Quaestio: How do our model organisms perform the life process of transport?

1. Quaestio: How do our model organisms perform the life process of transport? Nunc Agenda: Think about the path food takes. What happens to those nutrients after they are absorbed through the villi of the small intestine?

2. What is Transport? • Transport: The life process by which substances move into or out of cells or are distributed within cells. • Remember, every cell requires substances from the environment to survive and all organisms need to have a way of getting materials to and from each cell. • Question: Can you name some of these materials?

3. Key ideas • Nutrients, gases, and wastes must be transported throughout the organism • Small animals have cells in direct contact with the environment so diffusion alone is sufficient for transport • Larger, more complex organisms require circulatory systems to move materials within the body

4. A circulatory system must have 3 parts: • 1. A fluid in which materials are transported. • 2. A network of tubes or body spaces through which the fluid flows. • 3. A way of pumping fluid through the tubes or spaces.

5. Protozoans • Unicellular • Perform cell transport through diffusion and active transport • Cell is in direct contact with the external environment

6. Diffusion

7. Hydra • Recall: Hydras have two layers of cells. • The Ectoderm • The Endoderm • Both cell layers are in direct contact with the external environment. • Materials pass by diffusion and active transport

9. Earthworm • Large and complex • All cells NOT in contact with the external environment • Closed –circulatory system • Transports materials around the body within tubes or blood vessels

12. Earthworm anatomy • 4 main parts of circulatory system • Dorsal vessel • On top – over the digestive tract • Ventral vessel • On bottom – below the digestive tract • Aortic arches • 5 “hearts” that force blood down the ventral vessel • Capillaries • Smallest blood vessels - allows for diffusion of materials in and out of cells

15. Top View

16. Top View Aortic Arches

17. Earthworm blood • Blood = a fluid that carries nutrients, gases, wastes, water, and other dissolved substances • No red blood cells • But do have hemoglobin-like pigments to carry O2

18. Earthworm Circulation • Aortic arches pump blood into the ventral blood vessel • Blood then enters the dorsal vessel at the posterior end and return to heart • Capillaries branch off the main vessels

19. Grasshopper circulation • Open – circulatory system • Blood flows within vessels some of the time, but in other areas blood flows directly into body spaces called sinuses • Blood directly bathes cells for exchange of materials

20. Grasshopper Circulatory System: Side View

21. Grasshopper circulation • Single blood vessel = the aorta • Dorsal (on back) • A tubular set of hearts is located along the back of the animal. • Blood moves through a dorsal blood vessel and then out into sinuses and directly bathes cells. • Blood then reenters blood vessels.

22. Grasshopper Blood • Grasshopper blood does not contain hemoglobin. It is actually called hemolymph. • It is colorless. • It does not transport O2 or CO2. • These respiratory gases are transported on a different pathway. • Hemolymph’s function is to transport nutrients and wastes.

23. Comparison Of Open And Closed Circulatory Systems

24. Questions: • What are the main parts of a circulatory system? • Name the processes that are involved in the transport of materials in protists. • How does a closed circulatory system differ from an open circulatory system? • What type of circulatory system do you expect to find in a bee?