A5. Control of Heart Rate Flashcards
Structure of the nervous system
The nervous system is split into two different systems-the central nervous system (CNS) and the peripheral nervous system. The CNS is made up of the ________and ________ _____, whereas the peripheral nervous system is made up of the ______________that connect the ____ to the _____of the ______.
The peripheral nervous system also has two different systems - the __________and ____________nervous systems. The _____________nervous system controls _____________activities, e.g. running and playing video games. The _______________nervous system controls _____________activities, e.g. digestion.
The nervous system is split into two different systems-the central nervous system (CNS) and the peripheral nervous system. The CNS is made up of the brain and spinal cord, whereas the peripheral nervous system is made up of the neurones that connect the CNS to the rest of the body.
The peripheral nervous system also has two different systems - the somatic and autonomic nervous systems. The somatic nervous system controls conscious activities, e.g. running and playing video games. The autonomic nervous system controls unconscious activities, e.g. digestion.
Structure of the nervous system
The autonomic nervous system is split into the _______________and __________________nervous systems, which have ______________ effects on the body. The __________________nervous system is the ‘fight or flight’ system that gets the body ________for _______. The ___________________system is the ‘rest and digest’ system that _______the body down. The _____________nervous system is involved in the control of heart rate
The autonomic nervous system is split into the sympathetic and parasympathetic nervous systems, which have opposite effects on the body. The sympathetic nervous system is the ‘fight or flight’ system that gets the body ready for action. The parasympathetic system is the ‘rest and digest’ system that calms the body down. The autonomic nervous system is involved in the control of heart rate
Figure 1: The structure of the nervous system.
Control of heart beat
Cardiac (heart) muscle is ‘___________’ - this means that it can contract and relax without receiving signals from nerves. This pattern of contractions controls the regular heartbeat.
Cardiac (heart) muscle is ‘myogenic’ - this means that it can contract and relax without receiving signals from nerves. This pattern of contractions controls the regular heartbeat.
Control of heart beat
The process starts in the ____________node (SAN), which is a small mass of tissue in the wall of the right atrium. The SAN is like a ______________- it sets the rhythm of the heartbeat by sending out regular _________ of ___________ __________to the ________ ____-. This causes the ________and ______ ______to contract at the ______time. A band of non-_______________ __________tissue prevents the waves of electrical activity from being passed directly from the _______to the _____________. Instead, these waves of electrical activity are transferred from the SAN to the ________________node (_____).
The process starts in the sinoatrial node (SAN), which is a small mass of tissue in the wall of the right atrium. The SAN is like a pacemaker-it sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls. This causes the right and left atria to contract at the same time. A band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles. Instead, these waves of electrical activity are transferred from the SAN to the atrioventricular node (AVN).
Control of heart beat
The AVN is responsible for passing the _______of ___________ ________on to the ________ __ ____. But, there’s a _________ _______before the AVN reacts, to make sure the _______have _________before the ___________ __________. The bundle of His is a group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the ______(bottom) of the heart. The bundle splits into finer muscle fibres in the right and left ventricle walls, called the Purkyne tissue. The Purkyne tissue carries the waves of electrical activity into the muscular walls of the right and left ____________, causing them to contract __________________, from the __________ __.
The AVN is responsible for passing the waves of electrical activity on to the bundle of His. But, there’s a slight delay before the AVN reacts, to make sure the atria have emptied before the ventricles contract. The bundle of His is 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. 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.
Figure 2: The pathway of electrical activity in the heart.
Tip: Remember the route of the waves of electrical activity by Silly Ants Have Pants
SAN, AVN, bundle of His, Purkyne fibres.
Communication between the heart and brain
The SAN generates ____________impulses that cause the __________ ___________to ___________. The rate at which the SAN fires (i.e. heart rate) is unconsciously controlled by a part of the brain called the ___________.
The SAN generates 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.
Communication between the heart and brain
Animals need to alter their heart rate to respond to __________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. Internal stimuli are detected by ____________receptors and ___________receptors:
Animals need to alter their heart rate to respond to 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. Internal stimuli are detected by pressure receptors and chemical receptors:
Communication between the heart and brain
- There are pressure receptors called ________________in the ______and _________ __________. They’re stimulated by high and low blood pressure.
- There are chemical receptors called chemoreceptors in the ______, the
__________ __________and in the ___________. They monitor the _________level in the
blood and also ________ ___________and __(which are indicators of O2 level).
____________ impulses from __________are sent to the _________along _________neurones. The __________processes the information and sends ____________to the ____along _________________or ______________________neurones.
- There are pressure receptors called baroreceptors in the aorta and carotid arteries. They’re stimulated by high and low blood pressure.
- There are chemical receptors called chemoreceptors in the aorta, the
carotid arteries and in the medulla. They monitor the oxygen level in the
blood and also carbon dioxide and pH (which are indicators of O, level).
Electrical impulses from receptors are sent to the medulla along sensory neurones. The medulla processes the information and sends impulses to the SAN along sympathetic or parasympathetic neurones.
Control of heart rate in response to different stimuli
1. High blood pressure
__________________detect high blood pressure and send __________along ___________ ____________to the ____________, which sends ___________along ____________________ ___________. These secrete _______________, which ______to _______________on the ____. This causes the heart rate to _____down in order to __________ _______ _____________ ______ __ ___________.
Baroreceptors detect high blood pressure and send impulses along sensory neurones to the medulla, which sends impulses along parasympathetic neurones. These secrete acetylcholine, which binds to receptors on the SAN. This causes the heart rate to slow down in order to reduce blood pressure back to normal.
Control of heart rate in response to different stimuli
2. Low blood pressure
__________________detect low blood pressure and send ___________along ___________ _____________to the ___________, which sends ____________along __________________ ___________. These secrete ________________, which _______to _____________ on the ____. This causes the heart rate to ___________up in order to ___________ _______ _____________ _______ __ __________.
Baroreceptors detect low blood pressure and send impulses along sensory neurones to the medulla, which sends impulses along sympathetic neurones. These secrete noradrenaline, which binds to receptors on the SAN. This causes the heart rate to speed up in order to increase blood pressure back to normal.
Tip: The effectors in all of these situations are the _________ __________of the _______.
Tip: The effectors in all of these situations are the cardiac muscles of the heart.
Tip: Low blood ___ high _____ or low blood ___ levels are a result of _____________respiration.
Tip: Low blood O2 high CO2 or low blood pH levels are a result of increased respiration.
Figure 3: The control of heart rate.
