Human Nutrition

Essential Questions What life process? How do human carry out this life process? What happens to the foods we eat? How do nutrients get into our blood stream?

What is nutrition??? Organisms obtain preformed organic compounds from environment (ingestion, digestion, and egestion)ingestion, “You are what you eat!” Your body grows rapidly, the food you eat provides the material your body needs to build cells, tissues, and organs….

7 Groups of Nutrients 1.Carbohydrates energy sources; can be broken down to enter the cell 2.Lipids produce ATP, must be broken down to enter cell 3.Proteins- must be broken down to enter cells (growth & repair) 4.Vitamins small enough to be absorbed by cells without being broken down 5.Minerals 6.Water 7.Roughage- materials body cannot digest; mostly complex carbs (cellulose, fiber, fruits & veggies); serves to push food through large intestine (egestion)

2 Types of Digestion 1. Mechanical-  No chemical changes occur  Increase surface area exposed for chemical digestion  Occurs in mouth and stomach food is broken into smaller pieces by cutting, grinding, or tearing

Chemical- “hydrolysis”  Large molecules are changed chemically to smaller molecules  Complex carbs (disaccharides/polysaccharides) broken down to  Lipids broken down to  Protein broken down to simple sugars (monosaccharides) 3 fatty acids & 1 glycerol amino acids

Human Digestive System  Continuous 1 way tract with accessory organs  Food moves through the system by peristalsis (wave-like muscular contractions)- Peristalsis Video Peristalsis Video  A trip through your digestive tract takes about hours.

Parts of the Digestive System 1.Oral Cavity (mouth) (digestion begins approx 1 min)  Ingestion occurs  Contains teeth and tongue for mechanical digestion  Salivary glands produce saliva which contains amylase that digests starch during chemical digestion 2.Pharynx (throat)  Passageway from mouth to esophagus

Parts of the Digestive System 3.Esophagus (1 min) Food tube; connects throat to stomach No digestion here Swallowing initiates peristalsis Epiglottis- flap over trachea (wind pipe) which closes when you swallow, prevents choking, inhalation of food/fluids

4. Cardiac Sphincter- muscle that controls the opening from esophagus to stomach (“heartburn”)

Parts of the Digestive System 5. Stomach- thick walled muscular organ  Mechanical digestion occurs when the stomach grinds food.  Chemical digestion occurs here:  Lining secretes HCl and pepsin  Proteins begin digestion here (protease)protease  Pyloric glands secrete mucus so stomach doesn’t digest itself!  Chyme- the soupy liquid formed from digestion of solids

Chemical Digestion in the Stomach Ulcer- Digestion in the stomach occurs for 2-6 hours for solid foods. when the mucus layer breaks down, causing sores caused by bacteria (Helicobacter pylori), stress, diet; may bleed

6.Pyloric Sphincter- muscle that controls the opening from stomach to intestines

Parts of the Digestive System 7. Small Intestine- “small” refers to diameter, not length 6.5m long, 2.5cm in diameter Partially digested food from stomach goes to the small intestine Most digestion occurs here (not stomach) All digestion is completed here

Small Intestine Absorption of nutrients occurs in the small intestine!!! Lined with villi (fingerlike projections that increase surface area for absorption) Capillaries absorb glucose, amino acids Lacteals absorb: lipid end products (fatty acid, glycerol)- part of lymphatic system

Anatomy of the Small Intestine

8. Pancreas produces and secretes pancreatic juices Into the small intestine. Aids in chemical digestion Uses several enzymes: amylase, protease, lipase

9. Gall Bladder Stores Bile made by the liver Aids in chemical digestion Bile aids in preparing fats for digestion.

10. Liver  Liver produces bile – emulsifies fats (stored in the gall bladder  Aids in mechanical and chemical digestion  Liver is the body’s largest internal organ

Digestive Enzymes Intestinal Enzymes- Pancreatic Enzymes- (dumped into small intestine) Liver produces bile (stored in the gall bladder) which emulsifies fats Fat globules are broken down to smaller fat globules through mechanical digestion to increase surface area for chemical digestion Gall stones: maltase, protease, lipase amylase, protease, lipase hard cholesterol deposits accumulated in gall bladder

You are what you eat!!! Fate of Fat

Once absorbed by the small intestine, the body can use these nutrients for: Energy Synthesis Assimilation It takes approximately 12 hours for food to travel through the small intestine!

Large Intestine 11. Large Intestine (colon)  1.5m long, 6cm diameter  Water absorbed from waste too much absorbed= too little absorbed=  Undigested food forced out through anus by peristalsis, these wastes are called  It takes 3-4 hours for food to pass through the large intestine.  FYI: The appendix= small pouch where large and small intestine join- has NO FUNCTION! constipation diarrhea feces

Summary of Digestion…. NutrientDigestions BeginsDigestion Ends Carbohydrates Protein Lipids Mouth stomach small intestine

Inside Eddie Johnson

Disruption of Homeostasis Topic: Heterotrophic Nutrition Mode of DisruptionMalfunctionDescription InheritanceLactose intoleranceInability to digest diary products (lactose) b/c you lack the enzyme lactase; results in intestinal distress Toxic SubstancesFood poisoning: caused by bacteria such as E. coli & salmonella Toxins released by bacteria cause intestinal distress & kidney disease Poor NutritionDeficiency diseases: scurvy, rickets, & goiter Lack of a vitamin or mineral in diet. Results in poor general health- need to supplement diet.

Disruption of Homeostasis Topic: Heterotrophic Nutrition Mode of DisruptionMalfunctionDescription Organ FunctionGall Stones Constipation/ Diarrhea -Accumulation of hardened cholesterol, results in disruption of bile secretion -Too little or too much water in diet Personal BehaviorEating Disorders: -anorexia -bulimia - Robs your body of essential nutrients, leads to poor general health, ulcers, and death Infectious DiseaseTapeworm (contracted when we ingest larva in uncooked or undercooked meat- if the animal had tapeworm) -Worm grows in intestinal tract -Robs your body of nutrients -Leads to deficiency diseases