BIO3302 Circulatory Notes

Circulatory physiology


Suggested reading
 Chapter



8

Topics to be covered
 Roles

of circulatory system
 Design of circulatory systems
 Elements of circulatory systems
Pumps
 Blood vessels


 Control


of blood pressure and flow

Adjustments for exercise

BIO 3302 – SLIDE #1

Roles of the circulatory system
Time to 95% equilibration of O2 by diffusion

What animals need a circulatory system, and why?
 Once a circulatory system is in place, what else can it be used for?


0.1 mm ! 0.067 s

1 mm ! 6.7 s

1 cm ! 10.9 min

1 m ! 78 days

BIO 3302 – SLIDE #2



Diffusion vs. convection




Size (time α d2) and metabolic rate are limiting factors
Diffusion is always the final step in O2 transport
Convection is essential for






Complex organ systems
To support high metabolic rates
To achieve large body mass

Circulatory system functions in


Rapid mass transportation of:







respiratory gases (except insects) nutrients waste products hormones 




antibodies salts/acid-base equivalents heat Production of force:




Hydrostatic skeletons
Wing expansion in insects
Renal filtration and excretion in vertebrates (regulation of
ECF volume)
BIO 3302 – SLIDE #3

Fig. 33.34 Campbell & Reece 2002

Design of circulatory systems
 Three

essential components:

(1) Pump (usually a heart):





Positive vs. negative forces peristaltic pump chamber pump with contractile walls chamber pump driven by external forces

(2) Vascular system




arterial system capillaries venous system

Peripheral circulation (3) Circulating fluid

BIO 3302 – SLIDE #4

Fig. 8.2



Two broad trends (with increases in metabolic rate):


Open → closed systems
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



Undivided → divided systems




Open system = incomplete system of vessels