HomeostasisHomeostasisand the bodyand the body

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What is Homeostasis?What is Homeostasis?

Body cells work best if they have the Body cells work best if they have the correctcorrect TemperatureTemperature Water levelsWater levels Glucose concentrationGlucose concentration

Your body has mechanisms to keep Your body has mechanisms to keep the cells in a constant environment.the cells in a constant environment.

What is Homeostasis?What is Homeostasis?

The maintenance of The maintenance of a constant a constant

environment in the environment in the body is called body is called Homeostasis.Homeostasis.(It’s all about BALANCE!)(It’s all about BALANCE!)

What does the body What does the body balance?balance?

The body is always striving to maintain The body is always striving to maintain HOMEOSTASIS, which means balance or HOMEOSTASIS, which means balance or equilibrium between these two factors:equilibrium between these two factors:

External EnvironmentExternal Environment Internal Internal EnvironmentEnvironment

*temperature/weather*temperature/weather *sweat/shiver*sweat/shiver

*allergies*allergies *sneezing/swelling*sneezing/swelling

*work/stress*work/stress *faster heart rate/ *faster heart rate/

higher blood pressurehigher blood pressure

How does the body keep How does the body keep balanced?balanced?

In order to control In order to control homeostasis, your body homeostasis, your body uses a process called uses a process called feedback.feedback.

The body surveys the The body surveys the internal conditions and internal conditions and responds to external responds to external conditions to keep it in a conditions to keep it in a constant state of balance.constant state of balance. Any changes that vary from Any changes that vary from

the body’s normal condition the body’s normal condition result in a response. result in a response.

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It works much like a thermostat in a house!

Feedback: TemperatureFeedback: Temperature

Human beings have a body temperature of Human beings have a body temperature of aboutabout

3737ººC. If you are in a hot environment, C. If you are in a hot environment, then youthen you

begin to sweat and your skin becomes red.begin to sweat and your skin becomes red. External: Hot environmentExternal: Hot environment Internal: Blood vessels dilate and glands Internal: Blood vessels dilate and glands

produce sweatproduce sweat Feedback: Sensors tell the blood vessels to Feedback: Sensors tell the blood vessels to

relax and glands to produce sweat.relax and glands to produce sweat.

Feedback: Glucose levelsFeedback: Glucose levels

Your cells also need an exact level of Your cells also need an exact level of glucose in the blood. glucose in the blood.

Excess glucose gets turned into Excess glucose gets turned into glycogen in the liver.glycogen in the liver.

This is regulated by 2 hormones This is regulated by 2 hormones (chemicals) from the (chemicals) from the pancreaspancreas called: called:

InsulinInsulinGlucagonGlucagon

If there is too much glucose in the blood, Insulin converts some of it to glycogen

Glycogen

Insulin

Glucose in the blood

If there is not enough glucose in the blood, Glucagon converts some glycogen into glucose.

Glycogen

Glucagon

Glucose in the blood

DiabetesDiabetes

Some people do not produce enough Some people do not produce enough insulin.insulin.

When they eat food, the glucose levels When they eat food, the glucose levels in their blood cannot be reduced.in their blood cannot be reduced.

This condition is known as DIABETES.This condition is known as DIABETES. Diabetics sometimes have to inject Diabetics sometimes have to inject

insulin into their blood. They have to insulin into their blood. They have to be careful of their diet.be careful of their diet.

Time

Glucose Concentration

Meal eaten

Insulin is produced and glucose levels fall to normal again.

Glucose levels rise after a meal.

Normal

Time

Glucose Concentration

Meal eaten

Insulin is not produced so glucose levels stay high

Glucose levels rise after a meal.

Diabetic

Diabetic’s Response Diabetic’s Response After EatingAfter Eating

External FactorsExternal Factors

Organisms are affected by different Organisms are affected by different external (outside) factors:external (outside) factors: Abiotic (non-living, physical) factorsAbiotic (non-living, physical) factors

Examples: temperature, amount of water, Examples: temperature, amount of water, etc.etc.

Biotic (living) factorsBiotic (living) factors Examples: disease, predation, etc.Examples: disease, predation, etc.

What are some other biotic and What are some other biotic and abiotic factors that affect organisms?abiotic factors that affect organisms?