Ch14 Heart rate

Question 1

Sympathetic nervous system

Answer 1

1. stimulates effectors
2. speeds up activity
3. hightens awareness
4. prepare for activity

Question 2

Parasympathetic nervous system

Answer 2

1. inhibits effectors
2. slows down activity
3. conserves energy and replenishes body reserves
4. resting conditions

Question 3

Autonomic nervous system

Answer 3

Sympathetic and parasympathetic are antagonistic
- oppose one another

Question 4

Myogenic

Answer 4

contraction is initiated from within muscle

Question 5

Control basic heart rate

Answer 5

1.wave of depolarisation spreads out from sinoatrial node across both atria, causing contraction
2. wave enters atrioventricular node
3. after short delay, wave of depolarisation passes along bundle of His
4. bundle of His conducts wave through atrioventricular septum to Purkyne tissue at base of ventricles
5. release of wave causes ventricles to contract from base upwards

Question 6

Sinoatrial node

Answer 6

within wall of right atrium
initiates stimulus

Question 7

Control centre for heart rate

Answer 7

medulla oblongata

Question 8

Importance of insulating atrioventricular septum

Answer 8

1. prevents waves of electrical activity from entering ventricles from sinoatrial node
2. ventricles only respond to signals from atrioventricular node

Question 9

Excercise and heart rate

Answer 9

1. Rate of respiration increases
2. Increased CO2 concentration (pH decreases)
3. chemoreceptors in carotid arteries and aorta detect
4. Increases impulses sent to medulla
5. Increases impulses sent via sympathetic neurones to sinoatrial node
6. Increases heart rate

Question 10

Pulse

Answer 10

Caused by pressure
From one contraction

Question 11

Reduction of heart rate

Answer 11

1. Decteased CO2 concentration (pH decreases)
2. chemoreceptors in carotid arteries and aorta detect
3. Decrease impulses sent to medulla
4. Decrease impulses sent via sympathetic neurones to sinoatrial node
5. Heart rate decreases

Question 12

High blood pressure

Answer 12

1. Pressure receptors in aorta detect
2. send impulses to medulla
3. medulla stimulates impulses via parasympathetic nerves to sinoatrial node
4. Release of acetyl cholin inhibits the sinoatrial node
5. decreases impulses to the atrioventricular node
6. heart rate decreases

Question 13

Low blood pressure

Answer 13

1. Pressure receptors detect
2. send impulses to medulla
3. impulses sent to sinoatrial node
4. more impulses to atrioventicular node
5. heart rate increases