ANATOMY: DIGESTIVE SYSTEM Flashcards
Identify the organs of the digestive system.
2 components
- Gastrointestinal (GI) tract
• Mouth • Pharynx • Esophagus • Stomach • Small intestine • Large intestine
- Associated organs
• Tongue • Teeth • Salivary glands • Pancreas • Liver • Gallbladder
Describe the basic processes performed by the digestive system.
6 processes
- Ingestion
- Secretion
- Mixing & propulsion
- Digestion
- Absorption
- Defecation
Name and describe the abdominopelvic regions.
See diagram
Describe the peritoneum and the peritoneal folds.
The perteoneum is the serous membrane that forms the lining of the abdominal cavity
- Largest serous membrane in the body
- Parietal peritoneum
– Lines wall of abdominopelvic cavity
• Visceral peritoneum
– Covers organs in the cavity
– Serosa
Five major peritoneal folds
- Greater omentum
- Falciform ligament
- Lesser omentum
- Mesentery
- Mesocolon
– Transverse
– Sigmoid
Discuss peritonitis.
Peritonitis is an inflammation of the peritoneum, the thin tissue that lines the inner wall of the abdomen and covers most of the abdominal organs. Peritonitis may be localized or generalized, and may result from infection (often due to rupture of a hollow abdominal organ as may occur in abdominal trauma or inflamed appendix) or from a non-infectious process.
Describe the layers that form the wall of gastrointestinal tract.
1. Mucosa
- Epithelium
- Lamina propria
- Loose connective tissue
- Blood & lymph vessels
- Mucosal glands
- Gut-associated lymphatic tissue (GALT)
- Muscularis mucosae
• Usually 2 layers
– Inner circular
– Outer longitudinal
- Contraction produces movement of the mucosa
- Boundary between mucosa and submucosa
- 3 principal functions
- Protection - Barrier between lumen and tissues of the body
- Absorption - Movement of digested nutrients, water & electrolytes into blood and lymph vessels
- Secretion - Mucous, digestive enzymes, hormones & antibodies
2. Submucosa
- Dense irregular connective tissue
- Larger blood & lymph vessels
- Occasional glands
– Esophageal glands proper
– Duodenum (Brunner’s) glands
• Submucosal plexus (of Meissner)
– Part of the enteric nervous system
- Parasympathetic ganglia and postganglionic fibers
- Innervate muscularis mucosae
3. Muscularis externa
• 2 concentric & thick layers
- Inner circular
- Contraction compresses and mixes contents
- Forms sphincters at specific locations of the GI tract
– Upper esophageal sphincter
– Pyloric sphincter
– Ileocecal valve
– Internal anal sphincter
- Outer longitudinal
- Contraction propels contents by shortening the tube
- Thickened in the large intestine
– Bands called taenia coli
• Peristalsis
– Slow, rhythmic contraction of muscle layers
– Controlled by enteric nervous system
• Myenteric plexus (of Auerbach)
– Part of the enteric nervous system
– Parasympathetic ganglia and postganglionic fibers
– Located between the 2 muscle layers
– Innervate muscularis externa
- Serosa
– Serous membrane
- Simple squamous epithelium
– Mesothelium
- Small amount of underlying connective tissue
– Continuous with mesentery and lining of abdominal cavity
Describe the two nerve plexuses of the gastrointestinal tract.
• Submucosal plexus (of Meissner)
– Part of the enteric nervous system
–Parasympathetic ganglia and postganglionic fibers
– Innervate muscularis mucosae
• Myenteric plexus (of Auerbach)
– Part of the enteric nervous system
– Parasympathetic ganglia and postganglionic fibers
– Located between the 2 muscle layers
– Innervate muscularis externa
Describe the location and gross anatomy of the esophagus.
See diagram
Peristalsis is a series of wave-like muscle contractions that moves food to different processing stations in the digestive tract. The process of peristalsis begins in the esophagus when a bolus of food is swallowed.
Describe the histology and layers that form the wall of esophagus.
Mucosa
- Epithelium
• Nonkeratinized stratified squamous epithelium
- Lamina propria
- Loose connective tissue
- Diffuse lymphatic tissue
- Esophageal cardiac glands
– Mucous glands
» Neutral secretion
– Frequently present at initial region
– Present in terminal region
» Protects against regurgitatedstomach contents
» Excessive reflux results inpyrosis (heartburn)
- May progress to gastroesophageal reflux disease (GERD)
- Barrett’s esophagus
- Muscularis mucosae
- Primarily longitudinal smooth muscle
- Begins near level of cricoid cartilage
Submucosa
– Dense irregular connective tissue
– Diffuse lymphatic tissue and nodules
– Esophageal glands proper
• Mucous glands
– Slightly acidic secretion
– Lubricate lumen
- Scattered along the length
- Frequently more concentrated in upper half
- Excretory duct
– Meissner’s plexus
- Nerve fibers
- Ganglion cells
- Primarily supplies muscularis muscosae
Muscularis externa
– 2 muscle layers
- Inner circular
- Outer longitudinal
- Upper 1/3 striated muscle
- Middle 1/3 striated muscle & smooth muscle
- Lower 1/3 smooth muscle
– Myenteric (Auerbach’s) plexus
- Between inner and outer muscle layers
- Nerve fibers and ganglion cells
- Innervates muscularis externa
Adventitia
Explain the functions of the esophagus in the digestive process.
