1. Digestive System

2. The Digestive System
Digestion: mechanical and chemical breakdown of food and absorption of nutrients
Anatomy of the digestive system:
Alimentary canal: 8 meter long muscular tube from mouth to anus (mouth, throat, esophagus, stomach, intestines)
Accessory organs that aid in digestion (pancreas, liver, gallbladder, salivary glands)

3. Mouth
Tongue: skeletal muscle, mixes food with saliva, aids in swallowing, has taste buds
Teeth: 32 in adult, breaks food into smaller pieces
Salivary glands: secrete saliva to moisten food and start chemical process of digestion; contains amylase- enzyme that breaks down carbohydrates

4. Pharynx and Esophagus
Muscular tubes that propel food to stomach but do not digest food
Esophagus- 25 cm long, has esophageal sphincter at entrance to stomach to prevent food from coming back up

5. Stomach
Receives food from esophagus, mixes with gastric juice, begins protein digestion
Gastric juice: mix of hydrochloric acid, pepsin (digests protein), mucus
Mucus lining prevents stomach from digesting itself (acid eating through stomach wall)
Chyme- product of food mixing with gastric juice, sent to small intestine

6. Small Intestine
Receives secretions from pancreas and liver, digests chyme from stomach, absorbs nutrients, transports residue to large intestine
Intestinal villi- fingerlike projections that line wall of small intestine, increase surface area for absorption
Intestinal enzymes:
Peptidase- protein digestion
Sucrase, maltase, lactase- sugar digestion
Intestinal lipase- fat digestion

7. Pancreas Secretes mix of digestive enzymes- pancreatic juice
Enzymes in pancreatic juice:
Pancreatic amylase- breaks carbohydrates into sugars
Pancreatic lipase- digests fat
Trypsin, chymotrypsin, carboxypeptidase- protein-splitting enzymes

8. Liver High rate of fatty acid metabolism Formation of glucose
Very important role in protein metabolism
Removes toxins, filters blood for damaged RBCs and foreign substances
Secretes bile- helps digest lipids
Excess bile stored in the gallbladder

9. Large Intestine Absorbs water and electrolytes, forms and stores feces
Appendix- small projection with no function
Intestinal bacteria break down cellulose (plant carbohydrates) and synthesize some vitamins
Rectum- temporary storage for feces at end of large intestine
Anus- opening at end of large intestine

10. Vitamins and Minerals
Vitamins: organic compounds needed in small amounts for metabolism
Fat Soluble Vitamins: stored in fat, so overdose is possible; Vitamins A, D, E, K
Water Soluble Vitamins: dissolve in water, so any extra is excreted, not stored; B Vitamins, Vitamin C
Minerals: small amounts of elements needed in metabolism; Calcium, Phosphorus, Potassium, Sodium, Magnesium

11. Digestive System Review
Besides fat and protein digestion, what other important function does the liver perform?
In what digestive organ do most of the nutrients get fully digested and absorbed?
What organs play no role in digestion but are merely used for transport?

12. Urinary System

13. The Urinary System Functions:
Remove salt and nitrogenous waste from blood
Maintain water/electrolyte balance in body
Regulates volume of body fluids
Help control RBC production

14. Organs of Urinary System
4 main organs in urinary system:
Kidney- filters waste out of blood and controls how much water is excreted
Ureters- transport waste from kidneys to bladder
Bladder- stores waste (urine)
Urethra- transports urine from bladder to outside

15. The Kidney
Nephron: site of blood filtration in kidney, about 1 million contained in kidney

16. Urine Formation 3 Steps:
Glomerular Filtration: Water, ions, and other plasma substances are filtered out of blood and into glomerular capsule
Tubular Reabsorption: certain substances from filtrate are reabsorbed (glucose, amino acids, water, some ions)
Tubular Secretion: Waste substances missed in glomerular filtration are removed from blood (ammonia, hydrogen ions, potassium ions, penicillin, histamine)

17. Urine Composition
Volume of urine related to fluid intake (drinking more fluids produces more urine), between 0.6 and 2.5 L per day
About 95% water, with urea, uric acid, some amino acids and salts
Urea and uric acid: by-products of metabolism of amino and nucleic acids

18. Urine Elimination Travel from kidney to bladder through ureters
Bladder holds ~600 mL urine, urge to urinate comes from bladder contractions which start around 150 mL full
Sphincter at bladder opening keep bladder closed, urination occurs when muscles relax and sphincter open