Topic 7B Exercise

Question 1

what does myogenic mean

Answer 1

Electrical impulses in the heart originate from heart muscle alone
no neurones

Question 2

Another name for SAN

Answer 2

Pacemaker
sinoatrial node

Question 3

How does the heart contract

Answer 3

SAN sends impulse across the atria causing them to depolarise + contract
Non conducting collagen prevents ventricles from contracting at the same time
AVN conducts the impulse after 0.13s to bundle of His
Purkynje fibres conduct impulse to apex of heart causing ventricles to contract from bottom
pushes blood into the arteries

Question 4

bundle of His

Answer 4

group of purkynje fibres
conducts impulse from AVN to heart apex + ventricle walls

Question 5

normal ECG pattern

Answer 5

P wave (atrial systole)
QRS complex (ventricular systole)
T wave (ventricular repolarisation)
60-100 bpm

Question 6

abnormal heart beat

Answer 6

Arrhythmia-irregular beats
Tachycardia- over 100 BPM
bradycardia-under 60 BPM
Fibrillation- loss of rhythm
ectopic heartbeat- earlier contraction

Question 7

tachycardia

Answer 7

heartrate over 100BPM

Question 8

bradycardia

Answer 8

heartrate under 60 BPM

Question 9

ectopic heartbeat

Answer 9

extra heartbeat due to early contraction of atria/ventricles
occasional provides no danger

Question 10

fibrillation

Answer 10

Irregular heartbeat- atria or ventricles completely lose rhythm
can be dangerous- death

Question 11

where is heart rate controlled

Answer 11

the medulla oblongata’s cardiovascular control centre

Question 12

how is heart rate increased

Answer 12

the cardiovasular control centre recieves impulses from sensory neurones from chemical and pressure receptors.
impulses are sent down sympathetic neurones to the SAN causing more frequent firing of impulses, increasing heart rate

Adrenaline released from adrenal gland
binds to SAN causing it to fire more frequently

Question 13

what happens to heartrate when blood pressure is high

Answer 13

BP is detected by baroreceptors
CCC sends impulses through parasympathetic vagus nerve
SAN fires less frequently
heartrate decreases

Question 14

what happens to heartrate when blood pressure is low

Answer 14

BP detected by baroreceptors
CCC send impulse through sympathetic nerve
SAN fires more frequently
Heartrate increases

Question 15

What happens to heartrate during exercise

Answer 15

Increased respiration
blood pH decreases due to increased CO2
Chemoreceptors detect +send impulse to CCC
CCC sends impulse down sympathetic nerve
SAN fires more frequently
Heartrate increases

Question 16

Cardiac output

Answer 16

total volume of blood pumped out of the heart in a minute

Question 17

Cardiac output equation

Answer 17

Heart rate (bpm) x stroke volume (cm3)

Question 18

Tidal volume

Answer 18

volume of air in each normal breath

Question 19

breathing rate

Answer 19

breaths per minute

Question 20

oxygen consumption

Answer 20

the volume of oxygen used by the body

Question 21

minute ventilation

Answer 21

the amount of gas breathed in or out in one minute

Question 22

vital capacity

Answer 22

the maximum volume of air in one breath