New Unit-HUMAN PHYSIOLOGY

We’ll be covering the life functions of -

NutritionCirculation (Transport)

RespirationExcretionCoordination (Nervous

and Endocrine systems)

Locomotion (Skeletal/ Muscular systems)

HOMEOSTASIS

Is necessary for all life

Homeostasis is more easily maintained by multicellular organisms with “division of labor” in their organ systems.

First Life Function:NUTRITION

Six basic kinds of nutrients can be found in food-

Carbohydrates, fats, proteins, minerals, vitamins, and water

These are essential to proper body function.

We’ll begin with CARBOHYDRATES

Found in bread, fruits, vegetables, pasta, rice, cereal. Fiber, such as bran and pears, essential for good digestion.

Used for energyMade of

monosaccharides (glucose)

DIGESTION of carbohydrates

Begins in mouth-teeth make smaller particles for more surface area.

Salivary amylase begins chemical digestion.

Digestion is finished in small intestine, where products are absorbed

ENZYMES for carbohydrate digestion

Salivary amylase from salivary glands in mouth.

Maltase, Sucrase, Lactase from small intestine.

Pancreatic amylase from pancreas

LIPIDS (Fats, Oils)

Found in meats, nuts, dairy products, cooking oils, butter.

Used for energy and building materials (cell membrane)

Made of glycerol and fatty acids

DIGESTION of lipids

Begins and ends in Small intestine

Small intestine contains structures called villi to increase the surface area for absorption

ENZYME for digestion of lipids

Pancreatic lipase from pancreas

PROTEINS

Found in meats, fish, eggs, dairy, beans, whole grains

Used for enzymes, antibodies, hormones, muscles, plasma membrane

Made of amino acids

DIGESTION of proteins

Begins in stomachFinished in small

intestine

ENZYMES for digestion of proteins

Pepsin in stomachPeptidase in small

intestine

“Accessory” organs (not in the alimentary canal)

Salivary glands and pancreas produce enzymes to help digestion of food

Liver produces bile that “emulsifies” fat, making it into smaller bubbles for more surface area.

Galls bladder stores bile

Other important organs

Large intestine absorbs water and stores wastes before egestion. Some “friendly” bacteria help make some vitamins

AND

The mouth breaks food into smaller particles for more surface area. This is mechanical digestion, not a chemical change

The esophagus pushes food into the digestive tract, beginning peristalsis, rhythmic contractions that churn the food and move it on.

Chemical Reaction

The chemical reaction that is used in digestion is called HYDROLYSIS

This is a reaction where water splits the molecule into smaller parts:

Ex-Protein into polypeptides into dipeptides into amino acids

ENZYMES

What are they?A protein (coded for

by DNA) that changes the rate of a reaction.

Some of these reactions would be so slow that it would seem that they wouldn’t occur at all.

What affects enzyme action?

TemperaturepHAmounts of

“substrate”(the chemical it works on) and the amount of enzyme

ENZYME ACTION

There is an “optimum” temperature, and an optimum (or “best) pH for each enzyme action, depending on where it is working.

Example-Enzymes that work in the mouth would no longer work in the stomach. The pH changes dramatically. The enzyme is denatured, losing its shape.

ENZYME ACTION

The amount of substrate, the substance the enzyme works on, affects the rate of the reaction.

The amount of enzyme affects the reaction.

BUT, an enzyme can only work so fast, so the rate will level out.

Enzyme Action-What might the optimum pH be for each enzyme?

0

10

20

30

40

50

60

70

80

90

mouth stomach intestine

Lipasepepsinamylase

Enzymes are specific

An enzyme only works in a reaction with one molecule-lactase hydrolyzes lactose or assembles lactose.

Take your vitamins!

Vitamins are organic molecules that are required in small amounts to maintain growth and metabolism.

They are called co-enzymes because they help enzymes function.

Minerals aren’t just for miners!

Minerals are inorganic substances that serve as building blocks – bones- or take part in chemical reactions.

DISORDERS of digestive system

Diarrhea can be caused by infection or poor diet

Constipation is caused by lack of fiber and/or water in your diet

These can both be relieved by diet and/or medication