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40 Cards in this Set

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Digestive function
Absorb nutrients
Digestive Mechanism (7)
1. Ingestion
2. Mechanical processing
3. Secretion
4. Digestion
5. Absorbtion
6. Excretion
7. Defense
Mechanical Processing Mechanism
Chewing, manipulating. Breaks food into smaller chunks
Digestion Mechanism
Chemical process. Breaks small chunks into molecules
Defense Mechanism
Mucus membranes
Stomach acid
Lymphatics
Linings of Digestive Tract
1. Mucosa
2. Submucosa
3. Muscularis
4. Serosa
Mucosa
Innermost layer. In contact with food. Epitheliat
Submucosa layer
Pretty vascular, has lymph nodules
Muscularis layer
Smooth muscle - mechanically manipulates food in lumen
Serosa layer
Irregular dense connective tissue. Sheath that surrounds intestines.
Peristalsis
Wave of coordinated muscular contractions that move food along digestive tract
Pace Setter cells
Hypopolarized; when stretched (when bolus passes) sets off Action Potential, wave of peristalsis
Segmentation
Uncoordinated contractions of smooth muscles of digestive system; mechanically mixes food, not move it
Alimentary Canal
same as Digestive system (means feeding canal).
GI tract
Technically means stomach through small intestine, but often taken to mean entire digestive system
Accessory Glands
Produces chemical, dumps it elsewhere. Food does not come in contact with gland
Salivary Glands - 3
1. Parotid
2. Submandibular
3. Sub lingual
Saliva
Salivary Amylase - breaks glucose off of starch chains
Function of saliva - 4
1. Breaks down carbohydrates
2. Lubricates lips, teeth, food - allows food to move down esophagus
3. Defense. Lysozymes break down bacteria. IgA recognizes oral bacteria.
4. Taste. Dissolves "taste" chemicals, brings to taste buds
Tongue 3 functions
1. Supports taste buds
2. Physically manipulates food
3. Identifies food based on temperature, texture, taste and touch
Teeth function
Mastication - chewing grinding. Increases surface area of food for easier digestion by enzymes
Teeth types
1. Incisor. Front: clipping/cutting vegetable
2. Canines/Cuspids. Side: slash/tearing meat
3. Molars. Back: grinding grains
Teeth, one side
1 central incisor
1 lateral incisor
1 canine
1st premolar
2nd premolar
1st molar
2nd molar
3rd molar - wisdom tooth
Pharynx
Soft palate and uvula prevent food from entering nasal cavity
Nasal pharangeal cells
Simple squamous
Oropharangeal cells
Stratified squamous
Laryngopharangeal cells
?
Bolus
Mass of food, chewed up, with saliva
Esophagus
1. function
2. length
3. location
1. take food to stomach
2. 25- 30 cm long, muscular
3. In mediastinum. Passes through diaphragm at esophageal hiatus, ends at stomach.
Stomach function - 4
1. Temporary storage
2. Finishes mechanical processing of food
3. Major chemical processing begins.
4. Parietal cells produce intrinsic factor (required for absorbtion of Vitamin B12)
Stomach description
Holds 1.5 Liters
Rugae - folds in stomach
Bolus in stomach mixes with stomach acid (pH =1) and other gastric juices
Chyme
Mixture of food, stomach acids, gastric juices. Thick soupy mixture
Stomach Walls - 3 muscle layers
1. Longitudinal - lengthwise
2. Circular - around stomach
3. Oblique - angled to other two.
Very effective mixing of chyme
Stomach parietal cells
Secrete intrinsic factor and HCl (Hydrochloric acid)
Stomach chief cells
Secrete pepsinogen (inactive) until it hits stomach acid. Becomes pepsin, which breaks down proteins.
Greater Omemtum
Sheet of connective tissue. Connects at bottom of stomach, forms pouch, connects back to bottom of stomach
Function of omemta
1. Protects organs
2. Warms abdominal organs
Lesser Omemtum
Connects top of stomach to liver.
Why no absorbtion in stomach?
1. Food not completely digested
2. Very thick alkaline mucus membrane (protects from acid)
3. No transport mechanism from stomach
4. Lining of stomach impermeable to water
Pyloric Sphincter
Controls flow of chyme from stomach into small intestine. Allows time for gastric juices to buffer chyme.