Cardiovascular System Histology Flashcards Preview

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Flashcards in Cardiovascular System Histology Deck (44)
1

What are the 3 layers of blood vessels?

Tunica intima, media and adventitia (or serosa)

2

Outline the general composition of the tunica intima

Endothelium layer, layer of loose CT and internal elastic lamina (separates from tunica media)

3

Outline the general composition of the tunica media

Circular layer of smooth muscle (contraction regulates blood flow), supporting ECM (collagen and elastic fibres) and external elastic lamina (separates from adventitia)

4

Outline the general composition of the tunica adventitia

Loose CT, vasa vasorum (nutrient arteries) to supply outer portion of large vessels

5

What are the 3 layers of the heart wall?

Endocardium, myocardium and epicardium

6

Describe the composition of the endocardium

Endothelial lining supported by elastic fibrocollagenous tissue (allows stretch)

7

Describe the composition of the myocardium

Cardiac myocytes (intercalated discs connect) supported by vascularised fibrocollagenous tissue

8

Describe the composition of the epicardium

Fibrocollagenous tissue with adipose tissue, act to carry coronary arteries and autonomic nerves

9

What is mesothelium?

Epithelia that lines the pericardium

10

What are cardiac myoocytes?

Short, branching cells with round central nuclei which are connected by intercalated discs (muscle cells of heart)

11

What is angina?

Chest pain at times of increased heart demand

12

What is myocardial infarction?

Heart attack; tissue necrosis due to ischaemia

13

What is the biggest cause of death in the UK?

IHD

14

Describe what happens to necrotic cardiac muscle following myocardial infarction (heart attack)

Necrotic cardiac myoocytes are replaced by a fibrous scar tissue to an acute inflammation response where neutrophils invade the site and cause tissue granulation to form cellular and vascularised loose CT

15

What are the two main types of artery?

Elastic and muscular

16

How are elastic arteries characterised?

Predominance of elastin and little SM in tunica media

17

Describe the histology of elastic arteries

Intima: endothelium, loose CT and internal elastic lamina
Media: concentric fenestrated elastic sheets (merge with int/ext lamina) with smooth muscle and collagen between sheets
Adventitia: loose CT with vasa vasorum

18

How are muscular arteries characterised?

Predominance of smooth muscle in tunica media

19

Describe the histology of muscular arteries

Intima: smaller CT layer than elastic artery
Media: circular SM layers
Adventitia: Thick for vessel size with collagen and thicker elastic fibres

20

What is arteriosclerosis?

Thickening and loss of elasticity in arterial walls leading to increased PVR and BP, increasing the risk of rupture

21

What is atherosclerosis?

Most common pathology of arteriosclerosis and involves formation of yellow, fatty plaques in larger arteries

22

Outline the pathogenesis of atherosclerosis

Endothelial damage --> altered endothelial permeability --> LDL and cell adhesion factors present --> monocyte and T cell migration --> accumulation of T cells and lipid-laden foam cells (macrophages) and lipid-laden SM from tunica media --> fatty streak formed --> fibrous cap over plaque toped by endothelia

23

Which cells accumulate lipid in the development of atheromas?

Smooth muscle cells and macrophages

24

What type of cell cover atheromatous plaques?

Endothelial cells

25

What is a precapillary sphincter?

Band of SM at start of capillary (from arteriole) where contraction determined the extent of the capillary bed involved in exchange

26

What are thoroughfare channels?

A-V shunts, connects arterioles and venules and relaxation of SM causes the blood to shunt away from capillary bed to venules

27

What are pericytes?

Contractile cells which can proliferate to become mesenchymal cells in repair, which can differentiate into new endothelial cells, fibroblasts or myofibroblasts

28

Describe the histology of capillaries

Single layer of endothelial cells which don't have tunica media and have little/no adventitia

29

What are sinusoids?

Large diameter capillaries

30

What are the 3 types of capillary?

Continuous, fenestrated and discontinuous

31

Describe the structure of continuous capillaries

Uninterrupted endothelium on continuous basement membrane (form BBB and are relatively impermeable)

32

Describe the structure of fenestrated capillaries

Found at sites of great molecular exchange; have uninterrupted endothelium with circular pores (fenestrae)

33

Describe the structure of discontinuous capillaries

Found where blood components interact directly with tissue/organ; endothelium and basement membrane are discontinuous and endothelium is supported by reticulin fibre meshwotk

34

Describe the general structure of veins

Large lumen and thin walls

35

What are the two types of venules?

Post-capillary and muscle venules

36

Describe the structure of post-capillary venules

There are only pericytes surrounding epithelium

37

Describe the structure of muscular venules

Continuous smooth muscle (media) and fibrocollagenous adventitia present

38

What is the main role of venules?

Major site of leucocyte migration in tissues and venule endothelium is sensitive to histamine --> leakiness

39

Describe the histology of veins

Intima: endothelium and CT (elastic fibres)
Media: variable, more circular muscle in legs
Adventitia: thick fibrocollagenous CT with vasa vasorum in larger veins

40

What are valves?

Semi-lunar projections of tunica intima consisting of fibro-elastic tissue covered by endothelium

41

What is vasa vasorum?

Network of arteries which supply the tunica adventitia of larger blood vessels

42

What is the main type of connective tissue present in the heart walls?

Fibrocollageneous connective tissue

43

What is the main difference between elastic and muscular arteries?

Muscular have much smooth muscle in tunica media, elastic arteries do not

44

Where are pericytes found?

In tunica intima; form discontinuous layer external to the capillary endothelium