2. Pig Digestive System Chapter 6 (pages 42 – 49)

3. Digestion Digestion the breaking down of food molecules
Digestive System
organs that collectively perform the breaking down of food

6. Digestive Processes Ingestion taking food into the mouth
Mixing and movement of food
muscular contractions mix food and secretions and move food along the gastrointestinal tract
Digestion
breakdown of food by chemical and mechanical processes

7. Digestive Processes Absorption
passage of digested food from the GI tract into the cardiovascular and lymphatic for distribution to cells
Defecation
elimination of indigestible substances from GI tract

8. Digestive Processes Mechanical Digestion chewing/churning Peristalsis
waves of muscular contraction,
(peri=around; stalsis=contraction)
Takes place
esophagus
stomach
small intestine
large intestine

10. Digestive Processes Chemical Digestion
series of reactions that break down the large, complex carbohydrate, lipid, and protein molecules into small molecules we can absorb through the gastrointestinal wall
Carbohydrates
glucose
Lipids
Glycerol and fatty acids
Proteins
Amino acids

11. Organs of Digestion Gastrointestinal Tract /Alimentary Canal
begins with mouth – ends at anus
mouth, pharynx, esophagus, stomach, small intestine, large intestine
Accessory Structures
teeth, tongue, salivary glands, liver, gall bladder, pancreas

13. Mouth (Oral or Buccal) Cavity
Hard palate
Soft palate
Tongue
floor, food maneuvering
Lingual Frenulum
mucous membrane connects underside of tongue to floor over buccal cavity
Papillae
line tongue on top and sides
some contain taste buds

14. Salivary Glands Parotid under and in front of ears Submandibular
lies beneath base of tongue
Sublingual
lies in the tissues beneath and on each side of the tongue

16. Salivary Glands Saliva 99.5% water and 0.5% solutes
water helps to moisten food
mucous (mucin)
lubricates food, binds it into a bolus
amylase
bicarbonate
lysozyme
destroys bacteria to protect mucous membrane from infection and the teeth from decay

18. Wall of GI Tract – 4 Layers
Mucosa –
inner lining
mucous membrane
epithelium areolar connective tissue, smooth muscle (muscularis mucosae)
Submucosa
consists of areolar connective tissue that binds with mucosa to the muscle layer

19. Wall of GI Tract 4 - Layers
Muscularis
thick layer of muscle
smooth muscle
inner sheet of circular fibers and outer sheet of longitudinal fibers & nerves
Serosa and Peritoneum
outermost layer
serosa
composed of simple squamous epidermis and connective tissue

20. Wall of GI Tract 4 - Layers
Secretes serous (wet) fluid to allow the organs to glide
Peritoneum
largest serous membrane
Parietal
lines wall of abdominal cavity
Visceral
covers some of the organs

22. Gastrointestinal Tract
Begins with esophagus
Esophagus joins with stomach at esophageal sphincter
Stomach joins duodenum at the pyloric sphincter
Stomach can absorb water, electrolytes, certain drugs and alcohol

24. Pancreas pan=all kreas=flesh lies behind the stomach
Made up of pancreatic islets (islets of Langerhans)
produce glucagon and insulin
Made up of acini
exocrine glands that secrete digestive enzymes called pancreatic juice

26. Pancreatic juice includes
protease
lipase
amylase
nuclease
alkaline salts

27. Functions of Liver Carbohydrate Metabolism
convert glucose to glycogen when sugar level is high
insulin
breakdown glycogen to glucose when sugar is low
glucagon
Lipid (Fats) Metabolism
stores and breaks down

28. Functions of Liver Protein Metabolism synthesize and convert
Removal of Drugs
Synthesis of Bile
Weighs about 3 pounds
Located under the diaphragm
Divided into right and left lobes by the falciform ligament
Lobes divided into lobules

30. Gall Bladder Located under liver
Functions in storage of bile until needed in small intestine
Muscularis in gall bladder contracts following hormonal stimulation

31. Bile Excretory product and digestive secretion
salts aid in emulsification
conversion of triglyceride globules into droplets and absorption of triglycerides following their digestion

35. Small Intestine Area of digestion and absorption Duodenum Jejunum
beginning of small intestine
Jejunum
middle section of intestine
Ileum (2 meters)
joins colon at Ileoceal junction
Composed of same 4 layers as GI tract

36. Small Intestine Mucosa forms fingerlike villi 0.5 to 1 mm in length
increases surface area for absorption
Microvilli
found in the absorptive cells of the epithelium
microscopic cytoplasmic projections
increase surface area (1 sq millimeter contains 200 million microvilli)

38. Absorption each day 9.3 liters enters the SI nearly all is absorbed
0.1 passes into LI
also absorbed by osmosis
electrolytes are absorbed in small intestine
vitamins are absorbed in small intestine

39. Large Intestine Last stage of digestion is largely bacterial
40% of fecal mass is bacteria
converts remaining carbohydrates into H, carbon dioxide and methane gas
break down remainder of amino acids
ascending colon is a double coil /clockwise spiral
transverse colon continues after ascending on right side
descending is final portion that leads to the rectum

41. Absorption
By the time chyme has remained in the LI 3 to 10 hours, it has become semisolid as a result of water absorption
now known as feces
consists of inorganic salts, cells from mucosa of GI tract, bacteria, undigested parts of food, products of bacterial digestion