Week 3 - Autonomic Nervous System

Question 1

What helps with Regulation of stroke volume

Answer 1

1. End diastolic volume
2. Average aortic blood pressure
3. Strength of the ventricular contraction

Question 2

Explain the frank starling mechanism
(ON SHEET)

Answer 2

greater end diastolic volume results in a more forceful contraction (due to stretch of ventricles)

Question 3

Factors involved in regulation of venous return
(ON SHEET)

Answer 3

Venoconstriction - via SNS
Skeletal muscle pump
Respiratory pump - changes in thoracic pressure pulls blood towards heart

Question 4

How does the ANS control exercise HR
(ON SHEET)

Answer 4

Low resting due to parasympathetic tone
Increase in HR at onset of exercise - intial increase due to paraympathetic withdrawal, later increase due to increased SNS outflow

Question 5

What are the factors than regulate cardiac output

Answer 5

Cardiac output = cardiac rate x stroke volume
Factors effecting cardiac rate:
- Parasympathetic nerves
- Sympathetic nerves
factors effecting stroke volume:
- Mean arterial pressure
- End diastolic volume
- Contraction strength

Question 6

What is systolic pressure

Answer 6

Pressure generated during ventricular contraction

Question 7

What is diastolic pressure

Answer 7

Pressure in the arteries during cardiac relaxation

Question 8

What is pulse pressure

Answer 8

Difference between systolic and diastolic

Question 9

What is mean arterial pressure

Answer 9

Average pressure in arteries

Question 10

What are factors that influence arterial blood pressure

Answer 10

Cardiac output
Total Vascular Resistance
Mean arterial pressure = cardiac output x total vascular resistance

Question 11

What are the short term regulation factors in arterial blood pressure

Answer 11

Sympathetic nervous system
Baroreceptors in aortta and carotid arteries, increase in BP = decrease SNS activity
Decrease in BP = increase SNS activity

Question 12

What are the long term regulation factors than influence arterial blood pressure

Answer 12

Kidneys via control of blood volume

Question 13

What are the changes in cardiovascular variables during exercise

Answer 13

Increased metabolic need for o2, blood flow delivery to exercsing skeletal muscle is increased via increase cardiac output and a redistribution of blood flow from inactive organs to working skeletal muscle
Cardiac output increase during exercise is directly proportional to metabolic rte required to perform the exercise

Question 14

What are the circulatory responses to exercise dependent on

Answer 14

Depend on:
Type, intensity and duration of exercise
Environmental conditions
Emotional influence pre-exercise and during submaximal exercise due to increase SNS activity

Question 15

What is the transition from rest to exercise and exercise to recovery in relation to ANS

Answer 15

At onset of exercise:
Rapid increase in HR, SV, cardiac output
Plateau in submaximal exercise
During recovery:
Decrease in HR, SV and cardiac output towards resting levels
Depends on:
Duration and intensity of exercise
Training state of subject

Question 16

What are the effects of incremental exercise

Answer 16

HR and cardiac output:
Increase linearly with increasing work rate
Reaches plateau at 100% vo2 max
Blood pressure:
Mean arterial pressure increases linearly, systolic BP increases, diastolic BP remains fairly constant

Question 17

What are the effects of intermittent exercise

Answer 17

Heavy intensity intermittent exercise:
near maximal HR values are possible

Question 18

Whats the recovery of HR and BP between bouts dependent on

Answer 18

Fitness level
Temperature and humidity
Duration and intensity of exercise

Question 19

Whats the effects of prolonged exercise at a constant work rate

Answer 19

Cardiac iutput is maintained:
gradual decrease in stroke volume
Due to dehydration and reduced plasma volume
Gradual increase in HR during prolonged exercise. Cardiovascular drift