1 / 19

The Digestive System

The Digestive System. Group of organs working together to convert food into energy and basic nutrients to feed the body C arbohydrates, proteins, fats, vitamins, minerals. Digestive System – 4 Stages . Gastrointestinal Tract. Long tube that begins at the mouth and ends at the anus

hoang
Download Presentation

The Digestive System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Digestive System • Group of organs working together to convert food into energy and basic nutrients to feed the body • Carbohydrates, proteins, fats, vitamins, minerals

  2. Digestive System – 4 Stages

  3. Gastrointestinal Tract • Long tube that begins at the mouth and ends at the anus • Mouth→ Pharynx→ Esophagus→ Stomach→ Small Intestine→ Large Intestine→ Rectum→ Anus • Also called the alimentary canal

  4. Accessory Organs • Play a direct role in digestion but are not a part of the GI tract • Salivary Glands (parotid, submandibular, sublingual) • Secrete saliva, which contains enzymes that initiate breakdown of carbohydrates • Liver • Produces bile to help emulsify fats in the small intestine • Gall Bladder • Stores bile that the liver produces • Pancreas • Secrete bicarbonate ions to help buffer acid concentration of chyme • Secretes digestive enzymes

  5. Mechanical Digestion • Mouth, teeth, tongue, stomach • Food enters the mouth via ingestion • Food is prepared for chemical digestion by chewing, mixing, churning • Tongue pushes food back to prepare for swallowing • Bolus • Mass of food that has been chewed at the point of swallowing

  6. Propulsion • Process of moving food through the GI tract • Swallowing • Peristalsis • Smooth muscle contraction and relaxation • Esophagus, stomach • Sphincter (valves) • Circular muscle that controls movement of food throughout the GI tract

  7. Heartburn • Faulty sphincter • Gastric juice coming up from stomach causing damage to the esophagus • Causes • Smoking, alcohol, ibuprofen, aspirin, caffeine, large meals • Treatment • Zantac, Gaviscon, Pepcid, PeptoBismol, Prilosec, Acidopholous • Can Lead to GERD • Gastroesophageal reflux disease

  8. Chemical Digestion (Enzymes) • Salivary Glands • Secrete amylase – breakdown carbohydrates • Stomach • Secrete pepsin – breakdown protein • Pancreas • Secrete trypsin – breakdown protein • Secrete lipase – breakdown fat • Small Intestine • Secrete lactase – breakdown lactose

  9. Stomach • Bolus enters the stomach through the esophageal sphincter • Gastric juice • HCl – kills or inhibits bacteria and provides acidic pH of 2 • Enzymes – chemical digestion • Mucus – protects lining of stomach from acidic environment • Bolus is converted into chyme by gastric juice

  10. Helicobacter pylori • Bacteria that is found in the stomach • Causes gastritis, gastric ulcers by preventing mucus from forming • Also linked to stomach cancers

  11. Small Intestine • Site of nutrient absorption • Villi – increase surface area for absorption • Fingerlike projections that protrude from small intestine • Each villi contain a network of capillaries and microvilli • Nutrients are transported into capillaries via diffusion

  12. Large Intestine • Absorbs water from remaining indigestible food matter • Transmits waste matter from body • Houses over 700 species of bacteria • Digest polysaccharides • Produce vitamin K and biotin (B vitamin)

  13. Excretory System (Kidneys) Removes waste Balances blood pH Maintain body’s water balance Blood is supplied to kidney via renal artery Blood re-enters circulatory system via renal vein

  14. Nephrons Functional unit of the kidney (1 000 000 per kidney) Regulate water balance Conduct excretion

  15. Urinary Bladder Renal pelvis connects the kidney to the ureter which fills the bladder Holds ~300mL-400mL of urine before exiting the urethra

  16. Filtration Fluid and dissolved substances enter the nephron from blood Smaller molecules pass through Blood, platelets stay in bloodstream 1400L of blood pass through kidneys every day ~1.5L is excreted as urine daily

  17. Reabsorption Water, glucose, some ions (Na⁺, Cl⁻) and other useful substances return to blood from nephron

  18. Secretion Toxins and unwanted ions (H⁺) are secreted from the blood and into nephron for removal as urine

  19. Malnutrition • Insufficient, excessive, or imbalanced consumption of nutrients • Gravest single threat to global public health • Iodine • used to produce hormones that regulate thyroid gland • Deficiency • Impaired mental abilities • Goiter – swelling of thyroid • Vitamin A • Immune system uses to help fight infection • Deficiency • Impaired vision • Zinc • Healing of wounds, growth and repair of tissue, metabolism of macromolecules, alcohol • Deficiency • Retarded growth, recurrent infections

More Related