Q4: Nervous control of heart rate Flashcards
Autonomic nervous system
controls the involuntary activities of internal muscles and glands
Autonomic meaning
self governing
Two divisions of the autonomic nervous system
sympathetic nervous system
parasympathetic nervous system
The sympathetic nervous system
Stimulates effectors and speeds up any activity,
The sympathetic nervous system
acts as
an emergency controller
fight or flight
The sympathetic nervous system
controls
controls effectors when we exercise strenuously or experience powerful emotions
The parasympathetic nervous system
Inhibits effectors and slows down any activity.
The parasympathetic nervous system
controls
activities under the body’s normal resting conditions,
The parasympathetic nervous system
concerned with
conserving energy and replenishing the body’s reserves
The sympathetic and parasympathetic nervous systems
relationship
antagonistic
SAN
sinoatrial node
Sinoatrial node
A group of cells within the right atrium of the heart where the initial stimulus for contraction originates.
The sinoatrial node has
a basic rhythm of stimulation that determines the beat of the heart
AVN
atrioventricular node
Location of the atrioventricular node
lies between the atria
Purkyne tissue
a series of specialised muscle fibres
Bundle of His
made up of purkyne tissue
Essential that heart rate can be…
altered to meet varying demands of oxygen
Medulla oblongata
region of the brain that controls changes to the heart rate
Medulla oblongata
two centres
- a centre linked to SAN, by sympathetic nervous system which increases HR
- a centre linked to SAN, by parasympathetic nervous system which decreases HR
Chemoreceptors
location
wall of the carotid arteries
Carotid arteries
arteries that serve the brain
Chemoreceptors
Sensitive to changes in pH of the blood that result from changes in carbon dioxide concentration
Carbon dioxide effect on blood pH
in solution it forms an acid and lowers pH
Where are pressure receptors found?
within the walls of the carotid arteries and the aorta
When blood pressure is higher than normal, pressure receptors….
- transmit more nervous impulses to the centre in the medulla oblongata that decreases heart rate,
- this centre sends impulses via the parasympathetic nervous system to the SAN,
When blood pressure is lower than normal, pressure receptors….
- transmit more nervous impulses to the centre in the medulla oblongata that increases heart rate,
- this centre sends impulses via the sympathetic nervous system to the SAN