Functions
– Transport food to stomach
• Peristalsis is a series of wave-like muscle contractions that moves food to different processing stations in the digestive tract. The process of peristalsis begins in the esophagus when a bolus of food is swallowed.
– Secrete mucus
Discuss gastroesophageal reflux disease (GERD) and Barrett’s esophagus.
GERD occurs when stomach acid or, occasionally, stomach content, flows back into your food pipe (esophagus). The backwash (reflux) irritates the lining of your esophagus and causes GERD.
- Lower esophagus undergoes metaplasia (a)
- Gastroesophageal reflux through the lower esophageal sphincter
- Higher risk of developing dysplasia
- Risk of developing adenocarcinoma
Barrett’s esophagus is most often diagnosed in people who have long-term gastroesophageal reflux disease (GERD) — a chronic regurgitation of acid from the stomach into the lower esophagus.
Describe the function, location, and gross anatomy of the stomach.
Describe the histology and layers that form the wall of stomach.
1. Mucosa
– Prominent mucosal & submucosal folds (rugae)
– Gastric pits
– Gastric glands
- Extend from muscularis mucosae
- Empty into gastric pits
– 3 components
- Epithelium
– Simple columnar
» Surface mucous cells
- Lamina propria
– Surrounds gastric pits & glands
- Muscularis mucosa
– 2 thin layers
» Inner circular
» Outer longitudinal
– Some regions may have a 3rd circular layer
2. Submucosa
– Dense connective tissue
– Submucosal (Meissner’s) plexus
• Innervates blood vessels & muscularis mucosae
3. Muscularis externa
- Inner oblique
- Middle circular
- Outer longitudinal
– Myenteric (Auerbach’s) plexus
4. Serosa
What are 4 functional cell types of the gastric fundic glands?
1. Neck mucous cells
– Renewed every 5-6 days
2. Parietal cells (oxyntic)
– Renewed every 150-200 days
3. Chief cells (peptic)
– Renewed every 60-90 days
– Renewed every 60-90 days
Where are stem cells of the gastric (funic) glands located?
- Located in the isthmus & neck
- Give rise to the other cell types
How much and what are the compenents of gastric juice by the gastric glands?
Describe Parietal (Oxyntic) Cells.
Describe Chief (Peptic) Cells.
Describe Enteroendocrine Cells
Discuss peptic ulcer disease (PUD)
Peptic ulcer disease (PUD), also known as a peptic ulcer or stomach ulcer, is a break in the lining of the stomach, first part of the small intestine, or occasionally the lower esophagus.[1][2] An ulcer in the stomach is known as a gastric ulcer while that in the first part of the intestines is known as a duodenal ulcer.
Describe the function, location, and gross anatomy of the small intestine.
Describe the histology and layers that form the wall of small intestine.
Name 3 types of tissues/cell specializations found in the small intestines.
- Plicae circularis (circular folds)
– Valves of Kerckring
– Permanent transverse folds
• Contain core of submucosa
– Most numerous in distal duodenum and jejunum
– Reduced in size and frequency in ileum
- Villi
– Fingerlike & leaflike mucosal projections
• 0.5 - 1.5 mm
– Completely cover surface
– Lamina propria contains central lacteals
• Blind-ended lymphatic capillary
- Microvilli
– Major increase in luminal surface area
– Each cell possesses several thousand microvilli (Mv)
– Give the cells a striated border (SB) in the light microscope
• Brush border
– Glycocalyx (G)
– Terminal web (TW)
Describe the duodenum.
Describe the jejunum.
Describe the ileum.
Describe the intestinal glands including the cells of the small intestine.
Describe Enterocytes
Located in the small intestines
Descrie Goblet Cells
Located in the small intestines
Describe Enteroendocrine Cells
Located in the small intestines.
Describe Paneth Cells
Describe the function, location and gross anatomy of the large intestine.
Describe the histology and layers that form the wall of large intestine.
Describe the Mucosa of the large intestines.
Describe Muscularis Externa of the Large Intestines
Describe Vermiform Appendix of the Large Intestines
Describe Rectum & Anal Canal
Discuss appendicitis and Hirschsprung disease.
Appendicitis
– Inflammation
– Results from blockage of opening to the cecum
• Scarring, thick mucous or stool
