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Circuitry and Hemodymanic
Circutiry and Hemodynamics by Dr. Gibbons
81
Medical
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09/28/2011

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Term
What is the main function of the cardiovascular system?
Definition
1. to act as a transport system of body metabolism
a. to deliver oxygen and nutrients to tissues
b. to remove CO2 and waste products from tissues
Term
the following are functions of what body system:
Delivering hormones from their glands to their sites of action
Regulating body temperature
Re-distributing blood flow to key organs under stress (e.g. exercise)
Definition
the cardiovascular syatem
Term
At steady state, cardiac output equals ....
Definition
venous return
Term
WHich part of the circulation is under the highest pressure
Definition
systemic circulation
Term
Why are the muscles on the left side of the heart larger?
Definition
Because they are under a higher pressure and must pump blood out to the entire body
Term
Which pulmonary vessel carries oxygenated blood and which carries deoxygenated blood?
Definition
the pulmonary artery carries deoxygenated blood while the pulmonary vein carries oxygenated blood.
Term
the vessel that transports blood from the heart to the tissues under high pressure
Definition
arteries
Term
controls the blood before entering the capillaries, the last small branches of conduit arteries with highest resistance
Definition
arterioles
Term
vessels responsible for exchanging fluid, nutrients, etc between the blood and interstium
Definition
capillaries
Term
vessels responsible for collecting blood from the capillaries before caolescing into larger veins
Definition
venules
Term
vessels responsible for transporting blood from the tissues back to the heart under low pressure and serves as a major reservoir of blood
Definition
veins
Term
the layer of the aorta that allows it to move a large quantity of blood and is important in pressure and regulation
Definition
the muscle layer
Term
the vessel that has the largest surface area
Definition
capillaries
Term
the vessel system responsible for directing the flow of blood
Definition
arterial
Term
the vessel system that is a vascular resoir of blood volume
Definition
venous system
Term
the cahange in volume over the change in pressure
Definition
compliance
Term
Vessels that are not easily stretched (arteries, vessels in old age) have what level of compliance
Definition
low compliance
Term
vessels that are easily stretched and a large change in volume does not have much change in pressure (veins) are said to have this level of compliance
Definition
high compliance
Term
the capacity of a vessel to hold blood
Definition
capacitance
Term
a ballon is similar to which vessel
Definition
veins
Term
On what side does a small change in volume causes a larfe change in pressure
Definition
arterial side
Term
the effect of the sympathetic system on compliance
Definition
it decrease compliance by increasing vascular smooth muscle tone
Term
How hard the walls of the a vessel are being stretched when there is
pressure inside the vessel
It relates tension, pressure and radius
Definition
laplace relationship
Term
WHy does the aorta have the highest wall tension?
Definition
the aorta has the largest radius therefore based on laplace relationship the tension should also be high
Term
look over slide 21
Definition
Term
blood flow is determined by what law?
Definition
Ohm's law
Term
blood flow (Q)= change in pressure over resistance in what concept
Definition
ohm's law
Term
If the pressure gradient increases, what happens to flow?
Definition
flow will increase
Term
If the resistance decreases, what will happen to flow?
Definition
flow willl decrease
Term
A dimensionless number of the flow characteristics
influenced by inertial vs viscous forces
Definition
Reynold's Number (Nr)
Term
Nr = (velocity x diamter x density)/ viscosity
Definition
reynold's number
Term
A reynold's number less than 2000 is what type of flow
Definition
laminar flow
Term
A reynold's numer more than 2000 is what type of flow
Definition
turbulent
Term
What does increasing velocity do to flow
Definition
it increases laminar flow, smoother flow
Term
how is flow affected when a patient has aortic stenosis (narrowing of the aortic valve
Definition
the reynolds number will increase because the blood is going through a small hole and at a faster rate, more of a turbulent flow
Term
rate of blood displacement with respect to time (e.g. cm/s)
Definition
velocity
Term
volume per unit time (e.g. ml/s)
Definition
flow
Term
flow/ cross sectional area equals
Definition
velocity
Term
velocity is inversely proportional to the ....
Definition
cross section area
Term
What vessel has the smallest cross section area
Definition
aorta
Term
pressure difference between systemic arteries and veins over blood flow equals
Definition
resistance measured as Peripheral Resistance
Unit (PRU= mmHg/ml/sec
Term
WHat is a major determinant of vascular resistance?
Definition
vascular radius
Term
resistance = ((the viscosity of the blood* L {the length of the
vessel})/ (r = the radius of the vessel)* (8/pi)
Definition
Poiseuille's law
Term
What happens to resistance if the radius is decreased by half?
Definition
resistance will increase 16 times
Term
What happens to resistance when the radius is doubled?
Definition
it will decrease by 1/16th
Term
increased myogenic activity, oxygen consumption, endothelin, sympatheitc stimulation, vasopressin, angiotensin II and cold, and decreases carbon dioxide and other metabolites causes
Definition
vasoconstriction
Term
decreased myogenic activity, oxygen, and sympathetic stimulation, histamine relaesa, and heat and increased CO2 and NO causes what
Definition
vasodilation
Term
When resistor are in series the total resistance is
Definition
the sum of the individual resistors
Term
Where does the greatest decrease in pressure occur due to the very high resistance of the vessel
Definition
arterioles
Term
What is happening to central resistance when:
Flow decreases equally at all points (series system)
Pressure immediately upstream from R2 increases
Pressure immediately downstream from R2 decreases
Definition
central resistance increases
Term
What happens to central resistance when:
a) Flow increases equally at all points (series system)
b) Pressure immediately upstream from R2 decreases
c) Pressure immediately downstream from R2 increases
Definition
central resistance decreases
Term
the flow of blood from the aorta to the vena cava through the tissues of the body is an example of
Definition
parallel resistors
Term
In parallel resistors, the reciprocal of the total resistance is the sum of the
Definition
reciprocals of the individual resistances
Term
Total resistance is always ..... than any individual resistances

