efferent and cardio

Capalliries

Responsible for exchange with organs and tissues of Co2 , waste and O2, nutrients, and signals

Hearts ultimate goal

Deliver O2 to organs so you don’t die from lack of ATP

blood flow throughout the

body?

Gradients

Pressure gradients

High to low

Gradient creates blood flow

Largest pressure drop in arterioles

Flow

Q = change in pressure/resistance

The magnitude of Q is determined by the size of the pressure difference (P)

The direction of Q is determined by the pressure gradient (high to low)

Flow can be equal if they have the same pressure difference

Poiseulles law

n is viscosity of blood

L is length of vessel

r^4 is radius of vessel to the fourth

Viscosity and length are constants

R = 1/ r4

Viscosity is relevant because

• change in volume…e.g. dehydration

• change in # cells (increase in RBC)…e.g. polycythemia

Vessels in series

Vessel categories are all in series

Flow is constant between all categories

Pressure decreases

Vessels in parallel

When branched off

Flow of all categories are not equal to all

Pressure difference is the same for all

Velocity v

distance a given fluid moves within a unit of time (cm/sec) distance/time or rate of blood flow

Inversely proportional to A

Directly proportional to Q

How fast

v = Q/A

Flow Q

quantity of a given fluid that passes by a certain point within a unit of time (mL/sec) volume/time

Q = v * A

How much

Q vena cava = Q aorta

Total cross sectional area

Capillaries has the largest total cross section area so v is lowest here since it wants blood to move slow with exchange with tissues

Radius plays greatest role in determining resistance because

Radius can be regulated By constriction and dialation of vessels

Length and viscosity are constants

Radius factors in the equation to the 4th power