Histology Flashcards

1
Q

what are the roles of the cardiovascular system

A

Transport of oxygen and nutrients to the tissues.

Transport of CO2 and other metabolic waste from the tissues.

Temperature regulation.

Distribution of hormones and immune cells.

Reproductive function in males: penile erection.

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2
Q

what are the three layers of blood vessels

A
inner = tunica intima, middile = tunica media, 
outer = tunica adventitia
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3
Q

describe the tunica intima

A

single layer of squamous epithelial cells (endothelial) supported by a basal lamina and thin layer of connective tissue

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4
Q

what is a basal lamina

A

extracellular matrix on which epithelial sits (basement membrane)

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5
Q

describe the tunica media

A

predominantly smooth muscles, thickness varies

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6
Q

describe the tunica adventitia

A

supportive connecting tissue

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7
Q

what separates the tunica intima and the tunica media

A

layer of elastuc tissue called the internal elastic membrane

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8
Q

what separates the tunica media and the tunica adventitia

A

external elastic membrane

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9
Q

what are elastic arteries

A

largest arteries (e.g. aorta) as have many sheets of elastic fibres in their tunica media to provide elastic recoil

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10
Q

what does the recoil elastic arteries maintain

A

diastolic blood pressure

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11
Q

what are vasa vasorum

A

vessels of the vessel- supply nutrients to outpart of vessel that cannot obtain nutrients from the lumen

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12
Q

what is a lumen

A

inside of tubular structure

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13
Q

what happens to the composition of arteries as they become smaller

A

loose layers of smooth muscles

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14
Q

describe the composition of arterioles

A

one or two layers of smooth muscle in their tunica media with almost no tunica adventitia

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15
Q

describe the composition of capillaries

A

endothelial cells and a basal lamina (diameter of 4-8 micrometers)

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16
Q

what are pericytes

A

connective tissue with contractile properties local at intervals out basal lamina of capillaries

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17
Q

what are the three types of capillaries

A

continuous, fenestrated, sinusoidal/discontinuous

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18
Q

describe continuous capillaries

A

most common- found in muscle, connective tissue, lung, skin and nerves

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19
Q

describe fenestrated capillaries

A

have approx 50nm pore in wall. found in mucosa of the gut, endocrine glands, glomeruli of the kidney

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20
Q

describe sinusoidal or discontinuous capillaries

A

lack a basal lamina and have large gaps. found in liver, spleen and bone marrow

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21
Q

what is microvasculature

A

Small arterioles connect to a postcapillary venule through a network made up of metarterioles, thoroughfare channels and capillaries.

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22
Q

what are precapillary sphincters

A

smooth muscle rings at the beginning of the capillary to help control flow through the network

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23
Q

where do capillary networks drain into

A

post capillary venules

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24
Q

describe post capillary venules

A

endothelial cell-lined and contain a thin layer of connective tissue and occasional pericytes

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25
Q

what happens at post capillary venules

A

important sites for exchange

26
Q

when do post capillaries venules become ‘venules’

A

once vessel begin to acquire intermittent smooth muscle cells in a tunica media layer

27
Q

describe the tunica adventitia of the largest veins

A

thick with incorporated bundles of longitudinally oriented smooth muscle

28
Q

why do veins contain most of the blood in the body

A

as are flexible and can accommodate the expansion

29
Q

what are the valves in veins made of

A

inward extensions of the tunica intima

30
Q

how do you histologically differentiate an artery and vein

A

thickness of tunica media artery thick

31
Q

what are the three layers of the heart

A

endocardium (inner), myocardium (middle), epicardium (outer)

32
Q

what are the two layers of the serous pericardium

A

visceral and parietal

33
Q

what are the layers surrounding the epicardium

A

epicardium-visceral layer of serous pericardium-

pericardial cavity- parietal layer of serous pericardium- fibrous pericardium- adipose tissue

34
Q

what does endoCARDIUM line

A

entire inner surface of the heart including the valves

35
Q

describe the structure of the endocardium

A

endothelium, basal lamina, thin layer of collagen fibres, layer of denser connective tissue

36
Q

what is a subendocardium

A

in some areas of heart- loose connective tissue containing small blood vessels and nerves and the branches of the impulse conducting system.

