DIGESTIVE SYSTEM Purpose for digestive system To break

DIGESTIVE SYSTEM

Purpose for digestive system To break down food into useable nutrients that can be absorbed and transported to cells throughout body Remember – we are heterotrophs!

NUTRITION The Study of What we Eat • What it does to the body • What it does for the body…Biology, Chemistry, and Physiology. • WHY WE EAT WHAT WE EAT ? • Personal Preferences • Social • Values and Beliefs • Temptation • Reward or Consolation

We need… water, salts Vitamins and minerals – to maintain overall health Macromolecules – Carbs for energy – Proteins for building and repairing of tissues – Lipids for stored energy source, brain development (babies), essential for fatsoluble vitamins

ANATOMY- know pathway food travels

PHYSIOLOGY of human digestive tract Two main parts – Alimentary canal – the tube or pathway that the food travels through – Accessory glands – outside of the “tube” but aid in digestion by secreting enzymes into the tract

Accessory glands Fill in the enzymes they secrete as we go through the whole process – Salivary gland – – Pancreas – – Liver – – Gall bladder –

How does the Peanut Butter and Jelly sandwich we eat for lunch become the vitamins our body needs? ? Must be broken down into simpler substance and absorbed into the bloodstream

Digestive System Alimentary canal= a long winding tube (with openings at each end) made of organs through which food passes. Mechanical digestion = breaking down, mashing food Chemical digestion = changing food into simpler substances using enzymes

DIGESTION The Mouth Salivary glands=Secretion of saliva Contains amylase (enzymes) breaks down carbohydrate chains. Tongue assesses the amounts and type of tastes found in saliva, and pushes the food down The Esophagus Tube through which food is transported with peristaltic motion

Pharynx – passageway for both air into lungs and food into esophagus epiglottis – blocks trachea when swallowing so bolus (food ball) enters the esophagus

Opening called the glottis is covered by a flap called epiglottis. Which prevents choking by covering the trachea (breathing tube) when swallowing. The Stomach Digests proteins using gastric juices. Enzymes=gastrin and pepsin helps in large proteins. The p. H of stomach is critical to the activation of pepsin.

Average capacity is one liter. Food stay is stomach 2 to 3 hours. Fatty meals or solid food takes longer to digest then liquids or low fat meals. Absorbs only alcohol, water and a little fat Most of major nutrients are absorbed in the small intestines. The thick liquid/partially digested food becomes chyme

Stomach v gastric juice v pepsin v mucous

The Small Intestine Duodenum The first part of the small intestine where most chemical digestion begins Small intestine can be up to 10 ft. or longer Food may remain from 4 to 10 hrs. Most digestion occurs here. Villi increase surface area for absorption

Small Intestines – the main player

Inside lining of Small Intestine MAJOR SURFACE AREA FOR MAJOR ABSORPTION!

Asorption of nutrients in the small intestine capillaries receive – carbohydrates and proteins • Nutrient rich blood from S. I. is carried via hepatic portal vessel to the liver • Liver is in charge of distributing nutrients to blood (and rest of body

Asorption of nutrients in the small intestine Lacteals receive – packaged lipids • These lead to the lymphatic system which carries the lipids to the heart

The Pancreas Long soft gland lying behind the stomach Secretes enzymes into the duodenum…trypsin, amylase, bicarbon ate Tiny intestinal glands are in lining of small intestine. The liver supplies duodenum with bile.

Bile =A yellow-green juice acts like a dish detergent and breaks fats into little globules for fat digestion Absorption of nutrients into the blood occurs throughout the wall of the small intestine The intestine wall contains millions of tiny finger-like projections called villi. Each villus contains a network of blood vessels (capillaries) Blood carries these nutrients to liver before it goes to rest of body.

Functions of The Liver Changes surplus glucose to glycogen for storage until glucose is needed. Secrets bile Stores fat Breaks down and stores amino acids used to form proteins. Detoxifies alcohol and drugs Stores vitamins A, D, E, K, and B 12 Stores iron for use in red blood cells

The Large Intestine The large intestine (colon) Can be up to 6 ft. long Holds food for as much as 3 days Major function is to reabsorb the water used during digestion and the absorption of vitamins produced by bacteria that live there and elimination Bacteria are permanent residents

Large Intestine

Bacteria aid in the digestion of plant matter. Bacteria produce vitamins B-12, riboflavin, thiamine, and vitamin K for absorption in the large intestine. Water is removed from food. Waste matter is packaged for removal ( about ½ of it is dead bacteria)

Biochemistry of Food

THE SIX BASIC NUTRIENTS Nutrients That Provide Energy Carbohydrates…simple & complex Fats…saturated & unsaturated Protein…build and repair Nutrients That Regulate Vitamins…fat & water soluble Minerals…major & trace minerals Water…most abundant nutrient

Energy = Calories Food energy = Calories 1 Calorie=1 kcal=1, 000 calories

Biochemical Review Protein Carbohydrate Lipid

Proteins=CHONS Amino acids are the smallest units Complete proteins= contain all essential amino acids, come from animal products Incomplete proteins=contain some amino acids ex. Vegetables, grains, beans, etc.

