❤️ 3.6 - 3.6.1 - 3.6.1.3 Control of heart rate (A-level only) Flashcards
What muscle controls the regular beating of the heart?
The cardiac muscle.
What word is the cardiac (heart) muscle described as?
Myogenic.
What does the term myogenic mean?
That the heart can contract and relax without receiving signals from nerves.The pattern of contractions controls the regular heartbeat.
What is the first process of the cardiac muscle controlling the regular beating of the heart?
The process starts in the sinoatrial node (SAN), which is in the wall of the right atrium.
What is the SAN (sinoatrial node) like?
How?
A pacemaker.
It sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls.
What does the SAN cause?
It causes the right and left atria to contract at the same time.
What does a band of non-conducting collagen tissue prevent?
What happens instead?
The waves of electrical activity from being passed directly from the atria to the verticals.
Instead, the waves of electrical activity are transferred from the SAN to the atrioventricular node (AVN).
What is the atrioventricular node (AVN) responsible for?
Passing the waves of electrical activity on to the bundle of His. But, there is a slight delay before the AVN reacts, 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 (bottom of the heart). The bundle splits into finer muscle fibres in the right and left ventricle walls, called the purkyne tissue.
What is the role of the purkyne tissue?
It carries the waves of electrical activity into the muscular walls of the right and cleft ventricles, causing them to contract simultaneously, from the bottom up.
What 2 things does the control of heart rate involve?
The brain and autonomic nervous system.
What does the sinoatrial node (SAN) generate?
Electrical impulses that cause the cardiac muscles to contract.
The rate at which the SAN fires (i.e. heart rate) is unconsciously controlled by a part of the brain called the … .
medulla oblongata.
Animals may need to alter their heart rate to respond to what?
Internal stimuli.
(E.g. to prevent fainting due to low blood pressure or to make sure the heart rate is high enough to supply the body with enough oxygen.)
What are 1 types of receptors in which stimuli are detected by?
Pressure receptors and chemical receptors.
What is the name given to the pressure receptors?
Baroreceptors.
Where are the pressure receptors called baroreceptors located?
In the aorta and the carotid arteries (major arteries in the neck).
What are the pressure receptors called baroreceptors stimulated by?
High and low blood pressure.
What is the name given to the chemical receptors?
Chemoreceptors.
Where are the chemical receptors called chemoreceptors located?
In the aorta, the carotid arteries (major arteries in the neck) and in the medulla.
What do the chemical receptors called chemoreceptors monitor?
The oxygen level in the blood and also carbon dioxide and pH (which are indicators of O2 level).
Along what type of neurones are electrical impulses from receptors sent to the medulla along?
Sensory neurones.
What does the medulla do once it has received the electrical impulses from the receptors along via the sensory neurones?
Processes the information and sends impulses to the SAN along sympathetic or parasympathetic neurones (which are part of the autonomic nervous system).
What do stimuli detected by receptors cause the heart rate to do?
Speed up or slow down.
If the stimulus was high blood pressure, what would the receptor be?
Baroreceptors detecting the high blood pressure.
If the stimulus was high blood pressure what would the neurone and transmitter be?
Impulses are sent to the medulla, which sends impulses along parasympathetic neurones. These secrete acetylcholine (a neurotransmitter), which binds to receptors on the SAN.
If the stimulus was high blood pressure what would the effector be?
Cardiac muscles.
If the stimulus was high blood pressure what would the response be?
Heart rate slows down to reduce blood pressure back to normal.
If the stimulus was low blood pressure, what would the receptor be?
Baroreceptors detecting the low blood pressure.
If the stimulus was low blood pressure what would the neurone and transmitter be?
Impulses are sent to the medulla, which sends impulses along sympathetic neurones. These secrete noradrenaline (a neurotransmitter), which binds to receptors on the SAN.
If the stimulus was low blood pressure what would the effector be?
Cardiac muscles.
If the stimulus was low blood pressure what would the response be?
Heart rate speeds up to increase blood pressure back to normal.
If the stimulus was high blood oxygen, low carbon dioxide or high pH levels, what would the receptor be?
Chemoreceptors detecting the chemical changes in the blood.
If the stimulus was high blood oxygen, low carbon dioxide or high pH levels, what would the neurone and transmitter be?
Impulses are sent to the medulla, which sends impulses along parasympathetic neurones. These secrete acetylcholine, which binds to receptors on the SAN.
If the stimulus was high blood oxygen, low carbon dioxide or high pH levels, what would the effector be?
Cardiac muscles.
If the stimulus was high blood oxygen, low carbon dioxide or high pH levels, what would the response be?
Heart rate decreases to return oxygen, carbon dioxide and pH levels back to normal.
If the stimulus was low blood oxygen, high carbon dioxide or low pH levels, what would the receptor be?
Chemoreceptors detecting the chemical changes in the blood.
If the stimulus was low blood oxygen, high carbon dioxide or low pH levels, what would the neurone and transmitter be?
Impulses are sent to the medulla, which sends impulses along sympathetic neurones. They secrete noradrenaline, which binds to receptors on the SAN.
If the stimulus was low blood oxygen, high carbon dioxide or low pH levels, what would the effector be?
Cardiac muscles.
If the stimulus was low blood oxygen, high carbon dioxide or low pH levels, what would the response be?
Heart rate increases to return oxygen, carbon dioxide and pH levels back to normal.
