4. transferrin used transport iron other tissues, stored as ferritin haemosiderin, used again production rbcs
5. haem broken down to bilirubin, released into blood

134
Q

what happens to bilirubin from breakdown haem

A

binds albumin in blood, transported liver, taken up hepatocytes, released into bile. into intestine, degraded to urobilinogen, then 1 of 3:
1. degraded to stercobilinogen (brown) -> faeces
2. absorbed intestine, bypasses liver to kidneys -> urine
3. absorbed intestine -> liver, reexcreted in bile

bilirubin yellow colour - causes yellow of jaundice

135
Q

how is production/release leukocytes stimmed

A

by inflammatory cytokines from injured/infected areas

136
Q

major leukocyte types + key purposes

A
  1. neutrophils
  2. monocytes
  3. lymphocytes - adaptive immunity, can recognise foreign mat + directly destroy or prod antibodies
  4. eosinophils
  5. basophils

1 + 2 = innate immunity 1st defence -phagocytosis microbes
4 + 5 = defence against parasites + allergic reactions

137
Q

granulocytes + agranulocytes

A

granulocytes = polymorphonuclear w specific cytoplasmic granules + lobulated nuclei - neutrophil, eosinophil, basophil
agranulocytes = mononuclear = no granules in cyt - lymphocytes + monocytes

138
Q

neutrophils

A
  • lobulated nucleus - 3-5 lobules
  • small cyt granules, stained slightly pink - more visible some species, e.g. cow
  • proded bone marrow = BM pool -> blood pool (T(1/2) = 5-10hrs) -> tiss pool (few days) by migrating thru endothelium
  • bigger than rbcs
139
Q

wbc behaviour w/in blood pool

A
  1. circulating = flowing freely
  2. marginating = transiently attached endothelium

either or

140
Q

lymphocytes

A
  • small intermediate + large - large not in dogs, cats
  • round, densely-stained nucleus
  • scant amount light blue stained cyt = lightly basophilic cyt
  • proded BM
  • mostly present in + released from lymphoid tissues
  • blood pool (varying T(1/2)) -> tiss pool to perform function
  1. T cells = cell-mediated immunity - lyse cells directly, help other cells perform function
  2. B cells = antigen recognition + antibody production
  3. natural killer (NK) cells = cytotoxicity - lyse damaged/foreign cells
141
Q

monocytes

A
  • similar size neutrophils (or bit bigger)
  • variable shaped nucleus
  • lightly basophilic cyt (light blue)
  • proded BM -> blood pool (T(1/2) 0.5-3days) -> peripheral tissues -> macrophages + dendritic cells (10days-more than year)
  • innate immunity = phagocytosis, regulation inflammatory responses
142
Q

eosinophils

A
  • similar size neutrophils
  • lobulated nucleus
  • orange/red cyt granules = eosinophilic granules, always distinct
  • proded BM -> blood pool (T(1/2) = 8-18hrs) -> tiss pool (weeks-months)
  • reg allergic reactions + fight parasitic infections
143
Q

basophils

A
  • similar size neutrophils
  • lobulated nucleus
  • purple cyt granules = basophilic granules
  • proded BM -> blood pool (T(1/2) 2-3days) -> tiss pool (few days)
  • role in allergic reactions
144
Q

platelets descr

A
  • anucleate cytoplasmic fragments
  • pale blue/pink cyt
  • clusters purple granules
  • originate from big megakaryocyte in BM that tears apart cyt to prod 1000s
  • short lifespan 9-10 days

NOT CELLS

145
Q

function platelets

A
  1. clot formation w fibrinogen to stop bleeding
  2. clot retraction = contraction fibrin mesh to pull edges tiss together
  3. granules cont vasoconstrictors + growth-promoting prots
146
Q

heterophils

A

analogous neutrophil in birds, reptiles + amphibians
* rod-shaped granules not round
* red-orange granules like eosinophils
* most abundant granulocyte (like neutrophils)

147
Q

thrombocytes

A

analogous platelets in birds, reptiles, amphibians
* true cell w nucleus
* small amount cyt
* lil bit phagocytic activity asw

148
Q

overview cellular blood components

table

A
149
Q

diff types cartilage + their sub-grps

diagram

A
150
Q

2 main components all connective tiss

A
  1. cells
  2. ECM

bvs present asw

151
Q

what’s present in ECM

A
  • fibrous prots - collagen, elastic, reticular fibres
  • non-fibrous glycoprots - cell-ECM interactions
  • ground substance (= hydrating gel) - only ordinary + cartilage
152
Q

ground substance purpose

A
  • medium for exchance substances bet blood + cells
  • supports cells + fibres
  • binds cells + fibres together
153
Q

what’s in hydated gel

A
  1. glycosaminoglycans (GAGs) = hydrated sugars
  2. proteoglycans = GAGs attached small prot - huge, high water retention (= no stain well)
154
Q

derivation CT

A
155
Q

fibroblasts

A

active + large - prod ECM
* prominent nuclei
* basophilic granular cyt (rER) = sign active prot synth

