1. Cardiovascular introduction
i. Potential energy is the main type of energy in pushing blood around the
ii. In order to overcome frictional resistance, potential energy is used up
iii. Therefore the heart must be energized continuously
1. If blood stops bleeding no blood flow, death with follow
i. Allows us to divert the blood where we may not need as much to areas
we need it more
ii. Happens during exercise 1. Through the skeletal muscles
iii. Blood vessels in the gastrointestinal tract contract
iv. The blood goes down a vascular tree that is mostly a branching or parallel
circuit and not a series circuit. The former allows blood to be distributed to
many parts of the body, while the latter would only allow blood to move
through a small amount of body tissue.
1. A branching circuit also allows blood to change its distribution to
various tissues during different types of situations (e.g. exercise).
During exercise blood vessels dilate in exercising tissues (i.e.
skeletal muscles) and constrict in non-exercising tissues (e.g.
kidneys and GI tract).
i. Cross sectional area of the aorta is small, even though it is big(1 cm).
1. 5 Liters/min EVERYWHERE
a. At all locations
ii. The capillaries are quite small, but there are many many of them
1. Total cross sectional area is quite high
2. Due to branching circuitry