Cardiovascular System 5

Question 1

What are the 3 mechanisms that regulate the cardiovascular system in the short term

Answer 1

1. Autoregulation
2. Neural mechanisms
3. Hormonal mechanisms

Question 2

Describe the auto mechanism that regulate the cardiovascular system in the short term

Answer 2

Autoregulation involves changes in the pattern of blood flow within capilary beds as precapilary sphincters open and close in response to chemical changes in the interstitial fluid.

1. Homeostasis disturbed
   - Physical stress (trauma, high temperature)
   - Chemical changes (Decreased tissue O2 or increased CO2)
   - Increased tissue activity
2. Inadequate local blood pressure and blood flow
3. Local vasodilators are released, precapilary sphincters relax
4. Causing local decrease in resistance and increase in blood flow
5. Homeostasis is restored, where blood pressure and volume are normal

Question 3

Explain the baroreceptor reflex

Answer 3

Baroreceptors located in carotid sinus and aorta
Monitor degree of stretch
- When BP falls the baroreceptors are stretched less
- Send impulse to CV centre

Increased Cardiac Output (CO) = Vasoconstriction
Decrease Cardiac Output (CO) = Vasodilation

Question 4

Describe the neural mechanism that regulate the cardiovascular system in the short term

(Responses to increased baroreceptor stimulation)

Answer 4

1. Homeostasis is disturbed - Increasing blood pressure
2. Baroreceptors stimulated
3. Cardioinhibitory center stimulated = Decreased cardiac output
   Cardioacceleratory center inhibited = Decreased cardiac output
   Vasomotor center inhibited = Vasodilation occurs
4. Homeostasis restored = Blood pressure decreases = Normal range of blood pressure

Question 5

Describe the neural mechanism that regulate the cardiovascular system in the short term

(Responses to decreased baroreceptor stimulation)

Answer 5

1. Homeostasis is disturbed - Decreasing blood pressure
2. Baroreceptors inhibited
3. Cardioinhibitory center inhibited = Increased cardiac output
   Cardioacceleratory center stimulated = Increased cardiac output
   Vasomotor center stimulated = Vasoconstriction occurs
4. Homeostasis restored = Blood pressure increases = Normal range of blood pressure

Question 6

Describe the hormonal mechanism that regulate the cardiovascular system in the short term

Answer 6

Neural mechanism

1. Changes in Blood pressure
2. Cardiac center, vasomotor centers stimulated
3. Sympathetic stimulation
   - Increasing cardiac output (CO) and increasing blood flow
   - Vasoconstriction of most peripheral vessels, Norepinephrine (NE): arteries decreasing flow, veins increasing flow

Parasympathetic

• Decreasing cardiac output (CO) and decreasing blood flow
• Vasodilation of selected peripheral vessels

4. Homeostasis is restored