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year 1 foundations > histology > Flashcards

histology Flashcards

1
Q

describe the tunica intima

A

single layer of squamous endothelial cells supported by basal lamina and a thin layer of connective tissue called sub-endothelial layer

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2
Q

what is the sub-endothelial layer?

A

it’s the thin layer of connective tissue that has elastic fibres and an internal elastic lamina

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3
Q

describe tunica media

A

made of predominantly smooth muscle but also has elastic fibres (it alternates smooth muscle and elastic fibres)
-> the thickness of tunica media varies tremendously

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4
Q

describe tunica adventitia

A

made of supporting connective tissue and elastic fibres that provide strength
-has collagen fibres & fibroblast

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5
Q

what is fibroblast?

A

type of cell that contributes to formation of connnective tissue

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6
Q

what type of vasculature is it hard to distinguish between internal elastic lamina, external elastic lamina and tunica media?

A

in elastic arteries

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7
Q

what is tunica intima and tunica media seperated by?

A

internal elastic lamina

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8
Q

what is tunica media and tunica adventitia seperated by?

A

external elastic lamina

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9
Q

what is appearance of layers in elastic arteries?

A

=thicker tunica media than tunica adventitia
=tunica intima thicker than tunica adventitia
=they have sheets of elastic fibres in their tunica media to provide recoil

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10
Q

what are some examples of elastic arteries?

A

aorta, aortas branches and pulmonary arteries

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11
Q

how do you stain elastic fibres?

A

not stained using common stains (including H&E) but can be visualised with special stains like ones that stain fibres black

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12
Q

whats the vasa vasorum?

A

vessels have own vascular supply called vaso vasorum because in large arteries, only inner part of wall can obtain nutrients from lumen

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13
Q

what are the 2 types of arteriole?

A

meta arteriole and terminal arteriole

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14
Q

describe appearance of arterioles

A

-smallest division of arteries
-they lose smooth muscle from tunica media and start to lose layer so only 1 or 2 layers

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15
Q

what is typical diameter of arterioles?

A

30-200 micrometre

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16
Q

what are arterioles important for?

A

controlling blood flow in a tissue

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17
Q

describe terminal arteriole appearance

A

no internal elastic lamina & covered by smooth muscle

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18
Q

describe meta arteriole appearance

A

part right before capillaries so no smooth muscle, it’s replaced by non-contractile cells, still has endothelial cells

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19
Q

describe capillary appearance

A

only composed of endothelial cells

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20
Q

what is diameter of capillaries?

A

4-8 micrometres

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21
Q

what are the 3 types of capillaries?

A
  1. continuous
  2. fenestrated
  3. discontinous
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22
Q

describe continuous capillaries

A

endothelial cells have no gaps in between them hence the name
examples = muscle, nerve, lung, skin

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23
Q

describe fenestrated capilllaries

A

has parasites & small gaps in between endothelial cells. there is a continuous basal lamina so not clear opening. have small pores about 50nm
examples = gut mucosa, endocrine glands, kidney

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24
Q

describe discontinuous capillaries

A

endothelial cells have very clear gap and basal membrane also discontinuous so obvious gaps
examples = liver, spleen, bone marrow

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25
Q

describe microvasculature from arterioles to veins?

A

terminal arteriole -> meta arteriole -> thoroughfare channels (some routes skip) ->capillaries -> precapillary sphincters -> post capillary venules -> veins

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26
Q

what are precapillary sphincters?

A

they’re composed of smooth muscle at the beginning of capillary bed to control flow through the network

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27
Q

what are post capillary venules appearance

A

endothelial cell lined and contain a thin layer of connective tissue

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28
Q

why are capillary networks important?

A

they are important sites for exchange e.g. cells moving into tissue in inflammation

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29
Q

what is the diameter of venules?

A

10-30 micrometres

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30
Q

when do vessels start being referred to as venules?

A

when they begin to aquire intermittent (not continuous) smooth muscle in tunica media layer

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31
Q

describe appearance of veins

A

they have tunica intima, thin but continuous tunica media typically consisting of a few layers of smooth muscle and an obvious tunica adventitia

32
Q

what has valves to prevent backflow?

A

some smaller veins. varicose veins formed as a result of incompetent valves

33
Q

what produces flow in lymphatic system?

A

-smooth muscle in walls
-hydrostatic pressure in tissue
-compression of vessels by voluntary muscles
- valves in vessels

34
Q

what is lymphatic system?

A

system of relatively thin walled vessels that drain excess tissue fluid (lymph) into blood vessels and transports lymph to lymph nodes for immunological surveillance

35
Q

what are the components of blood?

A

plasma & formed elements (red blood cells, white blood cells and platelets)

36
Q

what are the 2 branch terms of white blood cells?

A

granulocytes and agranulocytes

37
Q

what types of white blood cells are granulocytes?

A

-eosinophils
-neutrophils
-basophils

38
Q

what types of white blood cells are agranulocytes?

A

-lymphocytes
-monocytes

39
Q

what is plasma made up of?

A

-water (55%)
-proteins (coloids)
-nutrients
-salts
-crystaloids (calcium, magnesium etc)

40
Q

when seperating bloods, after spinning what layers are there?

A

-red blood cells at bottom as densest
-white blood cells next densest
-plasma found at top

41
Q

what is serum part of blood?

A

blood with clotting factors are removed

42
Q

how do you usually obtain serum?

A

by allowing the blood to clot and then removing clot before spinning

43
Q

what are erythrocytes?

