Digestive System

MAIN FUNCTION: break food down into small enough pieces (nutrients) Nutrients diffuse into blood and cells

Nutrition (Life Process) Way organisms get their nutrients  Autotrophic – make “food” - Plants  Heterotrophic – get “food” - Animals, Fungi

Nutrition Humans… 3 Parts: 1. Ingestion- taking food in 2. Digestion- breaking food into small pieces (nutrients) 3. Egestion – removal of solid undigested wastes (POO)

There are two types of Digestion: 1. Mechanical (Physical) Digestion 2. Chemical Digestion

Mechanical/Physical Digestion WHAT  Where food is crushed, broken or cut into smaller pieces WHY  INCREASES the surface area to help chemical digestion Ex: Teeth – chewing

Chemical Digestion WHAT  enzymes (catalysts) break down food WHY  Smaller pieces so we can absorb them into cells Examples MMouth: Saliva - enzyme amylase breaks down starch into _______________ SStomach: Gastric Juice – enzyme pepsin which digests proteins into _____________

Which type of digestion is the following? 1. Chewing a saltine? - 2. Saliva breaking the saltine down into molecules of glucose? - 3. Your tongue breaking pieces of a hamburger apart? 4. Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids?

Fats Building Block: 33 fatty acids, 1 glycerol Function: EEnergy storage IInsulation &Protection Foods FFried Foods RRed Meats BButter Bad Fats: Saturated and Trans Good Fats: Unsaturated and Polyunsaturated

Proteins Building Block:  AMINO ACID Function:  Growth and repair Foods: - -Meats - -Nuts - -Eggs

Carbohydrates Building Blocks:  SUGAR Function:  Energy or Energy Storage Foods – o Bread/Pasta o Fruits/Veggies o Sweets o Fiber

Other Molecules Water Vitamins Minerals  can be absorbed without digestion (DIFFUSED)

GI (gastrointestinal) tract

PATH of FOOD!!!!!!!!!! Simple Animation

MOUTH – Ingestion occurs Physical - Teeth – break food into small pieces Chemical - Enzymes from salivary glands break  starches into sugars

Secretion of saliva is stimulated automatically (Conditioned reflex)

EPIGLOTTIS Flap of skin – covers larynx when _______________ swallow animation swallow animation

ESOPHAGUS - Tube connects Mouth to Stomach IT‘S NOT GRAVITY…… DEMO - straw

Pinching of food by circular muscles Occurs in esophagus and intestines Peristalsis

 Begins CHEMICAL digestion of PROTEIN into ___________  HCl Acid – stomach acidic (pepsin works best)  Food forms soupy substance  Chyme The Stomach

Gastrointestinal Surgery (Gastric Bypass)

Liver, Gallbladder, Pancreas Connect to the upper small intestine. Connect to the upper small intestine.

**LIVER ** (food does not pass through) (1 st of 3 major functions!!!!) Makes BILE  Digests ____________ globlets

** Gall bladder ** Small pouch under liver that STORES bile

** Pancreas ** (given to small intestine) Pancreatic Juice – ENZYMES digest all Carbs, fats, and proteins

Small intestine TWO FUNCTIONS 1. **All DIGESTION is FINISHED here** Proteins  Carbs  Lipids 

2. **Absorption of nutrients into blood!!!!!!** Small intestine

Ways to increase surface area Villi and Microvilli Folded up many times– feet long

VILLI

Large Intestine FUNCTION – Re-Absorbs water back into body!!! NO MORE DIGESTION!!! Push indigestible food down tube (peristalsis)  ROUGHAGE (fiber)

Rectum and Anus Rectum – Stores feces Anus – Release of feces Excretion????

egestion

Digestive Real Video Digestive

Disorders of digestive system

HEART BURN (acid reflux) ACID from the stomach backs up into the esophagus (“burns”)

Heartburn

ULCERS little holes caused by enzymes too much acid or not enough mucus protecting stomach Stress, spicy foods

Ulcers

–Too much water is reabsorbed from feces and the solid waste hardens (dry) CONSTIPATION

DIARRHEA Too little water reabsorbed from feces back into the body This results in watery feces. Can result in severe dehydration, especially in infants Diarrhea SONG!!! song #2 #3#3 atch?v=ln_crYIBw00

Appendicitis - inflammation Small sac between small and large intestine becomes inflamed (may have to be removed)

GALLSTONES – Hardened cholesterol found in gall bladder Can either be “passed” (OUCH!!), surgically removed, or blasted with waves (then passed)

RECAP Digestion Stomach Small Intestine Large Intestine Why do we need a digestive system??