Cardiovascular System

Question 1

Systemic system

Answer 1

delivery depends on pressure via reducing resistance. The neural system can override the organ system to shunt blood to the brain Ex. during hemorrhage

Question 2

True/false: blow flow is arranged in series and systemic vasculature is arranged parallel

Answer 2

true

Question 3

when distances are short AND large surface area for exchange

Answer 3

diffusion

Question 4

pressure formula

Answer 4

h x p x g

Question 5

True/False: hydrostatic pressure is caused by effects of gravity on the fluid, so P and h are not proportional and is dependent of the vessel shape.

Answer 5

False: hydrostatic pressure is caused by effects of gravity on the fluid, so P ∞ h and is independent of the vessel shape.

Question 6

pressure from cardiac pump. This energy moves blood through blood vessels and is dissipated in overcoming the resistance to blood flow offered by the blood vessels and the blood itself

Answer 6

hydrodynamic pressure (blood pressure is static and dynamic)

Question 7

How do you measure fluid pressure in fluid column?

Answer 7

height difference P2-P1 represents pressure of Hg

Question 8

formula of flow (darcy’s equation)

Answer 8

Flow = difference of pressure / resistance

Question 9

What influences blood flow through any vessel?

Answer 9

pressure gradient because blood flows from high to low, in systemic circulation it’s pressure difference between aorta and CVP. Also, resistance which comes from arterioles

Question 10

What are factors affecting resistance?

Answer 10

viscosity- friction between molecules so that each layer of lamina slows the flow and slowest layer is closest to vessel, vessel length, vessel radius, and if in series or parallel

Question 11

True or false: viscosity is constant

Answer 11

true, however blood doesn;t count because when the vessel diameter decreases the viscosity decreases because hematocrit decreases ONLY in small vessels such as capillaries (Fahraeus effect)

Question 12

blood flow into smaller vessels, RBCs bend, spin and align – along with plasma spinning – lowers viscosity in smaller vessels

Answer 12

Axial streaming (Fahreus effect)

Question 13

How does length of vessel affect flow?

Answer 13

If tube length doubles that the resistance would double and the flow would decrease by 1/2 (flow = 1/L, ex. so if length triples the flow reduces by 1/3)

Question 14

How does radius affect flow?

Answer 14

In smaller diameter vessel, a given volume of blood comes into contact with more of the surface area of the wall than a larger-radius vessel, resulting in greater resistance with smaller radius.

Question 15

How are resistance and radius related?

Answer 15

resistance is inversely proportional to 4th power of radius. So doubling the radius reduces resistance to 1/16 (2^4). That’s why contraction of arterioles is most important for regulating flow

Question 16

What does a closed circulatory system mean?

Answer 16

This means that the total volume of blood (~5 Liters) contained within the heart and vasculature cannot change as it moves through the various classes of vessels in CV system

Question 17

how are flow and velocity related?

Answer 17

Flow = velocity x area

Question 18

How do area and velocity affect flow?

Answer 18

if velocity increases then area will decrease this is how flow remains constant from arteries> arterioles> capillaries. Velocity is slowest in the capillaries and area is largest for diffusion purposes.

Question 19

What does resistance of blood flow depend on?

Answer 19

dimension of vessels

Question 20

How is resistance different in series vs parallel?

Answer 20

resistance in series is added which increases it. resistance decreases in parallel because you add the reciprocals

Question 21

When does flow become turbulent?

Answer 21

When pressure increases the flow can exceed critical velocity becoming turbulent

Question 22

Turbulence due to vessel plague (A), stenotic (B) or leaky heart valves (C)

Answer 22

Question 23

What are the noises you hear during blood pressure recording?

Answer 23

When cuff is pumped no sound heard, blood flows through creates systolic noise (turbulence), once blood becomes laminar no sound is heard and that’s diastolic

Question 24

Compliance

Answer 24

volume/pressure, the greater the compliance the greater in change of volume for pressure

Question 25

transmural pressure

Answer 25

Pi-Po; if Pi>Po the vessel open, if Pi<Po the vessel closes. Pi is the intraluminal presure that increases with force

Question 26

internal pressure at which blood vessel collapses

Answer 26

critical closing pressure

Question 27

inhibition of… relaxes aresteriolar smooth muscle – decreases critical closing pressure – less intraluminal pressure required to open vessel open.

Answer 27

sympathetic activity

Question 28

Wall tension vs wall stress

Answer 28

Tension = P x r (tension proportional to radius)
Stress = P x r/2(thickness)
This is why large arteries need thick walls

Question 29

Why is alveoli pressure inversely proportional to wall tension and proportional to radius?

Answer 29

the smaller the alveoli (radius) the greater the tension and tendency to collapse; surfactant offsets this