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ESA 2- Cardiovascular System > Histology of the CVS > Flashcards

Flashcards in Histology of the CVS Deck (134)
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31

What does the tunica intima consist of in elastic arteries?

Endothelial cells with long aces, orientated parallel to the long axis of the artery. 
Narrow sub-endothelium of connective tissue, with discontinuous elastic lamina

32

What is the main feature of the tunica media in elastic arteries?

40-70 fenestrated elastic membranes

33

What else does the tunica media of elastic arteries contain?

Smooth muscle cells and collagen between lamina

34

What is the purpose of smooth muscle cells in the elastic arteries?

Produce elastin, collagen, and matrix

35

How do the features of the tunica media of elastic arteries stain?

Fenestrated elastic lamallae stain black 
Collagen and extracellular matrix stain turquoise 
Smooth muscle stains red

36

What does the tunica adventitia consist of?

A thin layer of connective tissue, containing vasa vasorum, lymphatic vessels, and nerve fibres

37

Why are the vasa vasorum required?

Because the wall is so thick that they need their own blood supply

38

How does an aortic dissection arise?

If blood somehow breaks the endothelium and works its way into the tunica media, it can start getting between the elastic lamallae. The high pressure means that sections are forced apart.

39

What is the problem with aortic dissections?

Very painful 
Can be catastrophic 
The collected blood is susceptible to clotting. If this continues, may rupture the aorta

40

When does aortal dissection happen a lot?

Marfan’s syndrome, due to the defected elastin

41

Where in the aorta can a dissection occur?

Anywhere along the length of the aorta

42

How are aortal dissections treated?

An endovascular stent is placed, which means there is no flow to the aortic dissection, and the blood can flow through the stent graft

43

How does the tunica intima appear in small elastic arteries?

Indistinct endothelial cells

44

What does the tunica media of an elastic artery have?

Elastin lamellae, smooth muscle cells and extracellular matrix

45

What is the tunica adventita of small elastic arteries made of?

Collagen

46

What is the importance of the elastic walls of small elastic arteries?

They can store energy in systole, helping move blood along

47

What does the tunica media of muscular arteries consist of?

Endothelium, a sub endothelial layer, and a thick internal elastic lamina

48

What is the main feature of the tunica media of muscular arteries?

40 layers of smooth muscles, connected by gap junctions

49

Why are the muscle cells of the tunica media connected by gap junctions in muscular arteries?

For coordinated contraction

50

How are the smooth muscle layers in muscular arteries arranged?

In circles

51

What does the tunica adventitia consist of in muscular arteries?

A thin layer of fibroelastic connective tissue, containing vaso vasorum, lymphatic vessels and unmyelinated nerve endings

52

How do the vaso vasorum in muscular arteries differ in muscular arteries from those in elastic arteries?

They are not very prominent

53

What stimulates vasoconstriction?

Sympathetic nerve fibres

54

How does vasoconstriction of muscular arteries occur?

The neurotransmitter noradrenaline is released at nerve endings, and diffuses through fenestrations in the external elastic lamina into external tunica media, to depolarise some of the superficial smooth muscle cells. Depolarisation is propagated to all cells of the tunica media via gap junctions

55

What happens as branch and diminish in diameter?

The number of smooth muscle layers in the tunica media diminishes

56

What happens when smooth muscle is contracted?

The endothelial layer and nuclei stick out

57

What is an end artery?

The terminal artery supplying all or most of the blood to a body part, without significant collateral circulation, meaning there is no significant contribution to tissue from another artery

58

What do end arteries undergo?

Progressive branching, without the development of channels connecting with other arteries

59

What happens if an end artery is occluded?

There is insufficient blood supply to dependant tissues, so nutrient and oxygen supply is seriously compromised

60

Give 3 examples of end arteries

Coronary artery 
Splenic artery 
Renal artery