cardiovascular system Flashcards
what is stroke volume
volume of blood pumped out of heart per beat
what is cardiac output
amount of blood that leaves the left ventricle per minute
heart rate
heart contractions per minute
formula for cardiac volume
stroke volume x heart rate
units for heart rate, stroke volume and cardiac
HR= bpm
SV= ml
Q= l/min
what does myogenic mean
self regulating
what is the all or non law
how nerve cells either fire at full strength or do not.
what do chemoreceptors detect
chemical changes:
-pH
-02 levels
-CO2 levels
what do baroreceptors detect
blood pressure levels
what do proprioreceptors detect
muscle movement
what does hormonal control release
adrenaline to SA node
what does intrinsic control detect
temperature change
what happens during diastole
SA node repolarises while atria fills with blood. some of this blood passively drips into ventricles
what happens during atrial systole
SA node sends an impulse across the stria for it to contract which opens the valves and blood fills up the ventricles.
what happens during ventricular systole
the SA node sends an impulse to AV node which holds it until ventricle are filled then sends it down the Bundle Of His to the purkinje fibres where the ventricle walls contract pushing blood up and out
what is ejection fraction
blood left in ventricles after majority of it was pushed up and out
what does the arterioles and pre-capillary sphincters to working muscles/ organs do
-smooth muscle in arterioles vasodilate
-pre-capillary sphincters relax
what does the arterioles and pre-capillary sphincters to non-working muscles/ organs do
–smooth muscle in arterioles vasoconstrict
-pre-capillary sphincters contract
what is the systolic phase
when the heart contracts to push blood out of the heart
describe intrinsic control
-as temp increases the viscosity of blood decreases, can flow more fluidly.
-increases nerve transmissions which increases nerve transmissions and firing rate of SA node
mechanisms of venous return
respiratory pump
gravity
smooth muscle in blood vessels
skeletal pump
what affects does increasing temperature of the blood have (intrinsic control)
decreases blood viscosity - blood flows more freely
venous return increases-more powerful contractions
increases stretch of atrial walls
increases firing frequency of SA node
neural control of vascular shunt at the start of exercise
-chemoreceptors detect increase in CO2, decrease O2 and decrease in pH
-bari receptors detect increase in bp
-This information is sent to VCC
-smooth muscles in artérioles at working muscles are stimulated by the sympathetic nerve to vasodilate
-pre capillary sphincters are working muscles relax to
-this allows more blood flow
-smooth muscles in artérioles to non essential organs vasoconstrict
-pre capillary sphincters contract
-restricts blood flow
what is venous return
the rate of blood flow back to the heart
what are the changes in dissociation during exercise
-Bohr shift takes place, curve shifts to the right
-this increases CO2 levels, decreases pH, increases temperature
-this causes a reduced affinity of haemoglobin for O2
-this makes oxygen more available for diffusion into the muscles
how does the heart regulate HR during exercise
-chemoreceptors detect chemical changes, proprioreceptors detect movement, baro receptors detect a decrease in pH
-bari receptors tell CCC to lower HR but this is overridden by the chemoreceptors which tell CCC to increase HR. HR is then increased due to the stimulation of the SA node via the sympathetic nervous system and accelerator nerve. The SA node stimulates parasympathetic nervous system and vagus nerve less
how does the heart regulate HR after exercise
heart rate decreases, chemoreceptors detect chemical changes . The proprio receptors detect a decrease of movement, baro receptors detect a decrease of blood pressure. HR decreases by stimulating parasympathetic nerve and vagus nerves more than the sympathetic and accelerator nerve
