Cardiovascular system during exercise of differing intensities and during recovery

Question 1

What is the effect of submaximal intensity exercise on heart rate?

Answer 1

1. Anticipatory rise - rise in HR due to release of adrenaline before exercise.
2. Fast increase in HR to deal with increased demand for O2.
3. Plateau as supply meets demand of oxygen.
4. Fast drop due to drop in Venus return.
5. Slower decrease as heart rate returns to its pre-exercise value.

Question 2

What is the effect of maximum intensity exercise on heart rate?

Answer 2

1. Anticipatory rise - increase in heart rate pre-exercised due to adrenaline.
2. Fast increase in heart rate due to increase in demand for O2 from muscles.
3. Slower increase as anaerobic and oxygen supply never reaches demand.
4. Fast decreased post exercise due to drop in Venus return.
5. Slower recovery of heart rate than aerobic due to removal of more waste product (lactic acid).

Question 3

How does stroke volume change during exercise?

Answer 3

1. Stroke volume increases linearly with exercise intensity due to greater demand for oxygen from the muscles.
2. then stroke or plateau towards maximal intensity as minimum time required fully filled with blood.
3. Volume drops in maximum intensity exercise as heart rate continues to fall left ventricle can’t fully fill with blood before it is ejected again (cardiovascular drift).

Question 4

What happens to cardiac output during exercise?

Answer 4

1. Cardiac output increases linearly with exercise intensity.
2. cardiac output plateau during maximum intensity exercise.

Question 5

What is the vascular shunt mechanism?

Answer 5

The redistribution of cardiac output during exercise

Question 6

What do chemoreceptors do?

Answer 6

Detect chemical changes in the blood, e.g. oxygen and CO2.

Question 7

What do baroreceptors do?

Answer 7

Detect changes in blood pressure

Question 8

What do proprioreceptors do?

Answer 8

Detect changes in muscular activity.

Question 9

What is the vasomotor control centre (VCC)?

Answer 9

Situated in the brain and is responsible for controlling the vascular shunt mechanism.

Question 10

What is sympathetic stimulation?

Answer 10

Controls the diameter of the arterials and pre-capillary sphincters.

Question 11

What is an arterial for?

Answer 11

A small artery that carries oxygenated blood to muscles and organs with a muscular middle layer allowing for vasoconstriction and vasodilation.

Question 12

What are pre-capillary sphincters?

Answer 12

A small ring shaped muscle at the junction between arterials and capillaries which can vasoconstrict and vasodilate.

Question 13

What is vasodilation?

Answer 13

A decrease in sympathetic stimulation causes the widening in the diameter of arterials and pre-capillary sphincters.

Question 14

What is vasoconstriction?

Answer 14

An increase in sympathetic stimulation causes the narrowing of the arterials and pre-capillary sphincters.

Question 15

Why do we need the vascular shunt mechanism? (2)

Answer 15

1. Increase in demand of oxygen and nutrients from the muscles for respiration.
2. Increase the speed of the removal of waste products (such as lactic acid and carbon dioxide.)

Question 16

What happens to the vascular shunt mechanism during exercise? (4)

Answer 16

1. Chemoreceptors detect a decrease in blood pH; baroreceptors detect an increase in muscle activity.
2. Information is sent to the VCC.
3. VCC increases sympathetic stimulation of arterials and pre-capillary sphincters going towards organs to reduce diameter and reduce blood flow to those areas. (vasoconstrict).
4. The VCC decreases the sympathetic stimulation of arterioles and prevents-capillary sphincters going towards increase diameter and increase blood flow to those areas (vasodilation).

Question 17

What happens to the vascular shunt mechanism during recovery? (4)

Answer 17

1. Chemoreceptors detect an increase in blood pH; baroreceptors detect a decrease in blood pressure and proprioreceptors detect a decrease in muscle activity.
2. Information sent to the VCC.
3. the VCC decreases sympathetic stimulation of arterials and pre-capillary sphincters going towards organs to increase diameter and increased blood flow to those areas (vasodilation).
4. VC increases sympathetic stimulation of arterials and pre-capillarie sphincters going towards muscles to decrease diameter and decrease blood flow to those areas.(vasoconstruction).

Question 18

What are the two problems with Venous Return?

Answer 18

1. Blood pressure in the veins returning to blood to the heart is zero.
2. Most of cardiac output is in the legs so must travel against gravity back to the heart.

Question 19

What are the five solutions to the problems of Venus return?

Answer 19

1. Gravity - blood above the heart return return to heart by gravity.
2. Respiratory pump - during inspiration the diaphragm contract and flatten so volume in the abdomen decreases and pressure increases to below that of the thoracic cavity. this pressure actively pulls blood back up towards the heart.
3. Pocket valves - in larger veins to prevent backflow.
4. Skeletal muscle pump - when muscles contracts they shorten and widen squeezing veins and pushing blood back up towards the heart.
5. Smooth muscle – vein walls to allow for some vasoconstriction.

Question 20

What are the intrinsic factors regulating heart rate during exercise?

Answer 20

1. Temperature - increased body temperature during exercise increased speed of nerve transmission increased firing rate of SA note HR increases.
2. Venus return - greater volume of blood returning to the heart per minute increase stretch of ventricular causes heart rate stroke volume and cardiac output to all increase.

Question 21

What are the intrinsic factors regulating heart rate during recovery?

Answer 21

1. Temperature - decreases during recovery decreases speed of nerve transmission decreases firing rate of the SA node and so heart rate decreases.
2. Venus return - less volume of blood returning into the heart per minute, less stretch on ventricular wall causes heart rate stroke volume and cardiac output to all decrease.

Question 22

What are the extrinsic factors in regulating heart rate during exercise?

Answer 22

1. Chemoreceptors detect decrease in blood pH, baroreceptors detect increase in blood pressure, proprioreceptors detect increase in muscle activity.
2. Information sent to the cardiac control centre in the brain.
3. The cardiac control centre increases sympathetic stimulation to increase firing rate of the SA node causing heart rate to increase.
4. Adrenaline is released from the adrenal glands.
5. Stimulates sympathetic stimulation which increases firing rate of essay node so heart rate increases.
6. Adrenaline also increases the force of cardiac contractions causing SV and Q to also increase.

Question 23

What are the extrinsic factors in regulating heart rate during recovery?

Answer 23

1. Chemoreceptors detect increase in blood pH; baroreceptors detect decrease in blood pressure, proprioreceptors detect decrease in muscle activity.
2. Information sent to the cardiac control centre in the brain.
3. The CCC uses the parasympathetic stimulation to decrease firing rate of the SA node causing heart rate to decrease.
4. Release of adrenaline, adrenal gland is inhibited.
5. Decrease firing rate of essay node so heart rate decreases.