Circulatory system histology

Question 1

Which 2 systems comprise the circulatory system?

Answer 1

lymphatic system

cardiovascular system

Question 2

Roles of CVS system?

Answer 2

transport O2 & nutrients to tissues
transport CO2 & metabolic waste from tissues
temperature regulation
distribution of hormones & immune cells
reproductive function in males (penile erection)

Question 3

What is the basic 3 layer structure of blood vessels?

Answer 3

tunica intima
tunica media
tunica adventitia

Question 4

Describe the innermost layer of a blood vessel

Answer 4

intima

single layer squamous epithelial cells (endothelial cells supported by basal lamina + thin layer CT)

Question 5

Describe the middle layer of blood vessels.

Answer 5

media
predominately smooth muscle
thickness varies

Question 6

Describe the outermost layer of blood vessels.

Answer 6

adventitia

made of supporting CT

Question 7

What separates the intimacy and media?

Answer 7

internal elastic membrane

Question 8

What separates the media and adventitia?

Answer 8

external elastic membrane

Question 9

Which arteries are the elastic arteries?

Answer 9

the largest ones, e.g. aorta

Question 10

In which layer of the elastic arteries would the elastic fibres be found?

Answer 10

tunica media

Question 11

What is the vasa vasorum and in which vessels would it be found?

Answer 11

a blood supply for the large vessels - since only the inner part of the wall can obtain nutrients from the lumen

Question 12

Describe the structure of the arterioles.

Answer 12

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

Question 13

Describe the structure of capillaries.

Answer 13

endothelial cells + basal lamina

pericytes at intervals just outside basal lamina

Question 14

What are pericytes?

Answer 14

connective tissue cells with contractile properties

Question 15

What are the 3 types of capillary?

Answer 15

continuous
fenestrated
sinusoidal / discontinuous

Question 16

Where would you find the different capillary types?

Answer 16

continuous - muscle, CT, lung, skin, nerves
menstruated - gut mucosa, endocrine glands, kidney glomeruli
sinusoidal - liver, spleen, bone marrow

Question 17

Which capillary type lack a basal lamina and have large gaps for macromolecules to pass through?

Answer 17

sinusoidal / discontinuous

Question 18

What are pre-capillary sphincters composed of and where are they found?

Answer 18

smooth muscle

beginning of the capillary

Question 19

what do capillary networks drain into?

Answer 19

post-capillary venules - important sites for exchange

Question 20

Post-capillary venules need to acquire … before becoming venules?

Answer 20

intermittent smooth muscle in tunica media

Question 21

What are “inward extensions of the tunica intima”?

Answer 21

valves in small-medium sized veins

Question 22

What are the 3 layers of the heart?

Answer 22

Epicardium (outer)
Myocardium
Endocardium

Question 23

List in order from outside to in, the layers if the heart including pericardium etc

Answer 23

adipose tissue
fibrous pericardium
pericardium
parietal layer of serous pericardium
pericardial cavity
visceral layer of serous pericardium
epicardium
myocardium
endocardium

Question 24

What does the endocardium line?

Answer 24

the entire inner surface of the heart, including the valves

Question 25

What are the layers of the endocardium?

Answer 25

(lumen of heart)
endothelial cells
fibrous tissue (basal lamina + collagen fibres)
cardiac muscle

Question 26

What does the sub-endocardium contain?

Answer 26

loose CT containing small blood vessels + nerves + Purkinje fibres

Question 27

What is the structure of the myocardium?

Answer 27

Bundles & layers of contractile cardiac muscle fibres

Individual muscle fibres surrounded by collagenous CT & rich network of capillaries

Question 28

What is the structure of cardiac muscle cells?

Answer 28

single central nucleus

intercalated discs - pass across fibres at irregular intervals

Question 29

What is the role of the myocytes’ intercalated discs?

Answer 29

attach adjacent cells and allow spread of electrical activity

Question 30

What is mesothelium and in which layer of the heart is it found?

Answer 30

a thin layer of simple squamous epithelium

epicardium

Question 31

Describe the 2 parts of the pericardium.

Answer 31

Fibrous - a sac pf tough fibro-collagenous CT

Serous - layer of simple squamous epithelium, basal lamina + CT

Question 32

Which serous layer lines the inner surface of the pericardium?

Answer 32

parietal serous pericardium

Question 33

Which serous layer covers the surface of the heart?

Answer 33

visceral serous pericardium

Question 34

What separates the 2 serous layers?

Answer 34

pericardial cavity

Question 35

What is the purpose of the pericardial fluid?

Answer 35

provides lubrication for heart movement

Question 36

What is the lamina fibrosa and in which heart structure is it found?

Answer 36

core of dense CT of heart valves - is continuous with the fibrous skeleton

Question 37

What are the leaflets of the mitral and tricuspid valves anchored to?

Answer 37

papillary muscles

Question 38

How are the leaflets anchored to these muscles?

Answer 38

collagenous strands = chord tendinae

Question 39

What are the 3 types of specialised cardiac muscle cells?

Answer 39

contractile cells
pacemaker cells
conducting cells

Question 40

Which specialised cells appear pale?

Answer 40

pacemaker and conducting cells

Question 41

What is the lymph vascular system?

Answer 41

A system of thin-walled vessels that drain excess interstitial fluid (lymph) into the bloodstream.

Question 42

What produces flow through the vessels?

Answer 42

Smooth muscle in walls
Hydrostatic pressure in tissue
Compression of vessels by voluntary muscle + valves