Digestive & Excretory Systems Ch. 48

Digestive System Functions: -Breaks down food into molecules the body can use. -Molecules are absorbed into the circulatory system & carried throughout the body. -Also called the gastrointestinal tract.

First Organ of the Digestive System: Mouth: teeth and tongue 1.) mechanical digestion: chewing Salivary Glands: 2.) chemical digestion: secrete saliva (salivary amylase) for digestion of polysaccharides into diasaccharides.

Accessory Structures: Esophagus- muscular tube that connects your mouth to your stomach. -peristalsis Epiglottis- flap of tissue that seals off your trachea.

Stomach: digestion of proteins into dipeptides using mechanical & chemical digestion. Specialized stomach cells: 1. mucous cells: secretes mucous to protect the stomach. 2. parietal cells: secrete HCl. 3. chief cells: secrete pepsinogen which is converted to pepsin.

Cardiac sphincter muscle: prevents food from passing back up into the esophagus. Pyloric sphincter muscle: regulates the flow of chyme into the small instestine.

Pancrease: Secretes various digestive enzymes to the small intestines. Small Intestine: organ for completing the chemical digestion of all food and absorption of nutrients into the blood stream. -villi: increase surface area Pancrease: Secretes various digestive enzymes to the small intestines. -sodium bicarbonate, pancreatic amylase, trypsin, nucleases, lipase. Liver: functions include filtering toxic substances out of the blood, storing glucose, producing bile. Gall Bladder: stores bile for future use in the small intestine for digesting lipids.

Large intestine (colon): 1. Cecum 2. Appendix 3. Ascending colon 4. Transverse colon 5. Descending colon 6. Sigmoid colon 7. Rectum 8. Anal Canal Functions: vitamin K is produced by bacteria; remaining water is absorbed; solid waste is prepared for removal out the rectum.

Enzyme Origin Function Salivary Amalyse Salivary glands in mouth Digest polysaccharides in disaccharides. Pancreatin Amalyse Pancreas Sent to small intestines for digesting carbohydrates. Pepsin Chief cells in the stomach Digest proteins into individual amino acids. Trypsin Sent to small intestines for digesting proteins into amino acids. Bile* Liver Stored in gall bladder sent to small intestines for digesting large fat molecules into smaller fat molecules. Lipase Sent to small intestines for digesting lipids into individual parts of a fat molecules. Nucleases Sent to small intestines for digesting nucleic acids.

Excretory System Organs: 1. Lungs 2. Skin 3. Kidneys 4. Ureter- passageway from kidneys to bladder. 5. Bladder- stores liquid waste for removal. 6. Urethra- passageway leading out of the body for urine.

Kidneys…you have a pair. Functions: 1. Homeostasis 2 Kidneys…you have a pair! Functions: 1. Homeostasis 2. Removal of urea (from the liver) & other wastes. 3. Reabsorbs water back into the blood stream. 4. Regulates pH level within the blood. Nephrons (kidney ‘cells’)- act as numerous filters of the blood. Make urine!