Nervous & Hormonal Systems in Nervous & Hormonal Systems in
Controlling Heart Rate: Controlling Heart Rate:
Nervous Control:
Cardiac muscle is myogenic.
The SAN acts as a pacemaker & controls
heart rate when resting.
The medulla oblongata in the brain is
connected to the SAN by motor
neurones.
The nerves that connect the SAN & the
medulla oblongata are the vagus nerve
& the accelerans nerve.
The vagus nerve decreases heart rate.
The accelerans nerve increases heart
rate.
Stretch receptors in the muscles detect
movement of limbs & indicate that
more/less oxygen will be needed.
Baroreceptors in the aorta, vena cava &
carotid arteries detect changes in blood
pressure.
Chemoreceptors in the brain, aorta &
carotid arteries detect changes in pH
(from CO2) & indicate that more/less
oxygen is needed.
Hormonal Control:
Adrenaline binds to specific receptors in
cardiac muscle increasing the force &
rate of the heart beat.
Controlling Heart Rate: Controlling Heart Rate:
Nervous Control:
Cardiac muscle is myogenic.
The SAN acts as a pacemaker & controls
heart rate when resting.
The medulla oblongata in the brain is
connected to the SAN by motor
neurones.
The nerves that connect the SAN & the
medulla oblongata are the vagus nerve
& the accelerans nerve.
The vagus nerve decreases heart rate.
The accelerans nerve increases heart
rate.
Stretch receptors in the muscles detect
movement of limbs & indicate that
more/less oxygen will be needed.
Baroreceptors in the aorta, vena cava &
carotid arteries detect changes in blood
pressure.
Chemoreceptors in the brain, aorta &
carotid arteries detect changes in pH
(from CO2) & indicate that more/less
oxygen is needed.
Hormonal Control:
Adrenaline binds to specific receptors in
cardiac muscle increasing the force &
rate of the heart beat.