all CT

156
Q

fibrocytes

A

dormant, small, maintaining ECM
* condensed, small nuclei
* not proding ECM
* elongated parallel to collagen fibres
* can diff other CT cell types

all CT

157
Q

structure collagen fibre

A

triple α-helix chain = mol x10-15 together = fibril x15-20 together = fibre

158
Q

functions ordinary CT

A
  1. mechanical support binding cells together + tiss layers (e.g. epidermis to bone)
  2. metabolic support - O2 + nutrients bvs w/in tiss to cells by diff thru ECM
  3. defence
    * wbcs migrate into tiss to ‘patrol’
    * blood/lymph = liquid CT
    * mast cells formed in tissues
159
Q

mast cell formation + function

A

basophils leave circulation + form them in tissues
* lots vesicles w vasodilating substances (histamine, serotonin) + proteolytic enzs
* non-self mat = exocyt vesicle conts = local vasodil = greater blood flow = more wbcs

anaphylactic shock = widespread activation so big drop bp

160
Q

areolar loose CT

A

in subcut layer skin + under epithelial layer other organs (GI, respiratory, urinary) - diff ones diff amounts each fibre depending function
* collagen fibres strong = tiss high tensile strength
* elastic fibres recoil props so always w collagen limit stretch + prevent tearing

look for lots white spaces to indicate loosely packed cells = loose CT

161
Q

adipose CT

A

reserve E source, insulation, protect organs
* adipocytes = modified fibrocytes
* nuclei pushed to periphery as filled fat
* LM = inside cyt ring empty bc fat dissolved in tiss processing

all organs, e.g. abdomen, hypodermis of skin

162
Q

white adipose tissue (WAT)

A

no. adipocytes static w constant withdrawal + deposit (so turnover) of lipid
* each adipocyte supported network collagen + reticular fibres

E reserve from stored triglycerides = thermal insulation under epidermis (fat = poor heat conductor)
* also shock absorber in spinal column, feet

reticular fibres need special stain to see LM

163
Q

brown adipose tiss (BAT)

A

store E as heat = thermoregulation in proding heat in neonates
* darker bc more mitochond (they release E as heat)
* lots little fat-cont vacuoles, not 1
* nuclei more centrally placed

164
Q

reticular CT

A

forms internal skeleton, functions as filtration, e.g. in lymph node

provide support in bv walls + branching networks round cells - made collagen + glycoprot, v v fine

stain w silver stain

165
Q

dense irregular CT

A

lots + lots collagen fibres, looks all over the place

w/in all underlying sub-mucosal layers - gut lining, bladder

166
Q

dense regular CT

A

collagen/elastic fibres regularly arranged in bundles parallel for max strength
* specific sites like tendons, ligaments

ligaments = bone-bone; tendons = muscle-bone

167
Q

elastic CT

dense type

A

for recoil of tiss, e.g. maintain pulsing bloodflow + press in arteries + passive lung recoil

elastin = prot present to provide stretchiness

fibres v thin

coiled - stretch = straighten, then recoil
168
Q

basement mem

A

thin layer glycoprots bind epithelial cells (specific receptors, hemidesmosomes) + then collagen in ECM
* epithelial tiss no blood supply = how nutrients supplied
* cell adhesion

169
Q

where is hyaline cartilage found

A
  1. all joints on long bones - NO fibrous perichondrial layer + v hydrated for cushion compressive forces on bone
  2. trachea, 1 bronchi - rigid so open all time
  3. parts skeleton bone no required but inflexible support needed - saves weight but weight-bearing - nasal septum
  4. end of ribs
170
Q

how does cartilage grow

A
  1. appositional growth - division + activation chondroblasts from fibroblasts in perichondrium = new matrix on surface + build out
  2. interstitial growth = division chondrocytes in matrix
171
Q

hyaline cartilage structure w roles

A
  • surrounded perichondrium - dense fibrous CT (mostly irregular)
  • chondroblasts secrete ECM then become embedded in semi-solid gel in lacunae = dormant, now chondrocytes
  • chondrocytes transparent, smooth + glossy = less friction
  • collagen fibres limit amount hydration so swelling so hydrated gel stiff (turgor) for mechanical support
  • ECM avascular = diffusion nutrients thru gel for metabolic support

most common cartilage tiss

chrondrocytes shrink in fixation + pull away from sides lacunae

172
Q

chondroblasts + -cytes in cartilage

A

present all types

173
Q

fibrocartilage

A

fibro + chondro = strong attachment + rigidity, e.g. bet vertebrae
* lots collagen = tensile strength + intervertebral disks subject tensile forces
* chondrocytes in rows bet collagen layers

174
Q

elastic cartilage CT

A

lots elastic fibres instead collagen in perichondrium + ground substance = flexible for recoil + movement in organ but still rigid, e.g. ear move in direction sound still maintain shape

