Physio 15 Flashcards
A valuable characteristic of the vascular system is that all blood vessels are?
Distensible
It is the most distensible by far of all the vessels.
Veins
How much extra blood can veins store with even slight increases in venous pressure?
0.5 to 1.0 Liter
It provide a reservoir function for storing large quantities of extra blood that can be called into use whenever required elsewhere in the circulation.
Veins
It is expressed as the fractional increase in volume for each millimeter of mercury rise in pressure.
Vascular distensibility
A vessel that originally contained 10 milliliters of blood increases its volume by 1 milliliter when the pressure increases by 1 mm Hg. What is the distensibility of this vessel in per mm Hg?
0.1 per mm Hg
True or False. Walls of the arteries are weaker than those of the veins.
False. Walls of arteries are far stronger than those of the veins.
On average, how much distensible are veins compared to arteries?
8x more
Its distensibilities are similar to those of the systemic circulation.
pulmonary vein
In hemodynamics, what is more important than to know the distensibilities of the individual vessels
Total quality of blood that can be stored in a given portion of the circulation for each mm Hg
This value, the total quality of blood that can be stored in a given portion of the circulation for each mm Hg, is called as?
Compliance or capacitance
True or False. Compliance and distensibility are much the same.
False. Compliance and distensibility are different.
It is equal to distensibility times volumes
Compliance
True or False. A highly distensible vessel that has a slight volume may have far less compliance than much less distensible vessel that has a large volume.
True
The compliance of a systemic vein is about ______ times that of its corresponding artery.
24
A systemic vein is approximately ______ times more distensible than its corresponding artery.
8
The volume of a systemic vein is about _____ times as great as its corresponding artery.
3
True or False. A systemic vein has lower compliance than its corresponding artery.
False
True or False. The higher compliance of a systemic vein is partly due to its greater distensibility.
True
True or False. The volume of a systemic vein is about the same as its corresponding artery.
False
True or False. If a systemic vein is 8 times more distensible and has 3 times the volume of an artery, its compliance is 24 times greater.
True.
It is the absolute change in diameter or volume of a vessel wall in response to pressure
Compliance
Known as the measure of how easily the vessel wall can be stretched
compliance
Refers to the measure of the buffering function of the artery
Compliance
It refers to the relative change in diameter of a vessel wall in response to pressure
Distensibility
This is the measure of the elastic properties of the vessel wall and also the determinant of stress on the vessel wall
Distensibility
A distensible organ that can stretch or swell to become larger or wider than normal
Urinary bladder
True or False. Veins have high compliance, meaning they’re high volume, low-pressure vessels.
True.
A convenient method for expressing the relation of pressure to volume in a vessel or in any portion of the circulation
Volume-pressure curves
Increase in vascular smooth muscle tone caused by this component of autonomic nervous system increases the pressure at each volume of the arteries or veins
Sympathetic stimulation
What is the effect of sympathetic inhibition on vascular smooth muscle tone?
Decreases the pressure at each volume.
Sympathetic control of blood vessels is a valuable means for ______ the dimensions of one segment of the circulation.
diminishing
An increase in vascular tone throughout the systemic circulation often causes large volumes of blood to shift into the ______.
heart
True or False. Sympathetic control of blood vessels plays a role in redistributing blood within the circulatory system.
True
True or False. An increase in vascular tone generally causes blood to move away from the heart.
False.
True or False. Shifting blood into the heart can be a way for the body to increase its pumping capacity.
True
True or False. The parasympathetic nervous system is primarily responsible for diminishing the dimensions of blood vessels to shift blood.
False. It is the sympathetic nervous system
A valuable mechanism by which the circulation can accommodate extra blood when necessary
Delayed compliance
This refers to one of the ways in which the circulation automatically adjusts itself over a period of minutes or hours to diminished blood volume after serious hemorrhage
Delayed compliance in the reverse direction
The phenomenon where a blood vessel initially shows a large increase in pressure when exposed to increased volume, followed by a gradual decrease in pressure over minutes to hours due to smooth muscle stretching is known as what?
Delayed compliance
What is the term for the characteristic of all smooth muscle tissue that describes its ability to “creep” to longer lengths and reduce tension when subjected to increased volume over time?
