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18 Cards in this Set

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  • Back
function of the circulatory system...
1) transport respiratory gases
2)transport nutrients
3)transport waste products
4)transport hormones
5)transport heat
6)trasnport force
Types of Circulatory Systems
GV Cavity
Open Circ System
Closed Circ System
GV Cavity
Planaria and cnidarians --> GV cavity moves food and transports gases
Open Circ System
insects --> heart pumps blood forward and out of vessels. blood leaves the vessels.
closed circ system
blood always in the vessels
A good circ system must provide...
1)bulk transport(large arteries)
2)diffusional exchange(capillary beds)
The path of blood through the closed circulatory system...
right vent. pumps blood to aorta to the systemic circ system(body). the deoxy blood returns to heart via vena cavas and enter right atria. flows into right ventricles which pumps blood through pulmonary system (to lungs) to get oxygenated. then blood flows back to left atria/vent. to be pumped back into systemic.
systemic flow...
aorta -> arteries -> arterioles -> capillaries -> venules -> veins -> vena cavae -> heart
for good diffusional exchange
must have small blood vessels and long residence time.
deltaP=Q(8iu/Pi(rx10'4)
smaller radius (r) leads to deltaP being greater.
Ficks's Law of Diffusion
VO2 = -DA(delta P/deltaX)
Problem 1 - small blood vessels are best but great pressure are required to move blood...what is the solution?
BRANCHING --> more capillaries causes the resistence of a system to be less.
Problem 2 - small blood vessels are best for diffusion but they result in great velocities and low residence times (move too fast) ... what is the solution?
BRANCHING --> branching slows down blood flow because the area going out is greater than the area goind in.
veins and arteries
veins have valves -- move blood to heart. arteries have elastic tissue -- move blood away from heart
Where is the bottleneck in our system?
Arterioles --> the pressure change is the greatest at the arterioles therefore greater resistance. We control blood flow at arterioles with muscle fibers to control vasodilation. an increase PCO2 causes arterioles to open and bring more O2. Increased [H+] needs more 02 so vasodilation occurs.
Arterioles are controlled extrinsically -- hormones
-neurotransmitters: norepinephrine (fight/flee response) increased would decrease arterioles to skin and increase to brain/heart. decreased amound would have opp effects.(embarrassed)
-hormones: epinephrine(fight/flee)
decrease radii of arterioles to skin and increse arterioles to muscle
Venous Pooling
vena cava swells and collects blood. 60% of blood can be in pool at one time. Explains why ppl faint --> blood can't get to heart or brain.
combating venous pooling
skeletal muscle pump, pulmoary pump, venae comitans --> when muscles contract, squeeze veins and blood is pumped to heart.