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54 Cards in this Set

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Poiseuilles Law
the basic blood-flow equation is critical to determining physical factors which affect blood flow (BF). BF (for an individual organ) or cardiac output (if analyzing the total flow) = BP/R

blood flow = (delta BP x PI x r4) / 8 Lu

r = vessel radius
L = vessel length
u = blood viscosity
delta BP or delta AP = pressure gradient from one portion of the circuit to another
metabolic autoregulation
If you exercise one arm while keeping the other arm quiet, the blood flow to the
exercising arm will increase while the blood flow to the other arm will stay the same or
even decrease. What causes this? This phenomenon is called metabolic autoregulation,
which is caused by vasodilation of the arterioles resulting from LOCAL factors which
dilate the smooth muscles of the tunica media to decrease the vascular resistance, thus
allowing MORE flow into the region. These local factors might be carbon dioxide,
adenosine, K+ ions, or other metabolites. NO portion of the nervous system is involved
(neither the sympathetic nor the parasympathetic nervous systems, which would cause
more general changes in flow patterns).
myogenic autoregulation
is also prevalent in
some organs (such as the kidney), and is the local regulation of blood flow in response to
changes in local pressure. The arteriole smooth muscle cells respond by constricting or
dilating in response to an increasing or decreasing blood pressure, respectively. In other
words, if the blood pressure to the kidney increased, the arterioles would respond by
vasoconstricting which would tend to keep the blood flow fairly constant downstream.
Likewise, if the blood pressure decreased, the smooth muscle would dilate to increase the flow rate downstream to a level that existed at the higher pressures. Remember then that
autoregulation involves the local alteration of blood flow and does not involve the
nervous system. Be able to show the relationship between local blood flow and perfusion
(driving pressure) in myogenic autoregulation.
doppler flow meter
Velocity of blood in the arterial system
is rapid and variable during the heart beat which simply put means it is pulsatile. The
velocity of blood in the venous system is slow and intermittant (waxes and wanes) and is
not related to the pumping action of the heart, but rather to (1) muscle contraction
(skeletal muscle pump), (2) body position changes, and (3) respiratory activity which
affect the pressure in the thoracic cavity and therefore venous return.
varicose veins
permanent dilation and tortuosity of vein's, most commonly seen in the legs, probably as a result of congenitally incomplete valves; there is a predisposition to varicose vein's among persons in occupations requiring long periods of standing, and in pregnant women.
The formation, development or presence of a thrombus.


(Science: haematology) An aggregation of blood factors, primarily platelets and fibrin with entrapment of cellular elements, frequently causing vascular obstruction at the point of its formation. Some authorities thus differentiate thrombus formation from simple coagulation or clot formation.

Compare: embolism.

Origin: Gr. Thrombos = clot
The sudden blocking of an artery by a clot or foreign material which has been brought to its site of lodgment by the blood current.

Origin: L. Embolismus, from gr. Ballein = to throw occlusion of a blood vessel by an embolus (a loose clot or air bubble or other particle).An obstruction in a blood vessel caused by a foreign agent in the blood stream, such as a lipid molecule.
blood velocity
blood flow
Cardiac output (CO) = flow from each ventricle per minute.
Heart rate (HR) = beats per minute.
Stroke volume (SV) = volume ejected from heart per beat.
The blood flow equation is: Blood flow or cardiac output = BP/R, where BP = blood
pressure and R = resistance to blood flow.
continuity equation
The blood pressure drops continuously as we follow the pathway of blood from the aorta
back to the vena cava. The cross-sectional area is the greatest in the capillaries, and
because of this fact the blood velocity is the lowest of any vascular segment. The
relationship between flow, cross-sectional area (A) and velocity (V) is the continuity
equation (Blood Flow = V x A), and explains the low velocity in the capillaries.
contraction phase (usually referenced to ventricles, unless otherwise stated, but atria also have systole)
frank-starling law of the heart
the law which predicts that as the end-diastolic volume increases the stroke volume increases

within limits, the greater the preload, the greater the stroke volume
myocardial ischemia
insufficent blood flow to the myocardium
myocardial infarction
heart attach (death or necrosis of portions of the cardiac tissue). 40% of more of myocardium destroyed = certain death
ejection period
Systole is comprised of the isovolumentric contraction phase (IVCP) and the
ventricular ejection phase. During the IVCP, both heart valves on the left side are closed, the LV blood pressure is rapidly increasing, and the blood volume in the left ventricle is unchanging (isovolumetric = "same volume") because the valves are closed. When the
left ventricular blood pressure begins to rise, it quickly becomes higher than the pressure in the left atrium. As a result, the mitral valve or left AV valve closes (heart sound #1).
When the pressure in the left ventricle rises sufficiently so that its pressure is slightly higher than the pressure in the aorta into which the blood is to be pumped, the aortic
valve or left semilunar valve rapidly opens and the ejection period is initiated. The left
ventricular volume obviously declines from approximately 120 ml to about 60 ml. Since
the stroke volume is the difference between the end-diastolic volume and the end-systolic volume for the left ventricle, the stroke volume in this example would be 60 ml. What is the value for the ejection fraction?
all-or-none law
the whole heart either contracts maximally or not at all. this is in contrast to skeletal muscle which will exhibit gradations of contractions
the pressure just outside the semilunar valves opposing the opening of the valves; afterload is relatively constant in most since blood pressure doesn't change much
(Science: clinical sign) a slowness of the heart beat, as evidenced by slowing of the pulse Rate to less than 60 beats per minute.

