Lecture 19 Flashcards
Hemodynamics is
The study of blood flow
Motion of heart and blood flow is detected using
Doppler effect
Doppler US will _____ , ______- and _______ blood flow
Detect, qauntify and evaluate
Humans have _____L of blood
5L
Blood consists of (4)
RBC, WBC, platelets, pasma
Blood functions to carry
02 CO2 nutrients and waste
Arteries have valves or no
No
Veins have ______ pulsatile flow than arteries
Pulsatile flow
Pumping f the veins is from
Leg muscle contractions
Between arteries and veins which are compressible
Veins
Arteries become
Aterioles
Veins extend from
Venules
Capillaries
Nutrient and gas transfer
Few micormeters in fize
Join artioles and venules
Valves
One-way
Prevent backflow of blood
In the heart and veins
Stenotic valves
Dont open enough
Insufficiency/regurgitation
Valves od close enough
Hydrostatic pressure
Equivalent to the weight of a column f blood
Hydrostatic pressure _________ WITH DISTANCE BELOW HEART
INCREASES
In a supine patient the hydrostatic pressure is
0 mmHg
In a standing patient the pressure in the veins is
100 mm/Hg
Inspiiration
Diaphragm moves down
Increase in thoracic volume, decrease in thoracic pressure
Decreases in abdominal volume and increase in abdominal pressure
Stop venous return from legs
Valsalva
Patient can be asked to hold thier breath and bear down
Increase in abdominal pressure
Stops venous return from legs
Expiration
Diaphragm moves up
Decrease thoracic volume, increase in thoracic pressure
Increase in abdominal volume, decrease in abdominal pressure
Venous blod returns from legs
Pressure is
Driving force behind fluid flow
Pressure equation and unit
P = force/ area
Pa or N/m2
a _________ is required for a fluid to flow
Pressure difference (delta P)
Volumetric flow rate
Volume of blood passing a point per unit of time
Equation and units of volumetric flow rate
Q= delta P/ R
Delta P is pressure gradient driving flow
R is resistance within the vessel
Volumetric flow applies to a _____ _____ tube
Long straight tube
Resistance is also considered to be
Long straight tube
Resistance equations
R=8Ln/ pi r4
L- length of tube, cm
, n - viscosity, poise
, r - radius, cm
Viscosity is
Resistance of flow offered by a fluid
Unit and letter for viscosity
, n,
Unit is poise
Increase in radius or diameter of the tube ________ resistance
Decreases
What is the strongest parameter effect on resistance
Radius/diameter
Resistance and radius relationship
R ~~~ 1/r4
If radius doubles, R ______
Decreases by 16x
Vasoconstriction
Smaller blood vessels, restricts blood flow
Vasodilation
Larger blood vessels, allow more blood flow
What is poiseuille’s equation
Q= (delta P)(Pi)(diameter)^4/ 128(L)(n)
