1. LG 3 – Gas Exchange, Circulation, Digestion, and Excretion
Invertebrates
Gas Exchange
Aquatic –
Terrestrial –
Circulation
Open Circulatory System –
Closed Circulatory System –
Digestion
Intracellular –
Extracellular –
Excretion
Vertebrates
Fish –
Amphibians –
Reptiles –
Crocs, Birds, Mammals –
Carnivores vs Herbivores –
Kidneys –
Function -

2. Unit III Anatomy and Physiology of Animals
Learning Goal 3
Describe systems for gas exchange, circulation, digestion, and excretion in animals.

3. Invertebrates Gas Exchange
Most aquatic invertebrates exchange oxygen and carbon dioxide through gills. They are feathery structures that expose a large surface area to the water. Examples: mollusks, arthropods.

4. Terrestrial Invertebrates
have respiratory surfaces covered with water or mucus. They range from book lungs in spiders
to spiracles (openings) that open into tracheal tubes in insects.

5. Circulation
Open circulatory system – blood contained in vessels and sinuses (large spaces) pumped by one or more heart-like organs. Examples: arthropods and most mollusks

6. Closed circulatory system
a heart-like organ forces blood through vessels that extend throughout the body. Examples: annelids and some mollusks

7. Digestion
Intracellular digestion
Small particles of food enter cells, and are broken down, then nutrients are passed to other cells.
Examples: sponges, jellyfish

8. Extracellular digestion Food is broken down outside of cells in a digestive cavity or tract then absorbed by cells. Examples: mollusks, annelids, arthropods

9. Excretion:
Aquatic Invertebrates Ammonia (a toxic by-product of protein break down) moves out of cells directly into surrounding water.

10. Terrestrial Invertebrates
Tube-like structures called nephridia turn ammonia into less toxic substances like urea and uric acid, then release it into the environment.

11. Vertebrates Gas Exchange
Gills in aquatic vertebrates like fish and amphibian larvae (tadpoles)

12. Lungs in terrestrial vertebrates like mature amphibians, reptiles, birds, and mammals.
Both gills and lungs consist of moist surfaces containing many tiny blood vessels through which oxygen and carbon dioxide move.

13. Circulation
Fish – single loop circulatory system with a two chambered heart.

14. Amphibians – double loop system with one loop carrying blood between the heart and lungs and the other loop carrying blood between heart and rest of body. Heart has three chambers.

15. Reptiles
have a double loop system with a three chambered heart, but the heart is partitioned so that there is less mixing of oxygen-poor and oxygen-rich blood than in amphibians.

16. Birds, mammals, and crocodilians have a four-chambered completely divided heart in a double loop system.

17. Digestion
All vertebrates have extracellular digestion with digestive organs suited for different feeding habits.

18. Carnivores have short digestive tracts, while herbivores have longer digestive tracts.

19. Excretion
Most vertebrates rely on kidneys to get rid of nitrogenous waste.

20. Function
As proteins are broken down, ammonia forms but is converted to less toxic urea or uric acid, then eliminated by the kidneys.
Functional unit of the kidney is the nephron.
Kidneys are also important in regulating water and other substances in body fluids.

21. LG 3 Terms Gills vs Lungs - Spiricles – Tracheal Tubes –
Open Circulatory System –
Closed Circulatory System –
Intracellular Digestion –
Extracellular Digestion –
Nephridia –
Kidneys –
Nephron –