1. Circulatory System
Vessels, Blood & Lymph

2. Blood Vessels Three types Artery, Veins and capillaries Arteries:
Function: carry blood away from heart
Thick walls
3 layers:
Innermost: smooth epithelial cells
Middle: mostly muscle
Outermost: flexible connective tissue
Pulse: the alternating expansion and relaxation of the artery wall

3. Veins and Capillaries Vein: Capillary:
Function: carries blood to the heart
Similar to artery, but walls thinner
Closer to the surface of the skin
No pulse
Has valves to prevent blood backflow
Skeletal muscles pump the blood out of the extremities
Capillary:
Function- materials are exchanged between blood and other cells (oxygen and carbon dioxide)
One cell thick

6. Direction of Blood Flow (review)
1. Heart (pumps blood out and receives blood back)
2. Arteries
Right ventricle: blood goes to lungs
Left ventricle: blood goes to body
3. Capillaries :
Exchange of materials (oxygen & carbon dioxide)
4. Veins:
Blood returns to heart.

7. Blood Components
Four types:
RBCs, WBCs, platelets & plasma

8. Blood Components

9. Red Blood Cells Carry oxygen from lungs to body cells
Mostly made of hemoglobin
Iron containing molecule that chemically binds oxygen to molecules (iron is red)
Produced in bone marrow
Has no nuclei
Pinched disk shaped

10. White Blood Cells Body’s disease fighters Larger than red blood cells
Have a nucleus
For every one WBC: RBC

11. White Blood Cells Chasing Bacteria

12. Platelets Cell fragments Helps to form blood clots How a Clot forms:
1. Platelets collect and stick to any site where blood vessels are cut
2. Platelets release a chemical that causes production of the chemical fibrin
3. Fibrin weaves a net of fibers across the wound
4. The net trap blood cells and the clot is formed

13. Blood Clot Animation

14. Plasma Liquid part of blood Mostly water Contains dissolved materials:
Fats, minerals, proteins, vitamins and glucose
Protein gives plasma a yellowish color

15. Blood Types
Four types
Percent of Population
40%
11% 4%
45%

16. Blood & Lymph System
Fluid leaks out of the blood into surrounding tissues as it circulates
The fluid is called lymph
The lymphatic system is a network of vein-like vessels that return the lymph to the blood stream
They empty into the veins