MIDTERM Week 4: Cardiac

Question 1

Which valves are the AV valves and which structures are they between?

Answer 1

Tricuspid valve - On right side of heart between right atria and right ventricle

Bicuspid valve/Mitral valve – on left side of heart between left atria and left ventricle

Question 2

Which valves are the semilunar valves and which structures are they between?

Answer 2

Pulmonic valve – on right side of heart, between right ventricle and pulmonary artery

Aortic valve – on left side of heart, between left ventricle and aorta

Question 3

What are the names of the three layers of blood vessels?

Answer 3

Tunica intima

Tunica media

Tunica externa (or adventitia)

Question 4

Which layer of blood vessels is primarily involved in vasoconstriction and vasodilation?

Answer 4

Tunica Media – this middle layer is made up of smooth muscle and elastic tissue and is responsible for vasoconstriction/vasodilation

Question 5

Describe the composition and role of the innermost layer of blood vessels. What is the name of this layer?

Answer 5

tunica intima (innermost/intimal): single layer of endothelial cells with important roles in coagulation, antithrombogenesis, and fibrinolysis. Also involved in immune system function, tissue, and vessel growth.

Question 6

Describe the composition and role of the middle layer of blood vessels. What is the name of this layer? Difference between arteries and veins?

Answer 6

tunica media (middle/medial): smooth muscle layer and elastic tissue. Thicker in arteries and thinner in veins. Large arteries close to the heart have more elastic tissue to allow for stretch during systole and recoil during diastole. Medium and small arteries farther from the heart have more muscle fibre which supports blood flow via vasoconstriction and vasodilation.

Question 7

Describe the composition and role of the outermost layer of blood vessels. What is the name of this layer? Difference between arteries and veins?

Answer 7

tunica externa or adventitia (outermost/external): connective tissue, also contains nerves and lymphatic vessels. Thinner in arteries and thicker in veins.

Question 8

chylomicrons, chylomicron remnants, VLDL, IDL, LDL, HDL, and Lp (a) are classes of

Answer 8

Lipoproteins

Question 9

Of the 7 classes of lipoproteins, all but one are pro-atherogenic. What is the name of the one class of lipoproteins that is anti-atherogenic?

Answer 9

HDL

Question 10

Describe the ways in which lipoproteins contribute to the development of atherosclerosis

Answer 10

Short version: foam cell formation, which causes endothelial dysfunction, platelet aggregation and immune responses. This attracts even more lipoproteins and furthers plaque formation.

Question 11

Which is the “good” cholesterol and which is the “bad”. What does each type of cholesterol do?

Answer 11

HDL - high density lipoprotein “good cholesterol” - transports cholesterol from body to liver to be broken down
LDL - low density Lipoprotein “bad cholesterol” - transports cholesterol around the body and can deposit in artery walls. high levels of LDL = atherosclerosis

Question 12

Outline the 5 phases of the cardiac cycle

Answer 12

Phase 1: Atrial systole- atria contract, pushing blood through open mitral and tricuspid valves from atria to ventricles. Semilunar valves closed during this phase.

Phase 2: Beginning of ventricular systole- Ventricles contract, increasing pressure within the ventricles. Tricuspid and mitral valves close causing first heart sound (S1)

Phase 3: Period of rising pressure- semilunar valves open when pressure in ventricles exceed that of arteries, blood begins flowing from ventricles into pulmonary and aortic arteries.

Phase 4: Beginning of ventricular diastole- pressure in relaxing ventricles falls below the pressure in arteries, causing semilunar valves to snap shut creating second heart sound (S2).

Phase 5: Period of falling pressure- blood flows from veins into relaxed atria. Tricuspid and mitral valves open when pressure in ventricles falls below that in the atria.

Question 13

Describe Preload

Answer 13

Volume and pressure inside ventricle at end of diastole

Question 14

What are key factors influencing Preload?

Answer 14

Venous return and total circulating volume

Venous return is dependent on blood volume and flow through the venous system and the AV valves

Also affected by arterial contraction, resistance from valves, ventricular compliance, and heart rate

Question 15

Describe Afterload

Answer 15

Resistance against which ventricles have to pump to eject blood to produce cardiac output

Question 16

What are key factors influencing afterload?

Answer 16

Systemic vascular resistance, aortic pressure, valve disease, blood viscosity

Question 17

Tricuspid valve – how many cusps? Location in heart? Supporting structures? Open or closed during systole/diastole?

Answer 17

Three cusps

right side of the heart between right atria and right ventricle

When ventricles are relaxed (diastole), tricuspid valve is open and blood flows from higher pressure in the right atria to lower pressure in the right ventricle. During ventricular contraction (systole) the valve shuts to prevent backflow into the right atria.

Upper end attached to a ring in the heart’s fibrous skeleton, lower end attached by chordae tendineae to the papillary muscles of the myocardium

Question 18

Bicuspid/Mitral valve - how many cusps? Location in heart? Supporting structures? Open or closed during systole/diastole?

Answer 18

Location: between left atrium to left ventricle

2 cusps

Beginning of ventricular systole = closes (1st heart sound (S1 “lub”))

Prevents backflow of blood from the ventricle to the L atrium

Closed during systole ; open during diastole

Chordae tendineae attaches the end of the lower margin of the valve leaflets to the papillary muscles (extension of the myocardium)

Papillary muscles – hold the cusps together, and downward at the start of ventricular contraction, preventing backward prolapse into the atria

Question 19

Pulmonic Valve - how many cusps? Location in heart? Supporting structures? Open or closed during systole/diastole?

Answer 19

Three cusps

Located between right ventricle and pulmonary artery (the only artery that carries deoxygenated blood)

When right ventricle is relaxed (diastole) pulmonic valve is closed and when the right ventricle contracts (systole) pulmonic valve opens for blood to pump to the lungs.

There is no chordae tendineae attached to pulmonic valve, it arises from the fibrous skeleton

Question 20

Aortic Valve - how many cusps? Location in heart? Supporting structures? Open or closed during systole/diastole?

Answer 20

Location: between left ventricle to aorta

3 cusps

Beginning of ventricular diastole = closes (2nd heart sound (S2 “dub”))

prevents backflow of blood from the aorta to the left ventricle

closed during diastole; opens during systole

Cusps arise from the fibrous skeleton

Question 21

What are the two types of receptors involved in the neural control of blood pressure?

Answer 21

Baro receptors and arterial chemoreceptors