CVS 3 previous semester Flashcards
CO of left heart=
co of right heart
left sided CO is
systemic blood flow
right sided CO is
pulmonary blood flow
what carries blood away from the heart
arteries
____ are under high pressure
arteries
the blood volume contained in arteries is called
stress volume
arteries are thick walled with what type of tissue and muscle
elastic tissue and smooth muscle
what is the smallest branches of the artieries
arterioles
where is the highest resistance in CVS
the arterioles
what controls the arterioles resistance
autonomic nervous system
alpha 1 adrenergic receptors are found on the arterioles of which 3 areas
skin, renal and splanchnic circulation
beta 2 adrenergic receptors are found on the arterioles of the___
skeletal muscles
what has the largest total cross-sectional and surface area
capillaries
capillaries are the site of exchange for what three things
nutrients water and gases
what consist of a single layer of endothelial cells
capillaries
what are venules
formed from merged capillaries
what carries blood toward the heart
veins
veins progressively merge to form
larger veins
what is the pressure for veins
low pressure
veins are ___ walled, no ____ tissue
thin
elastic
what innervates the veins
autonomic nervous system (alpha 1)
which receptor innervates the veins
alpha 1 adrenergic receptor
the blood volume contained in veins is called___
unstressed volume
veins contain what proportion of blood in the CVS
HIGHEST PROPORTION (65%) reservoir function
hematocrit normal person
40-45%
hematocrit anemia person
10-20%
hematocrit polycythemia
increase crit increase viscosity=
60-70%
decreased flow rate
the percentage of blood that is cells (RBC, WBC, Platelets) is called
hematocrit
what three conditions increase blood viscosity
polycythemia
multiple myeloma
hereditary spherocytosis
V=
v=velocity
Q/A
Q=blood flow
A= cross sectional area
velocity is directly proportional to
inversely proportional to
proportional to blood flow
inversely proportional to cross sectional area
velocity as described greatest to least in capillaries small veins arterioles aorta
aorta
arterioles
small veins
capillaries
blood flow Q=
change P/R
change P= pressure difference between two ends of vessel
R= resistance
what is blood flow inversely proportional to
Blood flow is inversely proportional to the resistance of blood vessels
increased resistance=
decrease blood flow
decreased resistance
increased blood flow
circulation of an adult is how many liters/min
Overall flow in the circulation of an adult is 5 liters/min which is the cardiac output
co=
svXhr
mean arterial pressure=
co X TPR
map =
diastolic + 1/3 pulse pressure
pulse pressure=
systolic- diastolic
if the HR is too high what is diastolic filling and CO
diastolic filling is incomplete and CO drops
Causes of turbulent blood flow:
high velocities
sharp turns in the circulation
rough surfaces in the
circulation
rapid narrowing of blood vessels
Turbulence is increased by
decreased blood viscosity
increase blood velocity
SVR=
map-cap/COx80
MAP=
COxSVR/80+CVP
laminar flow - where is the highest velocity
in the middle
what does capacitance (compliance) describe
the distensibility of the blood vessels
vascular complicance=
volume/pressure
compliance- is it greater in the veins or arteries
veins
what is the result of capacitance with increasing age
capacitance decreases with age- in old age the arteries becomes stiffer and less distensible
capacitance is inversely related to
elastance or stiffness.
the greater the elastic tissue in blood vessel- higher elastance=lower compliance
when venous compliance decreases the stress volume
increase- due to shifting of blood from veins to arteries.
where is capacitance highest
in the vein
where is capacitance low
artery
where is capacitance lowest
artery (aging)
the force exerted by blood against per unit area of vessel wall
blood pressure
where does the largest decrease in pressure occur
across the arterioles because they are the site of highest resistance.
pressure is highest in the ___
pressure is lowest in the ___
highest in the aorta
lowest in the venue cavae
as blood flows through the systemic circulation, pressure decreases progressively because of what
resistance to blood flow
aorta pressure
100
arterioles pressure
50
capillaries pressure
20
vena cava pressure
4
is pulsatile
is not constant during cardiac cycle
what is this?
arterial pressure
what is the highest arterial pressure during a cardiac cycle
systolic pressure (120)
when is systolic pressure measured
after heart contracts and blood is ejected into the arterial system
the lowest arterial pressure during a cardia cycle
diastolic pressure (80)
when is diastolic pressure measured
when the heart is relaxed and blood is returning to the heart via veins
what is the difference between systolic and diastolic pressures
pulse pressure
when capacitance is decrease with aging what happens to the pulse pressure
increased pulse pressure
the most important determinant of pulse pressure is stroke volume
increase stroke volume does what to pulse pressure
increase it
decreasing sv decreases pulse pressure
Mean Arterial pressure
Is the average arterial pressure with respect to time
Can be calculated approximately as diastolic pressure plus on-third of pulse pressure
venous pressure
The veins have a high capacitance and , therefore, can hold large volumes of blood at low pressure
Atrial Pressure
Left atrial pressure is estimated by the pulmonary capillary wedge pressure (PCWP). A catheter (Swan- Ganz) , inserted into the smallest branches of the pulmonary artery, makes almost direct contact with the pulmonary capillaries. The measured pulmonary capillary pressure is slightly higher than the left atrial pressure
atrial pressure- pressure measurements
Its an indirect measurement of left ventricular performance
a wave
atrial contraction . Absent in atrial fib. Enlarge in pulmonary hypertension
c’ wave
RV contraction (tricuspid valve bulging into atrium)
v wave
atrial pressure due to filling against closed tricuspid valve. Enlarged in tricuspid regurgitation
‘x’ descent:
atrial relaxation + RV contraction (pulls atrium downward)
y’ descent:
emptying of right atrium after tricuspid valve opens
Cannon wave
large wave not corresponding to a , v or c wave. Due to complete heart block or junctional arrhythmias.
cvp reflects
how do we guide fluid replacement
CVP reflects right ventricular preload
Guide during intravenous fluid replacement
Anal veins
Hemorrhoids
varicose veins.
Faulty venous valves lead to
venous pump-
The venous valves and pump maintain a relatively low venous pressure in the legs.
what is important in the transport of nutrients to tissues
microcirculation
where is the site of waste product removal
micorcirculation
in microcirculation, with over 10billion capillaries with a surface area of 500-700 square meters- what is their function
perform solute and fluid exchange
the blood flow through the capillaries is regulated by what
contraction and relaxation of the arterioles and the precapillary sphinters
what is composed of unicellular layer of endothelial cells surrounded by a basement membrane
capillary wall
how does solute and water move across the capillary wall
via the intercellular cleft (space between cells)
the most important means by which substances are transferred between plasma and interstitial fluid is by____
simple diffusion
what diffuses directly through cell membrane of capillaries
lipid soluble substances (co2, o2)
how does water soluble substance move across the capillary wall
intercellular clefts
what enhances diffusion across capillary membranes
concentration differences/
concentration gradient
capillaries in different tissues have what distinction in their permeabilities
extreme differences
what is the description of the intracellular cleft in the brain
its exceptionally tight (BLOOD BRAIN BARRIER)
what is the description of intracellular clefts in the liver and intestine
exceptionally wide
why are they intracellular clefts in the liver and intestine very wide
to allow passage of protein
what are the capillaries in the liver and intestine called
sinusoids
the space between cells is called_____
the fluid in this space is called____
interstitial
interstitial fluid
almost all fluid in interstitium is in form of ___
gel (fluid proteoglycan)
