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Digestion Facts. Made up of the digestive tract and associated digestive structuresAlso called the alimentary canalGastrointistinal tract - below the diaphragmAccessory structures include: tongue, teeth, salivary glands, pancreas, liver, and gall bladder. Functions. IngestionTaking food into the bodyMotilityMovement of food through the digestive tractSecretionAdds substances to the lumen of the digestive tract to help digestion and absorption.
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1. Digestive System
2. Digestion Facts Made up of the digestive tract and associated digestive structures
Also called the alimentary canal
Gastrointistinal tract - below the diaphragm
Accessory structures include: tongue, teeth, salivary glands, pancreas, liver, and gall bladder
3. Functions Ingestion
Taking food into the body
Motility
Movement of food through the digestive tract
Secretion
Adds substances to the lumen of the digestive tract to help digestion and absorption
4. Functions Digestion
Breakdown of food into smaller molecules
Absorption
Transfer of digested nutrients from the digestive tract into the rest of the body
Elimination
Removes indigestible bits and waste from the body
5. Layers (tunics) of the Digestive Tract Mucosa
Mucous membrane, the innermost layer, made of epithelial cells, glands, and lymph tissue
Submucosa
Loose connective tissue
6. Layers (tunics) of the Digestive Tract Muscularis mucosa
2 layers of muscle circular and longitudinal
Mix contents of stomach and moves food through the digestive tract
Serosa
Peritoneum
7. Oral Cavity Contains the tongue and teeth
Sensitive to pain, heat, and cold
8. Teeth Mastication
Chewing breaks down food so that digestive juices can reach all parts
Deciduous teeth (primary) 6mo - 2 yrs
Baby teeth (20) that are replaced by -
Permanent teeth 6 yrs - adult
Odontoclasts, form permanent teeth (32), dissolve the roots of the deciduous teeth
9. Types of Teeth Incisors - biting, shearing
Canine - tearing food
Pre-molars - (bicuspids), biting and grinding
Molars - biting and grinding
Because humans are omnivores we have teeth to fit a varied diet
10. Tooth Anatomy Enamel
Hardest substance in the body, not replaced
Dentin
Like bone
Pulp
Blood vessels and nerves
11. Tooth Anatomy Periodontal membrane
Cementum and periodontal ligaments attach tooth to the jaw
12. Tongue Nearly fills the oral cavity when the mouth is closed
Body of the tongue is skeletal muscle
Mixes food with saliva
Sensitive to 4 flavors, salt, sweet, sour, bitter
13. Functions Speech
Swallowing
Taste
Papillae - bumps on the tongue
Frenulum - attaches tongue to the floor of the oral cavity
14. Sense of Taste Taste buds are the organs of taste
Associated with papillae
Found in smaller numbers on the roof of the mouth and walls of the pharynx
Chemicals of taste must be in water solution for the taste buds to sense them
15. Primary Taste Sensations Sweet - tip of the tongue
Salty - tip and on the sides
Bitter - at the back of the tongue
Sour - sides of the tongue
Alkaline and metallic are two other possible taste sensations
16. Palate Forms the roof of the mouth
Hard palate
Maxillary, palatine bones
Soft palate
Muscular arch extends down and back forming the uvula
Soft palate keeps food from going up the nose
17. Salivary Glands Parotid
Clear watery fluid with amylase
Submandibular
Serous fluid
Sublingual
Mucous
18. Salivary Gland Functions Puts food into solution so taste buds can pick up molecules
Begins digestion of starches with sallivary amylase
1-2 liters of saliva are produced each day
Mucous helps the food slide down the esophagus
19. Pharynx Nasal and oral cavities down to the level of the trachea
Refer to the respiratory notes for the divisions of the pharynx
20. Other Structures in the Mouth Tonsils
Pharyngeal
Lingual
Palatine
21. Swallowing Occurs in 3 stages
1. Food is chewed and mixed with saliva, mass is rolled into a bolus and moved to the pharynx by the tongue
2. Food reaches the pharynx and stimulates sensory receptors. This starts the swallowing reflex
22. Swallowing 3. Food is transported by the esophagus to the stomach by peristalsis, an involuntary muscular contraction
It takes about 9 seconds for food to travel the 10 inch esophagus
Deglutition (swallowing) both voluntary and involuntary
23. Esophagus 25 cm (10 inches)
Collapsible
Goes through the diaphragm
Lined with mucous membranes and smooth muscle
Cardiac or esophageal sphincter is the lowest limit of the esophagus
24. Stomach Upper left quadrant of the abdomen
Held in place by the greater and lesser omenta
May interfere with breathing if distended
25. Parts of the Stomach Fundus
part above the cardiac sphincter
Body
Main part of the stomach
Pylorus
Area at the intestinal end of the stomach
26. Parts of the Stomach Cardiac Sphincter
Muscle at the entrance to the stomach
Pyloric Sphincter
Muscle regulating the passage of food into the intestine
Antrum
Lowest part of the body
27. Layers of the Stomach Peritoneum
Parietal
Abdominal lining, is continuous with
Visceral
Covers some organs in the abdomen
Submucosa
Loose vascular layer
28. Layers of the Stomach Mucosa
Epithelial layer
Folded into Rugae inside the stomach
Glands
Gastric pits are located at the ends of gastric glands and form an outlet for gastric juice.
