Salivary Glands Flashcards
(29 cards)
Layers of the digestive system
Outer to Inner
*4 concentric layers/tunics
1.Adventitia
2.Muscularis externa (outer longitudal and inner cicular)
3. Submucosa
4. Mucosa (Muscularis mucosae, lamina propria, epithelium)
other features:
Crypts
Villi
Role of sympathetic and parasympathetic on ENS
sympathetic= overall inhibitory impact on enteric nervous sytsem (ENS) (divert blood to brain and muscles)
- Response assosciated with exercise, emotion, excitement
parasympathetic-= overall stimulatory impact on ENS (During and after meal time, stimulate secretion and transport in the gut)
- response assosicated with repletion, rest and relaxation.
Role of Mucosa
- each subcomponent
Epithelium
- not vascularised
- huge variety
- main role is protection: friction, chemicals, enzymes.
- secretion: acid, enzymes,
mucus
- absorption: mostly in the intestines
- stem cells by basement membrane
Lamina propria
- supplies oxygen s nutrients a removes waste from epithelial cells
- Support: STRUCTURAL (Connective tissue) and FUNCTIONAL (blood vessels, lymphatics, nerves)
Muscularis mucosae
- allows mucosa to have some movement independent from peristalsis of whole gut tube (difference in scale
Role of submucosa
Submucosa
support- > basically lamina propria enlarged
- all of the small vessels in lamina propriacome from/return to submucosa
Role of Muscularis externa
- allows peristalsis to happen, usually coordinated contraction of 2 muscle layers (except 3 in stomach)
2 layers = inner circular (narrow) and outer longitudal layer (shorten)
Role of Adventitia and Serosa (visceral peritoneum)
Adventia:
is the outermost connective tissue covering of any organ, vessel, or other structure
Serosa: aka viseral peritoneum. A slippery outer covering for the gut tube. Has mesothelial cells on outside which make the serous fluid
What are organs that are suspended covered in
and examples of organs
Organs totally suspended are covered in serosa. Lined with a single, thin, squamous layer of mesothelium
e.g. stomach, liver, ileum
Retroperitoneal organs are lined with?
Examples of organs
Retroperitoneal organs are lined with visceral peritoneum on anterior surface only posterior surface = adventitia.
e.g. kidneys, ureters, abdominal aorta
Organs covered in a mix of lining
Mixture: form as “intra”peritoneal but subsequently become retroperitoneal
e.g. pancreas; much of the duodenum
Clinical implications of serosa
Ascites
-ass with liver disease, heart failure, electrolyte imbalance
Acc of fluid causing ab swelling and mvoement of organs in body
= imbalance between secretion & reabsorption of peritoneal serous fluid
Peritonitis = inflammation of the peritoneum
Due to physical damage, chemical irritation, bacterial invasion.
Inflammation impairs normal functioning.
3 major salivary gland sources and what they secrete
- Sublingual
- Serous and mucous - Submandibular
- serous and mucous - Parotid
- Serous only
How do salivary glands form
develop as epithelial structuresa dig into connective
tissue underneath to form glandular structures.
they form islands called secretory lobules
Label the salivary gland drawing
- what are the key features and general role of them
Lecture Slide
Key features:
1. serous acinus - watery secretion that is enzyme rich
- Zymogen granules (enzyme precusrosr of amylase to breakdown carbs)
- dark staining
- Mucus acinus
- Much larger mucus granules in cytoplasm causing nuceli to flatten and be pushed to the outer edge of cell
-lighter staining of mucus glands
*If a mixed gland, only have serous if parotid gland
- Intercalated ducts
- Myoepithelial cells
- Modified epitheal cells that have contractile properties (squeeze acinar cells to propel secretions out)
- arround acinar cells and along ducts - serous deilune (mixed acinus)
- Striated ducts (Interlobular duct)
- lots of mitochondria alligned in coloumns giving the striated appearance thus lots of energy
- pumping of ions (bicarbonate) to act as a buffering agent
Role of acinus
- enzyme-rich, watery secretion
- zymogen granules (pre-enzymes) darkly staining
in cytosol - primary zymogen is
amylase- > helps start breakdown of carbs and starches
Role of intercalated ducts and modified epithelial cells
intercalated ducts:
very short
· function is to transport
secretions
modified epithelial cells
Surrounding acinar cells & along ducts
- contractile properties (myo= muscle
·squeeze acinar cells to propel secretions out
Key composition & functions of saliva and what allows those fucntions to happen
99% water with an assortment of ions, buffers, metabolites, enzymes.
