Arterial and Venous System and Lymphatics Flashcards
The least amount of damping of the pressure pulses would occur in which of the following components of the circulatory system? A.) Femoral Artery B.) Arterioles C.) Capillaries D.) Venles
A.) femoral artery
Which of the following factors affect(s) pulse pressure? A.) Vascular Elastance B.) Arterial Compliance C.) Stroke Volume D.) All of the Above E.) B and C only
E.) B and C only
Which of the following is the most important means for the exchange of substances between the blood and the interstitial fluid?
A.) Blood hydrostatic pressure
B.) Capillary oncotic pressure
C.) Diffusion
D.) Interstitial fluid hydrostatic pressure
E.) Osmosis
C.) diffusion
Vascular distensibility=?
Increase in volume/ (increase in pressure x original volume )
Veins are about _____ times more distensible than arteries
8
Pulmonary vein distensibilities are about the same as for what
systemic veins
Pulmonary artery distensibilities are about ____ times that of systemic arteries
6
Vascular compliance (capacitance) = ?
Increase in volume/ increase in pressure
Capacitance describes what
The distensibility of blood vessels
What does Vascular compliance (capacitance) tell us
the total quantity of blood (ml) that can be stored in a given portion of the circulation for each mm Hg rise in pressure
Capacitance is inversely proportional to ?
Elastance
Compliance is = ?
distensibility x volume
Capacitance is directly proportional to ?
Volume
Capacitance is inversely proportional to ?
Pressure
Capacitance is much greater in ____ than arteries
Veins
Capacitance of arteries _______ with age
Decreases
The greater the amount of elastic tissue in a blood vessel the ______ the elastance
Higher
The greater the amount of elastic tissue in a blood vessel the ______ the compliance
Lower
Vascular compliance=
total quantity of blood that can be stored in a given portion of the circulatory system
What is compliance
is a measure of the ease with which a hollow viscus may be distended
What is Elastance
Measure of the tendency of a hollow viscus to recoil toward its original dimensions upon removal of a distending or collapsing force
A systemic vein is about 8 times as distensible as its corresponding artery and has a volume about 3 times as great. How would its compliance compare to that of a corresponding artery?
24
Pulse pressure=
Stroke Volume/ Arterial Compliance
What is the most important determinant of pulse pressure?
Stroke volume output of the heart
Pulse pressure increases to the same extent as the ________
Systolic pressure
Diastolic pressure remains unchanged during ___________
Ventricular systole
What are two factors affecting the pulse pressure
Stroke volume output of the heart, compliance of the arterial tree
Decreases in compliance (capacitance) (i.e. aging), results in a ______ in pulse pressure
increase
Conditions causing abnormal contours of the pressure pulse wave
Aortic valve stenosis, Atherosclerosis, Patent ductus arteriosus, Aortic regurgitation
Due to aortic valve stenosis the blood flow into the aorta is
diminished
What is aortic stenosis and what is its effect on aortic pressure
Stenosis of the aortic valve leading to decrease in aortic pulse pressure
What is patent ductus arteriosus
Half or more of the cardiac output flows back into the pulmonary artery and lung blood vessels
What are two conditions that case abnormal contours of the pressure pulse wave
Patent ductus arteriosus
Aortic regurgitation
In a pt with patent ductus arteriosus what happens to diastolic pressure before the next heartbeat
It falls very low
What is aortic regurgitation
Blood flows back into left ventricle,
aortic valve is absent or will not close completely
What happens to the aortic pressure between heartbeats in a patient with aortic regurgitation
It may fall all the way to 0 between heartbeats
The progressive reduction of the pulsations in the periphery= _______ of the pressure pulses
Damping
What is the name of the sounds heard by the stethoscope when checking blood pressure
Korotkoff
When do you stop hearing sounds when checking blood pressure
When the pressure in the cuff is equal to or lower than diastolic pressure
Mean arterial pressure is the average _____ pressure with respect to time
Arterial
why is the mean arterial pressure not simply the average of diastolic and systolic pressures
because more of the cardiac cycle is spent in diastole
what is the equation for mean arterial pressure
mean arterial pressure= diastolic pressure + 1/3 pulse pressure
Central venous pressure is equal to what
pressure in the right atrium
What are the factors that regulate right atrial pressure
Ability of the heart to pump blood out of the right atrium/ventricle
tendency of blood to flow into the right atrium
How do you estimate left atrial pressure
Use pulmonary wedge pressure:
catheter inserted into the pulmonary artery will make almost direct contact with the pulmonary capillaries. This pressure is almost equal to the left atrial pressure.
