Organization and Homeostasis Animal Systems Organization and Homeostasis

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

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

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.

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

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

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

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

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

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

Why is positive feedback not a good way to maintain homeostasis? R K T G E H 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?

Draw a negative feedback loop for blood calcium regulation. H 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.