1. Circulatory System in Animals
Take a look at a skeleton and see how well a heart is protected — open heart surgery takes breaking a body to get to the heart.

2. Feeding Energy Needs Why do we need a circulatory system? supplies in
_______________________
______________________
waste out
need to pick up & deliver the supplies & wastes around the body

3. Circulatory System
Organ
______________
Tissues & cells

4. Vertebrate Heart 4-Chambered heart ____________ (atrium)
____________________
collection chamber
receive blood
__________________
pump blood out
left atrium
right atrium
right ventricle
left ventricle

5. Evolution of circulatory system
Not everyone has a 4-chambered heart
fish
amphibian
reptiles
birds & mammals
2 chamber
3 chamber
3 chamber
4 chamber
A powerful four–chambered heart was an essential adaptation in support of the endothermic way of life characteristic of mammals and birds. Endotherms use about ten times as much energy as equal–sized ectotherms; therefore, their circulatory systems need to deliver about ten times as much fuel and O2 to their tissues (and remove ten times as much CO2 and other wastes). This large traffic of substances is made possible by separate and independent systemic and pulmonary circulations and by large, powerful hearts that pump the necessary volume of blood. Mammals and birds descended from different reptilian ancestors, and their four–chambered hearts evolved independently—an example of convergent evolution.
Why is it an advantage to get big?
Herbivore: can eat more with bigger gut.
lowers predation
(but will push predators to get bigger as well, although no one east elephant s.) V A A A A A A A V V V V V

6. Lub-dub, lub-dub 4 valves in the heart Heart sounds Heart murmur
flaps of connective tissue
___________________________
Heart sounds
“Lub”
force blood against closed AV valves
“Dub”
force of blood against semilunar valves
Heart murmur
_________________________________________
blood squirts backward through valve SL AV AV

7. Electrical signals heart pumping controlled by electrical impulses
stimulates ventricles to contract from bottom to top, driving blood into arteries
allows atria to empty completely before ventricles contract
heart pumping controlled by electrical impulses
signal also transmitted to skin = ________

8. atria empty into ventricles fill (minimum pressure)
Cardiac Cycle
How is this reflected in blood pressure measurements?
chambers begin to fill
pump (peak pressure)
__________________
fill (minimum pressure)
The cardiac cycle. For an adult human at rest with a pulse of about 75 beats per minute, one complete cardiac cycle takes about 0.8 second.
During a relaxation phase (atria and ventricles in diastole), blood returning from the large veins flows into the atria and ventricles.
A brief period of atrial systole then forces all remaining blood out of the atria into the ventricles.
During the remainder of the cycle, ventricular systole pumps blood into the large arteries. Note that 7/8 of the time—all but 0.1 second of the cardiac cycle—the atria are relaxed and are filling with blood returning via the veins.
110 80
______
ventricles pump

9. Measurement of blood pressure
if top number > 150 or
if bottom number > 90
hypertension = (high blood pressure)

10. Have a heart? Ask Questions!!