Lecture 5 Flashcards
What is a species adaption in the oesophagus?
Species adaptations
Ability to control
peristaltic
contractions
◆ Reverse peristalsis
◆ Amount and location of
skeletal muscle
◆ Regurgitation vs. vomiting
In horses eosophagus can they belch out gas or vomit?
no they cant
Whats dogs eosaphagus muscles like?
Striated muscles throughout allow GREAT control of digesta
movement both directions
Whats different about ruminants oesophagus?
Different from monogastric esophagus
– Striated muscle along the entire length
* Provides greater strength
* Allows some voluntary control
– Funnel shaped
* Contains three sphincters active in rumination
and eructation
Whats the stomach regions?
-Oesophageal (Non-Glandular)
-Cardiac (secreted muscle)
-Fundic (Parential cells and cheif cells)
-Pyloric (Mucas)
What are the different muscles in the stomach?
-Longitudinal muscle
-Circular muscle
-Diagonal muscle
-Pyloric sphincter
Whats functions of gastric digestion
Reservoir for controlled release of digesta to small
intestine
* Horse has small capacity – requires increased number of
smaller sized meals
– Mixing food & mechanical breakdown of feed
– Hydrolytic digestion by acid and enzymes
* Mainly protein
– Kill most bacteria
– Hormone production
What does gastric fluid consist of?
-Mucas
-Hydrochloric acid
-Pepsinogen
What does mucas do in stomach?
coats and protects the lining of the
stomach.
What does hydrochloric acid do in the stomach?
kills most harmful
substances that have been ingested and it also
converts pepsinogen into pepsin
What is pepsin?
it is a protein digesting enzyme that breaks
large protein chains into smaller chains
Name the 4 secretions in the stomach?
-HCL (-Decrease’s pH -Denatures protein - Kills most bacteria -activated pepsinogen)
-Mucus (-Protects lining from acid and enzymes -No “autodigestion” -Lubricant)
-Pepsinogen (-activated form in pepsin -Hydrolyses)
-Rennin (abomasum, clots milk)
-Lipase (-some species)
What are gastric pits formed by?
-Formed by numerous folds in the
epithelium
- Glands empty into the gastric pit
- Many types of glands may empty
into one gastric pit
What does the acidity of the stomach allow pepsin to do?
To function and make the HCL effective at killing pathogens
What do mucus cells secrete ?
Secrete mucus to protect
epithelial cells from enzymes
& acid
What do parental cells secrete?
HCL
What do chief cells secrete?
Secrete pepsinogen which
gets converted to “pepsin”
when mixed with HCl; for
protein digestion
What do entero- endocrine cells secrete?
Secrete gastrin to regulate
stomach emptying
What 3 things controls gastric secretions and gastric mobility?
- Cephalic phase
- Gastric phase (chemical phase)
- Intestinal phase
1- What is the Cephalic phase? (2)
Vagal reflex:
It is induced by thinking , smelling , tasting or chewing food
Implies involvement of CNS (via release of acetylcholine , histamine and gastrin )
Increased saliva production, gastric mobility, enzyme and HCL secretion
2- What is the Gastric phase (aka Chemical Phase) and an example: (3)
This is a local reflex, it depends on presence of food in stomach eg: dietary protein stimulates G cells to release gastrin
-Its reinforced by gastrin (peptide hormone secreted by stomach)
-Increases HCL secretion
3- What is the intestinal phase (2)
-Stimulated by duodenal , distension, decreased pH, osmolarity, nutrients (fat and carbs)
-Decreases HCL secretion and gastric motility (cholecystokinin (CCK) is released by the small intestine
What are the two gastric mobility and emptying actions?
1- Mobility aids mixing , mechanical and hydrochloric reduction of feed to chyme
2- Emptying is stimulated by distension of antral wall and presence of liquid chyme
Why is the stomachs pH 2-3?
The acidity allows pepsin to
function and makes the HCL
effective at killing pathogens