Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
82 Cards in this Set
- Front
- Back
|
What is blood pressure? |
hydrostatic (fluid) pressure force of blood exerted against walls of vessels |
|
|
what is blood flow? |
volume of blood flowing through a structure per unit time (mL/min) |
|
|
what is resistance? |
opposition to blood flow through a vessel |
|
|
Where does blood always flow? |
from region of higher pressure to region of lower pressure bulk flow is down pressure gradient |
|
|
When does blood flow increase? |
as pressure difference between two points increases and as resistance to flow decreases |
|
|
Blood flow equation |
|
|
|
The change of pressure in the blood flow equation is referring to what? |
perfusion pressure |
|
|
Largest to smallest mean diameter of blood vessels |
vein>artery>capillary |
|
|
Compliance = |
change in volume/change in pressure |
|
|
What kind of pressure are we referring to in the compliance equation? |
transmural pressure |
|
|
What happens to compliance with age? |
decreases |
|
|
What does systole generate for blood flow? |
pressure gradient and it must be maintained during diastole |
|
|
What acts as pressure reservoirs to drive blood into vessels throughout cardiac cycle? |
large arteries have thick, elastic walls with lots of elastin helps smooth flow of blood throughout circuit |
|
|
Elastic recoil in arteries has two phases: |
ventricular contraction and ventricular relaxation |
|
|
3 steps in ventricular contraction |
ventricle contracts, semilunar valve opens, aorta and arteries expand and store pressure in elastic walls |
|
|
3 steps in ventricular relaxation? |
isovolumic ventricular relaxation occurs, semilunar valve shuts, preventing flow back into ventricle, elastic recoil of arteries sends blood forward into rest of circulatory system |
|
|
What are venules? |
collect venous blood from capillary beds decrease in smooth muscle, elastin or collagen |
|
|
what are veins? |
large vessels with all 3 layers of extensive sympathetic innervation walls are thin and lumens are large blood pressure is very low |
|
|
What do the thin walls and large lumens in the veins act as? |
volume reservoirs |
|
|
what aids return of blood to heart against gravity? |
venous valves in limbs |
|
|
What is the skeletal muscle pump relfex initiated by? |
stimulation of plantar surface of the feet |
|
|
what do muscle contractions do to the veins? |
squeeze veins in muscles and drives blood toward the heart this augments venous return |
|
|
what prevents retrograde blood flow? |
venous valves |
|
|
when do the veins refill? |
during relaxation of skeletal muscle |
|
|
what happens to skeletal muscle pump activity when walking or running? |
the activity is intensified |
|
|
What contributes to resistance? |
viscosity of blood total blood vessel length blood vessel diameter |
|
|
What type of relationship do resistance and viscosity have? |
they are proportional |
|
|
What type of relationship do resistance and vessel length have? |
they are proportional due to friction |
|
|
what is the most important fact in resistance to blood flow? |
blood vessel diameter |
|
|
Which vessel diameters change the most? |
arterioles |
|
|
what are diameters of arterioles constantly regulated to control? |
blood flow to specific tissues arterial blood pressure |
|
|
If you decrease the radius of a vessel by 1/2 you increase the resistance by |
16 fold |
|
|
What is R often referred to as in CV physiology? |
peripheral resistance, because R in heart is so low |
|
|
vasoconstriction? |
decrease in arteriole diameter |
|
|
vasodilation? |
increase in arteriole diameter |
|
|
What is total peripheral resistance known as? |
systemic vascular resistance |
|
|
TPR = |
(mean aortic pressure - mean vena caval pressure)/cardiac output |
|
|
Mean aortic pressure at rest? |
98 mmHg |
|
|
Mean vena caval pressure at rest? |
3 mmHg |
|
|
mean cardiac output at rest? |
2.5 L/min |
|
|
what is the average TPR at rest? |
38 mmHg/L/min |
|
|
Why is vena caval pressure often ignored? |
it is so low that it does not impact it |
|
|
Mean aortic blood pressure (Pa) = |
