Organization and Homeostasis Animal Systems Organization and Homeostasis

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

Four tissue types Epithelial Connective Nervous Muscular

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

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

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

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

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

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.

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.

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.

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.

Maintaining Temperature

Blood Glucose Regulation