CONNECT!CONNECT!

What was it like What was it like learning to ride a learning to ride a bike?bike?

Could you ride in a Could you ride in a straight line and straight line and balance, at first?balance, at first?

What happened if What happened if you couldn’t?you couldn’t?

If you viewed your If you viewed your path from above on path from above on your first your first successful, successful, independent ride, independent ride, what would it look what would it look like?like?

HomeostasisHomeostasis

is is maintaining a maintaining a stablestable internal internal environment environment even in a even in a changing changing environment environment

Responses to Environmental ChangeResponses to Environmental Change

OrganismOrganism Change Change (Stimulus)(Stimulus)

Reaction Reaction (Response)(Response)

PlantsPlants Hot and dry Hot and dry weatherweather

Stomates Stomates close to close to conserve conserve waterwater

Some species Some species of bacteriaof bacteria

Temp below a Temp below a certain pointcertain point

Produce an Produce an “antifreeze” “antifreeze” chemicalchemical

HumanHuman Hears a loud Hears a loud noise at nightnoise at night

Heart rate Heart rate increasesincreases

Homeostasis is Homeostasis is the maintenance the maintenance of internal of internal conditions within conditions within a narrow a narrow rangerange that varies only that varies only slightly over slightly over timetime

it is necessary to it is necessary to keep every keep every living thing aliveliving thing alive

Blood Sugar ExampleBlood Sugar Example Blood sugar levels show a rise after a meal Blood sugar levels show a rise after a meal

but the body quickly restores these levels but the body quickly restores these levels to equilibrium using the hormone insulin. to equilibrium using the hormone insulin.

This example illustrates why homeostasis This example illustrates why homeostasis can be considered can be considered dynamicdynamic equilibrium (or equilibrium (or adjusting balance), since the body adjusting balance), since the body constantly monitors and makes constantly monitors and makes adjustments to keep us adjustments to keep us alivealive..

Homeostasis GraphHomeostasis Graph

Chunk Time!Chunk Time! Define homeostasis.Define homeostasis. Define stimulus and response.Define stimulus and response. Give examples of how plants, some bacteria, and Give examples of how plants, some bacteria, and

humans respond to changes in their environment.humans respond to changes in their environment. Explain how the body maintains blood sugar level Explain how the body maintains blood sugar level

in a narrow range after a meal.in a narrow range after a meal. Why is homeostasis also called “dynamic Why is homeostasis also called “dynamic

equilibrium”?equilibrium”? Describe a graph of homeostasis – show it with Describe a graph of homeostasis – show it with

your hands.your hands. What happens if the body condition continually What happens if the body condition continually

increases or decreases?increases or decreases? Why do you think I chose a balance to be the Why do you think I chose a balance to be the

background for the homeostasis notes?background for the homeostasis notes?

Connect!Connect!

If you are the football player that catches If you are the football player that catches the quarterback’s passes, what is your the quarterback’s passes, what is your position?position?

If you still have a house phone line, and it If you still have a house phone line, and it rings, what do you pick up?rings, what do you pick up?

So…“receptor” is another word for _____.So…“receptor” is another word for _____.

A. Cell-to-cell CommunicationA. Cell-to-cell Communication

The “Ultimate Maintainer” is the cell The “Ultimate Maintainer” is the cell membrane membrane which is for allowing materials into and out of the which is for allowing materials into and out of the cell as well as receiving cell as well as receiving messagesmessages from other from other cellscells

IS MAINTAINED BY

IS ACHIEVED BY

BOTH USING

How do the different parts of your body How do the different parts of your body “know” how to play soccer when you want “know” how to play soccer when you want them to?them to?

How does your body “know” when to go How does your body “know” when to go through a growth spurt?through a growth spurt?

It’s all about It’s all about cell to cell communicationcell to cell communication and the two systems involved – the and the two systems involved – the nervousnervous and and endocrineendocrine systems, which systems, which together coordinate and control our bodies together coordinate and control our bodies by receiving and sending messages.by receiving and sending messages.

Chunk Time!Chunk Time!

What is the function of the cell What is the function of the cell membrane?membrane?

How is homeostasis maintained?How is homeostasis maintained? How is cell-to-cell communication How is cell-to-cell communication

achieved?achieved? What does “receptor” mean?What does “receptor” mean? What two systems coordinate and What two systems coordinate and

control our bodies by sending and control our bodies by sending and receiving messages?receiving messages?

Nervous SystemNervous System

Basically your body is “wired’ the same Basically your body is “wired’ the same way the electric company has wired our way the electric company has wired our homes for electricity. You have specific homes for electricity. You have specific cells that carry messages for you called cells that carry messages for you called neuronsneurons (nerve cells). (nerve cells).

Neurons Neurons conductconduct electrical signals electrical signals called impulses very quickly from called impulses very quickly from one part of the body to another. It one part of the body to another. It takes a fraction of a second for your takes a fraction of a second for your brain to tell your body to move out of brain to tell your body to move out of the way of a speeding car.the way of a speeding car.

Nerve cells secrete Nerve cells secrete chemicalschemicals that that signal adjacent nerve, muscle or signal adjacent nerve, muscle or gland cells. gland cells.

These secretions are detected by These secretions are detected by specific specific receptorreceptor molecules on the molecules on the cell membranes which receive the cell membranes which receive the message. message.

The chemicals are called neurotransmitters.

Chunk!Chunk!

What is the proper name for a nerve cell?What is the proper name for a nerve cell? What is the job of nerve cells?What is the job of nerve cells? What kind of signals do nerve cells carry?What kind of signals do nerve cells carry? What are the chemicals called that What are the chemicals called that

neurons release at the end of the cell?neurons release at the end of the cell? How does the next cell pick up the How does the next cell pick up the

message?message? What is the gap between one neuron and What is the gap between one neuron and

the next called?the next called?

What happens if homeostasis is not What happens if homeostasis is not maintained in an organism?maintained in an organism?