Control of heart rate Flashcards
What are the two parts to the nervous system?
Central nervous system
Peripheral nervous system
What is the central nervous system made up of?
Brain
Spinal cord
What is the peripheral nervous system made up of?
Somatic nervous system
Autonomic nervous system
What does the somatic nervous system control?
conscious activities
What is the autonomic nervous system made up of?
Sympathetic and parasympathetic
What does the autonomic nervous system control?
Unconscious activities
What does the sympathetic nervous system do?
controls the flight or fight response which gets the body ready for action
S for Stress
What does the parasympathetic nervous system do?
Controls the ‘rest and digest’ which returns the body back to normal once the threat has passed
Which nervous system is involved in the control of heart rate?
Autonomic nervous system
What does myogenic mean?
The heart muscle can contract and relax without receiving signals from nerves
What are the two nodes involved in the control of the heart beat?
Sinoatrial node (SAN) Atrioventricular node (AVN)
Where is the sinoatrial node found?
In the wall of the right atrium
What does the sinoatrial node do?
Sends out regular waves of electrical activity to the atrial walls which causes the right and left atria to contract at the same time
What does the band of non-conducting collagen tissue do?
Prevents the waves of electrical activity from being passed directly from the atria to the ventricles
Instead of going straight to the ventricles, where do the waves of electrical activity go from the atria?
To the atrioventricular node
What is the atrioventricular node responsible for?
Passing the waves of electrical activity to the Bundle of His
Why is there a slight delay in the AVN reacting to the electrical activity?
To make sure the atria have emptied before the ventricles contract
What is the Bundle of His?
A group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the apex of the heart
What is purkyne tissue?
The finer muscle fibre branches from the Bundle of His in the right and left ventricle walls
What is the purpose of the Purkyne tissue?
Carries the waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously from the bottom up
Why do animals need to alter their heart rate?
To response to internal stimulus to prevent fainting due to low blood pressure or make sure the heart rate is high enough to supply the body with enough oxygen
What is the SAN controlled by?
the medulla in the brain
What are baroreceptors?
Pressure receptors
Where are baroreceptors found?
In the aorta and the carotid arteries
What are baroreceptors stimulated by?
High and low blood pressures
What are chemoreceptors?
Chemical receptors
Where are chemoreceptors found?
In the aorta
In the carotid arteries
In the medulla
What do chemoreceptors monitor?
Oxygen level in the blood
Carbon dioxide and pH
Where does the medulla send information?
to the SAN along sympathetic or parasympathetic neurones
What is the response when there is a high blood pressure?
1) Baroreceptors detect high blood pressure and sends impulses along sensory neurones to the medulla
2) medulla sends impulses along parasympathetic neurones
3) They secrete acetylcholine which bind to receptors on the SAN
4) This causes heart rate to slow down to reduce blood pressure
What is the response when there is a low blood pressure?
1) Baroreceptors detect low blood pressure and sends impulses along sensory neurones to the medulla
2) The medulla sends impulses along the sympathetic neurones
3) They secrete noradrenaline which binds to receptors on the SAN
4) This causes the heart rate to speed up in order to increase blood pressure
What is the response when there is a high blood O2, low CO2 or high blood pH levels?
1) Chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the medulla
2) The medulla sends impulses along the parasympathetic neurones
3) They secrete acetylcholine which binds to receptors on SAN
4) this causes the heart rate to decrease in order to return oxygen, carbon dioxide and pH levels back to normal
What is the response when there is a low blood O2, high CO2 or low blood pH levels?
1) chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the medulla
2) The medulla sends impulses along the sympathetic neurones
3) They secrete noradrenaline which binds to receptors on the SAN
4) This causes the heart rate to increase in order to return oxygen, carbon dioxide and pH levels back to normal
