Blood Vessel Structure and Function

Question 1

What are the 4 general layers of every blood vessel?

Answer 1

• Lumen
• Tunica intima
• Tunica media
• Tunica adventitia

Question 2

What is the tunica intima layer made up of

Answer 2

Internal elastic lamina

Question 3

what is the tunica layer media made up of

Answer 3

External elastic lamina

Question 4

5. What is found in the tunica intima

Answer 4

• Endothelial cells
• Basement membrane that supports connective tissue

Question 5

6. What is found in the tunica media

Answer 5

Smooth muscle and elastin

Question 6

7. What is found in the tunica adventitia

Answer 6

Supporting connective tissue that contains fibres with some vessels & nerves

Question 7

8. Describe the differences in structure of the layers of arteries and veins

Answer 7

• Arteries: smaller lumen, large tunica media
• Veins: thin walls, larger lumen

Question 8

11. What is the importance of veins having thinner walls?

Answer 8

allows for stretch to occur which allows for additional blood volume into the vessel

Question 9

14. What are arterioles?

Answer 9

Small resistance vessels with muscular walls

Question 10

What are venules?

Answer 10

smallest vessels in the venous circulation

Question 11

16. Describe what happens when blood flow is reduced.

Answer 11

Reduced blood flow leads to improper perfusion of tissues and lack of nutrients (ischaemia). this can lead to cell death

Question 12

17. What does too much flow to arterioles do?

Answer 12

Too much flow damages delicate tissue structure.

Question 13

18. How do arterioles control reduced/ too much blood flow?

Answer 13

Arterioles control this by varying their diameter

Question 14

What is raynaud’s disease?

Answer 14

When smaller arteries that supply blood to the skin become limited, causing vasospasms

Question 15

Name 4 components of capillaries

Answer 15

• Endothelial cells (1 cell thick)
• Basement membrane
• Some collagen fibrils
• Occasional pericytes

Question 16

What are occasional pericytes

Answer 16

contractile cells that work with collagen fibrils to aid in the constriction and dilation of capillaries

Question 17

24. What is the diameter of capillaries

Answer 17

5-8 µm

Question 18

25. How are endothelial cells joined and what do they contain?

Answer 18

Joined together by tight junctions and contain many vesicles

Question 19

26. Name 6 functions of endothelial cells

Answer 19

• Permeability barrier
• Produces extracellular matrix
• Produces factors that modulate blood flow
• Produces anticoagulants and prothrombotics
• Regulates inflammation
• Cell growth

Question 20

27. Name 3 ways things inside the capillaries are transported across endothelial cells

Answer 20

• Diffusion
• Transcytosis via pinocytotic vesicles
• Via the intercellular space

Question 21

How do gases and ions travel across the endothelial cells?

Answer 21

diffusion

Question 22

How do proteins and lipids travel across the endothelial cells

Answer 22

Transcytosis via pinocytotic vesicles

Question 23

30. How do cells travel across the endothelial cells

Answer 23

Via the intercellular space

Question 24

What do fenestrated capillaries have in their walls

Answer 24

Fenestrae and diaphragm

Question 25

33. What do sinusoidal capillaries have in their walls?

Answer 25

literal gaps

Question 26

What type of system is the venous system

Answer 26

low pressure system

Question 27

Explain how valves and muscle surrounding the vein facilitates blood flow against gravity

Answer 27

1. muscle around the vessel relaxes, causing the valves to close 2. Muscle contracts. The upper valve opens, blood forced upwards. The lower valve stays closed 3. Muscle relaxes, upper valve closes and the lower valve opens due to muscle contraction elsewhere. Blood flows upwards through lower valve.

Question 28

36. What does incorrect functioning of valves lead to

Answer 28

leads to formation of varicose veins

Question 29

37. What is the texture of the endothelium

Answer 29

the endothelium is a smooth, non-stick surface texture

Question 30

38. What type of flow does the endothelium facilitate

Answer 30

facilitates Laminar flow

Question 31

39. When does turbulent flow occur

Answer 31

turbulent flow occurs where vessels branch and when blood pressure is raised

Question 32

What can turbulent flow lead to?

Answer 32

This can eventually lead to damage to the endothelium

Question 33

What does damage to the endothelium result in?

Answer 33

Results in exposure of the blood to collagen and other factors resulting in blood clotting

Question 34

42. What is a thrombus

Answer 34

Solid mass of blood constituents formed within the vascular system in life

Question 35

43. What is atherosclerosis

Answer 35

fatty deposits in the tunica intima that harden the walls and narrow the lumen of arteries

Question 36

44. What is arteriosclerosis

Answer 36

wall thickening and hardening affecting smaller arteries and arterioles

Question 37

45. What are the main factors resulting in arteriosclerosis

Answer 37

Main factors are: - Hypertension - Diabetes mellitus

Question 38

46. Why do thrombuses, atherosclerosis and arteriolosclerosis pose a threat?

Answer 38

They pose a threat because they narrow the lumen reducing blood flow to tissues which can lead to ischaemia.