Proteins, Plasma salts, glucose, FA Red blood cells hemoglobin 15 g/dl Other cells WBC Neutrophils Macrophages Platelets Hematocrit Vol RBC/total Vol 35-45%
Blood
High pressure & lower volume
Model of the circulatory system
Right & left pumps in series
Low pressure & higher volume
Vessel Composition
Capillaries
Blood vessels - anatomy
General arrangement & structure
Arteries
High pressure High
resistance
Delivery and
distribution network
Relatively stiff VSM,
connective tissue
Veins
Low pressure
side
Very compliant Thin walled Little VSM 1-way valves
Vessel Characteristics
Pressure & flow
Pressure = Flow x Resistance MAP = CO x TPR
Resistance & Flow
Flow rate, & velocity resistance
The outcome is that velocity
increases as the arteries narrow...
...But since velocity is
determined by the total cross sectional area of the vessels the velocity is dramatically slowed across the capillary bed.
Where do signals act?
Endothelium (EC) Vascular smooth muscle (VSM)
Calcium is the key second messenger for most signals If VSM Ca2+ increases, you get constriction If EC Ca2+ increases, you get vasodilation
Systemic blood pressure
One way valves and compression of the veins by active muscle combine to act as a pump to assist venous return.
Vessel Characteristics
BF Distribution with Exercise
BF must "shunt" from inactive to active
tissue to meet metabolic requirements