Neural, hormonal control and intrinsic control of HR Flashcards
Two nervous systems
Sympathetic nervous system - ⬆️HR
Parasympathetic nervous system -⬇️HR
Neural control of the heart
Cardiac control centre receives info from different sensory receptors around the body
4 type of receptors
Chemoreceptors
Baroreceptors
Proprioceptors
Thermoreceptors
Chemoreceptors
Detect change in pH
(Change in acitdity in blood)
CO2 and lactic acid ⬇️ blood pH (more acidic)
Increased CO2 and lactic acid at exercise is detected by chemoreceptors and stimulates sympathetic nervous system to make heart beat faster.
Baroreceptors
Special stretch receptors in walls of aorta, vena cava and carotid series which detect a change in blood pressure.
High blood pressure- causes increase in stretch of baroreceptors and stimulates parasympathetic nervous system to ⬇️HR
Low blood pressure- decrease in stretch of baroreceptors stimulates sympathetic nervous system to ⬆️HR
Proprioceptors
Detect increase in muscle movements.
⬆️ movement sends impulse to medulla which sends impulse through the sympathetic nervous system to the SAN to ⬆️HR.
Thermoreceptors
Detect change in body temperature.
⬆️body temperature detected by thermoreceptors which send info to the cardiac control centre to ⬆️HR.
What hormones does the sympathetic nervous system release
Adrenaline
Noradrenaline
To ⬆️HR
What is adrenaline
The stress hormone which stimulates the SAN to increase speed and force of contraction
What is noradrenaline
Neurotransmitter that aid the spread of the impulse throughout the heart.
Result of adrenaline and noradrenaline being released
Cardiac output increases so more blood pumped to working muscles.
What hormone does the parasympathetic nervous system release
Acetylcholine
Slows HR
What is acetylcholine
A neurotransmitter which slows the sorteas if impulses throughout the heart therefore slowing it don’t do resting levels.
Regulation of HR during exercise
Rest- parasympathetic nervous system overrides sympathetic nervous system. Keeps HR down.
Exercise- sympathetic nervous system stimulated. ⬆️CO2 means ⬇️pH - chemoreceptors detect change and sends message to CCC which sends impulse to SAN through accelerator nerves. Adrenaline and noradrenaline released. ⬆️strength and speed of contraction.
End- parasympathetic nervous system takes over. Vague nerve is stimulated and acetylcholine is released which slows heart rate.
Intrinsic control of HR means
It doesn’t depend on the nervous system
