Lecture 8; Salivary glands, oesophagus and stomach microanatomy Flashcards
What are the mucosal specialisations?
Stomach; gastric pits and glands
SI; Crypts of lieberhuhn and villi (small increase SA)
Transient folds; Rugae of stomach
Permanent folds; plicae circularis of SI
Lymphatic nodules
What are the tunics?
- Mucosa
- Epithelium
- lamina propria
- Muscularis mucosae - Submucosa
- Muscularis externa
- Adventitia or Serosa
Describe the mucosal function;
Epithelium;
- Secretion (glands)
- Mechanical protection (st. sq.)
- Absorption
Lamina propria;
- Support -> BV, lymph and nerve.
- > Structural (collagen)
Muscularis mucosae;
- Movement of mucosae indp. of peristalsis i.e for secretions
What is the function of the submocosa?
Support like lamina propria
What is the function of the muscularis externa?
Co-ordinated contraction of inner circular and outer longitudinal layers (Smooth muscle) (some exceptions to the two layers).
Describe the adventitia and serosa;
Adventitia; Outermost connective tissue covering of any organ, vessel or other structure.
Serosa; a.k.a visceral peritoneum. Slippery outer covering for the gut tube; two layered, Outer mesothelium sitting on a bed of connective tissue. (Serous fluid)
What is ascites?
- Accumulation of fluid from serosa lining (recycles fluid in peritoneum). leads to abdominal swelling, distortion of visceral organs.
- Unusual conditions can lead to this; Liver disease, heart failure, electrolyte imbalance.
What is peritonitis?
- Physical trauma, chemical irritation, bacterial invasion from surgery can cause peritonitis
- Inflammation interferes with normal function.
What are the three major salivary glands?
- Sublingual
- Parotid
- Submandibular
What are the fluids secreted by the three glands?
Sublingual -> Mixed, mainly mucous
Parotid -> Serous only
Submandibular -> Mixed serous and mucous
Describe the cells found in a serous acinar;
- Zymogen granules near lumen
- Large circular nuclei
- Surrounded by myoepithelial cells
Describe the appearance of the mucous acinar;
- Pushed squished peripheral nuclei
- No zymogen granules, but filled with many mucin granules.
Describe the ducts of the submandibular gland;
- Intralobular ducts are striated peripherally as they are filled with mitochondria.
- Intralobular lead to interlobular and submandibular ducts eventually.
Describe the composition of saliva;
- Water
- CHO glycoproteins (Mucins)
What is the function of mucins in saliva?
Protection against
- Bacterial adhesion and secretions
- Vomit
Mucous filled with bi-carb which mediates protection.
What are some specific immune factors in saliva?
- Lysozyme —-I B. cell wall
- Lactoferrin —I Fe- dependent B.
- IgA —–I Bac. / Virus
What are some specific enzymes in saliva?
Amylase (active pH 4-11)
Lipase (Optimal pH 4.0 (mainly stomach)
Haptocorrin
Kallikrein
What controls saliva regulation?
ANS; PSN and SNS
What can stimulate and decrease saliva regulation?
Increase: Sight, thought of food, nausea
Decrease: Fatigue, sleep, fear, dehydration, exercise.
How does the PNS influence salivary glands?
= Accelerates secretion
Results in a large amount of watery saliva
Myoepithelial cells contract, increased blood flow
How does the SNS influence salivary glands?
= Secretion of a small volume of viscous saliva containing high enzyme concentrations
dry mouth
blood vessels constrict.
What cause xerostomia?
Dry Mouth
- Mumps
- salivary duct calculi (stones)
- Salivary gland tumors (usually benign)
- Sjogrens syndrome
- Meds
What causes hypersalivation?
Water brash
- Associated with many conditions (peptic ulceration and IBD)
- Meds
- Toxins i.e organophosphates, arsenic
Describe the fourth tunic of the oesophagus;
- Adventitia mostly and serosa final portion
