1. THE DIGESTIVE SYSTEM
The Digestive System-- a long, hollow tube open at both ends called the ALIMENTARY CANAL
GI TRACT
GASTROINTESTINAL TRACT.

2. Food goes through THREE PROCESSES 1. DIGESTION 2. ABSORPTION 3
Food goes through THREE PROCESSES 1. DIGESTION 2. ABSORPTION 3. METABOLISM

3. DIGESTION: THE BREAKDOWN OF FOOD INTO SIMPLER MOLECULES THAT CAN BE ABSORBED AND USED BY THE BODY Two forms of digestion 1. MECHANICAL 2. CHEMICAL

4. MECHANICAL DIGESTION Breaks food down into a fine pulp
MECHANICAL DIGESTION Breaks food down into a fine pulp. Increases surface area and exposes food molecules to the actions of digestive chemicals.

5. CHEMICAL DIGESTION Molecules are chemically reduced
CHEMICAL DIGESTION Molecules are chemically reduced. Food must be simple/small enough to be absorbed through the intestinal wall lining and body cell membranes. Examples: STARCHES are reduced to SIMPLE SUGARS PROTEINS are reduced to AMINO ACIDS.

6. Main Organs of Digestion (pg 390) MOUTH PHARYNX ESOPHAGUS STOMACH SMALL INTESTINE LARGE INTESTINE RECTUM ANAL CANAL

7. Wall of the Digestive Tract Consists of Four Layers of Tissue 1
Wall of the Digestive Tract Consists of Four Layers of Tissue 1. Mucosa- mucous epithelium - it protects the GI tract wall, secretes substances, and absorbs the end products of digestion.

8. 2. Submucosa- connective tissue layer that contains blood vessels, lymphatic vessels, and nerve fibers

9. 3. Muscularis- two layers (small and large intestine) or three layers (in the stomach) of smooth muscle tissue. This layer is responsible for the movement of food by peristalsis, a rhythmic contraction of these muscles.
In some regions, the circular layer of smooth muscle enlarges to form sphincters, circular muscles that control the opening and closing of the lumen

10. 4. Serosa- lines the outside of an organ
Made up of serous membrane- The visceral peritoneum -lines the stomach, large intestine, and small intestine.
The mesentery is an extension of the visceral peritoneum that attaches the small intestine to the rear abdominal wall.

11. Lumen- the hollow space.

12. Mechanical and chemical digestion begin in the mouth
Mechanical and chemical digestion begin in the mouth. Hard Palate- front portion of the mouth formed by parts of the maxillary and palatine bones

13. Soft palate- consists mainly of muscle tissue
Soft palate- consists mainly of muscle tissue. Uvula-Dangling thing in the back of the throat. Prevents food and liquid from entering nasal cavity.

14. Tongue- Skeletal muscle covered by mucous membrane
Tongue- Skeletal muscle covered by mucous membrane. FRENULUM- a thin membrane that anchors tongue to the floor of the mouth. Tongue-tied.

15. Tongue divided into ROOT, TIP, and a central BODY
Tongue divided into ROOT, TIP, and a central BODY. PAPILLAE- elevations of the tongue Taste buds are located on the papillae

16. Teeth: 32 in an adult 20 baby teeth Three basic types each with a different function. Incisors Canines (cuspids) Molars (bicuspids and tricuspids)

17. INCISORS - SHARP FRONT TEETH USED FOR BITING INTO AND TEARING PIECES OF FOOD

18. CANINES - POINTED TEETH (VAMPIRE) NEXT TO INCISORS, USED TO TEAR OR SHRED FOOD.

19. MOLARS - BACK OF THE MOUTH, LARGE FLAT SURFACES THAT CRUSH AND GRIND FOOD. Bicuspid-two cusps Tricuspids-three cusps

21. Every Tooth has three main parts: 1. CROWN-Exposed portion 2
Every Tooth has three main parts: 1. CROWN-Exposed portion 2. NECK- narrow portion surrounded by gingiva 3. ROOT-fits into the socket of the jaw.

22. Teeth are composed of FOUR LAYERS of tissue 1. ENAMEL 2. DENTIN 3
Teeth are composed of FOUR LAYERS of tissue 1. ENAMEL 2. DENTIN 3. CEMENTUM 4. PERIODONTAL MEMBRANE (LIGAMENT).

23. The CROWN is covered by ENAMEL, a calcium-containing material THAT IS THE HARDEST SUBSTANCE IN THE BODY

24. DENTIN is a bone- like tissue that. makes up most of the inside of a
DENTIN is a bone- like tissue that makes up most of the inside of a tooth.
CEMENTUM bony substance that covers the dentin
of the root.

