Transcript Homeostasis
CONNECT! What was it like learning to ride a bike? Could you ride in a straight line and balance, at first? What happened if you couldn’t? If you viewed your path from above on your first successful, independent ride, what would it look like? Homeostasis is maintaining a stable internal environment even in a changing environment Responses to Environmental Change Organism Change (Stimulus) Reaction (Response) Plants Hot and dry weather Stomates close to conserve water Produce an “antifreeze” chemical Heart rate increases Some species of Temp below a bacteria certain point Human Hears a loud noise at night Homeostasis is the maintenance of internal conditions within a narrow range that varies only slightly over time it is necessary to keep every living thing alive Blood Sugar Example Blood sugar levels show a rise after a meal but the body quickly restores these levels to equilibrium using the hormone insulin. This example illustrates why homeostasis can be considered dynamic equilibrium (or adjusting balance), since the body constantly monitors and makes adjustments to keep us alive. Homeostasis Graph Chunk Time! Define homeostasis. Define stimulus and response. Give examples of how plants, some bacteria, and humans respond to changes in their environment. Explain how the body maintains blood sugar level in a narrow range after a meal. Why is homeostasis also called “dynamic equilibrium”? Describe a graph of homeostasis – show it with your hands. What happens if the body condition continually increases or decreases? Why do you think I chose a balance to be the background for the homeostasis notes? Connect! If you are the football player that catches the quarterback’s passes, what is your position? If you still have a house phone line, and it rings, what do you pick up? So…“receptor” is another word for _____. A. Cell-to-cell Communication The “Ultimate Maintainer” is the cell membrane which is for allowing materials into and out of the cell as well as receiving messages from other cells HOMEOSTASIS IS MAINTAINED BY CELL TO CELL COMMUNICATION IS ACHIEVED BY NERVOUS ENDOCRINE SYSTEM SYSTEM BOTH USING RECEPTORS IN CELL MEMBRANE How do the different parts of your body “know” how to play soccer when you want them to? How does your body “know” when to go through a growth spurt? It’s all about cell to cell communication and the two systems involved – the nervous and endocrine systems, which together coordinate and control our bodies by receiving and sending messages. Chunk Time! What is the function of the cell membrane? How is homeostasis maintained? How is cell-to-cell communication achieved? What does “receptor” mean? What two systems coordinate and control our bodies by sending and receiving messages? Nervous System Basically your body is “wired’ the same way the electric company has wired our homes for electricity. You have specific cells that carry messages for you called neurons (nerve cells). Neurons conduct electrical signals called impulses very quickly from one part of the body to another. It takes a fraction of a second for your brain to tell your body to move out of the way of a speeding car. Nerve cells secrete chemicals that signal adjacent nerve, muscle or gland cells. These secretions are detected by specific receptor molecules on the cell membranes which receive the message. The chemicals are called neurotransmitters. Chunk! What is the proper name for a nerve cell? What is the job of nerve cells? What kind of signals do nerve cells carry? What are the chemicals called that neurons release at the end of the cell? How does the next cell pick up the message? What is the gap between one neuron and the next called? What happens if homeostasis is not maintained in an organism?