Alimentary Flashcards
What is the dental formula and what is the dental formula for cats and horses?
Tells you how many teeth are on one side of the mouth on the upper and lower jaw, in the order of: Insicors-Canines-Premolars-Molars
Cats: 3-1-3-1
3-1-2-1
Horses: 3-1-4-3
3-1-4-3
Name the 3 main salivary glands in the head and where their located
Parotid - Base of the ear
Mandibular - origin of the mandible
Sublingual - very close to mandibular gland, slightly rostral.
What makes up the foregut and what is its blood supply?
- Supplied by Coeliac artery
- Stomach
- Liver
- Pancrease
What makes up the Midgut and what is its blood supply
- Cranial mesenteric artery
- Duodenum
- Jejunum
- Ileum
- Ascending colon
- Proximal 2 thirds of the transverse colon
What makes up the hingut and what is its blood supply
- Caudal mesenteric artery
- Later third of the transverse colon
- Descending colon
- Rectum
What is peristalsis?
Movement of a bolus/chyme in a antergrade direction. Contraction of circular muscle behind bolus ensures no retrograde movement, and longitudinal muscle contraction infront of bolus pushes it along
what occurs during interdigestive phase of peristalsis?
Peristaltic contractions over large segments of the intestine, known as the migrating motility complex. also used to transport bacteria
What prevents retrograde movement of food from colon back into ileum?
ileocecal sphincter
What are haustria & how are they formed?
Pouches in the colon giving it its segmented appearance. Cause by Teniae coli (smooth muscle).
The teniae coli are shorter than the colon so cause the formation of haustria
What is responsible for intrinsic control of GIT?
Basic Electrical Rhythm (BEM). Spontaneous slow wave activity of gut. When BEM reaches threshold, AP occurs.
what are the 2 subdivisions of ENS
- Submucosal plexus
- Mysenteric plexus
What are the 3 stages of gastric secretion ?
- Cephalic
- Conditioned reflex to sight/smell/taste of food
- via vagus nerve, release of histamine/gastrinStomach motility increased
- Increased stomach motility
- Gastric
- Stimulation of mechano/chemoreceptors leads to release of histmine and gastrin
- negative feedback loop once gastric ph is <3
-
Intestinal
* Presence of chyme in duodenum inhibits acid secretions and motility. done by release of Secretin (release of bicarbonate), Gastric inhibitory protein/GIP (decrease hcl secretion and motility) & choleycytokinin/CCK (stimulates pancreatic juices and bile production)
What are the compostition of secretions?
- Water
- ions
- mucous
- enzymes
What are the secretions of the stomach ?
- Gastrin - release when pylorus is distended. stimulates release of HCL from parietal cells
- histamine - causes H+ release
- chief cells secrete zymogen pepsinogen
What are the secretions of the small intestine ?
- Gastric inhibitory protein (GIP) - secreted from mucosa of duodenum/jejunum. Decrease secretions of hcl & inhibit gastric motility
- succus entericus
- Secretin - stimulates release of bicarbonate. released in response to low ph in duodenum
- Choleycytokinin (CCK) - synthesised in duodenum. inhibits gastirc emptying, stimulates release of pancreatic juices & increases bile production.
What are the secretions of the pancreas?
- Pancreatic juice - contains pancreatic enzymes such as Trypsinogen, Chymotrypsinogen & Pro-elastase
- Bicarbonate - neutralises chyme acting as a buffer
Explain the Entero-hepatic cirulation
- Bile salts converted into lipid soluble bile acids
- passively absorbed in hepatic portal circulation
- venous blood from ileum goes into portal vein
- bile acids then pass through the sinusoids of the liver where they are extracted
Describe the digestion and absorption of carbohydrates
Digestion
- alpha-amylase (endogylcosidase) secreted by pancrease.
- attacks the 1,4 glycosidic bond forming di, tri & most oligosaccharides
Absorption
- Isomaltase breaks down products of digestion
- glucose moves into cell by sodium glucose transporter (Na causes conformational changes)
- Leaves cell and enters blood via GLUT-2
Describe the digestion and absorption of proteins
Digestion
- Proteases attack peptide bonds and are secreted at zymogens to prevent autolysis
- Pepsin only activates at low PH.
- Main pancreatic endopeptidases are: trypsinogen, chymotripsinogen & pro-elastase
- after being attacked by endopeptidases, attacked by exopeptidases carboxyopeptidase and aminopeptidase.
Absoption
- 4 sodium dependant amino acid transporters. One for acidic, basic, neutral and amino acids. similiar to carbohydrate absorption
Describe the digestion on absorption of fats..
Digestion:
- Bile acids break lipids into micelles
- Lipase then digests thes TAG’s into free fatty acids, 2-monoacylglycerol, 1-monoacylglycerol and glycerol
Absorption:
- Fatty acids and glycerol recombine and form tiacylglycerol in the lymphatic system
- These TAG’s combine with cholesterol and phspholipds to for cholymicrons
- These are secreted into thoracic ducts
- lipoprotein lipase from capillary endothelium then break chylomicrons down, leaving remnants (metabolised into lipid particles eg HDL)
What are the muscles of facial epression and what nerve innervates them?
Innervated by cranial nerv VII
- Obicularis oris
- Levator labii superioris
- Buccinator
- Zygomaticus
Why must a horse be tube fed via intubation through the nasal cavity?
The horses soft palate and epiglottis come into contact, meaning if a tube was passed through the oral cavity the epiglottis would be pushed over the laryn/trachea. Making breathing difficult and causing respiratory problems
What are the 5 stages of tooth development?
- Thickening of oral epithelium causes formation of labiogingival lamina and dental lamina
- Underlying mesenchyme condenses, causing the formation of dental bud and labiogingival groove
- Dental bud epands and branches to form enamel organ. Surrounds Dental papilla (NC-derived)
- Small bud of cells called primordium buds off. This will form the perminant tooth.
- Primordium buds of completely. Inner layer of the enamel organ differentiates into ameloblasts (make enamel) & cells in dental papilla differentiate into odontoblasts (make dentine). This dentine will surround pulp to make root. Distal epithelial cells secrete cementum around tooth.