1. Biology 103 - Main points/Questions 1.What was the answer to that question? 2.Remember muscles? 3.How do organisms keep cells supplied?

2. Keeping cells supplied All cells require supply of energy and “parts” as well as removal of waste products. –For example – muscle cells need sugars and oxygen for ATP production –They also generate waste carbon dioxide How do organisms keep cells supplied and waste levels low?

3. Some organisms use diffusion as primary means of moving material around. This works well for single cells.

4. Remember diffusion? Movement from high concentration to low –Doesn’t require any energy expenditure to make happen –Works very quickly over short distances –Important transport mechanism of cellular material

5. Factors controlling diffusion rate: Temperature Size of molecule: Concentration gradient: Surface area: Distance: Medium

6. What are some Materials in a cell that need to diffuse Energy rich molecules (ATP, glucose...) Cellular products (proteins, tRNA...) Ions and cell nutrients (Na +, amino acids) Gasses (oxygen and carbon dioxide)

7. Diffusion is crucial for moving cellular material over small distances but…

8. Some have very simplified circulatory systems that simply move fluid into & out of a gastro-vascular cavity.

9. More complex organisms have more need for specialization of tissues/organs/organ systems

10. These specialized systems keep cells bathed in solutions full of the materials needed for life and free from waste products

11. Cells still use diffusion over short distance (the local environment) But these organisms need a circulatory system to move fluids throughout the organism.

12. Some use an internal pump to circulate fluid inside the body’s cavities. (called an open circulatory system!)

13. Others use pumps to circulate fluid inside interconnecting tubes. (called a closed circulatory system!)

14. Goal is to move fluids quickly over large distances so diffusion can do its work over small distances. Mammals use a 4-chambered heart to circulate blood. Blood movie

15. Blood = Connective tissue Has cells (red, white) surrounded by extracellular matrix (fluid = plasma) Transports nutrients like glucose, amino acids, oxygen… Removes waste products like carbon dioxide and urea Type of cells

16. (c) Mammals, birds lung capillaries body capillaries ventricles atria One pair of chambers collects blood from the body and pushes it to the lungs The other pair collects blood from the lungs and pushes it to the body

17. Each circuit of blood flows through a series of tubes as it leaves and then returns to the heart.

18. Blood flows into the heart from the body and enters into the right atrium From here it flows into the right ventricle and out to the lungs

19. Returning from the lungs into the left atrium And then into the left ventricle where it is pushed to the body through the aorta.

20. The energy for all of this fluid movement comes from the contraction of the heart - specifically cardiac muscle tissue.

21. The chambers contract in a very specific cycle that goes like this: Contraction of the two atria Contraction of the two ventricles Relaxation of the heart

22. The chambers contract in a very specific cycle that goes like this: Contraction of the two atria –This pre-pressurizes

23. 1 Atria contract, forcing blood into the ventricles.

24. The chambers contract in a very specific cycle that goes like this: Contraction of the two atria –This pre-pressurizes Contraction of the two ventricles –Forces blood out of heart into arteries

25. 2 Then the ventricles contract, forcing blood through arteries to the lungs and the rest of the body. This stage generates peak blood pressure called systolic pressure

26. The chambers contract in a very specific cycle that goes like this: Contraction of the two atria –This pre-pressurizes Contraction of the two ventricles –Forces blood out of heart into arteries Relaxation of the heart –Blood flows into atria and ventricles –Why not backwards?

27. 3 The cycle ends as the heart relaxes. This is where pressure is at a minimum - called diastolic pressure.

28. 1 Atria contract, forcing blood into the ventricles. 2 Then the ventricles contract, forcing blood through arteries to the lungs and the rest of the body. 3 The cycle ends as the heart relaxes.

29. systolic pressure diastolic pressure

30. Path of blood flow in circuits and role of capillaries

31. Arteries Blood leaving the heart Deal with high pressure Very little exchange with surrounding tissue

32. Capillaries Lower pressure Major location of exchange Very “leaky”

33. . Veins Return blood to the heart Lowest pressure

34. Fig. 29.7 Low pressure in veins means: Valves “muscle assist”

35. Why does exchange happen in capillaries? Speed of blood in capillaries is much lower Like a wide spot in a river… Capillary bed leaks fluid into interstitial fluid This “stirs” the interstitial fluid Makes diffusion even more efficient But more fluid leaves than returns…

36. Fig. 29.9 What type of tissue?