Control of heart rate Flashcards
What is the autonomic nervous system?
This system controls the involuntary activities of internal muscles and glands.
It is split into two parts:
- Sympathetic
- Parasympathetic
What region of the brain controls heart rate?
Medulla oblongata
What are chemoreceptors and baroreceptors?
Both are found in the walls of the carotid arteries. Chemoreceptors are sensitive to changes in the pH of the blood that result in changes in CO2 and lactic acid concentration changes. In solution, CO2 forms an acid which lowers pH. Baroreceptors are sensitive to pressure changes.
Name key structures of the heart that control heart rate and where are they located:
- The sinoatrial node(SAN) in the right atrium.
- Atrioventricular node (AVN).
- Bundle of His runs down the septum.
- Purkyne tissue in the walls of the ventricles.
Describe the process of the control of heart rate:
SAN will release a wave of depolarisation across the atria causing systole. The AVN will then release another wave of depolarisation. The bundle of His then conducts and passes the wave of depolarisation down the septum and into the purkyne fibers in the walls of the ventricles. As a result, there is a short delay until ventricular systole takes place. The cells then repolarise and cardiac muscle undergoes diastole.
Why is the bundle of His needed to conduct and pass the wave of depolarisation?
There is a non-conductive layer between the atria and ventricles therefore bundle of His is needed to bypass it. There is a delay that allows blood to fully pump into the ventricles.
Which of the parasympathetic or sympathetic increases heart rate?
The sympathetic nervous system.
Why is blood pressure too high bad?
Can cause damage to the walls of the arteries.
Why is blood pressure too low bad?
There may be an insufficient supply of oxygenated blood to respiring cells and the removal of waste.