25. The PERIODONTAL LIGAMENT holds the tooth in its socket
The PERIODONTAL LIGAMENT holds the tooth in its socket. Helps the tooth withstand large compressive forces

26. Salivary Glands- Three pair
Parotids- largest, lie below and
in front of each ear.
Mumps-inflammation of the parotid
glands
Submandibular glands:
Located beneath the floor of the
mouth on either side of the lingual
frenulum. In humans, they account for 70% of the salivary volume.
3. Sublingual gland- Lies anterior to the submandibular glands, under the tongue.
Saliva contains SALIVARY AMYLASE, an enzyme that begins the breakdown of food.

27. Once the teeth and salivary glands have completed the initial processing, the food is ready to be swallowed. The TONGUE pushes the BOLUS (a ball of food) toward the back of the mouth and into the PHARYNX. In the Pharynx, the GI tract and the respiratory system cross each other.

28. As food moves into the pharynx, it presses down on the epiglottis
As food moves into the pharynx, it presses down on the epiglottis. The epiglottis CLOSES the entrance to the respiratory tract and guides the food down the GI Track. The bolus moves from the pharynx into the ESOPHAGUS - A 25cm long, muscular tube that connects the pharynx with the stomach and actively pushes the food.

29. Peristalsis (contractions) of the esophageal muscles move the bolus to the CARDIAC SPHINCTER VALVE where the esophagus joins the stomach. The sphincter allows food to pass into the stomach but usually will NOT let it move back up into the esophagus.

30. Hiatal hernia- the protrusion (herniation) of the upper part of the stomach into the thorax through an opening in the diaphragm. Hiatal hernias can result in reflux (backward movement) of the stomach contents back into the esophagus. Gastroesophageal Reflux Disease or GERD

31. A J-shaped muscular sac with thick expandable walls.
THE STOMACH
A J-shaped muscular sac with thick expandable walls.
Located in the upper L side of the abdominal cavity, just below the diaphragm.
The stomach is
involved in both
mechanical and
chemical digestion.
The Stomach Walls
are made of layers
of muscles that
contract in OPPOSITE
DIRECTIONS

32. Chemical Digestion in the stomach begins with the actions of HYDROCHLORIC ACID and an enzyme called PEPSIN BOTH HCl and pepsin are gastric fluids that are secreted by GASTRIC GLANDS.

33. MUCUS is also secreted by glands in the stomach
MUCUS is also secreted by glands in the stomach. Mucus lubricates food so that it can travel through the digestive tract more easily. Mucus also COATS the walls of the stomach. After about 3-4 hours in the stomach food is reduced to CHYME- a soft semisolid mixture made up of partially digested proteins, starches, fats, acid, etc.

34. Divisions of the Stomach
1. FUNDUS- The left portion of the body of the stomach above the end of the esophagus. Formed by the upper curvature of the stomach.
2. Body- (or corpus) the main, central region
3. Pylorus- the lower section that facilitates emptying the contents into the small intestine.
The lining of the stomach lies in folds called rugae.

35. The PYLORIC SPHINCTER VALVE between. the stomach and DUODENUM opens,
The PYLORIC SPHINCTER VALVE between the stomach and DUODENUM opens, allowing small amounts of chyme to pass into the small intestine.

36. The Small Intestine- 7m long, 2.5cm diameter.
Three Parts:
Duodenum- first section
Jejunum- middle
Ileum- lower portion

37. Intestinal Glands- Some of the digestive fluids and enzymes that digest food in the small intestine come from glands located in the mucous lining.

38. MOST NUTRIENTS ARE ABSORBED INTO THE CIRCULATORY SYSTEM THROUGH THE CELLS THAT LINE THE SMALL INTESTINE. The lining is arranged in PLICAE- circular folds. These folds are covered by VILLI – Fingerlike projections that increase surface area. The Villi have extensions called MICROVILLI.

39. NUTRIENTS ARE ABSORBED THROUGH
1. CAPILLARIES
2. LACTEALS - TINY LYMPH VESSELS, IN THE VILLI that absorb fats.

41. Most chemical digestion occurs in the duodenum
Most chemical digestion occurs in the duodenum. The middle third of the duodenum is open to the Duodenal Ducts that empty pancreatic juice and bile into duodenum.

42. The LIVER is the largest gland in the body and lies above the stomach in the abdominal cavity. It secretes BILE by way of the HEPATIC duct (exocrine gland). Bile is stored in the gallbladder between meals and upon eating the bile is discharged into the duodenum.

43. Bile contains cholesterol, bile pigments, lecithin and bile salts
Bile contains cholesterol, bile pigments, lecithin and bile salts. Bile acts as a detergent , helping to emulsify (break down) fats. Fats in chyme stimulates secretion of cholecystokinin (CCK), a hormone, which stimulates the contraction of the gallbladder. If the amount of salt in the bile is insufficient, sharp, painful crystals can form, known as GALLSTONES.

44. The PANCREAS, located behind the stomach, secretes Pancreatic Fluid into the small intestine through the Pancreatic Duct. It also secretes hormones including insulin. (exocrine and endocrine) Pancreatic juice contains a variety of enzymes used to digest all three food types. It also contains a high concentration of bicarbonate ions which neutralize the gastric acid.