29. Layers of the Stomach Gastric Juice
Made up of HCl, digestive enzymes
Parietal cells
Produce HCl and intrinsic factor (B12 absorption)
Zygomatic (chief) cells
Produce enzymes and mucous that protects the lining of the stomach
30. Physiology Cephalic phase
Conditioned reflex, gastric juices begin to flow
Gastric phase
Solid food stimulates the production of gastrin, a hormone that stimulates the production of gastric juices
31. Physiology Intestinal Phase
Stimulated by distention, acidity, end products of digestion
Gastric contents are ready to enter the intestine
32. Motor Functions Storage of food
Mixing food with digestive juice until chyme is formed
Killing bacteria
Empty food into the small intestine at a suitable rate
33. Stomach Facts Liquids move through the fastest
Fatty foods move through the slowest
1 liter capacity
Mixing waves (peristalsis) occur every 20 seconds
Very little food is absorbed through the stomach, water, alcohol, and glucose can be
34. Vomiting
35. Causes Rapid changes in position
Distention
Excitement
Irritation of the stomach
Food
Illness
Vomiting center is in the medulla
36. Steps Take a deep breath
Soft palate closes nasal cavity
Glottis closes off the trachea
Cardiac sphincter relaxes
Stomach is squeezed between the abdominal wall and the diaphragm muscles
37. Gastritis Not a disease - usually a symptom of something else
An inflammation of the stomach
38. Other Organs Organs that help with digestion
39. Liver Largest gland in the body
Upper right side of the abdominal cavity
4 lobes, easily broken
40. Functions Produces bile
Emulsifies fats
Produces blood proteins
Fibrinogen
Prothrombin
Globulins
Albumin
Heparin
41. Functions Converts glucose to glycogen
Makes glucose from protein
Food metabolism
Detoxification
Stores vitamins A, D, E, K (fat soluble)
42. Gall Bladder Small sack under the liver
Stores bile
Bile emulsifies fats and helps with the absorption of vitamins A, D, and K
43. Pancreas Exocrine Functions
Secrete digestive enzymes
(1400 ml/day)
Large amounts of sodium bicarbonate are used to neutralize the acid
Endocrine Functions
Secrete insulin and glucogon
44. Small Intestines Duodenum
First section 22cm long
Digestive enzymes are pumped in here
Jejunum
2 meters
Ilium
3.5 meters
45. Functions Lining is made up of finger like structures called villi
Total surface area = tennis court
Most carbohydrate, protein and fat digestion occur in the small intestine
Controls the amount of fluid lost during digestion
46. Functions Fluid enters the small intestine from liquid (1.5 liters) and as secretions from the digestive tract (7.5 liters)
About 8.5 liters are reabsorbed before leaving the intestine
Absorption of break down products takes place in the small intestine
47. Large Intestine Larger diameter (6cm) but shorter in length (1.5m) than small intestine
Runs from ileocecal sphincter to the anus
Finishes absorption, forms and stores feces, and eliminates feces from the body
48. Large Intestine Parts Cecum
Pouch located in the lower right quadrant in the abdomen
Extending from the cecum is the appendix (8cm)
Colon
Ascending, Transverse, Decending, Sigmoid, and Rectum
49. Large Intestine Parts Hepatic, Splenic Flexure
Rectum
Last 12cm of the digestive tract
Anal Canal
Last 4cm
Internal and External Anal Sphincter
Internal is involuntary muscle, External is voluntary
50. Large Intestine Facts No enzymes are secreted here
Large amounts of mucous and water can be secreted if the large intestine is irritated
Material can stay in the large intestine for 24 hours
51. Defecation When fecal material reaches the rectum it initiates a desire for defecation
Feces generally contain about 75% water
Solid part of feces is about 30% bacteria along with cell debris cell salts, and bile pigments
Biliruben gives feces their brown color