Histology of the heart and blood vessels

Question 1

What are the 3 layers of the blood vessels?

Answer 1

Tunica intima
Tunica media
Tunica adventitia

Question 2

What makes up the tunica intima?

Answer 2

Squamous epithelium termed the endothelium which is supported by the basal lamina (Connective tissue)

Question 3

What makes up the tunica media?

Answer 3

Smooth muscle and some elastic fibres

Question 4

What makes up the tunica adventitia?

Answer 4

Supporting connective tissue

Question 5

What is found between the tunica intima and tunica media?

Answer 5

The internal elastic membrane

Question 6

What is found between the tunica media and tunica adventitia?

Answer 6

The external elastic membrane

Question 7

Which vessels contain smooth muscle in their tunica adventitia?

Answer 7

Veins

Question 8

Which vessels have the thickest tunica media?

Answer 8

Arteries

Question 9

Which vessels have the thickest tunica adventitia?

Answer 9

Veins

Question 10

What are vasa vasorum?

Answer 10

Blood vessels that branch from the main artery and move into the tunica adventitia in order to supply the outer most layers of the blood vessels with oxygen and nutrients

Question 11

How many layers of smooth muscle is found in the tunica media of an arteriole?

Answer 11

1 to 2 layers

Question 12

What are the characteristics of a meta-arteriole?

Answer 12

In meta-arterioles, the smooth muscle is replaced by discontinuous, non contractile cells called pericytes

Question 13

What forms the walls of a capillary?

Answer 13

Endothelial cells and a basal lamina only, with pericytes at intervals

Question 14

What are the 3 types of capillary?

Answer 14

Continuous
Fenestrated
Discontinuous/sinusoidal

Question 15

Where are continuous capillaries found?

Answer 15

Connective tissue, muscle, lungs, skin and nerves

Question 16

Where are fenestrated capillaries found?

Answer 16

Gut mucosa, endocrine glands and glomeruli

Question 17

Where are discontinuous/sinusoidal capillaries found?

Answer 17

Liver, spleen and bone marrow

Question 18

What are the characteristics of a fenestrated capillary?

Answer 18

Have occasional ~50mm pores in their walls

Question 19

What are the characteristics of a discontinuous/sinusoidal capillary?

Answer 19

They lack a basal lamina and have large gaps, allowing macro molecules to pass through

Question 20

What structures form the network between small arterioles and post capillary venules?

Answer 20

Meta-arterioles
Thoroughfare channels
Capillaries
Pre-capillary sphincters

Question 21

What are the characteristics of a post capillary venule?

Answer 21

They are endothelial cell-lined and contain a thin layer of connective tissue and some pericytes

Question 22

What is the difference between a post-cappilary venule and venule?

Answer 22

Venules form when post-capillary venules begin to acquire intermittent smooth muscle cells

Question 23

What is different about the veins of the scalp?

Answer 23

They have no valves

Question 24

What are the 3 layers of the heart wall?

Answer 24

Endocardium - Inner
Myocardium - Middle
Epicardium - Outer

Question 25

What are the layers of the endocardium?

Answer 25

Endothelium Basal lamina Thin layer of collagen fibres Layer of dense connective tissue Some areas of sub endothelium containing loose connective tissue, small blood vessels and nerves

Question 26

Describe the histology of the myocardium

Answer 26

Bundles and layers of contractile cardiac muscle Individual muscle fibres, surrounded by delicate collagenous connective tissue and a network of capillaries

Question 27

What are the characteristics of a cardiac muscle cell?

Answer 27

Single, central nucleus Intercalated discs containing desmosomes, adherent junctions and gap junctions

Question 28

What are the layers of the epicardium?

Answer 28

Mesothelium - single layer of flattened epithelium Basal lamina Fibroelastic connective tissue Adipose tissue

Question 29

What forms the fibrous pericardium?

Answer 29

Tough, fibrocollagenous connective tissue

Question 30

What forms the serous pericardium?

Answer 30

A layer of simple epithelium (Mesothelium), backed by a basal lamina and connective tissue

Question 31

What is the fibrous skeleton?

Answer 31

A supportive skeleton made up of bands of fibrous connective tissue around the heart valves, between the atria and between the ventricles This supports the valves and provides attachment for muscle fibres

Question 32

What is the structure of a heart valve?

Answer 32

They have an outer endothelial layer supported by a basal lamina They also have a core of dense connective tissue called the lamina fibrosa which is in continuation with the fibrous skeleton

Question 33

How do lymphatic capillaries begin?

Answer 33

Lymphatic capillaries begin as blind sacs