Blood Vessel Histology

Question 1

Name the 4 layers of the blood vessels

Answer 1

Lumen
Tunica Intima
Tunica Media
Tunica Adventitia

Question 2

What does each layer of the blood vessel contain?

Answer 2

Lumen - Blood
Tunica Intima - Endothelial cells and basement membrane. Supporting connective tissue
Tunica Media - Smooth Muscle and elastin
Tunica Adventitia - Supporting connective tissue (fibres with some vessels and nerves)

Question 3

Describe the structure and function of Arteries

Answer 3

Arteries are EFFERENT vessels and need smooth muscle to function in high pressure system.
Large Tunica Media for strength.
Small diameter of lumen

Question 4

Describe the structure and function of veins

Answer 4

AFFERENT vessels and need less smooth muscle to function under low pressure.

Question 5

Describe the function of muscular arteries

Answer 5

Also called Disturbing Arteries. Regulate blood flow to organs and part of body by contracting and relaxing smooth muscle.

Question 6

Describe structure and function of elastic arteries

Answer 6

Also called Conducting arteries. They are closest to the heart. High elastic walls to expand during systole and recoil during diastole.

Question 7

Describe the structure and function of Arterioles

Answer 7

They are small arteries with muscular walls. Thick TM.

Question 8

Describe the structure and function of Venules.

Answer 8

Smallest vessels in venous circulation. Large lumen. Thin TM.

Question 9

Explain the role of the Arterioles in resistance & blood pressure.

Answer 9

• Reduced blood flow leads to improper perfusion of tissues and lack of nutrients (ischaemia) which can lead to cell death
• Too much flow damages delicate tissue structure.
• Arterioles control this by varying their diameter

Question 10

Describe the structure and function of Capillaries

Answer 10

Thin wall vessels to facilitate exchange of nutrients with the tissue.
Diameter = 5-8um
Contains endothelial cels (1 cell thick), basement membrane and collagen fibrils
Occasional pericyte - contractile cells

Question 11

What is the function of Endothelial cells

Answer 11

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

Question 12

Name the different ways endothelial cells can transport through capillaries

Answer 12

• Diffusion (gases & ions)
• Transcytosis via pinocytotic vesicles (proteins and lipids)
• Via the intracellular space (cells)

Question 13

Name the different types of capillaries and their structure & function

Answer 13

Continuous = has tight junctions
Fenstrated = has small holes known as fenestrae which has more permeability
Sinusoidal = Has even larger holes therefore even more permeability so larger molecules can pass through

Question 14

Describe the Venous system

Answer 14

1. When muscle is RELAXED, valves CLOSE. This prevents the backward flow of blood and promotes unidirectional flow of blood towards the heart.
2. When muscle CONTRACTS, upper valve opens and blood is forced upwards (lower valve still closed)
3. Muscle then RELAXES, upper valve close and lower valve opens as a result of muscle contraction. Blood flows forwards.

Question 15

What are Varicose veins

Answer 15

Incorrect functioning of valves

Question 16

Describe the 2 types of blood flow

Answer 16

Laminar flow = due to endothelium being a smooth, non-stick surface

Turbulent flow = vessels branch. BP raised. Can cause damage to endothelium. Exposes blood to collagen and cause blood clot.

Question 17

What is the thrombus

Answer 17

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

Question 18

Describe the structure and function of ATHerosclerosis

Answer 18

fatty deposits in the TI. hardens the walls and narrow the lumen in arteries. Also affects bigger arteries. Narrows the lumen leading to reduced blood flow to tissues thus causing ischaemia.

Question 19

Describe the structure and function of ARTeriolosclerosis

Answer 19

Wall thickened. Affects small arteries and arterioles.
Causes hypertension and diabetes mellitus. Narrows the lumen leading to reduced blood flow to tissues thus causing ischaemia.