1. Chapter #31 Animal Systems and Homeostasis
Structure and Function Pg

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

3. Four Tissue Types
Epithelial
Connective
Nervous
Muscular

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

5. Connective Tissue Consists of living cells in a secreted matrix.
Examples: bone, cartilage, blood.

6. Muscular Tissue
Specialized protein fibers allow these cells to contract.
Examples: skeletal muscle, smooth muscle, cardiac muscle.

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

8. Tissues Form Organs Nerves Lymph Glands Vessels Lungs Small Intestine
Skin

9. Tissues Form Organs
The skin is an example of an organ made up of multiple tissues: epithelial, muscular, nervous, and connective tissues.

10. Organs To Organ Systems
Nervous System
Endocrine System
Musculo-skeletal System
Circulatory System
Respiratory System
Digestive System
Immune System

11. Organ Systems to Organisms
Mammals
Birds
Amphibians
Reptiles
Fish
Insects

12. 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.

13. 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.

14. Maintaining Temperature

15. Blood Glucose Regulation

16. 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.

17. Thinking Questions
1. Why is positive feedback not a good way to maintain homeostasis?
2. What are some other examples of positive feedback loops in the human body?
3. Why do young animals often have more body fat than adults? How does this maintain homeostasis?