Control of the Heart Rate Flashcards
What does myogenic means?
a muscle that can contract on its own
What is the SAN?
(sinoatrial node) is a group of cells/tissues found in the right atrium that can release a wave of electricity/depolarisation which causes contraction
What is the AVN? Where is it located?
Atrio-ventricular node, located in the atria, near the border of the right and left ventricles
What is the bundle of His?
conductive tissue located in the septum and ventricular walls
What are the Purkyne fibres?
connective tissues that go all the way through the walls of the ventricles
What does the AVN do?
release another wave of depolarisation (when the 1st reaches it)
Why cant the electricity from the AVN move straight to the ventricles?
insulating fibres between atria and ventricles
What is the role of the bundle of His?
to carry the wave of depolarisation from the atria through to the purkyne fibres in the walls of the ventricles
What part of the ventricles contracts first?
apex
Why is non-conductive tissue an advantage?
results in a delay, which allows enough time for the atria to fully contract, filling the ventricles allowing the maximum volume of blood to be pumped
What part of the nervous system controls the heart rate?
autonomic nervous system, controlled by the medulla oblongata
What nerves increase heart rate?
sympathetic nerves/nervous system
What nerves decrease heart rate?
parasympathetic nerves/nervous system
What receptors detect changes in the pH of the blood? changes in pressure?
chemoreceptors, pressure receptors/baroreceptors
Where these receptors found?
aorta and carotid artery
Why is it important that blood pressure is regulated?
too high- leads to damaged blood vessels, potentially clots/strokes
too low- insufficient oxygenated blood supply and insufficient removal of waste
How does increased respiration impact the pH of the blood?
decreases (CO2 and lactic acid)
Why might a faster heart rate be necessary if pH of blood is decreased?
pH may denature enzymes, increased heart rate allow CO2 to be removed and lactic acid to be broken down in liver
What does a stimulus cause to happen?
more electrical impulses sent to medulla oblongata
What is the role of the SAN?
to release a wave of depolarisation, causing both atria to contract
What hormone increases HR and is released when the sympathetic nervous system is sending impulses to the SAN?
noradrenaline
What hormone decreases HR and is released when the parasympathetic nervous system is sending impulses?
acetylcholine
