Ziolo Lectures Flashcards
The hematocrit is a
rapid assessment of blood composition.It is the percent of the blood volume that is composed of RBCs (red blood cells).
Buffy coat is negligible when calculating
hematocrit
Arterioles+capillaries+venules=
microcirculation
Flow =
volume per unit time
F= ΔP/R
Resistance is roughly
1/radius^4
Blood viscosity can
alter
resistance and thereby flow.
Main function of valves –
isolate electrically atria from ventricle.
cardiac muscle isElectrically coupled through
gap junctions located in intercalated disc.
Parasympathetic releases ——— to
acetylcholine to muscarinic receptors
Sympathetic releases ——— to
norepinephrine/epinephrine, Beta = beta adronergic receptors.
Both nodes can
spontaneously depolarize – SA does this faster.
Bundle of His
depolarizes slower than AV node.
The rapid opening of voltage-gated sodium channels is responsible for
the rapid depolarization phase.
The prolonged “plateau” of
depolarization is due to the
slow but prolonged opening of voltage-gated calcium channels PLUS closure of potassium channels
Calcium influx doesn’t allow for
repolarizing. Longer refractory period.
Opening of potassium
channels results in the
repolarization phase.
Sodium ions can “leak” in through
the
F-type [funny] channels
calcium ions
can move in through
the T [calcium] channels cause a
threshold graded depolarization.
The rapid opening of voltage-gated
calcium channels is responsible
for the
rapid depolarization phase
Reopening of potassium channels
PLUS
closing of calcium channels
are responsible for the
repolarization phase.
Excitation-Contraction Coupling links the
cardiac muscle cell action potentials
to contraction via control of calcium within the myocardium.
First heart sound –
closure of the AV valves
Second heart sound –
closure of the aortic and pulmonary valves
Murmurs
stenosis