Physio 14 Flashcards
Give the function of circulation
- to transport nutrients to the body tissues
- to transport waste products away
- to transport hormones from one part of the body to another
- to maintain an appropriate environment in all tissue fluids of the body for optimal survival
A body organ which serves as additional functions for circulation.
Kidneys
Controlled to provide the necessary cardiac output and arterial pressure to cause the needed
heart and blood vessels
Circulation is divided into:
- systemic circulation
- pulmonary circulation
Other terms for systemic circulation
- Greater circulation
- Peripheral circulation
Transport blood under high pressure to the tissues
arteries
Have strong vascular walls and blood flows at a high velocity
arteries
The last small branches of the arterial system that act as control conduits through which blood is released into the capillaries
Arterioles
Have strong muscular walls than can close or relax vessels, capable of vastly altering blood flow in each tissue in response to its needs
Arterioles
Exchange fluid, nutrients, electrolytes, hormones, and other substances between blood and interstitial fluid
Capillaries
Present in the capillary pores which allows permeability to water and other small molecular substances
Capillary pores
Collect blood from the capillaries and gradually coalesce into progressively larger veins
Venules
function as conduits for transport of blood from the venules back to the heart
Veins
Act as a controllable reservoir for the extra blood.
Veins
How many % of the entire blood volume of the body is present in the systemic circulation?
84%
How many % of the entire blood volume of the body is present in the heart and lungs?
16%
How many % of the blood volume in the systemic circulation is present in veins?
64%
How many % of the blood volume in the systemic circulation is present in arteries?
13%
How many % of the blood volume in the systemic circulation is present in arterioles and capillaries?
7%
Out of 16% of blood volume present in the pulmonary circulation, how much is present in the heart?
7%
Out of 16% of blood volume present in the pulmonary circulation, how much is present in the pulmonary vessels?
9%
How many seconds does the blood remains in the capillaries?
1-3 seconds
Average pressure of aorta
100 mm Hg
As blood flows through the systemic circulation, its mean pressure falls progressively to?
0 mm Hg
Systemic capillaries pressure near the arteriolar end
35 mm Hg
Systemic capillaries pressure near the venous end
10 mm Hg
Average functional pressure in most vascular beds
17 mm Hg
Average pulmonary artery systolic pressure
25 mm Hg
Pulmonary artery diagnostic pressure
8 mm Hg
Mean pulmonary arterial pressure
16 mm Hg
What are the three basic principles of circulatory function?
- The rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need.
- The cardiac output is controlled mainly by the sum of all the local tissue flows.
- Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control.
2 factors that determine the blood flow through the blood vessel
- pressure gradient
- vascular resistance
It is the pressure difference of the blood between the two ends of the vessel which is the force that pushes the blood through the vessel
Pressure gradient
Refers to the impediment to blood flow through the vessel
Vascular resistance
The flow through the vessel can be calculated by which law?
Ohm’s law
The quantity of blood that passes a
given point in the circulation in a given period of time
Blood flow
The overall blood flow in the total circulation of an adult person at rest
5000 ml/min
Refers to the the amount of blood pumped into the aorta by the heart each minute
Cardiac output
Mechanical and mechanoelectrical devices inserted in series with a blood vessels applied outside of the vessel to measure flow
Flowmeters
One of the most important devices for measuring blood flow without opening the vessel
Electromagnetic Flowmeter
Record changes in flow in less than 1/100 of a second allowing accurate recording of pulsatile changes in flow
Electromagnetic Flowmeter
Another type of flowmeter that can be applied to the outside of the vessel capable of recording rapid, pulsatile changes in flow
Ultrasonic Doppler Flowmeter
2 laminar flow of blood in vessels
- Laminar flow or streamline flow
- Turbulent flow
Refers to blood flowing at a steady rate through a long, smooth blood vessel that flows in streamlines
Laminar flow or streamline flow
Refers to blood flowing in all directions in the blood vessel and continually mixing within the vessel
Turbulent flow
Velocity of flow in the center of the vessel is far greater than that towards the outer edges
Parabolic velocity profile
Enumerate the causes of parabolic profile
- fluid molecules touching the wall move slowly because of adherence to the vessel wall
- next layer of molecules slips over these, the third layer over the second, the fourth layer over the third, and so forth
- fluid in the middle of the vessel can move rapidly because many layers of slipping molecules exist between the middle of the vessel and the vessel wall
- each layer toward the center flows progressively more rapidly than the outer layers
Refers to the blood flows crosswise in the vessel and along the vessel usually forming whorls in the blood
Turbulent flow
Refers to the whorls in the blood formed during turbulent flow
Eddy currents
When this is present, blood flows with much greater resistance than the flow is streamlined
Eddy currents
It add tremendously to the overall friction of flow in the vessel
Eddies
Measurement of blood pressure
millimeters of mercury (mm Hg)
It refers to the force exerted by the blood against any unit area of the vessel wall
Blood pressure
The impediment to blood flow in a vessel but cannot be measured by any direct means
Resistance
Resistance must be calculated from? (2)
- measurements of blood flow
- pressure difference between 2 points in the vessel
A basic physical unit used to express resistance:
CGS (centimeters, grams, seconds)
The rate of blood flow through the entire circulatory system is equal to the rate of blood pumping by the heart, which is equal to?
Cardiac output
What is the pressure difference from the systemic arteries to the systemic veins?
100 mm Hg
Refers to the resistance of the entire systemic circulation>
Total Peripheral Resistance
What is the total peripheral resistance?
100/100 or 1 peripheral resistance unit
In the pulmonary system, what is the average of mean pulmonary arterial pressure and left atrial pressure?
- pulmonary arterial pressure - 16 mm Hg
- left atrial pressure - 2 mm Hg
Give the net pressure difference of pulmonary system with a mean pulmonary arterial pressure of 16 mm Hg and left atrial pressure 2 mm Hg?
14 mm
Refers to the measure of the blood flow through a vessel for a given pressure difference.
Conductance
How is conductance generally expressed?
- Millimeters/sec/millimeter of mercury pressure
- Liters/sec/millimeter of mercury
It refers to the exact reciprocal of resistance.
Conductance
Give the variables of flow of liquid stated by law of Poiseuille (4)
- Length of the tube (L)
- Radius (r)
- Pressure gradient
- Viscosity of the fluid
It is directly proportional to the fourth power of the radius of the vessel.
Rate of blood flow
It plays the greatest role of all factors in determining the rate of blood flow through a vessel.
Diameter of a blood vessel
True or False. Arterioles have strong vascular walls allowing the internal diameters to change tremendously often as much as fourfold.
True.
True or False. A four-fold increase in vessel diameter can increase the flow as much as 256-fold.
True.
The arteries, arterioles, capillaries, venules, and veins are collectively arranged in?
Series
It is equal to the sum of resistance of the arteries, arterioles, capillaries, venules, and vein.
Total Peripheral Vascular Resistance
The blood vessels branch extensively to form ____ that supply the blood to many organs and tissues of the body.
Parallel circuits
Permits each tissue to regulate its own blood flow independently of flow to other tissues.
Parallel arrangement
