chapter 14: overview of circulation: biophysics of pressure, flow, and resistance. Flashcards
What is the function of circulation?
1) . to serve the needs of the body tissues:
2) . to transport nutrients to the body tissues,
3) . to transport waste products away,
4) . to transport hormones from one part of the body to another and, in general,
5) . to maintain an appropriate environment in all the tissue fluids of the body for survival and optimal function of the cells.
what controls the flow of Blood
1) the need for nutrients in tissues.
name the two division of circulation
pulmonary and systemic circulation
what is the function of systemic circulation?
systemic circulation supplies blood flow to
all the tissues of the body except the lungs.
another term for systemic circulation?
peripheral circulation or greater circulation, because it supplies blood flow to all the tissues of the body except the lungs.
what is the function of arteries?
transport blood under high pressure, so they have strong walls and pressure is high in arteries.
arterioles
- small branch of the arterial system.
- acts as control conduits through which blood is released into capillaries.
- strong muscular walls.
What is the function of the capillaries?
the function of the capillaries is to exchange nutrients and hormones with between blood and interstitial fluid.
are the capillaries wall thin or thick?
Thin
capillaries pores are permeable to what?
water and small molecules.
what is the function of venules?
- collection of blood into capillaries.
2. coalescing into larger veins.
what is the function of veins?
- Function as conduits for transport of blood
from the venules back to the heart; equally important,
they serve as a major reservoir of extra blood.
.
veins serve as what?
controllable reservoir of extra blood.
Is pressure in the venous system low or high?
Very Low, Because the pressure in the venous system is very low, the venous walls are thin
what is the percentage of blood in the systemic circulation?
84 percent of the entire blood volume: 64 percent is in the veins, 13 percent is in the arteries, and 7 percent is in the systemic arterioles and capillaries.
what percentage of blood is in the heart and lungs?
16 percent; The heart contains 7 percent of the blood, and the pulmonary vessels, 9 percent.
how long does blood remain in the capillaries?
1 -3 seconds; surprising to know we exchange nutreint within 1 -3 seconds.
what is the mean arterial pressure?
100 mmHg
arterial pressure alternates between?
120 mmHg and 80 mmHg ; systole/diastole
mean pressure of systemic circulation by
the time it reaches the termination of the superior and
inferior venae cavae where they empty into the right
atrium of the heart?
0 mmHg
pulmonary artery systolic pressure averages about?
25 mmHg
diastolic pressure averages about?
8 mmHg
Cross sectional area of Aorta
2.5 cm2
CSA of Small arteries
20 cm2
CSA of Arterioles
40 cm2
CSA of Capillaries
2500 cm2
CSA of Venules
250 cm2
CSA of small veins
80 cm2
CSA of Venae cavae
8 cm2
V = F/A
the velocity of blood flow.
Basic principles of circulatory function?
- Blood flow to most tissues is controlled according to
the tissue need. - Cardiac output is the sum of all the local tissue
flows. - Arterial pressure regulation is generally independent
of either local blood flow control or cardiac output
control.
INTERRELATIONSHIPS OF PRESSURE,
FLOW, AND RESISTANCE
Blood flow through a blood vessel is determined by
two factors: (1) pressure gradient and (2) vascular resistance.
The flow through the vessel can be calculated by the following formula, which is called Ohm’s law
F = delta P/ R
Blood flow means?
quantity of blood that passes a given point in the circulation in a given period of time.
blood flow is expressed as?
milliliters per minute or liters per minute
overall blood flow in the total circulation of an adult person at rest?
about 5000 ml/min: this is called cardiac output.
the amount of blood pumped into the aorta by the heart each minute?
cardiac output
Hematocrit
the Proportion of Blood That Is Red Blood Cells
how to increase blood viscosity?
Increasing Hematocrit Markedly Increases Blood
Viscosity.
polycythemia
increase in red blood cells.
