Nutrition, Digestion, & Excretion

Chapter 18

Nutrition

Nutrients are substances in foods that provide energy and materials for cell development, growth, and repair.

Energy measured in foods is in Calories. A calorie is the amount of energy needed to raise 1kg water 1 degree C.

There are six kinds of nutrients that we get in our food everyday: Carbohydrates, Proteins, lipids, vitamins, minerals, and water.

Nutrition

Proteins- large molecules made of C,H,O,N and sometimes sulfur. Proteins are made by the joining of amino acids. There are 20 different amino acids, that combine to form countless different proteins.

There are 8 essential amino acids, that our bodies cannot make and we get only from our food.

Found in eggs, milk, cheese, and meats.

Nutrition Carbohydrates- these are our main source of

energy. Made of C,H,O. There are three types: fiber, starch and

carbohydrates. Simple carbs are sugars like glucose and

fructose. Ex: in fruit, honey Complex carbohydrates include starch and

fiber, which are long chains of sugars. Ex: bread, potatoes are starch. Fiber is oats, and whole grains.

Nutrition Lipid-hold the most energy, but we do not readily

use them. They help to insulate us absorb vitamins like

A,D,E,& K. Lipids are broken down into simpler molecules

called Fatty acids. Saturated fat- these fats are solid at room temp. Bad

fat, that is found in meat and other animal products. Unsaturated fats- Liquid at room temp. Good fats

found in oils like vegetable oil. Diets high in Saturated fat is related to high

cholesterol which could lead to heart attacks.

Nutrition Vitamins- organic nutrients required in small

amounts for growth, regulation, and disease protection.

Bones need vit D, blood needs vit K. Water soluble vitamins dissolve in water. Fat soluble ones dissolve and are absorbed

only in fats. A,D,E,& K Minerals- inorganic nutrients that build cells,

send nerve impulses, and carry oxygen to blood. We use about 14 minerals.

Ex: Calcium, Potassium, Iron, Sodium.

Nutrition

Water-we are about 60% water and need to have a continuous supply to allow hydration, absorb nutrients, and excrete waste.

Food groups and pyramids.

H.W. pg. 541 ques. 1-10

Digestive System Ingestion, digestion, absorption, and elimination. Ingestion is the intake of food, digestion is the

breakdown of these food particles into useable nutrients.

Mechanical digestion is the physical breakdown of food by chewing.

Chemical digestion occurs in your digestive track by enzymes that break food down chemically.

Absorption is the body taking in the nutrients into the blood stream.

Elimination is the removal of food products that could not be used.

Enzymes

Enzymes exist in out digestive system inorder to chemically breakdown food into usable nutrients.

Ex: Amylase- breaks down carbs into simple sugars like glucose. (in mouth and stomach)

Lipase- breaks down Lipid into Fatty Acid. (from pancreas)

Protease- Breaks down proteins into amino acids. (In stomach and intestine)

Organs of the Digestive System

-Mouth- Takes solid food and mechanically breaks it down into a bolus, or ball of food. The tongue pushes this bolus down the esophagus.

Esophagus- flexible tube that connects the mouth to the stomach. And passes the bolus to the stomach through peristalsis, or involuntary muscle movement of the esophagus.

Stomach- has 2 sphincters, a cardiac and a pyloric sphincter. Food enters the stomach and is ground up by the strong walls of the stomach into a watery substance called chyme. (Chem dig)

Organs of the Digestive System

Small Intestine- accepts chyme from the stomach through the pyloric sphincter. Here digestion of solid food occurs as well as absorption of nutrients.

These nutrients are absorbed through the small intestines villi, or small folds in the small intestine.

Large intestine- Here water from the undigested food is absorbed.

Large intestine-

Organs of the Digestive System

Pancreas- attached to the first section of the Small intestine and secretes amylase into the sm. Intestine for aid in break down of food.

Liver- makes bile and send it to the gall bladder which is also attached to the sm. Intestine and allows the easier breakdown of fats