Cardiovascular Flashcards
define stressed volume?
volume of blood contained in the arteries
arteries are under the highest pressure in the vasculature
where can we find the highest resistance to blood flow?
why?
Arterioles
they have a lot of smooth muscle which is tonically active (innervated by sympathetic adrenergic nerve fibers)
what adrenergic R can we find in the arterioles in the skin and splanchnic vasculature?
what is the consequences?
a1-Adrenergic -> contraction -> decrease in diameter of the arteriole -> increase the resistance to blood flow
which vessels have large capacitance and why?
veins
bcs their walls contain much less elastic tissue than arteries
equation for the relationship btw velosity, flow and crossectional area
V=Q/A
what two factors eefect the blood flow through a blood vessel?
- pressure difference
2. resistance of the vessel
equation for the relationship btw flow, pressure and resistance?
Q=P/R
mL/min
direction of blood flow is allways from:
high pressure to low pressure
what will higher resistance do to flow?
inversley prop. higher resistance -> decreased flow
define TPR
the resistance of the entire systemic vasculature
how can we measure TPR?
we can put cardiac output instead of flow in the Q=P/R equation
and the difference in pressure btw Aorta and Vena Cava
what does compliance describes?
the volume of blood the vessel can hold at a given pressure
compliance equation
C=V/P
C- Compliance (mL/mmHg)
V- Volume (mL)
P- Pressure (mmHg)
SA node BPM
60-80 BPM
sinus rythm
what is the reason for the delay 0.1 sec in the AV node conduction?
- less amount of Gap Junction
2. diameter is smaller (slower conductance)
connection btw nodal cells
Gap Junction
funny channels function
allow slow leaking into the cell of Na+
resting membrane potential of nodal cells
around -60 mV
T-type channels are for ___ and open at ___
Ca++
-55 mV
threshold point in the nodal cells
-40 mV
which channel opens when the membrane otential reaches the threshold?
L-type Ca++ channels
what happens to the contractile cells when the nodal cells reach depolarization (at +40mV)?
how?
positive cations moves from the nodal cells into the contractile cells through the Gap Junction
define intercalated disks
Desmosomes+Gap Junction
btw nodal and contractile cells
resting membrane potential of the contractile cells in the heart
around -85 mV / -90 mV
