1. Every cell in body needs nutrients and oxygen to function
Circulatory system- transports blood and other materials vital to the cells and carries away wastes

2. The circulatory system moves blood to all parts of the body
Functions to transport O2 and nutrients to body cells and carry oxygen poor blood and CO2 back to the heart and lungs

3. Main parts of system are heart, blood, and blood vessels
a. Heart- muscular pump
b. Blood- circulates through a closed system
1). About 5 liters
2). Takes about 60 seconds for round trip

4. Blood vessels- three types
1). Arteries- carries blood away from heart (oxygen rich)
2). Veins- carries blood back to heart (oxygen poor)
3). Capillaries- smallest vessels where materials can diffuse into and out of cells

5. The tissues and structures of the heart make it an efficient pump
Consists of four chambers
a. Atrium- right and left sides (smaller chambers)
b. Ventricles- right and left sides (larger chambers)
c. Valves- flaps of tissue that prevent blood from flowing backwards

6. Blood flow in heart
a. Oxygen poor blood enters right atrium and pumped into right ventricle
b. Right ventricle pumps blood to lungs for gas exchange
c. Returns to left atrium and pumped to left ventricle
d. Left ventricle pumps blood to rest of body (this is the largest chamber)

7. The heart pumps blood through two main pathways
Pulmonary circulation – heart pumps oxygen-poor blood to the lungs, blood becomes oxygen-rich & returns to the heart
Systemic circulation – heart pumps oxygen-rich blood to body tissues & then the oxygen-poor blood returns to the heart

8. Blood Vessels and Transport
Arteries carry blood away from the heart
Must be strong & flexible to withstand the pressure of the heart pumping the blood through
Walls are made up of 3 thick layers of tissue

9. Veins carry blood back to the heart
Larger in diameter and have thinner layers of tissue
Valves prevent the backflow of blood

10. Capillaries allow materials to diffuse in and out of the blood quickly & easily
Very small in diameter
Made up of a single layer of tissue, sometimes only 1 cell layer thick

11. Factors that Affect Blood Flow
Inner walls of blood vessels must be smooth and free of obstruction to allow for proper blood flow
Factors that affect blood flow include:
Blood viscosity (thickness)
Blood clots
Diameter of blood vessels

12. Blood pressure- force with which blood pushes against wall of an artery (E.g. 120/70)
Blood pressure rises naturally with activity, stress, & strong emotions
Permanently high blood pressure (hypertension) can be a sign of circulatory disease and can lead to heart attack or stroke
Blood pressure can usually be lowered through proper diet & exercise
Low blood pressure (hypotension) can be caused by problems such as shock or capillary leak syndrome

13. Lifestyle plays a key role in circulatory disease
1. Increased risk of developing circulatory disease with: smoking, lack of exercise, excessive weight, long-term stress, diet high in saturated fats

14. 2. Arteriosclerosis- artery walls become thick and inflexible
3. Artherosclerosis- blood flow partially or fully blocked by sticky material called plaque