blood flows towards heart

no exchange

blood flows from heart

no exchange

exchange of oxygenated blood with deoxygenated blood takes place

open and close

do not allow back flow

atrioventricular valve

bicuspid valve

microvalve

blood moves because..

created by ventricle

if vessels constrict - pressure increases

if vessels dialate - pressure decreases

blood flows only if there is a positive pressure gradient

no pressure gradient means there is no pressure change

no pressure gradient = no flow

the bigger the tube the greater the flow

the smaller the resistance the greater the radius

the narrower the vessel...

mean arterial pressure is directly reated to..

mostly myocardium

ventricles occupy the bulk of the heart

atria

have single nucleus per fiber

smaller

have intercalated disks

larger in cardiac than skeletal

and branch

pacemakers

creates autonomic rhythm due to If channels

can generate action potentials spontaneously without the nervous system 

potential starts at -60 mV then drifts toward threshold

does not sit at resting potential

How Autorhythmic cells work?

Na+/K+ channels open at resting potential

which causes depolarization

which causes action potential

adrenaline/ epinefrin

norepinefrin (nueron sympathetic)

slows down autorhythmic cells

nueron parasympathetic

increase permeability to Na+/ Ca++

depolarization speeds up

increases heart rate

decrease permeability to Ca++/ increased K+ permeability

slows depolarization

slows heart rate

called the pacemaker

sets the pace for the whole heart

signal overrides the inherit rhythm of the heart

sets direction of electrical signals

delay the transmission of action potentials

atria is allowed to complete the contraction first

waves

segments

depolarization of the atria

contraction begins at the end of the wave

progressive wave of the ventricle depolarization

repolarization of the atria

p-wave initated by AV node

atria contract after p-wave, conduction thru AV node

initiate ventricle depolarization (Q wave)

spread to fibers (R wave)

goes to S wave

ventricles contract

ventricle repolarization (t wave)

isovolumic ventricle contraction (volume does not change)

AV valves closed

pressure rises and exceeds pressure in the arteries

semilunar valves open and blood is ejected

just finished systole

moving to diastole

pressure increase/volume decrease

cardiac output =

determined by renous pump

skeletal musle pump

respiratory pump

sympathetic intervention