- Lubrication
- Salivia has Carb rich glycoproteins (Mucins) which are slippery and stop bacteria adhereing to teeth and allow lubrication.
2.Protection
- Bicarb ions (buffers influx of acidic secretions from bacteria)
- Lysozyme - break down cell walls
- Lactoferrin - block iron dependent bacteria
-IgA: fight off bacteria and viruses in general
3.Digestion
- Amylase - digest carbs
-lipase - some lipid digestion, but mostly in stomach due to low pH
-Haptocorrin - B12 absorption
-Kallikrein - increase blood flow
Control of salivary secretion
-how does consistency change
↑ = Sight and thought of food (preparation, presentation, smell, taste, chewing); nausea
PSNS: accelerates secretion, resulting in the production of large amounts of watery saliva; myoepithelial
cells contract; increased blood flow (sustains demand for metabolism).
↓ = Fatigue; sleep; fear; dehydration; exercise
SNS: secretion of a small volume of viscous saliva containing high enzyme concentrations; reduced
volume produces the sensation of a dry mouth. Blood vessels are contstricted (restricts blood flow and
secretion)
Clinical Application of reduction in salvia production
and hyper secretion
Xerostomia (dry mouth)
* Mumps (a virus that preferentially targets the parotid glands)
* Salivary duct calculi (stones)
* Salivary gland tumours (usually benign)
* Sjögren’s syndrome (SHOH-grinz) - autoimmune condition (generalised dryness)
* Medications
Hypersalivation (water brash)
* Associated with many conditions (inc. peptic ulceration & IBD)
* Medications
* Toxins (organophosphates; arsenic)
Peristalsis vs segmentation
Lecture Slide
Examples of Gastro-oesophageal diseases
Reflux oesophagitis
Barrett’s oesophagus
Label the areas of the stomach
- what are the 4 areas
- what are the 3 layers
Lecture Slide
4 areas:
(RHS) Fundus
(RHS) Body
(LHS) Cardia
(LHS) Plyorus
Label the cell types at different areas in the stomach
Fundus and Body:
Parietal cells (make HCL, IF, Pepsinogen, somastatin)
Cardiac
Mucus
Pyloric
Mucus
Pepsinogen
Gastrin
Somatostatin
(1)Simple columnar mucous cells of surface and pits
(2) Mucous neck cells of gastric glands
(3) Undifferentiated stem cells
(4) Parietal cell (oxyntic cell)
(5) Chief cell (zymogenic cell)
(6) Enteroendocrine cells
Insoluble, alkaline/neutral glycoproteins forms a protective mucous bicarbonate barrier sheet above the epithelium.
Soluble, acidic glycoproteins secreted when food is present; mucous granules are less densely packed
Rapidly replace simple columnar mucous cells &
can migrate down to replace specialised cells
· make HCI ,
H+ Cl ions secreted into lumen where they combine
· make intrinsic factor
· HC) helps sterilise food helps acidifiy enviro. To activate pepsinogen
· not HCl inside cell to protect from autodigestion
Enzyme pepsin secreted in inactive form
(pepsinogen) into the lumen of the gland
G cells (gastrin)
ECL (histamine)
D Cells (Somatostatin)
Two nerves plexus of the enteric system
- Myenteric (located between circular and longitudal)
- Meissner’s (located between submucosa and inner circular layer)