Stress-relaxation
What property of the arterial tree helps to smooth out the pulsatile flow of blood from the heart?
compliance of the arterial tree
Were it not for arterial system distensibility, new received blood would have to flow through the peripheral blood vessels almost _____, only during _____.
a. no flow; systole
b. instantenously; systole
c. instantenously; diastole
instantenously; systole
It is mainly continuous with very little pulsation.
Tissue blood flow
Give the two major factors affecting the pulse pressure:
- stroke volume output of the heart
- compliance (total distensibility) of the arterial tree
Name the least important factor that affects the pulse pressure.
Character of ejection
It is determined approximately by the ratio of stroke volume output to compliance of the arterial tree
Pulse pressure
Enumerate at least 3 distinctive abnormal pressure pulse contours
Aortic stenosis
Patent ductus arteriosus
Aortic regurgitation
Diameter of this valve opening is reduced, with aortic pressure decreasing significantly due to diminished blood flow outward through the stenotic valve
Aortic valve stenosis
One half or more of the blood pumped into the aorta by the left ventricle flows immediately backwards
Patent ductus arteriosus
What heart condition, involving an open vessel between the aorta and pulmonary artery, results in a very low diastolic pressure before the next heartbeat?
patent ductus arteriosus
This heart condition is characterized by absent aortic valve or will not close completely.
Aortic regurgitation
Which of the 3 abnormal pressure pulse contours mentioned in the textbook cause aortic pressure to fall all the way to zero between heartbeats?
Aortic regurgitation
What initially prevents the blood from moving suddenly all the way to the periphery?
inertia of the blood
What happens to the aorta immediately when the heart ejects blood during systole?
Only the proximal portion of the aorta becomes distended.
What spreads along the aorta as the pressure in the proximal aorta rises?
wave front of distention
What term is used to describe the spreading of this distention and pressure change along the arteries?
Transmission of the pressure pulse in the arteries.
During systole, when the heart ejects blood, only the _____ portion of the aorta initially becomes distended.
proximal
True or False. The entire aorta distends simultaneously when the heart ejects blood.
False
True or False. The transmission of the pressure pulse is a slow process.
False. It is rapid.
What is the velocity of pressure pulse transmission in the normal aorta?
3-5 m/sec
What is the velocity of pressure pulse transmission in the large arterial arteries?
7-10 m/sec
What is the velocity of pressure pulse transmission in the small arteries?
13-35 m/sec
It refers to the progressive diminution of the pulsations in the periphery:
Damping of the pressure pulses
What happens to the intensity of pulsation in the smaller arteries, arterioles, and especially the capillaries?
It becomes progressively less.
2 causes of damping of the pressure pulses
- resistance to blood movement in the vessels
- compliance of the vessels
It is almost directly proportional to the product of the resistance times compliance
Degree of damping
It damps the pulsations due to more compliant vessel, the greater quantity of blood required at the pulse wave front
Compliance
It damps the pulsations due to small amount of blood that must flow forward at the pulse wave front to distend the next segmented vessel
Resistance
What do you call the sounds heard during auscultatory method?
Korotkoff sounds
A clinical method for measuring systolic and diastolic pressure wherein a stethoscope is placed over the antecubital artery and a blood pressure cuff is inflated around upper arm.
Auscultatory method
Believed to be caused mainly by blood jetting through the occluded vessels and vibrations of the vessel wall.
Korotkoff sounds
Causes turbulence in the vessel beyond the cuff during auscultatory method
Jet
The organs primarily responsible for the long term regulation of arterial pressure
Kidneys
A slight extra increase in systolic pressure usually occurs beyond the age of?
60 years
What is the final effect of aging on the blood pressure control mechanisms?
Higher systolic pressure with increase in pulse pressure
Refers to average of the arterial pressures measured millisecond by millisecond over a period of time
Mean arterial pressure
True or False. A greater fraction of the cardiac cycle is spent in DIASTOLE than is systole thus the arterial pressure remains nearer to diastolic pressure than to systolic pressure
True.
What is the mean arterial pressure determined by the diastolic pressure?
60%
What is the mean arterial pressure determined by the systolic pressure?