CO x TPR |
|
|
Pulmonary vascular resistance = |
(mean pulmonary artery pressure - mean pulmonary venous pressure)/CO |
|
|
What effect would dehydration have on arterial pressure? |
causes decreased CO because preload is decreased which reduces SV TPR is increased because arterioles in the kidneys, splanchnic circulation and resting skeletal muscle are constricted to minimize the fall in arterial pressure and diverts blood to essential organs |
|
|
What happens to blood pressure in exercise? |
cardiac output increases which would increase blood pressure but... TPR decreases in a compensatory manner |
|
|
how does TPR decrease in a compensatory manner during exercise? |
with a four fold increase in CO during exercise, skeletal muscle arterioles increase in diameter decreasing TPR by about 1/4th causing aortic pressure change to be negligible |
|
|
What happens to renal and splanchnic arterioles during exercise? |
decreases flow by about 20% |
|
|
What is MAP? |
blood pressure driving blood into tissues over entire cardiac cycle |
|
|
estimate MAP by: MAP = |
diastolic pressure + (pulse pressure/3) |
|
|
What is pulse pressure? pulse pressure = |
systolic P - diastolic P |
|
|
What is peak pressure? |
systolic pressure (SP) |
|
|
what is the pressure just prior to ventricular ejection? |
diastolic pressure |
|
|
what is DP determined by? |
arterial compliance and the residual arterial volume immediately prior to the next cardiac region |
|
|
What is low pulse pressure called? |
thready |
|
|
what is high pulse pressure called? |
bounding |
|
|
What factor determine mean arterial pressure in the long term? |
blood volume (renal physiology) |
|
|
what factors determine short-term mean arterial pressure? |
MAP = CO x TPR Cardiac output = HR x SV TPR is sum of R to blood flow of all vessels |
|
|
How is MAP controlled? |
use the autonomic NS to increase MAP |
|
|
increased SV directly increases pulse pressure |
|
|
decreased heart rate increases time for aorta to empty so lowers diastolic pressure increasing pulse pressure |
|
|
increased SV and decreased heart rate together increase pulse pressure even more |
|
|
Stiffening of arteries leadsto leads to higher systolicpressure (increased pressurerequired to distend) and lowerdiastolic pressure increasingpulse pressure |
|
|
Increased vasoconstrictionincreases TPR which causesblood to back up and pusharteries to their elastic limitand stiffen them leading toincreased pulse pressure |
|
|
Combined stiffening andincreased TPR has a dramaticeffect on pulse pressure |
|
|
PDA leads to increased LVSV and increased aortic systolicpressure. Additionally, aorticdiastolic pressure is lowerbecause blood runs out of theaorta by two pathways sopulse pressure is dramaticallyincreased Aortic regurgitation has asimilar effect in that bloodleaves via two pathways bothinto the systemic circuit andback into the left ventricle soSV is increased in systole dueto the backflow and increasespulse pressure |
|
|
increase in SV leads to |
greater increase in aortic volume |
|
|
greater increase in aortic volume leads to |
increase in pulse pressure |
|
|
increase in pulse pressure leads to |
increase in SP |
|
|
decrease in SV leads to |
smaller increase in aortic volume |
|
|
smaller increase in aortic volume leads to |
decreased pulse pressure |
|
|
decreased pulse pressure leads to |
decreased SP |
|
|
increase in C leads to |
decrease in pulse pressure |
|
|
decrease in pulse pressure leads to |
decrease in SP |
|
|
decrease in C leads to |
increase in pulse pressure |
|
|
increase in pulse pressure leads to |
increase in SP |
|
|
increase in HR leads to |
decreased time for run off |
|
|
decreased tim for run-off leads to |
greater arterial volume remaining at the end of diastole |
|
|
greater arterial volume remaining at the end of diastole leads to |
increase in DP |
|
|
Decrease in TPR leads to |
increased rate of run off |
|
|
increased rate of run-off leads to |
less arterial volume remaining at the end of diastole |
|
|
less arterial volume remaining at the end of diastole leads to |
decreased DP |
