Lecture 21 - Integration III

Question 1

What stimulates SV and HR increase during exercise?

Answer 1

Central command centre

Question 2

What does central command do during steady exercise?

Answer 2

At steady exercise, central command stimulate parasympathetic system, parasympathetic neruons, and vagus nerve - release AcH which decelerates rate of sinus discharge,

Question 3

What does central command do during increasing exercise intensity?

Answer 3

During exercise increase, central command stimulates sympathetic system to override parasympathetic system. Sympathetic nerves stimulate the AV node and SA node to beat faster. We also have sympathetic nerves going to ventricles to tell cardiac muscle to contract stronger
- Increase in HR and force of contraction of ventricles (increase in SV and CO)

Question 4

What does central command do during anticipation?

Answer 4

Elevate HR, MAP, and respiratory rate in anticipation for exercise/movement

Question 5

What is maximal HR based off?

Answer 5

Age not fitness

Question 6

How is maximum heart rate defined?

Answer 6

The maximum HR is the highest HR value achieved in an all-out effect to the point of volitional fatigue.

Question 7

What is steady state?

Answer 7

The plateau that heart rate reaches when exercise is held constant

Question 8

How long does it take for HR to adjust to intensity increase in exercise?

Answer 8

2-3 mins

Question 9

What phases BP increases most during elevated HR?

Answer 9

Systolic
Diastolic does not increase as much

Question 10

What BP does the baroreceptor reflex respond to?

Answer 10

High blood pressure
Baroreceptor acts to reduce BP by decreasing sympathetic nervous activity

Question 11

What does central command do to regulate BP during exercise?

Answer 11

Central command increases BP AND prevents a decrease in sympathetic nerve activity

Question 12

How is blood flow distributed during exercise?

Answer 12

Increased blood flow to areas with greatest metabolic need (contracting skeletal muscle)
Sympathetic nerve activation leads to vasoconstriction & shunts blood away from less-active regions

Question 13

What is local vasodilation triggered by during exercise?

Answer 13

Local vasodilation triggered by metabolic, endothelial products

Question 14

What offsets sympathetic vasoconstriction in muscle during exercise?

Answer 14

Sympatholysis

Question 15

What areas experience vasodilation during exercise?

Answer 15

Skeletal muscle and skin

Question 16

What is the relative increase of ventilation from rest to exercise?

Answer 16

32X

Question 17

What is the relative increase of tidal volume from rest to exercise?

Answer 17

8X

Question 18

What is the relative increase of breath frequncy from rest to exercise?

Answer 18

4X

Question 19

Why does Ve increase in exercise?

Answer 19

Increases because of increased tidal volume (and vital capacity) and increase in respiratory rate

Question 20

Why does tidal volume increase during exercise?

Answer 20

Tidal volume increases because more muscles become engaged (abdominal, diaphragm, external intercostal muscles) - expiration becomes active process

Question 21

What is the increase in Ve during exercise controlled by?

Answer 21

The increase in ventilation during exercise is controlled by both neural and humoral (chemical) pathways. Involves both mechanoreceptors in joints and muscles and chemoreceptors in carotid body and aortic body.

Question 22

How does an increase in CO2 increase respiration rate?

Answer 22

Increase in CO2 leads to increase in respiration rate, via buffering of hydrogen bicarbonate and H+ sensing or chemoreceptors sensing increased CO2 in circulating blood.