9.8 Control of heart rate in mammals Flashcards
What is the cardiac output?
Cardiac volume x heart rate
How can cardiac output be increased?
Increasing the cardiac volume
Increasing the heart rate
Which nervous system controls heart rate?
Autonomic
Where is the cardiac control centre found?
Medulla
Explain how the CCC is involved in increased demand of for oxygen
Baroreceptors/chemoreceptors detect changes
Sends signal to the CCC in the medulla oblongata
Sends signals down the sympathetic nervous system
Released noradrenaline
Stimulates SAN and ventricles
Increased heart rate and contraction
Explain how the CCC is involved in the decreased demand for oxygen
Baroreceptors/chemoreceptors detect changes
Sends signals to the CCC in the medulla oblongata
Sends signals down the parasympathetic nervous system
Releases acetylcholine
Inhibits SAN
Decreased heart rate and contraction
Where are baroreceptors found?
Sinuses of the carotid arteries in the neck and aorta
What do baroreceptors respond to?
Stretch
How do baroreceptors bring about an increased heart rate?
Exercise starts Vasodilation in response to adrenaline BP falls Reduces stretch on baroreceptors Sends reduced signals to CCC Sends signals along sympathetic nerve to stimulate heart rate Increases bp by vasoconstriction
How do baroreceptors bring about a decreased heart rate?
Blood is being pumped harder and faster than it needs to be
High bp - more stretch on the receptors
Sends signals to CCC
Sends signals down the parasympathetic nerve
Causes vasodilation
Reduces bp
What are chemoreceptors sensitive to?
pH of the blood
Where are chemoreceptors found?
Walls of the aorta and carotid arteries
How can chemoreceptors bring about an increased heart rate?
More exercise = more CO2 in the blood therefore lower pH
Chemoreceptors detect the lower pH
Send signals to the CCC in the medulla oblongata
Sends signals down the sympathetic nervous system
Releases noradrenaline at the SAN
Increases heart rate
CO2 is removed from body bc of increased blood flow
What gland is adrenaline produced in?
Adrenal glands
What causes the release of adrenaline?
Stress or shock