175
Q

functions bone

A
  1. support soft tiss + attach sk musc
  2. structure + anatomy whole bod
  3. protect internal organs
  4. mineral homeostasis - stores + releases
  5. prod bcs from red BM
  6. triglyceride fat storage as yellow BM
176
Q

bone cell types

A

osteogenic cell -> osteoblast (forms matrix in periosteum + endosteum) -> osteocyte (maintains tiss, trapped lacunae)
osteoclast - reabsorption + breakdown ECM, formed fusion macrophages (=multinucleated)

177
Q

endosteum

A

cellular layer lining bone cavity

178
Q

osteoid

A

organic bony matrix

179
Q

calcification front

A

where Ca2+ + electrolytes exocytosed from osteoblasts so added osteoid = matrix becomes hard + calcified + cells trapped -> osteocytes = ossification

180
Q

osteoclasts how work

A

release acid to dissolve inorganic matrix + proteolytic lysosomal enzs to breakdown organic matrix - Ca2+ + PO43- to blood

181
Q

osteoclast purposes

A
  1. general turnover bone
  2. bone remodelling in growth
  3. fracture repair
  4. increase blood Ca2+ levels
182
Q

bone ECM contents

A

osteoid conts only collagen fibres (resist compression + tension), ground substance, prots bind Ca2+, phosphatases

calcification adds rigidity (support) bc precipitation hydroxyapatite crystals (inorganic)
* cytoplasmic projections osteocytes w gap junctions = communicate

183
Q

gross anatomy long bone juvenile

A

BM red when young, old = mostly made fat = yellow
whole thing surrounded periosteum = thin fibrous layer from which cells for repair come

physis = epiphyseal plate = growth plate = line cartilage, only in animals actively growing then becomes just bone
184
Q

causes osteocyte apoptosis

A
  • reduction mechanical stimulation (astronaut)
  • overstimulation - stress fractures
185
Q

long vs flat bones

A

long = limbs, ribs; flat = skull, mandible

186
Q

2 types bone tiss

A

new bone formation = woven (immature, irregular) - early stages development + repair

develops lamellar (mature, regular, layered) - compact or spongy

187
Q

compact bone other names + structure

A

dense, cortical

channels in matrix (Haversian canals) w bv surrounded 2/3 concentric layers (lamellae) matrix + cells = osteon
* metabolic support from bv
* in each layer calcified collagen fibres same orientation but diff direction next lamella = high tensile strength AND resist compression from all directions

mostly long bones - osteons not as well organised flat

188
Q

spongy bone other names + structure

A

trabecular, cancellous

bridges outer compact shell of bone w cavity by reinforcing network trabecular rods
* rods present sites greatest stress long bones @ epiphyses, NOT @ diaphysis
* porous + not dense = shock absorber + scaffold for weight bearing

mostly long bones, trabeculae not as well organised in flat

189
Q

process of bone remodelling

A

woven -> lamellar

woven = osteoblasts surrounded matrix randomly + collagen fibres random = less strong

  1. osteoclasts on outer bone surface tunnel + erode through bone = channel for bv to grow
  2. endosteum (reticular CT) lines tunnels w osteoblasts
  3. layer osteoid laid, mineralised make bone
  4. osteoblasts trapped -> osteocytes, occurring in waves inward towards bv = osteon w concentric layers
190
Q

ossification type flat bones + why

A

intermembranous - arise in mem of mesenchyme w increased partial press O2

191
Q

how does intermembranous ossification occur

A
  • grps mesenchymal cells diff into osteoblasts, lay down osteoid islands, calcified to bone
  • on surface more cells diff to osteoblasts, lay more matrix
  • osteoid islands eventually fuse = woven bone

no cartilage stage

192
Q

type ossification long bones + vague outline

A

endochondral/intracartilagenous
* hyaline cartilage template made then replaced woven bone
* blood arrives = higher conc O2 = chondrocytes replaced osteocytes

193
Q

endochondral ossification

A

@ 1 centre ossification (diaphysis):
1. cartilage matrix forms shaft centre, calcified + hollows as chondrocytes die (by osteoclasts)
2. cavity filled BM by invading bvs

@ 2 centre @ same time (epiphyses)
* = layer actively growing cartilage each end (physes) for bone lengthening
* when 1 + 2 centres meet lengthening stops + it is adult bone

194
Q

appositional growth of bone

A

increase bone diameter
* osteoblasts inner layer periosteum lay new bone (intermembranous ossification)
* whilst osteoclasts erode inner bone surface (= cavity bigger)

195
Q

joint formation

A

cystic degeneration mesenchyme bet bone ends by apoptosis
* cruciate ligament surfaces to form synovial lining

giant bone splits smaller

196
Q

primary + secondary spongiosa

A

1 = bone spicules w calcified cartilage core
2 = bone spicules w/o cartilage core

blue = 1; green = 2
197
Q

resting osteoblasts

A

flattened cells making up endosteum
* activated = diff into bone-proding osteoblasts
* protect bone + filter blood to send ions + nutrients osteoblasts + osteocytes

present if bone happy + healthy

198
Q

prepping bone for histological viewing

A

need to grind down for thin enough to stain
* = dust in gaps, can’t see cellular detail, have to decalcify

NSF (22 decks)

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