Transcript Nerve activates contraction

The Digestive System
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Functions of the Digestive System
 Ingest food
 Digest food
 Absorb nutrients
 Eliminate indigestible waste
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Digestive anatomy overview
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Organization of the Digestive organs
Alimentary Canal
Accessory organs
Mouth
Teeth
Pharynx
Tongue
Esophagus
Salivary glands
Stomach
Gall bladder
Small intestine
Liver
Large intestine
Pancreas
Anus
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The Digestive Process
Ingestion
Propulsion
Mechanical
Digestion
Chemical
Digestion
Absorption
Defecation
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This is your basic alimentary tract structure.
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Sagittal view of abdominal viscera
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Peristalsis
Figure 24–4
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Segmentation
 Cycles of contraction:
 Churn and fragment bolus
 mix contents with intestinal secretions
 Does not follow a set pattern:
 does not push materials in any 1 direction
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The oral cavity and pharynx Say “ahhh”
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Salivary Glands
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Road map of the tongue
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Anatomy of Teeth
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Primary and Secondary Dentitions
Figure 24–9
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Histology of the Esophagus
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Gastroesophageal junction
Stomach
Esophagus
Stratified squamous epithelium
Simple columnar epithelium
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The Swallowing Process
Figure 24–11
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The Stomach
Figure 24–12a
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The Stomach
Figure 24–12b
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The Stomach Lining
Figure 24–13
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It’s the pits! (Gastric pits that is…)
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Micrograph of the Fundic region of the gastric
mucosa
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The duodenum, gall bladder and pancreas
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Hormonal Regulation of Pancreatic secretions
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The small intestine
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Histology of the small intestine
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Cells of the mucosa
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Duodenal wall
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Duodenal mucosa
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Brunner’s (duodenal) glands
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Crypts of Lieberkuhn!
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Peyer’s patches in the ileum
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The Pancreas
Figure 24–18
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Exocrine tissues of the pancreas
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Pancreas: Acinar cells
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The Liver
 Is the largest visceral organ (1.5 kg)
 Lies in right hypochondriac and epigastric
regions
 Extends to left hypochondriac and umbilical
regions
 Performs essential metabolic and synthetic
functions
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The Anatomy of the Liver
Figure 24–19
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Liver Histology
Figure 24–20
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3 Functions of the Liver
1.
Metabolic regulation
2.
Hematological regulation
3.
Bile production
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Metabolic Regulation

The liver regulates:
1. composition of circulating blood
2. nutrient metabolism
3. waste product removal
4. nutrient storage
5. drug inactivation
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Metabolic Activities of the Liver
 Carbohydrate metabolism
 Lipid metabolism
 Amino acid metabolism
 Waste product removal
 Vitamin storage
 Mineral storage
 Drug inactivation
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The Gallbladder and Bile Ducts
Figure 24–21
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The Gallbladder
 Stores bile
 Releases bile into duodenum:
 only under stimulation of hormone
cholecystokinin (CCK)
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Gallstones
 Are crystals of insoluble minerals and salts
 Form if bile is too concentrated
 Small stones may be flushed through bile duct
and excreted
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Activities of Major Digestive Tract Hormones
Figure 24–22
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Hormones of Duodenal Enteroendocrine Cells
 Coordinate digestive functions:
 secretin
 cholecystokinin (CCK)
 gastric inhibitory peptide (GIP)
 vasoactive intestinal peptide (VIP)
 gastrin
 enterocrinin
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Absorption of Nutrients
 Nearly all occurs in the small intestine.
 80% of the electrolytes and virtually all food
 Most nutrients are absorbed by active transport.
 Glucose, amino acids, & nucleic acids are absorbed by
secondary active transport with sodium.
 Iron and calcium require transport proteins (ferritin) or
cofactors (vitamin D).
 Anions follow Na+.
 Vitamins  Fat soluble (A, D, E & K) vitamins are carried with micelles.
Much of the K is absorbed in the colon.
 Water soluble vitamins diffuse with the exception of B12,
which requires intrinsic factor.
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Protein digestion in the small intestine
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Bile salts emulsify fats
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Absorption of lipid
Dietary fats are
absorbed into the
“lacteals” of the
lymphatic system
before being
transferred to the
circulatory system.
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Digestive Secretion and Absorption
Figure 24–27
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Absorption of Ions and Vitamins
Table 24–4
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Anatomy of the large intestine
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The rectum and anus
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3 Parts of the Large Intestine
1.
Cecum:

2.
the pouchlike first portion
Colon:

3.
the largest portion
Rectum:

the last 15 cm of digestive tract
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Characteristics of the Colon
 Lack of villi
 Abundance of goblet cells
 Presence distinctive intestinal glands
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The End
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