Control of heart rate

Question 1

heart must meet

Answer 1

changing demands of tissues

Question 2

changing demands of tissues

Answer 2

exercise

metabolic demands of tissues

Question 3

3 ways for heart to accomodate changing demands

Answer 3

change heart rate
changing force of contractions
changing stroke volume(volume of blood pumped for heart)

Question 4

cardiac muscle is found in

Answer 4

heart

Question 5

cardiac muscle is

Answer 5

myogenic

Question 6

myogenic

Answer 6

can initiate own contraction at regular intervals

Question 7

atria has higher myogenic rate than

Answer 7

ventricles(contract faster than ventricles)

Question 8

sa node sends wave of

Answer 8

exertion throughout atria

Question 9

sa node exertion causes

Answer 9

atria to contract

Question 10

electric impulse SA node sent out would

Answer 10

reach band of insulating tissue between atria and ventricle

Question 11

all the force

Answer 11

and exertion passes through the septum and AVN which is also located in the septum

Question 12

electrical impulse then travel down to

Answer 12

apex of heart through perkinje fibres

Question 13

after perkinje fibres exertion would eventually spread upwards from

Answer 13

apex to ventricles making them to contract

Question 14

cardiac muscle responds

Answer 14

directly to adrenaline(increases heart rate)

Question 15

At Rest

Answer 15

No adrenalin in heart
Just SAN control heart rate
fires 60-80 bpm
firing maybe altered by cardiovascular centre in the medulla

Question 16

SAN

Answer 16

Internal pacemaker

Question 17

medulla-SAN

Answer 17

Accelarans nerve

vagus nerve

Question 18

Accelerans nerve

Answer 18

sympathetic nervous system
responsible for increasing heart rate
fight or flight response

Question 19

Vagus nerve

Answer 19

Parasympathetic

decreases heart rate

Question 20

which two muscles are antaganostic

Answer 20

accalarans

vagus

Question 21

control comes from increasing firing of these

Answer 21

two nerves

Question 22

if one fires it does not mean the other stops firing

Answer 22

it just mean its firing slower than the other nerve

Question 23

cardiovascular centre stimuli

Answer 23

muscle stretch receptor
chemoreceptor
muscle receptor in the wall of carotid sinus

Question 24

muscle stretch receptor

Answer 24

when exercising,
muscle will be moving
movt will be detected by stretch receptor
which will communicate to CVC
if stretchings a lot CVC will increase firing rate

Question 25

Chemoreceptors can be found in:-

Answer 25

Carotid Arteries
Aorta
Brain

Question 26

chemoreceptor monitors

Answer 26

PH of blood.Once CO2 gets in blood it forms carbonic acid with the h2o.it later dissasociates into hydrogen carbonate and hydrogen ions then will affect PH,exercising more will have low PH

Question 27

Barroreceptor

Answer 27

muscle receptor in wall of carotid sinus.It monitors bp.If bp too high it can be dangerous to the organs and increase the risk of diseases like CVD.It tells CVC to start increasing rate of vagus nerve

Question 28

if all the 3 responses fails

Answer 28

then people may need artificial pacemaker

Question 29

artificial pacemaker

Answer 29

connected directly to SA nerve or ventricular muscle.Takes over the role of SAN and delivers impulse to the heart muscle/

Question 30

artificial pacemaker is

Answer 30

usually implanted under skin and fat of chest or sometimes within the cavity of chest

Question 31

explain how atmosphere near volcano can lead to an increasing in breathing rate

Answer 31

conc of blood in the lung is high.
due to co2 conc ph becomes low and is detected by chemoreceptors carotid bodies,Aorta
brain.It communicates to cvc in medulla which sends impact through neurons for intercostal muscles and diaphragm.

Question 32

suggest how an increase in breathing rate can help to reduce the conc of co2 in a person walking away from the volcano

Answer 32

inhaled air has low co2 . the co2 in blood is higher than in lungs so co2 moving down conc gradient

Question 33

tissue that controls resting heart

Answer 33

SAN

Question 34

what is measured by ECG

Answer 34

Electrical volume

Question 35

describe how heart rate can be measured by nervous system

Answer 35

low ph is detected by chemoreceptor in caortic bodies

it communicates to medulla which activates accelerator nerve

Question 36

give 1 diff and 1 sim between hormonal and nervous system

Answer 36

sim
both involuntary
diff
hormonal is slower
hormonal lasts longer

Question 37

morphine reduces sensitivity of co2 in the blood.this affects breathing rate and can be cause death.suggest why high dose of morphine can cause death

Answer 37

co2 will not be removed from blood
carbonic acid increases,ph decreases
change not detected by chemoreceptor
so medulla not stimulated