40%
They are capable of constricting and enlarging therefore can store small or large amount of blood
Veins
The peripheral can propel blood forward by means of a so-called _____ _______
venous pump
Blood from all the systemic veins flows into the right atrium of the heart, therefore, the pressure in the right atrium is called as?
Central venous pressure
Right atrial pressure is regulated by a balance between?
- the ability of the heart to pump blood out of the right atrium and ventricle into the lungs
- the tendency for blood to flow from the peripheral veins into the right atrium.
What happens to the right atrial pressure if the right heart is pumping strongly?
Decreases
Talking about central venous pressure, what elevates the right atrial pressure?
Weakness of the heart
Give 3 factors that can increase venous return (and thereby increase right atrial pressure)
- increased blood volume
- increased large vessel tone throughout the body with resultant increased peripheral venous pressures
- dilatation of the arterioles
The same factors that regulate _____ ______ pressure also contribute to regulation of cardiac output.
right atrial
What are some abnormal conditions wherein right atrial pressure increases to 20-30 mm Hg?
- serious heart failure
- after massive transfusion of blood
They have so little resistance to blood flow when they are distended that the resistance then is almost zero and is of almost no importance
Large veins
Which veins are often compressed by different organs and by the intraabdominal pressure?
Veins coursing through the abdomen
In a recumbent person, what is the average pressure in the abdominal cavity?
+6 mm Hg
Pressure in the abdominal cavity can rise to +15 to 30+as a result of? (Enumerate at least 4)
- Pregnancy
- Large tumors
- Abdominal obesity
- Ascites
True or False. When the intra-abdominal pressure rise, the pressure in the veins of
the head must rise above the abdominal pressure before the abdominal veins will open.
False. It should be the veins of the legs
In a body of water exposed to air, the pressure at the surface is equal to?
atmospheric pressure
For every 13.6 millimeters of depth below the surface of water, the pressure increases by?
1 mm Hg
The name given to the pressure resulting from the weight of a liquid.
gravitational pressure or hydrostatic pressure
When a person is standing, what is the approximate pressure in the right atrium, and why does it remain at this level?
0 mm Hg because the heart pumps into the arteries any excess blood that attempts to accumulate at this point.
In a standing adult, what is the approximate pressure in the veins of the feet, and what is the primary reason for this pressure?
+90 mm Hg simply because of the gravitational weight of the blood in the veins between the heart and the feet
True or False. The gravitational pressure in the veins DECREASES with increasing distance below the level of the heart.
False. It increases
The pressure in the arm veins at the level of the top rib is typically around +6 mm Hg due to:
(a) Gravitational pressure
(b) Contraction of arm muscles
(c) Compression of the subclavian vein
(d) High blood pressure
Compression of the subclavian vein
What primarily determines the gravitational pressure down the length of the arm?
(a) The width of the arm veins
(b) The rate of blood flow
(c) The distance below the level of the top rib
(d) The person’s overall blood volume
The distance below the level of the top rib
Why do the neck veins of a person standing upright almost completely collapse?
(a) High blood pressure in the neck
(b) Low blood flow to the brain
(c) Atmospheric pressure on the outside of the neck
(d) Muscle contractions in the neck
Atmospheric pressure on the outside of the neck
What is the approximate pressure within the collapsed neck veins of a standing person along their entire extent?
(a) +6 mm Hg
(b) +90 mm Hg
(c) 0 mm Hg
(d) Atmospheric pressure plus gravitational pressure
0 mm Hg
If the pressure in a collapsed neck vein tends to rise above zero, what happens?
(a) The vein collapses further.
(b) Blood flow increases, and the pressure falls back to zero.
(c) Atmospheric pressure increases to compensate.
(d) The heart rate slows down.
Blood flow increases, and the pressure falls back to zero.
(T/F) The compression of the subclavian vein over the top rib contributes to the pressure in the arm veins at that level.
True.
(T/F) Gravitational pressure in the arm increases as you move closer to the top rib.
False.
Without these, gravitational pressure effect would cause the venous pressure in the feet always to be about +90 mm Hg in a standing adult.
Valves in the veins
Arranged in a manner that the direction of venous blood flow can be only toward the heart.
Valves in the veins
If veins lacked valves, what would be the approximate venous pressure in the feet of a standing adult due to gravity?