Carbohydrates Sugars = CHO simple= fructose, glucose, lactose, sucrose complex= starches, fibers

Simple sugars

Complex Carbs

Fats = Lipids do not dissolve in water Most concentrated form of energy Satisfied feeling Saturated- solid @ room temperature Unsaturated- liquid @ room temperature

Saturated vs Unsaturated Fats

Cholesterol Found in foods that come from animals LDL= Good cholesterol HDL= Bad cholesterol

Biochemistry of Food

THE SIX BASIC NUTRIENTS Nutrients That Provide Energy Carbohydrates…simple & complex Fats…saturated & unsaturated Protein…build and repair Nutrients That Regulate Vitamins…fat & water soluble Minerals…major & trace minerals Water…most abundant nutrient

Vitamins Compounds found in living things needed for life growth Prevent disease Found in foods Look at chart on p. 214

Minerals Simple substances found in the environment, essential to the body’s functioning Ca, Mg, P, K, Na, Cl Regulate the body’s processes: building bones, clotting blood Osteoporosis= lack of Ca, weak and brittle bones Hypertension= high blood pressure, caused by too much Na

Energy = Calories Food energy = Calories 1 Calorie=1 kcal=1, 000 calories

THE FOOD GUIDE PYRAMID A Guide to Daily Food Choices Guidelines for making food choices by grouping foods and recommended number of servings from each group

PRODUCT IDENTIFICATION Food and Drug Administration (FDA) Regulates the labeling of foods. The Name of Product -predominant food first…. . chicken and gravy Style of The Product- sliced peaches…. whole kernel corn. Name and Address of Manufacturer Net Weight- weight of contents only

INGREDIENTS-descending order by weight NUTRITIONAL INFORMATIONcalories and the amount of nutrients FOOD ADDITIVES- can be classified: – Preservatives-prevent food from spoiling. – ENRICHED-added to help replace those nutrients that are lost

– FORTIFIED-those having vitamins and minerals added. – EMULSIFIERS-substances that make food smooth. – LEAVENING AGENT- substances such as baking soda that makes bread and cakes rise. Over 2, 800 additives have been approved by the FDA in the U. S. PRODUCT DATING- freshness, sell and pull date, expiration.

SERVING SIZE- standard serving size determined by FDA NUTRITION LABELING- law requires all processed foods that are sources of nutrition. Calories, percentage of daily requirements, vitamins and minerals and recommended amounts HEALTH CLAIMS- can be made if the product contains certain nutrients that have proven to affect health conditions

NATURAL=No Additives ORGANIC=Grown without soil chemicals or fertilizers. HOMOGENIZED=Fat is dispersed throughout into a smooth mixture. PASTERUIZED=Partial sterilization of a substance (as milk) at a temperature for a period of exposure that destroys objectionable organisms without alteration of substance.

METABOLISM The means by which your body releases the energy in food and uses it to build and repair body tissue. The factor that determines your energy is BASAL METABOLISM the amount energy needed by the body when at rest and fasting to carry out basic life functions such as breathing, circulation and maintain body temp. which may vary with age and size.

BMR. . The rate at which the body uses energy to support its basal metabolism. MALE…. . little faster(larger mass) FEMALE…. slower CALORIE…A measure of the energy content of food. They are a measure of heat energy released when nutrients are burned or broken down. The more calories a food has, the more energy it contains.

Every gram of fat has 9 calories per gram. Every gram of Carbohydrates has 4 calories per gram. Every gram of protein has 4 calories per gram. ADIPOSE TISSURE(FAT)…. . Occurs when someone takes in more nutrients than he/she burns. Healthy goal is…. number of Kcal consumed = Kcal required by body.

CALORIES IN…incoming calories from food, the basic nutrients. CALORIES OUT…to accurately measure, estimate total energy used by the body. 3 FACTORS: 1. BMR 2. Physical Activity 3. Digestion of Food