An organ system comprised of organs with the major function to convert food into simpler, absorbable nutriments to keep the body functioning and healthy
Digestive system in humans
Fundamentally comprised of the gastrointestinal tract
Digestive system phases
1. Ingestion
2. Movement
3. Mechanical and chemical digestion
4. Absorption
5. Elimination
Ingestion
The process of taking food into the mouth
Mechanical digestion
Chew
Tear
Grind
Mash
Mix
Chemical digestion
Breaking larger molecules into smaller molecules through enzymatic reactions
Enzymatic reactions to improve digestion of
Carbohydrates
Proteins
Lipids
Absorption
The process of moving nutrients, water, and electrolytes from the lumen of the small intestine into the cells and then into the blood
Elimination
Molecules that are not absorbed and undigested are eliminated and pass out of your body as wastes through anus
Gastrointestinal (GI) tract
Tube within a tube
Direct link/path between organs
Structures of the GI tract
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large Intestine
Rectum
Mouth
Teeth mechanically break down food
Tongue mixes food with saliva (contains amylase, which helps break down starch)
Epiglottis, flap-like structure, prevents food entry (located in Pharynx)
Esophagus
Approximately 20 cm long
Secretes mucus
Moves food from throat to stomach via peristalsis (muscle movement)
Causes heartburn if stomach acid enters
Stomach
J-shaped muscular bag for food storage and digestion
Mixes food with Digestive Juices that contain enzymes to break down Proteins and Lipids
Kills bacteria with acid (HCl)
Chyme (food) found in stomach
Small intestine
7 meters long
Lining features finger-like villi for increased surface area
Villi covered in microvilli for increased absorption
Large intestine
1.5 meters long
Accepts what small intestines don't absorb
Rectum (short term storage which holds feces before it is expelled)
Bacterial digestion: Ferment carbohydrates, Absorb more water, Concentrate wastes
Liver
Directly affects digestion by producing bile (helps digest fat)
Filters out toxins and waste including drugs, alcohol and poisons
Gallbladder
Stores bile from the liver, releases it into the small intestine
Fatty diets can cause gallstones
Pancreas
Produces digestive enzymes to digest fats, carbohydrates and proteins