NS - CVS IV

Question 1

What 2 components are involved in cardiac circulation?

Answer 1

Coronary Arteries
- Carry oxygenated blood to the heart
- From aorta

Coronary Veins
- Carry deoxygenated blood to the right atrium
- From myocardium

Question 2

How does blood return to the heart via veins?

Answer 2

Have very low resistance and pressures
Valves- one way flow

Question 3

Where does fluid leakage occur?

Answer 3

Capillaries

Question 4

What does the lymphatic system do?

Answer 4

Returns fluid from tissues to the bloodstream

Question 5

Why does the CVS system need to be controlled?

Answer 5

Running the system is energetically expensive

Question 6

What are 4 ways the CVS is regulated?

Answer 6

1. Overall volume controls
2. Control of local blood flow
3. Control of venous return
4. Control of cardiac output

Question 7

How does the control of local blood flow regulate the CVS?

Answer 7

Regulation of flow to specific tissues occurs to meet metabolic demands

Main regulators

• Vasodilators
• Oxygen / nutrient lack

Question 8

How does the control of venous return regulate the CVS?

Answer 8

Venous smooth muscle contracts to match BP demand
- Increases venous return

Slow- ADH (vasopressin), Renin-Angiotensin … cause vasoconstriction

Fast- Sympathetic signals/Circulating catecholamines

Question 9

How does the control of cardiac output regulate the CVS?

Answer 9

Determines the amount of blood pumped by the heart per unit of time

Influenced by factors:

• Neuronal
• Hormonal

Question 10

What is pre-load and how does it alter cardiac output?

Answer 10

The initial stretching of the cardiac myocytes prior to contraction

• Increased preload, Increased cardiac output

Question 11

What is after-load and how does it alter cardiac output?

Answer 11

Force which the heart must pump against

• Increased afterload, decreased cardiac output

Question 12

What involves the Nervous control of the heart?

Answer 12

Parasympathetic and Sympathetic

Question 13

Where are Baroreceptors found and how do they function? (4)

Answer 13

Found in the aortic arch or carotid sinus

• Detect blood pressure changes
• Stimulate Na+ channels
• AP is signalled to Medulla Vasomotor Centre
• Parasympathetic or Sympathetic stimulated

Question 14

Where are Chemoreceptors found and how do they function? (3)

Answer 14

Found in medulla surface / Aortic or Carotid bodies

• Detect H+ changes in medulla or O2 changes in bodies
• Chemoreceptors fire
• Parasympathetic or Sympathetic stimulated