Circulatory System

Question 1

Differences between closed and open systems

Answer 1

Open: transport nutrients and molecules to the body
Closed: blood is separated from interstitial fluid, main purpose to deliver O2, resurrection of blood by varying diameter

Question 2

AV valves

Answer 2

Tricuspid: right
Bicuspid: left
Prevent back flow to atria when ventricles contract

Question 3

Pulmonary and aortic valves

Answer 3

All are tricuspid

Prevent back flow when ventricles relax

Question 4

Describe the phases of heart contraction

Answer 4

Systole: ventricles contract (contraction)
Diastole: atria contract (relaxation)
“Lub” happens at beginning of systole
“Dup” happens at the end of systole

Question 5

SA Node

Answer 5

Bundle of cells in right atria that depolarize spontaneously through automaticity. Through gap junctions they allow depolarization of both atria at the same time. No gap junction btwn atria and ventricles.

Question 6

Atrial Contraction

Answer 6

SA node depolarizes and causes both atria to contract simultaneously. This leads to depolarization of AV node which is connected to the bundle of his. Na and Ca ions lead to action potential and L type Ca channels cause action potential. Cells are repolarized by K+ ions.

Question 7

Ventricular contraction

Answer 7

AP goes down bundle of his to the purkinje fibers and this allows for the ventricles to contract at the same time. There is a delay while the AP reaches the AV node. Rapid Na+ influx and slow Ca2+ influx cause rapid depolarization of cells. K+ leads to repolarization

Question 8

Sympathetic nervous system:

Answer 8

uses norepinephrine to increase permeability of Ca and N channels to increase heart rate

Question 9

Parasympathetic nervous system

Answer 9

Uses acetylcholine to increase permeability of K+ channels and decrease perm. of Ca channels to decrease heart rate.