control of heart rate

Question 1

Process (5)

Answer 1

-SAN sends a wave of electricity that stimulates atria to contract
-Signal passes down atrial septum to AVN
- AVN conducts signal to ventricles
-bundle of his transmits wave to the base of the heart
-purkyne fibres branch up each ventricle causing them to contract after the atria is empty

Question 2

Which two nerves is the SAN connected to and where are they located

Answer 2

accelerator nerve- sympathetic nervous system which delivers higher frequencies of impulses to increase heart rate
vagus nerve- parasympatheric nervous system which delivers a lower frequency of impulses to decrease heart rate
In medulla oblongata

Question 3

Which receptor detects chemical changes

Answer 3

chemoreceptors

Question 4

Which receptor detects changes in blood pressure

Answer 4

baroreceptors

Question 5

How does medulla oblongata control heart rate

Answer 5

alters the speed at which the SAN fires

Question 6

Which neurotransmitter is secreted by parasympathetic neurons

Answer 6

acetylcholine - decreases heart rate

Question 7

Which neurotransmitter is secreted by sympathetic neurons

Answer 7

noradrenaline - increases heart rate

Question 8

What happens with high blood pressure (4)

Answer 8

-baroreceptors detect
-send impulses to medulla down parasympathetic neurones
-acetylcholine released in cardiac muscle, binding to receptors in the SAN
-heart rate slows, decreasing blood pressure

Question 9

What happens with high blood pressure (4)

Answer 9

-baroreceptors detect
-send impulses to medulla down sympathetic neurones
-noradrenaline released in cardiac muscle, binding to receptors in the SAN
-heart rate speeds up, increasing blood pressure

Question 10

What happens with high blood O2 or pH, or low CO2 (4)

Answer 10

-detected by chemoreceptors
-send impulses to medulla down parasympathetic neruones
-acetylcholine is released into cardiac muscles, binding to receptors on the SAN
-heart rate slows, lowering blood to normal levels

Question 11

What happens with low blood O2 or pH, or low CO2 (4)

Answer 11

-detected by chemoreceptors
-send impulses to medulla down sympathetic neruones
-noradrenaline is released into cardiac muscles, binding to receptors on the SAN
-heart rate speeds up, increasing blood to normal levels