And
Adding a resistor in parallel .... the total resistance of the
system
Definition
smaller/ decreases
Term
is there a loss of pressure in a parallel resisatnce arrangment
Definition
no
Term
What conditions will lead to an increase in resistors leading to a lower blood pressure
Definition
pregnancy
Term
in life increasing parallel channels
Definition
is like opening more lanes at a store to increase the flow
Term
which circulation pathway has the highest resistance
Definition
systemic circulation, because it must pass through all the tissues of the body
Term
the internal stickiness of the fluid
Definition
viscosity
Term
viscosity of the blood changes with
Definition
hemocrit
Term
what is the normal hemocrit level
Definition
Normally in man = 42
& in women = 38
Its lower when anemic
Term
the force exerted by the blood against any unit
area of the vessel wall
Definition
blood pressure
Term
is the peak aortic pressure, occurs during
the ejection of the blood from the left ventricle into aorta
Definition
systolic pressure
Term
the minimum aortic pressure
Definition
diastolic pressure
Term
systolic pressure-diastolic pressure equals
Definition
pulse pressure
Term
Both of these equations equal
= Diastolic Pressure + 1/3 Pulse Pressure
= 2/3 Diastolic Pressure + 1/3 Systolic Pressure
Definition
Mean arterial pressure
Term
Cardiac output * total peripheral resistance equals
Definition
mean arterial pressure
Term
What condition can cause a decrease in total peripheral resistance, cardiac output and MAP
Definition
hemorrhage
Term
Whaen state can cause an increase in total peripheral resistance, cardiac output and MAP
Definition
Exercise
Term
The following factors have what effect on arterial systolic pressure:
1. increase stroke volume
2. decrease compliance of the arterial tree
Definition
increases
Term
The following factors have what effect in arterial diastolic pressure
1. decrease in total peripheral resistance (TPR)
2. decrease in heart rate
3. decrease in stroke volume
Definition
decrease
Term
The following factors have what effect on pulse pressure
1. increase in stroke volume
2. decrease in compliance of the arterial tree
3. decrease TPR
Definition
increase because the systolic pressure increases and diastolic pressure increases
Term
What dampens the systolic and diastolic pressure and reduces the pulsatile pattern of blood flow
Definition
the distensibility of the aorta
Term
these causes lead to:
1) the resistance to blood
movement in the vessels
2) The compliance of the vessels

 the degree of damping
 resistance x compliance
Definition
The progressive diminishment
of the pulse pressure in the
peripheral circulation
Term
Systolic and diastolic blood pressure increase with age due to
Definition
changes of the pressure control mechanisms
Term
What are the two main control mechanisms that change bp with age
Definition
1) Kidney, long term regulation of the blood pressure
2) Arteries, decrease elasticity  increase in systolic blood pressure
Term
These factors have what effect on venous return
1) Increased blood volume
2) Increased vessel tone  increased peripheral venous pressure
3) Dilatation of the arterioles  decreases the peripheral resistance
 increased flow of the blood from arteries to veins
Definition
increase venous return
Term
the factors have what effect on venous return:
Decreased blood flow into the heart
Blood loss
2) Pooling of blood in venous system (venodilation)
Definition
decrease venous return
Term
Occurs due to incompetence of the
venous valves
Definition
varicose veins
Term
degree of distension of
neck veins e.g., neck vein start to
protrude when the jugular venous pressure
exceeds 8 cmH2O ( e.g. heart failure)
Definition
clinical estimation of venous pressure
Term
Why do people faint
What are the underlying physiological
concepts that explain fainting?
Definition
The tension built up in the muscle and the venous blood is going down and pooling in the lower extremity
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