Nutrients & Homeostasi

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Metabolism & Body Heat

• Metabolism– All of the chemical reactions of the body taken

together• If rxns happen fast fast metabolism

– These people use the energy in food (measured in calories) more quickly

• Most adults need between 1700-2500 calories per day

• Exercise use more caloriesgive off more heat

• Nervous use more caloriesgive off more heat

Nutrients & Homeostasis

• Your body needs a constant supply of energy, but you don’t eat constantly

• Certain organs regulate the amount of nutrients in the blood

Liver

• Takes glucose (direct energy) out of blood and stores as glycogen (stored energy)

• OR• Converts glycogen into

glucose if body needs• Hormones regulate this

Pancreas

• Makes hormones, insulin and glucagon, which work together to control level of glucose in blood

The Hormones

• Insulin– Causes a decrease in blood glucose – If too much glucose, insulin triggers liver

to store as glycogen

• Glucagon– Causes an increase in blood glucose – If not enough glucose, glucagon triggers

liver to convert glycogen into glucose

The Cycle for Glucose Homeostasis

1. Blood glucose level is LOW2. Pancreas releases glucagon3. Glucagon directs liver to convert glycogen into

glucose4. Blood glucose level increases5. Blood glucose level becomes too HIGH6. Pancreas releases insulin7. Insulin directs liver to store glucose as glycogen8. Blood glucose level decreases9. Cycle repeats

The Cycle

What happens if this cycle gets messed up?

• Diabetes mellitus– A condition of

abnormally high blood glucose concentration

Type I Diabetes• Juvenile-onset diabetes• Severe childhood disorder in which

insulin-producing cells of pancreas die

• Treated with daily injections of insulin

Type II Diabetes

• Adult-onset diabetes• Usually diagnosed after age 40• More common and less severe• Caused by insufficient amounts of

insulin• Hereditary, but its onset often

correlates with obesity• Often controlled with diet & exercise

Diabetes• In people w/ diabetes, too much glucose

inhibits water reabsorption by the kidneys, producing large amounts of urine

• Can result in kidney damage and dehydration

Lack of insulin

• Lack of insulin can cause:– Nausea & rapid

breathing– Circulatory &

nervous system failure

– Urinary & Sexual Dysfunction

– Diabetic coma– Death