Lesson Objectives Students will understand the importance of homeostasis Students will understand the two types homeostatic of organisms Students will understand the two main ways organisms respond to stimuli Students will be introduced to the important factors of homeostasis in humans

Homeostasis The ability of an organism to adjust its internal intracellular environment to deal with the outer environment for survival.

Organisms must live with-in certain parameters to survive optimally! The CONFORMERS of the world- Say “Tell me how it’s going to be ‘environment’ and I’ll do what you say.” The REGULATORS of the world say “The heck with what the ‘environmental factors’ are, I’m doing it my way!!” That said, there are 2 types of organisms in this world….

Regulators Most regulators are usually endothermic animals, mammals and birds. They maintain a relatively constant body temperature.

CONFORMERS Conformers are mostly ectothermic animals. They consist of most all organisms other than mammals and birds. Their body temperatures are able to fluctuate quite a bit.

Homeostatic systems have 3 parts 1- Receptor- Something that determines what the environment is like. Monitors changes in the outer environment. Think of a thermometer or water sensor in a greenhouse. Tells us how hot or cold our outer conditions are. 2-Control center- Part of the system that determines when something needs to be done and decides what will be done to deal with the change in the external environment. The thermostat or greenhouse monitoring system. *Determines how hot or dry things are and then determines whether to turn on the heater or the air conditioner and determines when and how much to water.* 3- Effector- The reaction of the organism to the outer environment, to return the organism back to optimal working conditions. This is the heater, the a/c unit or the sprinkler. Whatever is used to return the system to optimal levels.

Feedback is the system’s response to a stimulus Positive Feedback Feedback that accelerates the normal output of a system Positive feedback mechanisms are designed to push levels out of normal ranges. Examples- Accumulation of blood platelets to promote blood clotting. Negative Feedback feedback reducing the output or activity of any organ or system back to its normal range of functioning. Blood vessels sense resistance of blood flow against the walls when blood pressure increases. The blood vessels act as the receptors and they relay this message to the brain. The brain then sends a message to the heart and blood vessels, both of which are the effectors. The heart rate would decrease as the blood vessels increase in diameter (or vasodilation). Resulting in less pressure.

What part of your body does homeostasis effect?...Pretty much all of it!! Quick question, what would happen if we couldn’t sweat?

In humans there are 6 main bodily levels that need to be controlled. CO2 and Urea need to be disposed of, and Ion content, water content, sugar content (of the blood), as well as temperature all need to be kept at a constant level. CO 2 – Created and removed by gas exchange in the lungs. Urea- Poisonous fluid created as a by product of breaking down amino acids. Ion content- minerals taken in with food and absorbed in the bloodstream. Removed by the kidneys and sweating. Water content- levels in the blood are monitored by the hypothalamus. The kidneys are responsible for water levels. Sugar content- The liver and pancreas work to control sugar levels in the blood. The pancreas produces insulin, which makes the liver turn glucose into glycogen. Temperature- Blood temperature is monitored by the hypothalamus, which then sends nerve impulses to the skin.

Almost all mammals can regulate their body temperatures to conform to a certain temperature parameter. Why not me!!!

Homeostasis In conclusion  Organisms ability to keep constant intracellular conditions.  2 Types of organisms REGULATORS and CONFORMERS  3 Parts of a homeostatic system  Receptor  Control Center  Effector  2 Types of responses  Negative feedback  Positive feedback  There are many different types of organisms and all organisms rely on homeostasis for optimal growth and production.