5.2 Heart Rate

Question 1

what is normal heart rate

Answer 1

70 beats per minute

Question 2

is heart rate voluntary or involuntary?

Answer 2

involuntary

Question 3

what nervous system controls heart rate?

Answer 3

autonomic

Question 4

which area of the brain is responsible for controlling heart rate?

Answer 4

medulla oblongata

Question 5

what are the 2 centres of the medulla oblongata?

Answer 5

cardiac excitatory

cardiac inhibitory

Question 6

what does the cardiac excitatory centre do?

Answer 6

increases heart rate by sending impulses through sympathetic nerve to SAN

Question 7

what does the cardiac inhibitory centre do?

Answer 7

decreases heart rate by sending impulses through parasympathetic nerve to SAN

Question 8

which centre is stimulated is depends upon what?

Answer 8

information from receptors

Question 9

what are baroreceptors? what do they detect?

Answer 9

pressure receptors detecting changes in blood pressure

Question 10

where are baroreceptors found?

Answer 10

aorta
vena cava
cartoid arteries

Question 11

what are chemoreceptors? what do they detect?

Answer 11

chemical receptors

detect changes in levels of chemicals within the blood

Question 12

where are chemoreceptors found?

Answer 12

cartoid artery (supplies brain with blood)

Question 13

what are chemoreceptors sensitive to changes in?

Answer 13

blood pH

Question 14

if CO2 levels in the blood increase what happens to blood pH?

Answer 14

it decreases

Question 15

why does blood pH decrease if CO2 levels increase?

Answer 15

CO2 interacts with H2O in the blood forming carbonic acid

Question 16

when blood pH decreases chemoreceptors send an impulse to where?

Answer 16

medulla oblongata

Question 17

(decrease in pH) response is coordinated in which centre? resulting in an impulse being sent where?

Answer 17

cardiac excitatory centre

along sympathetic nerve

Question 18

(decrease in pH) from sympathetic nerve the impulse reaches the SAN causing what?

Answer 18

increase in heart rate

Question 19

(decrease in pH) increase heart rate moves CO2 where?

Answer 19

away to the lungs in order to get rid of it

Question 20

(decrease in pH) as the CO2 is exhaled from the lungs what happens to pH?

Answer 20

returns to normal

Question 21

(decrease in pH) as pH returns to normal what happens?

Answer 21

change detected by chemoreceptors sends an impulse to medulla oblongata then to cardiac inhibitory centre sends an impulse down parasympathetic as no more increase needed.

Question 22

increase in blood pressure is detected by what?

Answer 22

baroreceptors

Question 23

(increase in bp) baroreceptors send messages to the…..

Answer 23

medulla oblongata

Question 24

(increase in bp) the medulla oblongata sends an impulse to where?

Answer 24

cardiac inhibitory centre

Question 25

(increase in bp) the cardiac inhibitory centre coordinates a response along where? resulting in what?

Answer 25

parasympathetic nerve leading to SAN

decrease in heart rate until bp returns to normal

Question 26

(increase in bp) when bp returns to normal what happens?

Answer 26

baroreceptor sends message to medulla oblongata then to cardiac excitatory centre as decrease is no longer needed

Question 27

when might more CO2 be produced?

Answer 27

exercising