What is this a picture of? What does this picture show you? What can you observe?

What is homeostasis? Describes the body's ability to maintain stable internal conditions even though the outside world is constantly changing.

Another way…. The body’s ability to keep an internal balance even though conditions outside the body change.

When is the body in homeostasis?

The Body is in Homeostasis when: The body's needs are being met - 5 survival factors - water - oxygen - nutrients - proper body temp - proper atmospheric pressure

When is your body in Homeostasis? All organ systems play an equal role in maintaining our internal functions.

Can you give an example of how the following organs maintain homeostasis? 1.Heart 2.Lungs 3. Brain 4. Kidneys

Can you give an example of how the following organs maintain homeostasis? 1. Heart: pumps oxygen to all body cells 2. Brain: controls all our internal organs and functions 3. lungs: takes in oxygen and gets rid of carbon dioxide 4. kidneys: rids the body of toxic wastes from the cells

Example: Body temperature What is normal body temperature? ______ What happens to your body when you exercise (run) in PE class?

Example: Body Temperature Normal Body temperature is 98.6 o F. (37 o C.) What happens to your body when you exercise (run) in PE class? Temp goes up slightly….and a result of that is: –Sweat –Heart rate increases slightly –Blood vessels in skin dilate and move to surface

Example: Body Temperature What happens to your body when you get cold (waiting for the bus)?

Example: Body Temperature What happens to your body when you get cold (waiting for the bus)? Temp goes down slightly….and the result of that is: - shiver - goose bumps (hair stands straight upon body) - Blood vessels in skin constrict and move away from the surface.

What happens when our body is not in homeostasis?

Called: Homeostatic Imbalance

Homeostatic Imbalance Illness –Common cold –Chicken pox –Flu Disease –Diabetes –Ulcer –cancer Aging –Organs become less efficient heart disease Cataracts (eye ) Osteoporosis (brittle bones)

Which would you rather be? A B Why??????

Negative Feedback How does the human body maintain a stable internal environment?

The body is an active system that maintains homeostasis. This system is called negative feedback. Negative feedback is the name of the MECHANISM that causes internal changes. These changes enable the body to stay in homeostasis. This keeps the body’s functions at a state of equilibrium. Negative feedback pathways keep the body function out of a homeostatic imbalances.

Characteristics of a Negative Feedback System 1. Variable: a body function maintained by NF Hasan optimal level (balance) in the human body called set point –Body temperature ( F) –Blood glucose (90 mg/dl) –Calcium levels (9-11 mg/dl) –Water levels (20% of body weight)

2. Stimulus Causes the variable to change from its optimal level to a slight imbalance. –Body temperature F to 99 0 F from exercise –Blood glucose 90 mg/dl to 150mg/dl from eating sugary meal –Calcium levels 9-11 mg/dl to 5mg/dl due to diet without calcium –Water levels 20% to 15% due excessive sweating SO WHATS THE PROBLEM????

Need to get back to Homeostasis! 3. Receptor: detects a change in body’s condition (variable not at set point). –Nerves specialized for response to particular types of stimuli.

Need to get back to Homeostasis! 4. Control Center: compares the set point of a variable to the actual condition.

Need to get back to Homeostasis! 5. Effector: the body organ or tissue that performs a function. Skeletal muscles – regulate a drop of temp control Organs –Kidneys regulate water levels Glands – pancreas release insulin to regulate blood sugar –Sweat glands regulate a rise in body temp

Need to get back to Homeostasis! NET EFFECT Body function back to homeostasis. Variable is back to its set point.

Negative Feedback Mechanism Once body is back to set point the process “turns off” the control center. As a result this turns off effector, returning the body to a state of equilibrium. Equilibrium is called ___________????????

HOMEOSTASIS!!!!