Control of Heart Rate Flashcards
Where does much of the sensory information reaching the central nervous system come from?
It comes from receptors within the body that respond to internal stimuli
What does the autonomic nervous system help regulate?
It helps regulate internal systems to maintain homeostasis and respond to changing demands
How do the sympathetic and parasympathetic nervous systems interact?
They are antagonistic, meaning they have opposing effects. If one system contract a muscle, the other relaxes it
How are the activities of the internal glands and muscles regulated by the autonomic nervous system?
They are regulated by a balance between the sympathetic and parasympathetic nervous system
What is the sinoatrial node, where is it located?
The sinoatrial node is a group of specialised cells in the all of the right atrium that initiates the heartbeat
What does it mean for cardiac muscle to be myogenic?
It means the contraction is initiated from within the muscle itself rather than by external nervous impulses
What initiates the wave of electrical excitation in the heart?
The sinoatrial node
What effect does the wave of excitation from the sinoatrial node have on the atria?
It spreads across both atria, causing them to contract
Why doesn’t the wave of excitation pass directly from the atria to the ventricles?
A layer of non - conductive tissue (atrioventricular septum) prevents it from crossing
Where does the wave of excitation go after spreading across the atria?
It enters the atrioventricular node, located between the atria
What is the function of the atrioventricular node?
It delays the impulse slightly before sending it to the ventricles, ensuring the atria empties fully before ventricular contraction
How does the electrical impulse travel from the atrioventricular node to the ventricles?
It is transmitted alng the bundle of His, a structure made of Purkyne tissue
Where does the bundle of His conduct the wave of excitation>
Through the atrioventricular septum to the base of the ventricles
How does the wave of excitation cause ventricular contraction?
It spreads through smaller Purkyne fibres, causing both ventricles to contract simultaneously from the bottom upwards
Why must the heart rate be able to change?
To meet varying oxygen demands, such as during exercise when the heart rate may need to more than double
What are the two centres in the medulla oblongata that control heart rate?
- A centre that increases heart rate , linked to the sinoatrial node via the sympathetic nervous system
- A centre that decreases heart rate, linked to the sinoatrial node via the parasympathetic nervous system
Which part of the brain controls changes to heart rate?
The medulla oblongata
What determines which heart rate centre in the medulla oblongata is stimulated?
Nerve impulses received from receptors responding to chemical or pressure changes in the blood
Where are pressure receptors located?
In the walls of the carotid arteries and the aorta
What happens when blood pressure is higher than normal?
Pressure receptors send MORE impulses to the MEDULLA OBLONGATA THAT DECREASES HEART RATE. This centre sends impulses via the PARASYMPATHETIC NERVOUS SYSTEM to the sinoatrial node, REDUCING HEART RATE
What happens when blood pressure is lower than normal?
Pressure receptors send MORE impulses to the MEDULLA OBLONGATA CENTRE THAT INCREASES HEART RATE. This centre sends impulses via the SYMPATHETIC NERVOUS SYSTEM to the sinoatrial node, INCREASING HEART RATE
