1. Chapter 3: The Human Body

2. Body Cells  Form tissues  Tissues form Organs  Organs form Systems (e.g., digestive)  Turnover  Require nutrients

3. Organelles Cytoplasm Mitochondria—Power plant  Major site for energy production Nucleus  DNA Endoplasmic reticulum - communication network  Rough endoplasmic reticulum - protein synthesis  Smooth endoplasmic reticulum -fat synthesis

4. Four Types of Tissues  Epithelial Lines the outside surfaces and external passages Lines the outside surfaces and external passages  Connective Holds structures together Holds structures together  Muscle Able to contract Able to contract  Nervous Transport nerve impulses Transport nerve impulses

5. Digestive System Mouth to anus called the alimentary canal. 24 ft long. Functions  ingestion  Propulsion  Mechanical digestion  Chemical digestion  Absorption  Defecation

6. Communication  Mediated by the nervous system and the endocrine system  Digestion of food occurs with the help of Short reflexes. Local sensors inside GI tract. Sensitive to stretch, PH, osmolarity Short reflexes. Local sensors inside GI tract. Sensitive to stretch, PH, osmolarity Long reflexes. Sensors in the CNS Long reflexes. Sensors in the CNS Hormones. Produced by stomach, and SI in response to short reflexes. Hormones. Produced by stomach, and SI in response to short reflexes.

7. Structure of GI Tract  Peritoneum. Protection, mobility and lubrication  Blood supply. Supplied by the abdominal aorta. All blood from GI tract moves directly to liver via portal vein.  Mucosa. Specialized cells to protect organs from disease. Secretes mucus.  Muscles. Movement of organs. Peristalsis.

8. The Digestive System mouth salivary glands esophagus stomach small intestine large intestine rectum anus pancreas gallbladder liver

9. The Mouth  Mastication  Saliva Enzymes to help breakdown simple sugars Enzymes to help breakdown simple sugars Mucus to lubricate the food for easier swallowing (bolus) Mucus to lubricate the food for easier swallowing (bolus) Lysozyme to kill bacteria Lysozyme to kill bacteria  Tongue Taste receptors Taste receptors Enzymes to help breakdown fatty acids Enzymes to help breakdown fatty acids

10. The Esophagus  Long tube  Connects pharynx to the stomach  Epiglottis prevents choking  Peristalsis, muscle contraction  Lower esophageal sphincter  Heartburn

11. The Stomach  Cardiac sphincter and pyloric sphincter  Capacity of ~4 cups  Secretion of acid, enzymes, and intrinsic factor  Holds food for 2-4 hours  Formation of chyme  Mucus layer prevents autodigestion

12. Physiology of the Stomach

13. Stomach Acid  Destroys activity of protein  Activates digestive enzymes  Partially digests dietary protein  Assists in calcium absorption  Makes dietary minerals soluble for absorption

14. The Small Intestine  Three parts Duodenum Duodenum Jejunum Jejunum ileum ileum  Villi projections are located on the folds  Absorptive cells are located on the villi  Increases intestinal surface area by 600x  Rapid cell turnover

15. The Small Intestine

16. The Large Intestine  ~3 1/2 feet in length  No villi or enzymes present  Little digestion occurs  Creation of SCFA  Absorption of water, some minerals, vitamins  Contains bacteria  Formation of feces for elimination

17. Rectum  Stool remains  Stimulates elimination  Muscle contraction  Anal sphincters Internal-involuntary Internal-involuntary External-voluntary External-voluntary

18. Movement Along the Intestine  Peristalsis A ring of contraction propelling material along the GI tract A ring of contraction propelling material along the GI tract  Mass movement Peristaltic wave that contracts over a large area of the large intestine to help eliminate waste Peristaltic wave that contracts over a large area of the large intestine to help eliminate waste

19. Movement

20. 1. The presence of food in the stomach and chyme in the duodenum stimulate mass movement in the colon. 2. Mass movements are integrated by the enteric plexus. 3. They propel the contents of the colon toward the rectum. 4. The presence of feces in the rectum stimulates parasympathetic and local reflexes that result in defecation. Presence of chyme in the duodenum Mass movements Stimulation of parasympathetic controlled defecation reflexes Stimulation of local defecation reflexes Stimulates mass movement Feces Presence of food in the stomach Rectum Colon Stomach 1 4 2 2 2 2 2 2 3

21. The presence of food in the stomach and chyme in the duodenum stimulate mass movement in the colon. Colon Mass movements Rectum Presence of chyme in the duodenum Stimulates mass movement Presence of food in the stomach

22. Mass movements Mass movements are integrated by the enteric plexus. Colon Rectum

23. They propel the contents of the colon toward the rectum. Mass movements Colon Rectum

24. Mass movements The presence of feces in the rectum stimulates parasympathetic and local reflexes that result in defecation. Stomach Stimulation of parasympathetic controlled defecation reflexes Feces Colon Rectum Stimulation of local defecation reflexes

26. Accessory Organs  Pancreas. Both endocrine and digestive organ. Releases bicarbonate, enzymes that break down nutrients, and insulin and glucagon to control blood sugar.  Gallbladder. Holds and excretes bile.  Liver Receives all nutrients from the SE Receives all nutrients from the SE Produces bile Produces bile Dismantles and assembles protein Dismantles and assembles protein Metabolizes fat. Metabolizes fat. Detoxifies drugs and alcohol Detoxifies drugs and alcohol Plays major role in metabolic pathways Plays major role in metabolic pathways

27. Circulatory System  Heart and blood vessels  Systemic circuit  Pulmonary circulation  Lymphatic system  Blood

29. Lymphatic System  Contains lymph  Immune cells  Passage for large particles like lipids  Empties into veins leading to the heart

30. Nutrient Absorption

31. Exchange of Nutrients  Insert Fig. 3-4