CV system: overview (LT - extra)

Question 1

How big is the heart (roughly) and where does most of its mass lie?

Answer 1

The size of a fist, weighs roughly 300gm.

Lungs lie laterally and partially overlap the heart.

2/3 of the mass of the heart lies to the left of the midsternal line.

Question 2

What nerve supplies the diaphragm?

Answer 2

Phrenic nerve

Question 3

What part of the heart divides it into right and left sides?

Answer 3

A central septum

Question 4

What are the 2 AV valves of the heart called?

Answer 4

Tricuspid (right)
Mitral (left)

Question 5

What are the 2 semilunar valves of the heart called?

Answer 5

Aortic (left)
Pulmonary (right)

Both prevent backflow of blood from major arteries into ventricles. Relative pressure in heart chambers and connecting vessels determines when valves open/close.

Question 6

The heart has 2 sounds when it beats. What are the first AND second beats?

Answer 6

1st = closing of mitral and tricuspid valves
2nd = closing of aortic and pulmonary valves

Question 7

Are the 2 heart pumps arranged in parallel or series?

Answer 7

Series = same volume of blood/minute must be being pumped through the 2 circulations.

Question 8

What are the two large veins which carry deoxygenated blood back to heart (left atrium)?

Answer 8

Vena cavae
superior - returns blood from upper body
inferior - returns blood from lower torso and below.

Question 9

What are coronary arteries?

Answer 9

A network of blood vessels which carry O2 and nutrient-rich blood to cardiac tissue.

Left and right coronary arteries exist from ascending aorta.

Question 10

What happens to narrowing/blockage of coronary arteries?

Answer 10

Causes heart muscle in the region supplied to lack O2 and nutrients (become ischemic), may lead to death of heart cell (myocardial infarct)

Question 11

What is the cardiac cycle?

Answer 11

The events that occur from the beginning of one cardiac contraction (heartbeat) to the beginning of the next

Question 12

What is a tunic?

Answer 12

Blood vessel walls have of a combination of endothelium, smooth muscle, elastic tissue, and fibrous tissue, all organized into three layers called tunics.

The thickness, composition, and presence of each layer differs depending on the vessel type.

Question 13

What is the composition of the tunica intima (internal)?

Answer 13

Endothelial cells in a single layer, a basement membrane, and a subendothelial layer of connective tissue surrounded by a network of elastic fibres

Question 14

What is the composition of the tunica media (middle)?

Answer 14

Smooth muscle and elastic fibres

Question 15

What is the composition of the tunica adventitia (external)?

Answer 15

Predominantly collagen fibres

Question 16

Describe the structure of a capillary

Answer 16

They only have a single layer of endothelial cells supported by a basement membrane.

Between cells, intercellular cleft provides a pathway for movement of water, ions, and small MW solutes.

Adjacent endothelial cells held together through the cleft by tight junctions (desmosomes) and adherenes proteins and there are also gap junctions that allow cell to cell comms.