A

red blood cells

44
Q

what diameter are red blood cells?

A

7 micrometre

45
Q

what is structure of red blood cells?

A

they are biconcave discs
-not true cells as have no nucleus or organelles
-basically they are deformable bags with about 1/3 of volume taken up by iron containing protein haemoglobin

46
Q

what property of rbc’s allow them to deform and slip through small spaces?

A

their network of flexible cytoskeleton

47
Q

how long do erythrocytes last in circulation? how are they removed when aged?

A

they last about 4 months and are removed by spleen and liver

48
Q

what is hematocrit?

A

proportion of blood that is red blood cells

49
Q

what is the avergae hematocrit of:
a) men
b) women

A

a) 42
b) 38

  • means 42/38% of blood volume is red blood cells
50
Q

what are the proportions of each type of white blood cells?

A

neutrophils = 40-75%
eusinophils = 5%
basophils = 0.5%
lymphocytes = 20-50%
monocytes = 1-5%

51
Q

what are some appearances of neutrophils?

A

-cytoplasm contains many granules but these stain poorly with acidic/basic dyes (hence neutro)
-prominent, multi-lobed nucleus

52
Q

what are some functions of neutrophils?

A

they circulate in inactive state but if stimulated by e.g. bacteria or inflammation, they enter tissue where they act as highly motile phagocytes

53
Q

what are some features of eosinophils?

A

-bilobed nucleus
-prominent granules in cytoplasm have high affinity for red acidic dye eosin (so look red)
-they’re slightly larger than neutrophils

54
Q

where are neutrophils production?

A

bone marrow - as they’re highly abundant and short lived, a large proportion of bone marrow is devoted to them

55
Q

what are some functions of eosinophils?

A

-granules contain a variety of hydrolytic enzymes and they’re important in inducing and maintaining inflammation (particularly in allergic reactions&asthma)
-important in fighting paristic infection

56
Q

how long do eosinophils circulate? and then what happens?

A

8 - 12 hours and then they move into tissue (particularly spleen, lymph nodes & GI tract) where they live

57
Q

what is some features of basophils?

A

-prominent granules have high affinity for basic dyes like methylene blue so stains intensely blue-purple
-cells have bilobed nucleus but it’s often obscured by granules

58
Q

what is function of basophils?

A

acts as effector cell in allergic reactions.
high affinity IgE receptors in their cell membrane are directed against a particular allergen and when they bind their antigen to cell its stimulated to release granules (termed degranulation).

= this leads to hayfever, allergic asthma, allergic dermmitus etc

59
Q

what do granules in basophils contain?

A

-histamine
-heparin
-other inflammatory mediators

60
Q

what is appearance of monocytes?

A
  • numerous small lysosomal granules in cytoplasm (not normal granules)
    -they’re the largest cells circulating in the blood and have a non-lobulated nucleus which often appears kidney bean shaped
61
Q

what are the functions of monocytes?

A

-serve as precursor of tissue macrophages & together they form what is termed mononuclear phagocyte system

62
Q

what are macrophages?

A

monocytes that have migrated into blood stream
(Monocytes typically circulate through the blood for 1–3 days before migrating into tissues, where they become macrophages or dendritic cells)

63
Q

where abouts in body are macrophages?

A

they’re widely distributed but are particularly found in loose connnective tissue

64
Q

what is appearance of lymphocytes?

A

-they have round nucleus by a thin to moderate rim of cytoplasm that doesn’t have granules

65
Q

what are the 2 types of lymphocytes and can you distinguish between them?

A

B lymphocyte and T lymphocyte
= can’t be distinguished in routine stained sections

66
Q

where are the lymphocytes produced?

A
  • both arise in bone marrow
    -but T cells differentiate in the thymus
67
Q

what are functions of lymphocytes?

A

-both cell types participate in specific immune response
-B cells give rise to antibody secreting plasma cells
-T cells form a complex set of cells that perform many defuse functions (aiding other immune cells, killing defective cells etc)

68
Q

what are platelets?

A

-part of formed element of blood
-small cell fragments about 2 micrometres in diameter found in large numbers in blood

69
Q

what is composition of platelets?

A

-they have well developed cytoskeleton, which participates in extrusion of granules and in clot retraction
-platelets have some organelles but no nucleus
-they have conspicuous granules that include, among other things some coagulation factors

70
Q

what are coagulation factors?

A

proteins in your blood that help to form blood clots to stop bleeding when you have an injury

71
Q

what is platelets main function?

A

they play a key role in hemostasis (prevention of blood loss)

72
Q

what is hematopoeisis?

A

formation of blood cellular components

73
Q

where is development of blood cells in embryology?

A

earliest site of erythrocyte formation is outside embryo in yolk sac (beginning at about 3 weeks gestation)
-later the liver, and to some extent the spleen is colonized by hemapoetic stem cells so in 2nd trimester, liver principal site of blood formation

74
Q

by birth, where is development of blood cells?

A

bone marrow, essentially all bones participate

75
Q

by maturity, where is development of blood cells?

A

only vertebrae, ribs, skull, pelvis and proximal femurs retain hematopoeisis
-marrow in other bones is largely adipose tissue although in emergency they can revert to blood formation

76
Q

what are megakaryocytes?

A

large cells of bone marrow that produces plateletes by undergoing multiple duplications of nuclear material but it doesn’t undergo cell division so nucleus is very large
-the platelets are formed as extensions at outer margin of cell which fragment from cell

year 1 foundations (36 decks)

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