37
Q

what is backing the endothelial layer of the endocardium

A

fibrous tissue

38
Q

describe the structure of the myocardium

A

thick middle layer,

bundles and layers of contractile cardiac muscle fibres,

individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rich network of capillaries

(cardiac muscle cells in connective matrix)

39
Q

describe the myocardium structure

A

single central nucleus cardiac muscle cells.

intercalated discs passing across the fibres at regular intervals

40
Q

what is the purpose of the intercalated discs passing across the muscle fibres in the myocardium

A

acts to attach cells but allows spread of electrical activity- creates extensive network that stops intracellular junction ripping apart when the cells contract

41
Q

what allows the spread of electrical activity between cells

A

gap junctions

42
Q

describe the epicardium

A

on the surface of the heart

a single layer of flattened epithelium called mesothelium

basal lamina

fibroelastic connective tissue and (in some places) adipose tissue

43
Q

where are the coronary arteries and what does their placement allow

A

on surface in adipose tissue (under connective tissue and mesothelium) allows easy access- bypass

44
Q

what is the mesothelium

A

the simple squamous epithelium that lines the pleurae, peritoneum, and pericardium

45
Q

describe the fibrous pericardium

A

sac of tough fibrocollagenous connective tissue

46
Q

describe the serous pericardium

A

layer of simple squamous epithelium (mesothelium), backed by a basal lamina and connective tissue

47
Q

what does the serous pericardium line

A

the inner surface of the fibrous pericardium (parietal) and covers the surface of the heart (visceral)

48
Q

what separates the two mesothelial layers of the serous pericardium

A

pericardial cavity which contains a small amount of pericardial fluid

49
Q

describe the fibrous skeleton of the heart

A

formed by thick bands of fibrous connective tissue around the heart valves between the atria and ventricles

50
Q

what is the role of the fibrous skeleton of the heart

A

supports the valves, but also provides the attachments for the cardiac muscle fibres and acts as electrical isolator between atria and ventricles

51
Q

are there blood vessels in the heart valves

A

no

52
Q

describe the structure of the heart valves

A

Have an outer endothelial layer with basal lamina.

Layer of collagen and elastin fibres.

A core of dense connective tissue, called the lamina fibrosa, that is in continuity with the fibrous skeleton.

The leaflets of the valves separating the atria from the ventricles (the mitral and tricuspid) are anchored to papillary muscles in the wall of the ventricle by collagenous strands called the chordae tendineae, which merge with the lamina fibrosa.

53
Q

describe the lamina fibrosa

A

the core of a heart valve and is dense irregular connective tissue that is continuous with the fibrous skeleton of the heart.

54
Q

what covers the heart valve on both sides

A

endothelium

55
Q

what are the three types of cardiac muscle cell

A

contractile, pacemaker and conducting

56
Q

describe pacemaker cells

A

pale because of organelles within them

embedded in extensive matrix of connective tissue

fer myofibrils, little glycogen

57
Q

how does electrical signals travel through the skeleton

A

tunnel in skeleton for AV bundle

58
Q

describe purkinje cells

A

larger than normal cells,

They have, abundant glycogen, no T-tubules, no intercalated discs and sparse actin and myosin filaments, which tend to be found at the periphery of the cells.

found in the subendocardial layer just deep to the endocardium, they appear pale, and often exhibit a very pale/clear centre.

59
Q

where in the body are lymphatic vessels missing

A

brain and bone

60
Q

what is the role of the lymph system

A

system of relatively thin walled vessels that drain excess interstitial fluid (lymph) into the blood stream

61
Q

what is the role of lymph nodes

A

immunological surveilance

62
Q

describe lymphatic vessels

A

no central pump, but smooth muscle in walls, hydrostatic pressure in the tissue and compression of the vessels by voluntary muscle, combined with valves in the vessels, produces flow.