Body Systems and Cells: Temperature Regulation

I. How do living things stay alive in extreme temperatures? One of the characteristics of living things is that they can maintain stable internal conditions. This is called homeostasis. One type of balance that organisms must maintain is temperature balance. Why do you think organisms would want to maintain stable temperatures? Why not just let your body be any temperature? _______________________________________

Some organisms are ectotherms – they get heat from their external environment. ECTO = outside THERM = heat Some organisms are endotherms – they make their own heat through metabolism (chemical reactions) and other ways such as shivering. ENDO = inside THERM = heat I. How do living things stay alive in extreme temperatures?

Some Ways Living Things Carry Out Thermoregulation: Dogs – panting Squirrels – laying on cool surfaces Lizards – sitting in the sun Cows – finding shade Kangaroos – licking arms Humans – sweating and vasodilation Kangaroo licking its arms to cool down on a very hot day

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? Two body systems that are involved in thermoregulation are the circulatory system and the nervous system.

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? CIRCULATORY SYSTEM: The circulatory system includes the heart, veins, arteries, and capillaries. These last three are called blood vessels. The specialized function of this body system is to pump blood to cells in the body. Blood carries oxygen, carbon dioxide, and nutrients to and from cells.

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? CIRCULATORY SYSTEM: Red blood cells are specialized cells that have iron atoms in them. Oxygen diffuses through lung tissues into blood vessels and binds to (sticks to) the iron in the red blood cell. Then when the red blood cell reaches an area that has a low amount of oxygen, the oxygen diffuses into the cells that need it.

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? How does the structure (shape and make-up) of a red blood cell match its function (its job)? ______________________

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? NERVOUS SYSTEM: The nervous system includes the brain, spinal cord, and nerves. The specialized function of this body system is to send and receive messages through the body with electrical currents and chemical signals.

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? NERVOUS SYSTEM: Nerves are specialized cells that have many protein pumps. The pumps can pump + or - ions into our out of the cell. When these ions flow back to equilibrium, they create an electric current.

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? NERVOUS SYSTEM: Nerves also have dendrites and axon terminals, extensions that let them communicate with many other nerve cells to create complex thoughts. Video

II. How Do Humans Maintain Homeostasis in Extreme Temperatures? How does the structure of a nerve cell match its function? _____________________

III. So What Do These Systems Have To Do With Temperature Regulation? A part of the brain called the hypothalamus is constantly monitoring body temperature. (For humans, it should be 98.6°F) If the body is too hot or too cold, the brain sends an electrochemical signal to other parts of the body.

III. So What Do These Systems Have To Do With Temperature Regulation? TOO HOT  Brain sends a signal telling veins to dilate (get larger). This allows heat to leave the blood more quickly.

III. So What Do These Systems Have To Do With Temperature Regulation? TOO HOT  Brain sends a signal telling skin to start sweating. This allows hot water molecules to leave the skin, making the skin cooler.

III. So What Do These Systems Have To Do With Temperature Regulation? TOO COLD  Brain sends a signal telling veins to constrict (get smaller). This allows the body to conserve (save) heat.

III. So What Do These Systems Have To Do With Temperature Regulation? TOO COLD  Brain sends a signal telling muscles to shiver (shake). This creates heat, raising the internal temperature.