Animal Systems

1. Animal Systems • Organization and Homeostasis

2. Which of these is the correct sequence of levels of organization? • Organs -> cells -> tissues -> organs • Cells -> organs -> organ systems -> tissues • Cells -> tissues -> organs -> organ systems

3. W O R K T O G E T H E R • Of all human body systems, which do you think is most important. Discuss. Try to explain your answer.

4. Organization in Living Things • Cells are organized into tissues • Tissues are organized into organs • Organs are organized into systems • Systems form an organism

6. Four tissue types • Epithelial • Connective • Nervous • Muscular

7. Epithelial tissue • Epithelial cells form the outer covering, line the internal cavities, and make up the glands. • Examples: Skin, mucous membranes.

9. Connective tissue • Consists of living cells in a secreted matrix. • Examples: bone, cartilage, blood.

10. Muscular tissue • Specialized protein fibers allow these cells to contract. • Examples: skeletal muscle, smooth muscle, cardiac muscle.

11. Nervous tissue • Neurons have the ability to pass an “electrical” signal from one cell to another, or to target cells (muscles, glands, organs).

12. Tissues form organs • The skin is an example of an organ made up of multiple tissues: epithelial, muscular, nervous, and connective tissues.

13. A group of cells that perform a similar function is know as: • Tissue • Organ • Organ system • Organism

14. One cell type that must undergo continual loss and replacement is: • Epithelial tissue • Connective tissue • Muscle tissue • Nervous tissue

15. Which tissue type is in direct contact with the environment? • Epithelial • Muscle • Nervous • Connective

16. Homeostasis • Homeostasis is the act of keeping the internal environment of a living organism within an acceptable range of conditions. • Homeostasis controls temperature, pH, blood volume, oxygen levels, blood sugar levels, and other conditions. • Negative feedback maintains homeostasis.

17. Negative Feedback • Negative feedback keeps conditions within an ideal range. • As conditions exceed the limits of the ideal range, chemical signals (hormones) regulate conditions. Most often this is controlled by the hypothalamus in the brain.

18. Positive Feedback • Positive feedback takes a condition out of the normal range, often to some end point. • During labor, oxytocin increases contractions, which stimulate more oxytocin production, until birth occurs.

19. Maintaining Temperature • Ectotherms are animals that derive body heat from the environment. Their body temperature may vary widely. • Endotherms rely on metabolic reactions and physiological systems to maintain a steady body temperature.

20. Maintaining Temperature

21. Blood Glucose Regulation

22. Body systems maintain homeostasis through: • Positive feedback systems. • Negative feedback systems. • Uncontrolled feedback systems.

23. True or false: “cold blooded” animals always have a lower body temperature than “warm-blooded” animals. • True • False

24. W O R K T O G E T H E R • Why is positive feedback not a good way to maintain homeostasis? • What are some other examples of positive feedback loops in the human body? • Why do young animals often have more body fat than adults? How does this maintain homeostasis?

25. W O R K T O G E T H E R • Draw a negative feedback loop for blood calcium regulation. • Falling calcium level signals release of parathyroid hormone from the parathyroid glands. Calcium is released from bones, increased uptake by digestive system. • Rising calcium level signals release of calcitonin from the thyroid. Blood calcium is taken up into bone tissue.