the heart, blood vessels and tissue fluid Flashcards
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
what is the role of the thin inner lining in the vessel
smooth to reduce friction
what is the name of the inner lining within a vessel
endothelium
what is the role of arteries
carry blood away from the heart towards organs
describe the structure of a vein
thin muscular walls
thin elastic layer
large lumen
valves
what are the role of arterioles
link arteries to capillaries
structure of a capillary
walls made of enothelium
one cell thick
what are plasma protiens
proteins within the plasma that are involved with the transport of other substances
what is hydrostatic pressure
pressure of the blood against the wall - blood pressure
what is osmoitc pressure
how much water is likely to move into an area
what is lymph
colourless fluid containing white blood cells
what is tissue fluid
fluid that fills the spaces between cells
what is the role of tissue fluid
allows transport between blood and cells
what is tissue fluid made up of
oxygen water nutrients
how is tissue fluid formed
hydrostatic pressure inside the capillaries forces the blood plasma out causing ultrafiltration
osmotic pressure - removal of the blood plasma causes a decrease in water potential in the blood, water moves back in
where in the capillary is the hydrostatic pressure highest
arteriole end
where in the capillary is the oncotic pressure highest
venous end
what happens to the tissue fluid that is not reabsorbed
drains into the lymphatic system
what is the lymphatic system
carries lymph around the body to drain back into the circulatory system - part of the immune system
what does tissue fluid contain
water
white blood cells
glucose
amino acids
mineral ions
what does lymph contain
similar to plasma
lymphocytes
fatty acids
describe the process of the formation of tissue fluid
the heart pumps the blood which creates hydrostatic pressure which is higher than the osmotic pressure at the arteriole end of capillaries which forces tissue fluid out of blood plasma