What are some factors that increase venous return (and increase right atrial pressure)
increased blood volume
increased peripheral venous pressures due to increased large vessel tone.
Dilation of the arterioles
Do large veins have some resistance
yes
in a person lying down the pressure in peripheral veins is _______mm Hg greater than the right atrial pressure
+4 to +6
When intra-abdominal pressure increases, what must happen for the venous blood in the legs to pass the abdomen
The venous pressure in the legs must increase above the abdominal pressure before blood can flow from the legs to the heart thought the abdominal veins
Where are varicose veins most often present
in the superficial veins secondary to valve issues
What is the name for the veins that connect the superficial veins to the deep vein
perforating veins
_______ control blood flow to each tissue
Small arterioles
______ in tissues control diameters of arterioles
local conditions
Arterioles are highly ________
Muscular
Where is the continuous muscular coat of an arteriole lost
in the metarterioles
______ encircles capillary at point where it originates form a metarteriole
Smooth muscle
What is the precapillary sphincter
Smooth muscle fibers encircle capillary at point where it originates from a metarteriole
How many layers is the capillary wall
unicellular layer of endothelial cells
The capillary wall has a thin what
basement membrane
what is the total thickness of a capillary wall
0.5 micrometers
What is the internal capillary diameter
4-9 micrometers
What are slit pores in a capillary
intercellular clefts; spacing of 6-7 micrometers
allow for rapid diffusion of water, water-soluble ions, and small solutes
What are the plasmalemmal vesicles of a capillary formed from
Caveolins
What is the role of plasmalemmal vesicles in a capillary
Play a role in endocytosis and transcytosis
Name three organs that have capillaries with pores
Liver, GI tract, kidneys
What is the most important factor in regulating vasomotion
Concentration of oxygen in the tissues
What is the most important means for the exchange of substances between the blood and the interstitial fluid
Diffusion
_____ substances can diffuse readily through the capillary cell membranes: give two examples
lipid-soluble, oxygen, and Carbon dioxide
Non-lipid-soluble substances diffuse through the
intercellular pores/clefts
The rate of water diffusion through the capillary membrane is _____ than flow of plasma within the capillary
80x faster
The rate of diffusion is directly proportional to what
Concentration differences of the diffusing substances
Passage of substances through the interstitium is mostly via ____ rather than ____
diffusion rather than flow.
Passage of substances though the interstitium is mostly via diffusion rather than flow because of
The large numbers of proteoglycan filaments found in the interstitium
_____ that allow fluid flow through the interstitium do sometimes form
Rivulets
what are rivulets
“free” fluid and small free fluid vesicles
means fluid that is free of the proteoglycan molecules ad therefore can flow freeely
_____ determine direction of diffusion into or out of a capillary
Starling forces
What are the 4 starling forces
Capillary pressure (outward force)
Interstitial fluid pressure (inward force)
Capillary plasma colloid osmotic pressure (inward force)
Interstitial fluid colloid osmotic pressure (outward force)
sum of starling forces equals
net filtration pressure
Capillary filtration coefficient
takes into consideration the number and size of pores
not all capillaries are equal
Filtration=
Kf (capillary filtration coefficient) x NFP
osmotic pressure caused by the plasma proteins is called
colloid osmotic pressure
When fluid enters the lymphatics, the lymph vessel walls contract momentarily to what
pump fluid into the blood circulation
When fluid enters the lymphatics, the lymph vessel walls contract momentarily and creates a slight ______ pressure in the interstitial spaces
negative
What is the mean net outward force
0.3
The mean forces tend to move fluid
Outward
The lymph vessels possess ____ valves
1-way
Lymph flow reaches maximum when
interstitial pressure rises slightly above atmospheric pressure
What is the capillary pressure (Pc)
Tends to force fluid outward through the capillary membrane
What is the interstitial pressure (Pif)
tends to force fluid inward through the capillary membrane when Pif is positive but outward when Pif is negative
What is the capillary plasma colloid osmotic pressure
tends to cause osmosis of fluid inward through the capillary membrane
The interstitial fluid colloid osmotic pressure
tends to cause osmosis of fluid outward through the capillary membrane
Factors that increase lymph flow (and also interstitial fluid pressure)
Elevated capillary hydrostatic pressure
decreased plasma colloid osmotic pressure
increased interstitial fluid colloid osmotic pressure
Increased permeability of capillaries
Rate of lymph flow =
interstitial fluid pressure x activity of lymphatic pump
