2. Intro to cardiovascular system

Question 1

What is the spleen?

Answer 1

Large flat oval organ located below the diaphragm - main function is to store blood and filter it

Question 2

What is different about the equine and canine spleen?

Answer 2

Can release red blood cells from the spleen during exercise in order to have a greater oxygen carrying capacity of the blood

Question 3

What are some functions of the CVS?

Answer 3

1. Transport of O2 and substrates to cells
2. Transport of CO2 and metabolites from cells
3. Distribution of hormones - e.g., epinephrine (catecholamine)
4. Defence
5. Haemostasis - leads to cessation of bleeding (platelets)
6. Thermoregulation

Question 4

What is contraction of the heart controlled by?

Answer 4

Intrinsic pacemaker and autonomic nervous stimulation

Question 5

What is the function of arteries?

Answer 5

Distribution channels

• carry blood away from the heart
• muscular elastic walls; terminate in capillary beds

Question 6

What is the function of veins?

Answer 6

Blood reservoirs

• carry blood back to the heart
• less muscular than arteries but very elastic walls

Question 7

What is microcirculation?

Answer 7

Where exchange with tissues occurs; capillaries very thin walls (endothelial cells only); site of exchange of gases and nutrients

Question 8

Describe the mammalian circulatory system

Answer 8

Double circulatory

Fully developed septum that separates the atria and ventricles

Question 9

Describe the aquatic circulatory system

Answer 9

Single circulatory circuit

Single atrium and single ventricle

Question 10

Describe the amphibian circulatory system

Answer 10

Double circulatory system

2 atria and a single ventricle

Question 11

Describe dual circulation

Answer 11

Pulmonary circulation = to and from the lungs

Systemic circulation = to and from the body

Question 12

Describe the pressures in the systemic and pulmonary circulations

Answer 12

Left side of the heart pumps oxygenated blood to systemic circulation at high pressure
Right side of the heart pumps deoxygenated blood to the pulmonary circulation (shorter distance = lower pressure)

Question 13

What are systolic and diastolic pressures?

Answer 13

Systolic = contraction pressure 
Diastolic = relaxation pressure

Question 14

What are the pressures of blood in the major arteries/veins?

Answer 14

Vena Cava = deoxygenated @ 3 mmHg
Aorta = oxygenated, systemic, to rest of body @ 100 mmHg
Pulmonary artery = deoxygenated, pulmonary circulation @ 12 mmHg
Pulmonary vein = oxygenated @ 7 mmHg

Question 15

What are tricuspid valves?

Answer 15

3 leaflets on the right side of the heart

Question 16

What are mitral valves?

Answer 16

2 leaflets on the left side of the heart

Question 17

What are the AV valves

Answer 17

Atrioventricular valves

• tricuspid
• mitral

Question 18

What are the semi-lunar valves?

Answer 18

Aortic = 3 cusps 
Pulmonary = 3 cusps

Question 19

How do the AV valves work?

Answer 19

Left and right AV valves separate atria from ventricles and are therefore inlet valves to the ventricles

Question 20

How is evasion of the cusps prevented?

Answer 20

Action of papillary muscles through the chordae tendinae

Question 21

How do the SL valves work?

Answer 21

Outlet valves of the ventricles

• both have three cusps
• aortic and pulmonary valves prevent backflow at the end of systole into the left and right ventricles, respectively

Question 22

Between which ribs can you listen to the valves?

Answer 22

3-6
3-4 = P
4-5 = A
5-6 = L A-V

Question 23

What are the functions of the cardiac skeleton?

Answer 23

1. Helps to provide structural integrity to the heart (fibrous tissue)
2. Breaks up continuity between cardiac muscle cells of the atria and those of the ventricle

Question 24

What are the coronary arteries?

Answer 24

First branch off the aorta

• 5% of the cardiac output is delivered directly into the myocardium
• extensive capillarisation

Question 25

Describe the development of a mammalian foetuses heart

Answer 25

1. Foramen ovale connecting the atria (becomes fossa ovalis)

2. Ductus arteriosus - vessel between the pulmonary trunk and the aorta becomes the ligamentum arteriosum

Question 26

Describe the function of elastic vessels

Answer 26

Large arteries

• accomodate stroke volume (high elastance)
• convert intermittent ejection (stop-go-flow) into continuous flow

Question 27

Describe the function of conduit and feed vessels

Answer 27

Medium to small arteries

- conduct blood flow to organs

Question 28

Describe the function of resistance vessels

Answer 28

Arterioles, terminal arteries

• Control arterial blood pressure
• Control local blood flow

Question 29

Describe the function of exchange vessels

Answer 29

Capillaries

• nutrient delivery to cells
• lymph formation
• removal of metabolic waste

Question 30

Describe the function of capacitance vessels

Answer 30

Venules, veins

• control cardiac filling pressure
• reservoir of blood

Question 31

Describe the structure of a artery

Answer 31

Round with a thick wall

• tunica intima, rippled, with internal elastic membrane
• tunica media, thick, dominated by smooth muscle cells & elastic fibres, with external elastic membrane present
• tunica externa (adventita), collagen and elastic fibre; nerves terminals; vasa vasorum

Question 32

Describe the structure of a vein

Answer 32

Flattened/collapsed with a thin wall

• tunica intima, smooth with no interal elastic membrane present
• tunica media, thin, dominated by smooth muscle cells & collagen fibres, no external elastic membrane
• tunica externa, collagen and elastic fibres; smooth muscle cells; nerve terminals

Question 33

Define flow (velocity)

Answer 33

Amount of blood flowing through a vessel at any given time (ml/min)

Question 34

Define perfusion

Answer 34

flow per unit mass of tissue

Question 35

What is the relationship between resistance and radius of lumen?

Answer 35

Inversely proportional to the 4th power of the radius

- small vessels = ↑ resistance

Question 36

What is the significance of the body being able to change the size of its lumen?

Answer 36

If body changes size of lumen then it can regulate the overall resistance of the circulation
- how blood pressure is regulated

Question 37

Describe the relationship between blood flow (F) and blood pressure ΔP

Answer 37

Directly proportional

- if ΔP increases blood flow speeds up

Question 38

Describe the relationship between blood flow F and peripheral resistance R

Answer 38

Inversely proportional
- if R increases then blood flow decreases
F = ΔP/R

Question 39

What are the forces that move fluid across the capillary wall?

Answer 39

• oncotic pressure = pressure exerted by proteins

- hydrostatic pressure = pressure exerted by blood

Question 40

What are the Starling forces dependant on?

Answer 40

Four variables that control the movement of fluid

Question 41

What is the lymphatic system?

Answer 41

Lymphatic vessels carry interstitial fluid to the cardiovascular system

Question 42

What is oedema?

Answer 42

Abnormal accumulation of interstitial fluid

• excess filtration
• defective reabsorption
• defective lymphatic drainage