physiology Flashcards
what is homeostasis
the maintenance of steady states within our bodies by coordinated physiological mechanisms
how do feedforward systems work
response in anticipation of a change
how do feedback systems work
response after a change
how does negative feedback work
opposes initial change
how does positive feedback work
amplifies a change
what is hypertension
clinic BP over 140/90 and day time average of 135/85
what is pulse pressure
difference between systolic and diastolic
what is average BP
140/90
what is normal pulse pressure
30 - 50
how do you calculate MAP
DPB + 1/3pulse pressure
what is map
average blood pressure over one cardiac cycle
what is the normal range for MAP
70-105
why is an MAP of at least 60 needed
to perfuse vital organs
what happens if MAP is too high
puts strain on the heart and blood vessels
where are the two sets of baroreceptors
aortic arch
carotid sinuses
what is the equation for MAP
cardiac output x systemic vascular resistance
what is the equation for CO
stroke volume x heart rate
what is systemic vascular resistance
the sum of resistance of all vasculature in the systemic circulation
where are the sensors for temperature homeostasis
central thermoreceptors (hypothalamus) and peripheral thermoreceptors (skin)
where is the control centre for temperature homeostasis
hypothalamus
what part of the hypothalamus is activated by cold
posterior
what part of the hypothalamus is activated by hot
anterior
what are the effectors for temperature homeostasis
skeletal muscle
skin arterioles
sweat glands
what is osmolarity
the concentration of osmotically active particles present in a solution
what is tonicity
the effect a solution has on cell volume
what is isotonic
no movement of water, no change in cell volume
what is hypotonic
water moves into cells, they swell.
what is hypertonic
water moves out of cells so they shrink
what is membrane potential (em)
separation of opposite charges across membrane due to differences in the concentration & permeability of ions
what is an action potential
rapid, transient changes in their membrane potential when excited
