1. Heart Overview and EC Coupling Flashcards
what is a mm of mercury pressure mean
reference system - how much pressure does it take to push up mercury one mm high in a tube?
which part of heart pumps under very high pressure
left side
if you increse pressure on right side what will happen to right ventricle
right ventricle will get bigger
say blood flow of heart
right atrium through tricuspid valve to right ventricle to pulmonary valve to pulmonary artery to lungs to pulmonary veins to left atrium to mitral valve to left ventricle to aortic valve to aorta
heart cells are connected by
intercalated disks and gap junctions
in each part of the hart the AP is
different
AP is intimately connected to
the function of the part of the heart it is located
SA node is the
pacemaker of the heart
describe resting potential in SA node
goes up - b/c it fires on its own
draw out AP of SA node
pg 7
draw out AP of atrial muscle
pg 7
describe AP in ventricles muscle
sustained AP so the heart has enough time to pump out the blood
what kind of gated channels are in ventricular muscle
voltage
if positive charges leave the cell membrane wht happens
it is more negative
if positive charges go into cell what happens
cell more positive
phase 4 is
resting membrane potential
what ion is primarily responsible for resting membrane potential
potassium
phase 0 is called
depolarization pahse
phase 0 what is happening
fast sodium channels open
what causes fast sodium channels to open
sodium comes in and cause the membrane to reach the threshold and then the channels open and they rush in
why does sodium rush inside cellw hen the channels open
positive ions outside b/c its negatively charged
down concentration & electrical gradient
what does sodium do when it “closes”
inactivates
what is happening in phase 1
fast sodium channels close (inactive)
fast potassium channels open
what is phase 2
plateau phase
what happens in phase 2
L type calcium channels open
fast potassium channels close
why do calcium channels close
just time, they are open for certain amount of time then close
what happens in phase 3
calcium channels close
SLOW potassium channels open
what is the slow potassium channel called
delayed rectifier
what does IKr stand for
potassium channel - delayed rectifier. it is the slow potassium channels
what happens in phase 4
inward rectifier potassium channel Ik1
what is Ik1
inward rectifier potassium channel
what does AP look like in cell giving lidocain?
it will go up a lot slower, so phase 0 will be much slower (it blocks sodium channels)
what does AP look like with potassium channel blockers
prlonged AP
what is the absolute refractory period
nothing will cause aonther contraction/firing in that cell during the absolute refractory period
what is the relative refractory period
a high enough stimulus will cause another AP
why can’t there be another AP during absolute refractory period
the inactivation gates are still closed in sodium channels
what does potassium blocker do to refractory period
makes refractory period longer
if an area of the heart is ischemic, AP is now due to
calcium
look at pg 12
say blood flow through the heart
pg 4