(a) 0 mm Hg
(b) +20 mm Hg
(c) +90 mm Hg
(d) Atmospheric pressure
+90 mm Hg
What happens to the veins when leg muscles tighten or contract?
(a) They dilate and increase blood flow away from the heart.
(b) They are compressed, squeezing blood out.
(c) The valves close, preventing blood flow.
(d) Gravitational pressure increases significantly
They are compressed, squeezing blood out.
What is the primary effect of leg movement or muscle tension on venous blood?
(a) It causes blood to pool in the feet.
(b) It propels venous blood toward the heart.
(c) It reverses the direction of venous blood flow.
(d) It has no significant effect on venous blood.
It propels venous blood toward the heart.
What is the name given to the pumping system that relies on muscle contraction to move venous blood?
Venous pump or muscle pump
Under ordinary circumstances, what is the approximate venous pressure in the feet of a walking adult due to the action of the venous pump?
Less than +20 mm Hg
(T/F) Venous valves prevent the backflow of blood in veins.
True
(T/F) Contraction of leg muscles helps to push venous blood towards the heart.
True
(T/F) The venous pump is most effective when a person is standing still.
False. The venous pump relies on movement and muscle contraction.
Approximately what percentage of the total blood in the circulatory system is typically found in the veins?
More than 60 percent
The venous system is considered a blood reservoir due to:
(a) The high pressure within the veins.
(b) The rapid flow of blood through the veins.
(c) The large volume of blood it holds and its compliance.
(d) The oxygen-rich blood it contains.
The large volume of blood it holds and its compliance.
What is the initial physiological response when blood is lost from the body and arterial pressure begins to fall?
Nervous signals are elicited from pressure-sensitive areas.
Where do the nervous signals that cause veins to constrict originate when blood pressure drops?
The carotid sinuses and other pressure-sensitive areas
Through which part of the nervous system are signals mainly sent to the veins to cause constriction in response to falling blood pressure?
Sympathetic nerves
According to the textbook, even after losing up to what percentage of total blood volume can the circulatory system sometimes function almost normally due to the venous reservoir function?
20 percent
(T/F) Arteries typically hold the majority of the blood volume in the circulatory system.
False
(T/F) The compliance of veins contributes to their function as a blood reservoir.
True
(T/F) A decrease in arterial pressure leads to the activation of the parasympathetic nervous system to constrict veins.
False. The sympathetic nervous system is activated.
(T/F) Venous constriction helps to compensate for blood loss by reducing the overall volume of the circulatory system.
True
A blood reservoir which can decrease in size sufficiently to release as much as 100 ml of blood to other areas of circulation
Spleen
Release several hundreds of milliliters of blood into the remainder of the circulation
Liver
A blood reservoir that can contribute as much as 300 milliliters
Large abdominal veins
A blood reservoir beneath the skin which can also contribute several hundred of milliliters
Venous plexus
Not part of the systemic venous reservoir system but must be also considered blood reservoirs
Heart and lungs
Shrinks during sympathetic stimulation and in this way can contribute some 50 to 100 milliliters of blood
Heart
Can contribute another 100 to 200 milliliters when the pulmonary pressures decrease to low values.
Lungs
A special reservoir that contains large quantities of concentrated RBCs
Red pulp of the spleen
What forms the red pulp in the spleen?
(a) Concentrated white blood cells
(b) A network of arterial vessels
(c) A trabecular mesh where red blood cells are trapped
(d) Lymphoid tissue producing antibodies
A trabecular mesh where red blood cells are trapped
What happens to the plasma after the whole blood oozes into the trabecular mesh of the red pulp?
It flows into the venous sinuses and then the general circulation.
What triggers the release of concentrated red blood cells from the splenic red pulp into the general circulation?
Excitation of the sympathetic nervous system
How much concentrated red blood cell volume can the spleen typically release into the circulation?
As much as 50 milliliters
What is the effect of the release of concentrated red blood cells from the spleen on the hematocrit?
It raises the hematocrit by 1 to 2 percent.
What is found in other areas of the splenic pulp, forming the white pulp?
Islands of white blood cells
What is manufactured in the white pulp of the spleen?
Lymphoid cells