Origin: gr. Kardia = heart
(Science: cardiology, pathology) The progressive narrowing and hardening of the arteries over time.

this is known to occur to some degree with aging, but other risk factors that accelerate this process have been identified.

These factors include: high cholesterol, high blood pressure, smoking, diabetes and family history for atherosclerotic disease.
isovolumetric contraction phase (IVCP)
During the IVCP, both heart valves on the left side are closed, the left ventricle blood pressure is rapidly increasing and the blood volume in the left ventricle is unchanging (isovolumetric = "same volume") becasuse the valves are closed
filling period
capacity for becoming short in response to a suitable stimulus.
cardiac arrhythmia
coronary artery bypass graft
A tube made of metal or plastic that is inserted into a vessel or passage to keep the lumen open and prevent closure due to a stricture or external compression.

stents are commonly used to keep blood vessels open in the coronary arteries, into the oesophagus for strictures or cancer, the ureters to maintain drainage from the kidneys, or the bile duct for pancreatic cancer or cholangiocarcinoma.

The stents are usually inserted under radiological guidance and can be inserted percutaneously.
isovolumetric relaxation phase (ISRP)
the time from when the semilunar vavle closes to the point immediately before the AV valve opens.
functional syncytium
(Science: clinical sign) The excessive rapidity in the action of the heart, the term is usually applied to a heart rate above 100 per minute and may be qualified as atrial, junctional (nodal) or ventricular and as paroxysmal.

Origin: Gr. Kardia = heart
relaxation phase (usually refering to ventricles)
systolic blood pressure
(SBP) maximum blood pressure in the arterial system, i.e. that which would exist at the peak of systole. SBP can also be measured for the right and left ventricles
diastolic blood pressure
(DBP) minimum blood pressure in the arterial system, i.e. that which would exist at the end of diastole. DBP can also be measured for the right and left ventricles
pulse pressure
the difference between systolic and diastolic blood pressure. the pulse pressure is an indicator of cardiac and vessel function. for example, if the arteries are stiffer, as might occur with aging and atherosclerosis, the pulse pressure is often elevated. when the stroke volume increases, the pulse pressure also increases since the vessel wall cannot expand rapidly to accommodate the new volume. the reverse is true as well when the stroke volume decreases
mean blood pressure
is not merely the average of the top and bottom, since the pressure waveform is shaped so that a longer time is spent at the lower pressures than the peak.

the approximation for determining the mean blood pressure is:

mean blood pressure = 1/3 pulse pressure + DBP = 93 mm HG
(for a person with BP = 120/80)
end-diastolic blood volume
(EDV) the volume of blood in a ventricle at the end of diastole (example: 150 ml)
end-systolic blood volume
(ESV) the volume of blood in a ventricle at the end of systole (example: 80 ml)
stroke volume
(SV) the volume of blood ejected from the heart per beat

SV = EDV - ESV = 70 ml/beat
heart rate
(HR) the number of times the heart beats per minute
cardiac output
(CO) the volume of blood pumped by the heart (either right ventricle or left ventricle) in one minute.

HR x SV = cardiac output
(approximately 5-6 liters/minute)
ejection fraction
(EF) the fraction of blood ejected in one beat.

(normal is around 0.55)

a very low ejection fraction would suggest poor emptying of the ventricle. a high EF indicates increased cardiac performance (high stroke volume). the EF is a measure of "contractility"
blood vessels have the capacity to not only carry blood but to also selectively permit diffusion of gases and nutrients. vessels may change their dimensions (diameter) during the process of vasodilation or vasoconstriction and thus exhibit vasoactivity. the particular functions depend on the structural make up of the various vessel types
angina pectoris
chest pain associated with metabolites produced in the myocardium during low blood flow. these affect pain receptors
an x-ray procedure involving the injection of a contrast dye such as special iodine, into the artery which then permits the visualization of the coronary arteries. if the image shows a narrowed region of vessel, a constricted coronary arter exists
the initial stretch on the ventricular muscle prior to contraction or it is the end-diastolic volume.

