A&P IV
Midterm Exam Review Packet
Ch. 24
DIGESTIVE PROCESSES
1. Ingestion
2. Digestion (mechanical and chemical)
3. Motility (mixing and propulsion)
4. Secretion
5. Absorption
6. Defecation
GI
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A&P IV
Midterm Exam Review Packet
Ch. 24
DIGESTIVE PROCESSES
1. Ingestion
2. Digestion (mechanical and chemical)
3. Motility (mixing and propulsion)
4. Secretion
5. Absorption
6. Defecation
GI TRACT AND ACCESSORY DIGESTIVE STRUCTURES
BE ABLE TO IDENTIFY EACH ORGAN ON THE IMAGE ABOVE.
GI TRACT INNERVATION
• Autonomic NS
o Parasympathetic NV (enhances digestion)
o Sympathetic NV (inhibits or slows down digestion)
• Enteric Nervous System
o Submucosal plexus
o Myenteric plexus
Be able to identify all parts of the GI tract
What are the histological significances of the GI tract? The GI tract consist of 4 layers:
Mucosa- Divides into 3 layers Epithelium – Surface Epithelium
Lamina Propria – Connective Tissue Muscularis Mucosae – Smooth Muscle
Submucosa- Areolar Connective Tissue
Muscularis- In all GI tract organs except the stomach Serosa
ENZYMES originating in the oral cavity What are the functions of the oral cavity?
Salivary glands
Parotid glands (under the cheek bones) Submandibular glands (under the mandible) Sublingual glands (under the tongue)
• All secrete SALIVA, which contains:
o Mostly water
o Ions
o Buffers
o Lysosyme
o Salivary amylase
Salivary Amylase (made by the salivary glands)
- Break down carbohydrates
- Converts Polysaccharides to monosaccharides, maltose, maltotriose and alpha-dextrins
- Deactivated by stomach acid
Lingual Lipase (made by the lingual glands of the tongue)
- From lingual glands of the tongue
- Break down lipids
- Activated by HCl of stomach
- Converts triglycerides to fatty acids and monoglycerides
- What are the components of saliva?
Among these polynucleotides, what is digested in the oral cavity? (proteins, lipids, nucleic acids, carbohydrates)
THE SIGNIFICANT CELLS OF THE STOMACH AND THEIR SECRETIONS (GASTRIC JUICE)
Parietal Cells
- Secrete HCl
- makes the chyme acidic
- kills bacteria
- denaturing (unfolding) proteins
- activates pepsin along with lingual lipase.
- Secrete intrinsic factor, which allows for absorption of vitamin B12
Chief Cells
- The major stomach cells
- Secrete pepsinogen, which is activated (by stomach acid) and becomes pepsin, a peptidase
- Pepsin breaks down proteins
- Secrete gastric lipase
- breaks down triglycerides into monoglycerides and fatty acids
G Cells
- Secrete Gastrin (hormone): contracts cardiac sphincter; loosens pyloric sphincter; promotes stomach motility; promotes secretion of pepsinogen from chief cells and HCl from parietal cells
Mucous Cells
- THEY SECRETE MUCOUS
- Mucous forms a protective barrier against acidic chyme
What is the function of stomach acid?
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