45. LARGE INTESTINE or COLON - the final stage of the alimentary canal in vertebrate animals. 1.5m long, 6cm. Undigested, unabsorbed food material passes through the Ileocecal Valve into the colon. When most of the water has been removed from the undigested material, FECES, a solid waste matter, remains.

46. Functions: Absorb the remaining water from indigestible food matter
Functions: Absorb the remaining water from indigestible food matter. Stores this matter(wastes) Eliminates the wastes from the body. The gut also contains somewhere between 300 and 1000 different species of bacteria. These bacteria synthesize and help in absorption of needed vitamins like Vitamin K and B-complex vitamins. They may also help the body absorb nutrients such as calcium, magnesium and iron.

47. Major Subdivisions of the Large Intestine 1. Cecum 2. Ascending Colon 3. Transverse Colon 4. Descending Colon 5. Sigmoid Colon 6. Rectum 7. Anal Canal

48. Veriform Appendix –blind ended tube connected to the cecum, near the junction of the small and large intestines. Contains lymphatic tissue. No known digestive function.

49. Appendicitis - The mucous. lining of the appendix
Appendicitis - The mucous lining of the appendix becomes inflamed, the appendix must be removed.

50. Peritoneum-the serous. membrane that forms
Peritoneum-the serous membrane that forms the lining of the abdominal cavity
The outer layer, called the parietal peritoneum, is attached to the abdominal wall.

51. Visceral peritoneum- the inner layer
Visceral peritoneum- the inner layer. Wraps around the internal organs inside the abdominal cavity

52. Peritoneal cavity-space between visceral and parietal layers
Peritoneal cavity-space between visceral and parietal layers. Filled with a small amount of serous fluid that allows the two layers to slide freely over each other.

53. Extensions of the peritoneum
Mesentery-a peritoneal fold attaching the intestine to the posterior abdominal wall.

55. 2. Greater Omentum- lace apron
2. Greater Omentum- lace apron. Large double fold of the peritoneum attached to the duodenum, the greater curvature of the stomach, and a portion of the large intestine.

58. DIGESTION:
Physical and chemical processes that prepare food for absorption.

59. Mechanical Digestion 1. Mastication 2. Deglutition(swallowing)
3. Peristalsis
4. Defecation
Chemical Digestion
Chemical reactions catalyzed by enzymes

60. CARBOHYDRATE DIGESTION The cells of the human body obtain MOST of their energy from CARBOHYDRATES Sugars and Starches Digestion of carbohydrates begins in the mouth with salivary amylase. Most carbohydrate absorption occurs in the small intestine.

61. Polysaccharides are catalyzed by pancreatic amylase
Polysaccharides are catalyzed by pancreatic amylase. Disaccharides are catalyzed by intestinal enzymes including maltase (maltose), sucrase (sucrose), and lactase (lactose).

62. PROTEIN DIGESTION Proteins- GROWTH AND REPAIR Proteases- 1
PROTEIN DIGESTION Proteins- GROWTH AND REPAIR Proteases- 1. PEPSIN (gastric) partially digests proteins in the stomach. 2. TRYPSIN (pancreatic) continues digestion. PEPTIDASES finish protein digestion in the intestine. Eleven of the 20 amino acids are made by components already present in the body, the other nine must be ingested…these are the essential amino acids

63. FAT DIGESTION Bile emulsifies fats in the duodenum LIPASE (pancreatic)– Breaks fat into glycerol and fatty acids. Cell membranes, prostaglandins.

64. Absorption
The process by which nutrients (amino acids, glucose, fatty acids, etc) move into the circulating fluids from the small intestine.
Occurs mainly in the small intestines.  A teeny bit in the stomach and a teeny bit in the large intestines

65. What are we absorbing & how?
What is being absorbed?
Example of that type of material
How does it occur?
broken food pieces
tiny pieces of food that broke off the original piece... these can include more than one type of macromolecule
Endocytosis-- because these tiny pieces are still very large to a cell.
macromolecules
protein carbohydrate nucleic acid or broken off pieces of these molecules
lipid
Endocytosis-- of proteins, carbohydrates, or nucleic acids... these molecules, even if broken a bit, are still too large to go through the membrane.
Simple Diffusion-- of lipid, only. (note: lipids tend to go into the lacteal rather than the blood)
monomers
amino acids monosaccharides (like glucose & fructose) nucleotides
lipids don't have monomers, but some smaller pieces of them, like fatty acids or monoglycerides can sort of fit this category.
Facilitated Diffusion-- of amino acids, monosaccharides, and nucleotides enables them to cross the membrane.
Simple Diffusion-- of the lipid.  (note: lipids tend to go into the lacteal rather than the blood)
Water
Salts- especially sodium
Simple Diffusion– osmosis
Active Transport– in the large intestine