Within limits, the greater the stretch (greater the preload), the greater the force of contraction and the larger the stroke volume.
very elastic and this large artery stores considerable energy during each
contraction of the heart and subsequent ejection of blood into the aorta. The aorta has a
high blood pressure and a high blood velocity especially during peak systole. During
diastole (relaxation) when the heart is in the relaxation phase (and not beating), the blood
still maintains a pressure gradient allowing the blood to continue to push blood to the
capillaries and beyond. Since the aorta is so elastic, the blood flow in the
microcirculation is less pulsatile than it would be if the aorta were stiff (like that of a
galvanized pipe) hence producing large pressure fluctuations (resulting in large swings in
volume of flow to the smaller vessels and especially the capillaries). The aorta acts like
an internal pump during the time the heart is not beating in that the contraction or recoil
of the vessel walls pushes blood to the tissues.
large arteries
arteries--less elastic than the aorta with more muscular tissue. The larger
arteries basically act as conduits to continue the distribution of flow toward the tissues
although they may slightly change dimensions under the influence of vasoactive agents
which cause vasodilation (enlargement) or vasoconstriction (narrowing) of these vessels.
the "little arteries", which MAINLY control blood flow to the capillaries.
The large degree of smooth muscle in the walls of arterioles makes them able to
vasodilate (enlarge) and allow more flow through them or vasoconstrict (get smaller) and
hinder flow through them. These vessels are called the resistance vessels because they
control the flow to the tissues by way of the capillaries. There is only so much cardiac
output which can be distributed to the tissues thus the arterioles play a huge role in
regulating the specific flow to the various tissues. How then can flow increase to
accommodate the needs required during exercise? Answer: Vasodilation of the arterioles
of the specific exercising muscles directs more blood to these areas (supplied by the
arterioles which have just dilated) which along with the increased cardiac output
produces huge blood flows to the tissues requiring the increased flow). Quite often, other
tissues not involved in the exercise will exhibit decreases in the % of cardiac output being
supplied to them. For example, during this exercise, the kidneys will receive a lower
percentage of the cardiac output.
endothelial cell "tubes", which are the exchange vessels of the circulatory
system. Even though they are small in diameter, the huge number of capillaries creates a
large surface area for exchange of nutrients between the tissues and the blood
compartment via diffusion. The velocity in the capillaries is very low (a few mm/sec),
which allows for rapid diffusion of oxygen and nutrients from the blood stream to the
tissues and in reverse, the removal of chemicals such as carbon dioxide and other
metabolic waste products from the tissues.
"little veins", which connect the capillaries to the larger veins in the circuit.
The arterioles, capillaries and venules comprise the microcirculation.
these vessels have one-way valves, which allow blood to only move forward
under the influence of a low pressure. The low pressure in the veins can be altered during
the skeletal muscle contractions, which squeezes the blood through these one way valves
back toward the heart. This is called venous return. These vessels, in conjunction with
venules, contain nearly 60-70% of the blood volume at any one time on the average at
rest. As the venous volume decreases when the veins contract, more blood is mobilized
in the form of venous return to participate in the cardiac output. Because of the huge
storage of blood volume, these vessels are called the capacitance vessels. Changing the
size of the veins does not significantly affect the resistance to flow! It does affect the
volume of blood or the capacitance.
= blood. Approximately 7-9% of your body weight is blood. So then, how much
blood do you have in your body? This is very practical since when you donate blood you
are donating as much as 8% of your blood volume. If you lose much more than 30% of
your blood volume, you are in deep trouble. In experimental animal research, it is useful
to know how much blood you can withdraw from an animal for analyses. In a neonatal
mouse for example, the volume is obviously extremely small! How much blood then do
you have in your body?
For example:
A 100 Kg person (220 pounds) would have about 7-9 Liters of blood.
(.07 or .09 x 100 Kg = 7000 or 9000 ml)
How much blood in a person weighing 120 pound (55 Kg)?
Answer: approximately 3800 ml.
aortic valve (left semilunar valve) stenosis
causes a systolic murmur because the
blood volume would be ejected through the narrowed opening during the systolic phase
and turbulence would be created by the high velocity through the small cross-sectional
area. The turbulence would be detected as a systolic murmur.
mitral valve (left AV valve) stenosis
causes a diastolic murmur. Since the blood
flowing from the left atrium to the left ventricle would be going across a narrowed orifice
or opening, turbulence would be created during diastole when blood normally flows from
the atrium to the ventricle.
aortic valve (left semilunar valve) regurgitation
If the valve doesn’t close completely,
when would you expect to hear the turbulence as blood squirts or leaks across this valve?
Since the pressure in the aorta is quite high when the aortic valve is closed during
diastole, the murmur would be heard during diastole thus this type of valvular problem
would be a diastolic murmur.
mitral valve (left AV valve) regurgitation
When do you think the murmur would
occur associated with this defect? This would be a systolic murmur since during the
IVCP of the systole, when the blood pressure in the left ventricle is increasing, the blood
could leak backwards into the left atrium and be heard as an abnormal heart sound.