Homeostasis is everything organisms do to keep their internal state stable The inside of the organism is kept constant

Homeostasis includes: Eating Eating Drinking Drinking Sleeping Sleeping Resting Resting Searching for resources Searching for resources And so much more… And so much more…

Everything that is alive does homeostasis including: Cells Bacteria Mammals Insects Lizards Birds Sponges Mollusks Fungus Plants

We will focus on plants and humans.

The problem is everything is always changing. Day turns to night Day turns to night Weather changes Weather changes Resources are limited so we have to find new ones Resources are limited so we have to find new ones And other organisms are competing with us And other organisms are competing with us The resources in our bodies get used up The resources in our bodies get used up Waste piles up Waste piles up And so much more… And so much more…

When something changes and an organism has to react – that is called a stimulus. A stimulus is a change that an organism has to react to More than one stimulus are called stimuli.

Stimuli can be internal or external External Internal External

Whatever the organism does – that is the response A response is what an organism does when it reacts to a stimulus.

A stimulus is a cause, and the response it the effect.

The rule is that the response has to be an action. (like eating, drinking, getting a fever, growing a certain way, running away, and so muc more…)_

The rule is that the response has to be an action. (like eating, drinking, getting a fever, growing a certain way, running away, and so muc more…)_

A response can be positive, like growing or moving toward something. Or a response can be negative, like running away from or growing in the other direction

A an organism called a baby smells bacon (a stimulus) and crawls toward it (a positive response).

A an organism called a baby is burned by a frying pan (stimulus) and cries and rolls away (response).

 The dog wants the sausage because he is very hungry and the sausage looks very juicy.  The dog cannot resist the urge to eat the sausage so it goes and eats it.  Organism = Dog  Stimulus = Hunger  Response = Eat sausage

What organ systems are involved in this reaction? When the sugar hits the brain, the brain tells the pancreas to release insulin, which tells the body to suck up that sugar and start turning it into fat for storage. Digestive (getting the sugar) Nervous (brain) Endocrine (pancreas)

What organ systems are involved in this reaction? The muscles tell the nerves, the nerves tell the adrenal glands, and the adrenal glands tell the heart and lungs to try harder Muscular (muscles) Nervous (nerves) Endocrine (adrenal glands)

What organ systems are involved in this reaction? The immune system tells the brain, and the brain tells the rest of the body to turn up the temperature and try not to work to hard while the invaders are defeated. Immune system Nervous (brain)

What organ systems are involved in this reaction? The brain detects the change and coordinates shivering muscles, and pulls blood into the center of your body away from the skin. Nervous (brain) Integumentary (skin) Everything else that gets blood

What organ systems are involved in this reaction? Eyes tell the brain that it is time to run away. The brain tells the digestive system to wait for a better time, and sends all resources to the muscles. Plus it puts the heart and lungs into overdrive. Nervous (eyes and brain) Digestive Muscular Cardiovascular / Circulatory Respiratory