Digestion and Nutrition Chapter 30 (M)

Food and Nutrients Food  Any substance, either raw or processed which is meant for human consumption Nutrients  The components of food that the body can use for growth, repair and energy

How Nutrients are Obtained Heterotrophs get nutrients in various ways

Types of Nutrients Carbohydrates Proteins Fats Vitamins Minerals Water

Food as Fuel Carbohydrates, fats and proteins are all used to generate ATP Fats  9 Calories/gm, Proteins and Carbs  4Calories/gm 1 Calorie (kilocalorie)= 1000 calories Basic Calorie need  2200 for female teens, 2500 males

Essential nutrients Must be ingested, cell can’t construct these  Essential Fatty Acids  Linoleic Acid  Essential Amino Acids  8 AA  Vitamins  water soluble (can be excreted) and fat soluble( excess might cause damages), reqd for enzyme function  Minerals  reqd, but large amts can cause damage

Nutrition and a Balanced Diet Balanced Diet  provides nutrients in adequate amounts and enough energy to maintain a healthful weight Balancing your diet  Food labels  Food guide pyramid

The Food Guide Pyramid

Number of calories depends on:  Age  Sex  Size  Whether or not you are a pregnant or breastfeeding woman  Whether you have a chronic illness The National Academy of Sciences recommends the following calorie categories:  1,600 calories - Many sedentary women and some older adults  2,200 calories - Children, teenage girls, active women and many sedentary men.  Women who are pregnant may need around 500 calories more per day and an additional 300 calories for breast-feeding  2,800 calories - Teenage boys, active men and very active women The Food Guide Pyramid can be extremely useful - whether you want to gain weight, lose weight or maintain your weight. Eating a healthy diet is a little easier if you base your choices on the Food Pyramid.

MyPyramid  USDA's newest food pyramid guide Encourages consumers to make healthier food choices To get regular exercise Food groups are arranged in vertically bands, instead of horizontal ones Band width indicates portion size The wider the band, the more food from that group should be eaten.

The Digestive System Converts food into small molecules that can be used by all cells of the body Food is processed in four phases by the digestive system

Stages of Food Processing 1. Ingestion: eating or drinking 2. Digestion : Breaking food into smaller molecules Mechanical Chemical (Enzymes) 3. Absorption: nutrient molecules enter blood, the circulatory system transports it through out the body 4. Elimination: undigested material passes out of the body

The Digestive System Functions like a series of tube like organs which pass through the body from the mouth to the anus  Alimentary Canal Alimentary Canal  can be about 30’ long Accessory organs  Pancreas, Liver, Gallbladder  secrete enzymes that are released into the food tube

Digestion in the Mouth

It all begins in the mouth... Teeth, tongue Salivary glands  Mucus  Amylase Only carbohydrates are digested here

SWALLOWING AND PERISTALSIS GLOTTIS AND EPIGLOTTIS

Peristalsis Rhythmic muscular contractions propel a bolus of food

The human digestive system

Digestion in the Stomach Muscular organ Acts as a reservoir where food is prepared for digestion in the SI Produces Gastric Juices

Stomach Functions 1. Food Storage 2. Mechanical Digestion 3. Chemical Digestion Secretions: 1. Mucus 2. Enzyme  Pepsinogen 3. HCL CHYME  semi-fluid food mixture leaves.

Protection from Self-Digestion Protective lining Main enzyme -Pepsin is inactive Pepsinogen when secreted

Digestion in the Stomach Pepsinogen  Comes in contact with HCl  Pepsin Pepsin  converts proteins into peptones Acidity of Gastric juices  kills some bacteria that enters with food Gastric Juices  stimulated by psychological and chemical means Peristaltic process of moving chyme into the SI takes place for 6hrs

Small Intestine

Digestion in the Small Intestine Main stage of Digestion As chyme enters the SI secretes juices that are alkaline and neutralizes the acidity SI  maltase,lactase,sucrase  breaks disaccharides Liver secretes bile  emulsifies fats Dipeptidases  dipeptides into AAs Pancreas  Trypsin & Chymotrypsin  break down proteins  Amylase  converts starch into maltose  Lipase  breaks fats Process is complete in about 4 hrs

Pancreas Secretes Hormones Sodium bicarbonate Digestive enzymes  Lipase  Trypsinogen  Amylase

Secretes Blood clotting enzymes Stores glycogen Bile  Stored in gall bladder  Emulsifies fat Liver

The structure of the Small Intestine

1.Anatomy: 2.Functions a. Reclaim water b. Synthesis of vitamins by E. coli Feces Rectum Anus Diarrhea Constipation LARGE INTESTINE = COLON

Can you name the parts and tell what they do?