w2 histology of the heart

Question 1

What substances does the cardiovascular system transport?

Answer 1

Gases O2 and CO2.
Nutrients
Waste
immune cells
Hormones.

Question 2

Give an overview of arteries.

Answer 2

Large thick walled vessels with a small lumen (ideal for high pressure blood flow)
Transport oxygenated blood towards the capillaries
Get progressively smaller away from the heart (elastic, muscular then arterioles)
Arteries split into branches

Question 3

What is the site of gas exchange in the cardiovascular system?

Answer 3

Capillaries.

Question 4

Give an overview of veins.

Answer 4

Large thin walled and large lumen vessels (ideal for low pressure blood flow)
Some have valves
get progressively larger towards the heart.
Blood drains into veins through its tributaries.

Question 5

What are the three different layers found in blood vessels histology?

Answer 5

Tunica intima
Tunica media
Tunica adventitia.

Question 6

What is the deal with the tunica intima?

Answer 6

Consists of mainly endothelium
Basal lamina / basement membrane.

Question 7

What is the deal with the tunica media?

Answer 7

Tunica media is composed of mainly smooth muscle (circular) and elastin (elastic tissue)
Is thickest in arteries.

Question 8

What is the deal with the tunica adventitia?

Answer 8

Consists of mainly connective tissue including fibroblasts.
Smooth longitudinal muscle
Vaso vasorum (vessels supplying vessels)
Is most prominent in veins

Question 9

What is the histological difference between a muscular and elastic artery?

Answer 9

Muscular artery has an internal and external elastic lamina (int - after tunica intima, ext - after tunica media)
Elastic artery - has concentric rings of elastin within the tunica media.

Question 10

What is a good clue histologically is something is an arteriole of a venule?

Answer 10

Arterioles have a more circular and organised layers, often slightly thicker than venules.

Question 11

What is a thrombosis?

Answer 11

High cholesterol depositis in the tunica intima, forming a plaque that then ruptures and obstructs blood flow as narrows the diameter of the lumen.
Most common in veins of the leg.

Question 12

What is the role of elastic in blood vessels?

Answer 12

Store energy, resists bursting under high pressure during ventricular systole,
Elastic recoil maintains blood pressure during diastole.
When there is not enough elastic in the blood vessels, peripheral resistance increases.

Question 13

What is the role of muscle in blood vessels?

Answer 13

Contracts and relaxes to regulate the diameter of the blood vessel hence the volume of blood flow.

Question 14

What is the most abundant blood vessel in the body?

Answer 14

Capillaries, make up 90%.

Question 15

What makes up the capillary wall?

Answer 15

The endothelium
The basement membrane
Occasional scattered cells called pericytes.

Question 16

What are pericytes?

Answer 16

A type of cell found at intervals along capillaries.
They control the entry of immune cells across the blood brain barrier, they maintain the blood brain barrier and have a role in the formation of new blood vessels.

Question 17

What are the three different types of capillaries?

Answer 17

Continous
Fenestrated
Sinusoidal

Question 18

Give an overview of continuos capillaries.

Answer 18

These are ‘tight’ capillaries, they have an uninterrupted epithelium with reduced permeability.
They are found in the blood brain barrier.

Question 19

Give an overview of fenestrated capillaries.

Answer 19

Have fenstrations within endothelial cells.
Are permeable to fluid and small soluble molecules.
Found in the renal corpuscle in the kidney’s.

Question 20

Give an overview of sinusoidal capillaries

Answer 20

Have wider gaps, pores between cells and fenestrations within cells.
Facilitate the movement of fluid, larger molecules and blood cells.
Found in the liver and spleen.

Question 21

What are the three different coverings lining the heart

Answer 21

Fibrous pericardium - tough external layer
Parietal pericardium - inside of pericardial sac (part of the serous membrane)
Visceral pericardium - external surface of the heart (part of serous membrane)

Question 22

What are the three different layers of heart tissue?

Answer 22

Inside
Endocardium
Myocardium (muscle)
Epicardium - also known as the visceral pericardium.

Question 23

What makes up the endocardium?

Answer 23

Regularly arranged elastic and collagen fibres
Mainly a single layer of endothelial cells.

Question 24

What are some features of cardiac muscle?

Answer 24

Is a type of striated muscle (made of repeating sarcomere units that are able to contract).
intercalated discs between each muscle cell
Rounded and centrally placed nuclei

Question 25

What is the role of intercalated discs in cardiac muscle?

Answer 25

Ensure electrical continuity.

Question 26

What are some features of the epicardium?

Answer 26

Flattened mesothelial cells
Fibrocollagenous stroma
Contains vessels supplying the heart
Adipose tissue.

Question 27

What is vasculitis?

Answer 27

Inflammation and damage to blood vessels.
Often results in ischemia of the tissue supplied by these vessels.

Question 28

What is angina?

Answer 28

Chest pain associated with ischemia of the myocardium, due to severe atherosclerosis.
Often described as substernal pressure.
Note arteries are narrowed (not blocked as in a myocardial infarction).

Question 29

What is a myocardial infarction?

Answer 29

Also known as a heart attack, is the necrosis of cardiac muscles due to the blockage of coronary arteries often by atherosclerosis.

Question 30

What is atherosclerosis?

Answer 30

A type of arteriosclerosis caused by an accumulation of lipid causing plaque formation and narrowing of the arteries.

Question 31

What is ateriosclerosis?

Answer 31

A general term that refers to hardening of the arteries, lose elastic properties. Often caused by high blood pressure.