Cardiovascular system

Question 1

Tunica intima (internal)

Answer 1

Endothelium- simple squamous epithelium

Question 2

Tunica media (middle)

Answer 2

Smooth muscle
Bigger in arteries

Question 3

Tunica adventitia (external)

Answer 3

Connective tissue
Thicker in veins

Question 4

Difference between artery and vein histologically

Answer 4

Question 5

Capillary histology

Answer 5

capillaries in paraffin sections can be recognized by nuclei adjacent to small lumens or by highly eosinophilic red blood cells in the lumen.

Question 6

Vessels summary table

Answer 6

Question 7

Types of vessels

Answer 7

Question 8

Elastic arteries

Answer 8

relatively thin walled compared to overall diameter. Elastic fibres store energy, resist over distension during systole, return vessel to original shape during diastole and maintain diastolic pressure. Lack of elastin would result in there being greater peripheral resistance (as seen with age and pathology), which leads to hypertension. The diagnostic characteristic of large, elastic arteries is the presence of numerous, fenestrated elastic sheets in tunica media. Elastic arteries have a large lumen with a relatively thin wall

Question 9

Muscular arteries

Answer 9

these are further down the arterial tree and therefore are not subjected to the force exerted by the heart. The greater volume of smooth muscle allows for greater (involuntary) contraction of the vessel walls (controlled by autonomic nervous system), which means these arteries are more able to regulate blood flow compared to elastic arteries.

Question 10

Capillary types

Answer 10

Contains pericytes which help with control of blood flow, especially in brain. Pericytes contain tropomyosin, isomyosin, and protein kinase, which are all related to the contractile process that regulates blood flow through the capillaries.

Question 11

Heart layers

Answer 11

Endocardium (internal)
Myocardium (middle)
Epicardium (external)

Question 12

Endocardium histology

Answer 12

Regularly arranged collagen in middle layer, also contains elastic fibers. Irregularly arranged collagen in outer layer.

Question 13

Myocardium (cardiac muscle) histology

Answer 13

Cardiocytes and cardiac myocytes

Striated cardiac muscle

Single centrally placed nucleus

Intercalated disk- allows direct electrical connection between the cells, as well as maintaining structural integrity and strength. Because all cardiac myocytes are electrically coupled via the gap junctions, the entire myocardium behaves as a single unit or ‘functional syncytium’

Question 14

Epicardium histology

Answer 14

Question 15

Artery vs vein

Answer 15

Artery has thicker muscular wall and tunica media, it has internal and external elastic laminae which veins dont have
Veins have a larger lumen and the thickest layer is the tunica adventitia