Nutrition and Digestion: Key Concepts for Biology Students

Hunger

Physical need for food.

Appetite

Psychological desire to eat.

Satiety

Feeling of fullness after eating.

Variety

Eating different foods.

Proportionality

Balanced intake from all food groups.

Moderation

Avoiding excess calories, sugar, fat, and sodium.

Mouth

Begins digestion with saliva.

Stomach

Breaks down food with acid.

Small Intestine

Absorbs nutrients.

Large Intestine

Absorbs water.

Liver

Produces bile.

Pancreas

Produces digestive enzymes.

Simple

Monosaccharides (glucose, fructose), Disaccharides (sucrose, lactose)

Complex

Polysaccharides (starch, fiber, glycogen)

Natural

Found in whole foods, provide nutrients.

Added

Found in processed foods, provide empty calories.

Starch

Digestible carbohydrate.

Fiber

Indigestible, supports gut health.

Soluble

Dissolves in water, lowers cholesterol, slows digestion.

Insoluble

Adds bulk, helps with constipation.

Soluble

Oats, legumes, apples, bananas

Insoluble

Whole grains, fruit skins, broccoli, lentils

Soluble

Heart health, blood sugar control

Insoluble

Digestive regularity

Insulin

Lowers blood sugar

Glucagon

Raises blood sugar

RDA

130g/day

AMDR

45-65% of calories

AI for fiber

~25g (women), ~38g (men)

Added sugar

<10% of calories

Type 1

Autoimmune, insulin-dependent

Type 2

Lifestyle-related, insulin resistance

Immediate symptoms of uncontrolled diabetes

Fatigue, excessive thirst, frequent

Long-term problems of uncontrolled diabetes

heart disease, nerve damage, kidney