principles of hemodynamics

Question 1

how many tissue types does the arterys and veins have and what are they?

Answer 1

-4
- endothelium
- elastic tissue
- smooth muscle
- fibrous tissue

Question 2

how many tissue types do capillaries have? what is it and why

Answer 2

-1
- endothelium
- has to be a thin layer so that diffusion can occur

Question 3

how are the vascular beds of the circulatory system organized?
- if the their is increased resistance in one vascular bed how does this affect the flow in another vascular bed?

Answer 3

• in series or in parallel
• if the resistance in one vascular bed increases due to vasoconstriction then the resistance somewhere else will decrease.

Question 4

how do the arteries effect pressure and resistance in the closed loop circulation
- how ?

Answer 4

• the elastic systemic arterires are a pressure resvioir that maintain blood flow during ventricular relaxation
• they can do this because they have elastic recoil so when pressure expands them the elastic recoil pushes back on the blood so it can further be pushed into the arterioles

Question 5

how do the arterioles effect pressure or resistance in circulation

Answer 5

• the arterioles alter their diameter and thus are the site of variable resistnace
• by doing this they can adjust flow into different capillary beds

Question 6

what role do veins have in the closed pressure / resistance loop.

Answer 6

• they act as a expandable reivoir

Question 7

what is the regulation of the flow of blood dependent on

Answer 7

• dependent on the regulation of pressure and resistance in a closed loop

Question 8

where are the pressures highest and the lowest

Answer 8

• pressure is highest in the aorta and lowest in the right atrium

Question 9

how does the blood flow in regard to pressure give an example

Answer 9

• blood flows from higher pressure to lower pressure
• ex) from the heart ( high pressure) in the closed loop of the vessels (lower pressure )

Question 10

flow is dependent on a ____ ____ not a _____ ____

Answer 10

pressure gradient / absolute pressure

Question 11

what is hydrostatic pressure

Answer 11

pressure exerted in all directions

Question 12

how does the pressure of a fluid change with distance traveled ?
- why

Answer 12

• the pressure of a fluid in motion decreases with distance
• bc pressure is lost due to friction

Question 13

if a tube has the same pressure at both ends where would fluid travel and why

Answer 13

• wouldsnt travel anywhere bc rhere is no difference in pressure

Question 14

if pressure of one tube is 100mmhg on one end and 75 on the other
and
another tube is 40mmhg on one end and 15 on the other which has the higher flow rate

Answer 14

• they both have the same flow rate bc they both have the same differences in pressure

Question 15

what is the relationship between the cardiac output ( Q) and pressure dradient ( delta P)

Answer 15

• cardiac out put is proportional to pressure gradient

Question 16

what is the relationship between caridac out put (Q) and vascular resistance

Answer 16

• CO is inverselt proportional to vascular ressitance

Question 17

what are the two defintions for mean arterial pressure

Answer 17

• primary drivinf force for blood force
• pressure reserved in the arteries during heart relaxation

Question 18

what is the equation for mean arterial pressure

Answer 18

Question 19

what does the body try to do when mean arterial pressure changes and how
- give an example

Answer 19

• trys to maintain it
• if delta P changes CO or PR will be altered to bring BP back to normal
• ex) if CO increases then PR will decreases to maintain meana rterial blood pressure
• if there is hemmorage and mean arterial pressure decreases the resistance will increase and sometimes CO will increases too

Question 20

what is vascular resitance determined by?

Answer 20

• overall length of the circuit L
• viscocity of blood n
• radius of the blood vessel, r

Question 21

what is Poiseuille’s equation
- what are the relation ships for this equation

Answer 21

• it puts together the relationships between cardiac output and vascular resistace
• when mean arterial pressure increases flow increases
• when radius increases flow increases
• when viscoscity increases flow decreases
• when length increases flow decreases

Question 22

how is peripheral vascular resistance exerted

Answer 22

• in series or in parallel

Question 23

if vasconcstriction in the legs occur what will the vascular system do to maintain blood flow

Answer 23

• it will decreaes resitance somewhere else to maintain blood flow

Question 24

what is the definition of flow rate (Q)

Answer 24

• the volume of blood that passes a given point in the system per unit time

Question 25

what is velocity of flow (V)

Answer 25

• the distance a fixed volume of blood travels in a given period of time

Question 26

what is the equation for velocity of flow

Answer 26

Question 27

what happens to velocity as cros sectional area increases
- what happens to flow rate

Answer 27

• velocity decreases
• it stays the same because total mass doesn’t change

Question 28

what is the continuity principle

Answer 28

• explains mass conservation
• the product of velocity and cross sectional area is a constant K
• vA=k

Question 29

why is it that flow rate stays the same even when velocity of blood flow is low in the capillaries vs the aorta

Answer 29

• the flow rate stays the same bc the capillaries have a greater cross-sectional area compared to the aorta for example
• so the greater cross-sectional areas compensates for the slower velocity

Question 30