2.5 Flashcards
how much blood in % do they get?
- Cerebral
- Coronary
- Renal
- GI
- Skeletal M
- Skin
- Cerebral = 15%
- Coronary = 5%
- Renal = 25%
- GI = 25%
- Skeletal M = 25%
- Skin = 5%
volume in % of blood in (5L in total)
- Arteries
- Capillaries
- Veins
- Pulmonary
- Heart
- Arteries = 13%
- Capillaries = 7%
- Veins = 64%
- Pulmonary = 9%
- Heart = 7%
total number of capillaries and their total crossectional area?
~ 10^10
CS Area= 2,500 cm^2
what happens to resistance when there is contraction of the vessel?
resistance ↑ (bcs inversly prop to CS Area)
how can we contraoll perfusion of capillaries?
smooth muscle precapillary sphincters
continuity equation?
A1V1=A2V2
fluid will flow faster in lengthf with smaller CS Area
where will we find the slowest flow velocity?
in the capillaries bcs their CS Area is the larger
define benoulli’s law
an increase in the speed of a fluid occurs simultaneously with a decrease in pressure
why do we use serial resistance?
to describe the resistance of blood flow through vessels
R = R arteries + R arterioles + R capillaries + R venules + R veins
why do we use parallel resistance?
to describe the resistance of the flow of blood through different organ systems
1/R = 1/R GI + 1/R coconary + …..
define TPR
the resistance that must be overcome to push blood through the circulatory system and create flow
how can we modify TPR? (best way)
via vessel radius
define Reynold’s number
N(R)= Determines the tendency of a flow to ba laminar or turbulent
Laminar= < 2,000
Turbulent= > 3,000
btw 2,000-3,000, many conditions may occur
Example of Reynold’s number
- Anemia is associated with decreased Hematocrit -> decreased viscosity -> increased Reynold’s number
