Digestive System: Histo Flashcards
Mucosa
Parts:
A.Lining epithelium
a.Nonkeratinized stratified squamous epithelium
b.Simple columnar epithelium
B.Lamina propria - loose (areolar) connective tissue
C.Muscularis mucosae - smooth muscle tissue
Submucosa
- Dense irregular connective tissue
- Meissner’s plexus
Muscularis externa
•Smooth muscle tissue
a.Inner circular layer - can be thickened to form sphincters or valves
b.Outer longitudinal layer
•Myenteric nerve plexus (a.k.a. Auerbach’s plexus)
Serosa or Adventitia
•Serosa (a.k.a. visceral peritoneum)
a.Mesothelium
b.Loose (areolar) connective tissue
•Adventitia
a.Loose (areolar) connective tissue
What does the digestive system consists of?
:
1) The Alimentary Canal (also called the gastrointestinal (GI) tract)
2) Associated or Accessory Digestive Organs
Describe the Alimentary Canal
also called the gastrointestinal (GI) tract
organs of the GI track include
- the mouth
- most of the pharynx
- esophagus
- stomach,
- small intestine, and large intestine.
Name the different layers of the wall of the alimentary canal.
The structural organization of the wall of the alimentary canal from the proximal part of the esophagus to the distal part of the anal canal is the same, although some specializations based on functional needs will be present.
From the lumen outward:
1.) Mucosa
A.Lining epithelium
B.Lamina propria
C.Muscularis mucosae
2.) Submucosa
3.) Muscularis externa
4.) Serosa or Adventitia
For the esophagus Describe and identify histologically. What wall modifications are associated? What lining epithelium (or epithelia) is associated? What cells are associated with epithelium? What is the function of these different cells? What glands are associated? Relate these wall modifications to function.
- Non-keratinized stratified squamous epithelium
- Sub mucosa
- Muscularis externa (proximal 1/3 is skeletal muscle) (distal 2/3 is smooth muscle)
- Adventitia: proximal, Serosa: distal
- Mucous glands
- Esophageal Glands (proper): submucosa mostly in upper portion
- Esophageal Cardiac Glands: in lamina propria
For the stomach. Describe and identify histologically. What wall modifications are associated? What lining epithelium (or epithelia) is associated? What cells are associated with epithelium? What is the function of these different cells? What glands are associated? Relate these wall modifications to function.
- Glands
- Cardia
- cardiac glands: gastric pits
- make mucous
- cardiac glands: gastric pits
- Fundus
- gastric/fundic glands very long gastric pits
- mucous, HCl, and pepsinogen
- 3 parts, Isthmus, Neck, Base
- gastric/fundic glands very long gastric pits
- Body, Pylorus
- pyloric glands: mucous
- Cardia
- Mucosa
- Simple columnar epithelium (goblet mucous cells)
- Submucosa
- No glands
- Muscularis Externa
- Three layers:
- outer longitudinal
- middle circular
- inner oblique
- Three layers:
- Serosa
- Rugae: allow stomach to expand
For the small intestine Describe and identify histologically. What wall modifications are associated? What lining epithelium (or epithelia) is associated? What cells are associated with epithelium? What is the function of these different cells? What glands are associated? Relate these wall modifications to function.
- Absorption, Duodenum, Jejunum, Ileum
- Villi and microvilli present for absorption
- Mucosa:
- Epithelium: simple columnar epithelium
- Enterocytes+Goblet cells
- Crypts of Liberkuhn (intestingal glands)
- Never extend past muscularis mucosae
- don’t extend to submucosa
- Paneth Cells: found at base
- Epithelium: simple columnar epithelium
- Submucosa
- In duodenum: brunner’s glands
- In the ileum, groups of lymphatic nodules
- in the lamina propria and submucosa.
- These aggregated lymphatic follicles are referred to as Peyer’s patches
- Muscularis Externa
- Outer longtidunal layer
- Inner circular layer
- Serosa or Adventitia
For the large intestine: Describe and identify histologically. What wall modifications are associated? What lining epithelium (or epithelia) is associated? What cells are associated with epithelium? What is the function of these different cells? What glands are associated? Relate these wall modifications to function.
- No plicae circulares and no Villi
- Teniae Coli
- Haustra
- Omental Appendages (epiploic appendages)
Mucosa
- Simple Columnar Epithelium (no villi)
- Crypts of Lieberkuhn (intestinal glands)
- Has more goblet cells than small intestine
- No paneth cells
- Absorptive Cells (Colonocytes)
Lamina Propria
- lymphoid cells/nodules
Submucosa
Muscularis Externa
- Two Layers (Teniae Coli = outer longitudinal)
Serosa/Adventitia
Describe and histologically identify the parts of the pancreas. What is the role of the pancreas? What parts function as an exocrine gland? Endocrine gland? Describe the acinar cells of the pancreas.
Parts
- Head
- Body
- Tail
Function
- 99% exocrine gland (compound acinar duct)
- secretes pancreatic juice (digestive enzymes + bicarbonate) into duodenum
- Acinar cells are most common and darker staining
- 1-2% functions endocrine glands (Islets of Langerhans)
Describe blood flow to/from the liver.
Liver receives blood from 2 sources
- Hepatic Artery: receives oxygenated blood
- Hepatic Portal Vein: receives deoxygenated blood with absorbed nutrients (possible microbs/toxins) from GI tract
Blood flow
- GI tract → hepatocytes (sinusoids of liver) → central v → hepatic v → IVC → rt atrium of heart
Describe and histologically identify the parts of the liver (e.g. portal triad, hepatic lobule, hepatocytes, Kuppfer cells, bile canaliculi, etc.). What are some functions of the liver?
Parts
- Hepatic Lobule:
- 6 sided structural and functional unit, consists of hepatocytes surrounding a central vein
- stacked plate structure, separated by sinusoids
- Sinusoids are lined with Kupffer cells, that phagocytize old RBCs
- Triads at the corners
- bile duct, hepatic artery, portal vein
Functions
- Bile production
- metabolize fats, proteins and carbs,
Gall Bladder
- Stores bile to be excreted into duodenum
- Simple Columnar Epithelium
