1. Comparative Anatomy Circulation Putting all cells in contact with the surrounding environment!

2. Circulation Organisms of small number of cells DO NOT need circulation structures ALL cells are in contact with environment for food, gases, and waste removal

3. Organisms of Large Number of Cells need circulation structures due to not all cells being in contact with the environment Substances made/collected in one part of the organism are needed in another part. Transportation Structures are needed.

4. Protozoa No Circulation Structures Only one cell All cells in contact with the environment

5. Hydra No circulatory structures 2-cells thick All cells in contact with the Environment

6. Planaria No circulation structures Yes, multi-celled, but the organism is flat. All cells are in contact with environment

7. Earthworm Closed Circulatory System 5 pairs of “hearts” Dorsal blood vessel (along back) - to head Ventral blood vessel (along belly) - to tail Branches off at each segment and connects both top/bottom vessels.

8. Grasshopper Open Circulation System “Heart” Dorsal Blood Vessel trickles through the spaces between cells (no blood vessels) Returns back to heart.

9. Human Closed Circulation 4-chambered Heart Right - to Lungs Left - to Body Pathway: Body, Rt. Atrium, Rt. Ventricle, Lungs, Lt. Atrium, Lt. Ventricle, Aorta, Body

12. Arteries AWAY from heart carry oxygen-rich blood thick, elastic walls to handle pressure allow to expand under pressure

14. Capillaries smallest of blood vessels allow one blood cell through at a time material exchange occurs here. Unites arteries with veins. BP drops

15. Veins TOWARDS Heart collect blood after pass through capillaries. Thin walled, less elastic one-way valves near Skeletal Muscles help pump blood back to heart. Exercise is important

16. Blood Pressure Body sensors too low - surrounding smooth muscles contract too high - surrounding smooth muscles relax Kidneys too high - remove water too low - re-absorb more water

17. Blood 4-6 liters of blood 45% of Blood Red Blood Cells (RBC) White Blood Cells (WBC) Platelets 55% Plasms

18. Red Blood Cells Hemoglobin Iron containing protein that increases the blood’s ability to carry oxygen Produced in Bone Marrow No Nucleus Life span 120 days Replace 1% each day

19. White Blood Cells Do not contain hemoglobin Made in bone marrow Have nuclei (long life - many months / years) Immunity Function destroy foreign invaders (bacteria, virus, parasites, etc.)

20. Platelets Blood Clotting proteins reach cut, become “sticky” and clump together - clot forms