the heart, blood vessels and tissue fluid Flashcards
(45 cards)
what is the sinotrial node
initiates the cardiac cycle and generate electrical impulses that causes the atria to contract.
where is the SAN located
the wall of the right atrium
what is the atrioventricular node
delays the impulse to allow the atrium to finish contracting
what is the bundle of his
Purkyne fibres that distribute impulses causing the ventricle contraction
What is the stages of the cardiac cycle
- SAN sends out an electrical impulse
- non conducting tissue prevents immediate contraction of ventricles
- atria contract
- AVN sends an impulse
- Bundle of his conducts the impulse making the ventricle contract from the base up
where is the cardioregulatory centre found
the medulla
how does heart rate increase
increased rate of respiration increases CO2 concentration which makes the PH is more acidic. This is detected by chemoreceptors which activates the acceleratory centre in the medulla. Impulses are sent along the sympathetic neurones to the SAN which increases the frequency of of the waves
how does heart rate decrease
decreased rates of CO2 increases PH which is detected by chemoreceptors. This activates the inhibitory accelorator in the medulla. Impulses are sent along the sympathetic neurones to the SAN. This causes the SAN to reduce the frequencey of the waves and reduces the heart rate
what is a closed circulatory system
blood is pumped in contained vessels
where does the right side of the heart pump blood
to the lungs
where does the left side of the heart pump blood
the whole body
when do the AV valves in the heart open
when the pressure in the atrium is higher than the pressure in the ventricle
role of the valves within the heart
important for maintaining a constant pressure and preventing backflow
where do the coronary arteries pump blood
supplies heart muscles with blood to aerobically respire for muscle contraction
where is the interatrial septum
separates between the atriums
where is the interventricular septum
separates between the ventricles
what are the AV valves
tri and bi cuspid
main risk factors of coronary heart disease
genetics
age/sex
high blood pressure
what is the risk of coronary heart disease
less blood gets to the heart, less oxygen, anerobic respiration occurs
mass transport system
needed to take materials from exchange surfaces to cells when transport is over large distances
describe the strucutre of an artery
tough fibrous outer layer included collagen - resists pressure changes
thick muscle layer - contracts and relaxes to control flow of blood eg vasoconstriction
thick elastic layer - can stretch and recoil to maintain pressure changes
thin inner lining, enothelium - smooth to reduce friction of blood flow
what is the role of a tough fibrous layer in a blood vessel
resists pressure changes
what is the role of muscle layer in a blood vessel
allows the vessel to contract and relax to control the flow of blood - vasoconstriction/dilation
what is the role of the elastic layer in a blood vessel
allows the vessel to stretch and recoil to maintain blood pressure
