1. Pharynx

1. 1. Pharynx • cavity • not involved in digesting food • passageway leads to stomach • connection between nasal & oral cavities to larynx & esophagus

2. 3 parts to pharynx • nasopharynx- connects w/ nasal cavity • oropharynx- passageway food moving down & air moving into trachea • laryngopharynx- passageway to esophagus

5. 3 Stages of Swallowing • 1st stage: • voluntary • food chewed- mixed w/ saliva • rolled into mass by tongue- BOLUS- forced into pharynx

6. 2nd Stage- swallowing reflex stimulated • food is prevented entrance to nasal cavity • epiglottis slaps shut over larynx to keep food from going down trachea • tongue seals off oral cavity • different muscle actions open esophagus & forces food down it

7. epiglottis trachea

8. 3rd Stage • breathing momentarily inhibited • peristalsis transports food down into & through esophagus • choking occurs when food lodges in larynx • Heimleich maneuver can dislodge food

9. Heimleich maneuver

10. 2. Esophagus • straight tube • ~ 25 cm long • food passageway from pharynx to stomach • goes thru opening in diaphragm • contains mucous glands w/ secretions that moisten & lubricate inner lining

12. Peristalsis • wavelike motion propels food down tubular structures • contraction of muscle occur above food & relaxation below it

14. hiatal hernia • acid reflux • Barrett’s esophagus

15. Caution!

17. 3. Stomach • j-shaped, pouched organ • ~ 1 L capacity • fxns: receives food from esophagus, mixes food w/ gastric juices, begins protein digestion, limited absorption, moves food into small intestines

19. Regions of stomach: • cardiac- • fundus- temp storage area • body- main part • pylorus- approaches small intestines

21. inner lining contains gastric glands w/ 3 types secretory cells: • mucous cells- secrete mucus w/ other secretions keeping stomach from digesting itself • chief cells- secrete digestive enzymes- pepsinogen • parietal cells- release HCl & intrinsic factors all these form GASTRIC JUICE (2-3 L/day)

23. Ulcer

24. inner lining= RUGAE- disappears when stomach is distended ulcer is open sore in the lining of stomach may be caused by presence of H pylori bacteria

25. pepsinogen is released & when hits HCl forms PEPSIN which digests almost ALL types of protein • intrinsic factors aid in vitamin B12 absorption in small intestines • mostly digestion occurs in stomach, but some absorption of water, salts, and drugs does occur

26. mechanical & chemical digestion begin here resulting in a semi-paste called CHYME rate at which this enters sm intestine depends of type of food liquids pass thru quickly fatty foods 3-6 hours proteins & carbs pass thru more quickly

27. Vomiting • medulla oblongata- vomiting center • body prepares for the process by closing off nasal cavity, trachea, contraction of diaphragm, contraction of abdominal muscles, etc

28. 4. Pancreas • dual fxn- endocrine gland & digestive gland • closely associated w/ small intestine in the curve of duodenum • fxn: release pancreatic juice • juice contains enzymes that digest carbs, fats, nucleic acids, proteins

30. PANCREATITIS- condition where there is a blockage in release of juice • essentially pancreas digests itself

33. 5. Liver & Gallbladder • largest internal organ in body • inferior to diaphragm on right side of body (under ribs) • 4 lobed organ (2) • connected to sm intestines by ducts • main fxn: manufacture bile salts

36. Functions: • imp role in carb metabolism • regulates glucose in bld • imp in lipid metabolism- converting subst into fats (bile salts) • imp in protein metabolism

37. produce plasma proteins • destroy bacteria/old rbc & wbc

38. produce enzymes that break down poisons that are harmful to body • stores certain vitamins/minerals needed by body • also stores poisons that can’t be broken down & excreted • activates vitamin D

40. Diseases of Liver • cirrhosis • hepatitis • cancer

41. surrounds gallbladder- small, green sac embedded in liver • stores & concentrates bile

42. gallstones • gallbladder attacks

43. 6. Small Intestine • major digestive organ • ~ 21 feet long • 3 subdivisions: • duodenum- ~10” long (25cm) diameter: ~ 2” (5cm) C-shaped around the pancreas B. jejunum- ~ 8’ long greater diameter thicker walls, more vascularized

44. C. ileum- ~ 12’ long hard to distinguish between jejunum & ileum

45. mesentery- thin membrane that suspends the portions of the intestines from walls • contains blood vessels, nerves, lymphatic vessels

47. only processes small amount of food at a time so pyloric sphincter muscle considered gatekeeper • produces enzymes to digest food (w/ help of pancreatic enzymes & bile)

48. enzymes secreted by mucosal cells break down proteins, carbs, fats • wall of intestine has many tiny projections called villi • microvilli project off the villi • the epithelial lining is replaced every 3 to 6 days • food absorption occurs thru these structures

50. carries on mixing movements & peristalsis • chyme moves slowly; 3-10 hours • if wall becomes distended/irritated, a peristaltic rush pushes contents to large intestine so quickly that water, nutrients, & electrolytes aren’t absorbed - diarrhea