The Digestive System Flashcards
Tongue function
taste buds, thermoregulation, aid digestion
Brachydont teeth
developed roots, small crown, do not continually grow, carnivores dogs humans
Hypsodont teeth
continually grow, open root apex, horses,rodents
Dog dental formula
I(3/3) C (1/1) P(4/4) M(2/3) 42 teeth
Cat dental formula
I(3/3) C(1/1) P(3/2) M(1/1) 30 teeth
Horse dental formula
I(3/3) C(1/1) P(3/3) M(3/3) 40 teeth
Bovine dental formula
I(0/3) C(0/1) P(3/3) M(3/3) 32 teeth
3 main salivary glands
parotid, sublingual, mandibular
Parotid gland
At base of the ear, opens up into 4th premolar buccal cavity
Mandibular gland
produces mucoid and serous mucous, runs along floor of the mouth
Sublingual gland
under tongue, drains via ducts
Where are the tonsils located? What is their function?
In the pharynx, protects animal from disease
What is the omentum
A double layered connecting peritoneum which connects the stomach to the abdominal wall or other organs. It stores fat and acts as an insulator
What does the stomach produce?
Intrinsic factor, needed for vit B12 absorption
What’s the function of 1) Cardiac sphincter 2) Pyloric sphincter
1) prevents reflux of food back into the oesophagus 2) controls release of food into the small intestine - 2/4 hrs
Name the glandular parts of the monogastric stomach
Cardia, fundus, corpus, pylorus **Oesophageal part not glandular
what is rugae? where can you find it?
found on the fundus. it is gastric folds that increase surface area after meals
Name the cell types of the stomach and what they secrete
parietal cells- hcl and intrinsic factor, mucin cells- mucous, chief cell - pepsinogen (which becomes pepsin when mixed with hcl, which breaksdown protein into peptides)
Stomach motility decreases when…
food enters the stomach
Stomach motility increases when…
food moves towards the pyloric sphincter
what are the two phases of chemical digestion?
- luminal digestion (hydrolysis- breaking of a bond by insertion of a water molecule) 2. membranous chemical digestion (hydrolysis repeated, molecules broken down into most basic components)
Which of the forestomachs in a ruminant in NOT glandular
reticulum, rumen, omasum
Describe the rumen
fermentation occurs here, occupies most of the LHS of abdominal cavity, pillars (mucous folds) divide the rumen, has papillae to inc. surface area.
Describe the reticulum
lies against diaphragm, fermentation, has honeycomb mucosa, ‘reticulorumen’ (they work together)
Describe the omasum
important in young animals (tube for milk), folds of mucosa, papillae on surface, absorption of water and salt
Describe the abomasum
glandular, rugae, continuous flow of ingesta, secretes pepsinogen and hcl -> pepsin,
Describe rumination
1) regurgitation, 2) resalivation, 3) remastication, 4) reswallowing. Ingesta moves from reticulorumen into the oral cavity and then goes through these four steps
Describe eructation
this is how ruminants belch. occurs once a minute, releases gases (CO2 and CH4 produced during fermentation). Cows release up to 4000L in 24hrs
What is the small intestine?
A tube that carries away chime from the stomach and deposits it into the large intestine
Which ducts open into the duodenum?
pancreatic and bile duct
Which glands release digestive enzymes? and into what part of the S.I?
Brunner’s glands release digestive enzymes into the duodenum
What occurs in the jejunum?
Most chemical digestion & absorption takes place here. The crypts of lieberkuhn (Paneth cells) release digestive enzymes.
What occurs in the ileum?
Peyer’s patches (protect against disease) empty into the large intestine at cecum (horse), at colon (dogs and cats) or in colon and cecum (pigs & ruminant)
How has the small intestine made adaptions?
villi to increase surface area = better absorption. Lacteals carry chyle, a milky fluid resulting from fat digestion. Blood capillaries transport small molecules from breakdown of carbohydrates and proteins to liver via hepatic portal vein
What does the small intestine secrete?
Cholecystokinin (CCK) which stimulates pancreatic secretions, chyme with a high fatty acid and high amino acid concentration.
The pancreas is a mixed gland (endo and exocrine) Explain the endocrine part of it
Releases hormones, B cells release insulin which lowers blood level glucose. A cells release glucagon which increases blood glucose (gluconeogenisis)
Explain the exocrine function of the pancreas
Releases digestive enzymes and bicarbonate via the pancreatic duct
What is exocrine pancreatic insufficiency (EPI)?
When the pancreas fails to produce sufficient enzymes to digest food, the digestion of fats are particularly effected (fatty stool-light coloured)
What does the liver do?
Processes blood coming from the GI tract, meaning it prevents toxins getting into the bloodstream
Name some functions of the liver
Secretes substances needed for digestion/absorption of nutrients. Excretes toxic substances. Produces plasma proteins, cholesterol and blood coagulation factors.
What two sources does the liver receive blood from?
hepatic portal vein (GI tact) and hepatic artery (branch of celiac artery - abdominal aorta). They come together and empty their blood into the sinusoids
Which cells in the liver engulf foreign objects?
Kupffer cells
Where is bile excreted from?
by hepatocytes (also secrete protein) into the canaliculi
What controls the entrance of the bile duct into the duodenum?
Sphincter of Oddi, when closed, bile back up into the gall bladder
What is the gall bladder?
Storage area for bile, which is produced by the liver. It also transports the bile to the bile duct. Bile enters duodenum to digest high fat and peptide conc.
What is bile made up of?
bile salts, phospholipids, cholesterol, bile pigments
What is bilirubin (produced by bile acids)?
Breakdown product of haemoglobin
What are the four stages of lipid digestion?
1) emulsification 2) hydrolysis 3) micelle formation 4) absorption
What are the functions of the large intestine?
absorption of water and ions, absorption of carbs & proteins that remain undigested, has mucus secreting goblet cells.
Name the 4 parts of the large intestine
Cecum, colon, rectum, anus.
The cecum is..
a blind diverticulum at beginning of colon (edges off to the side)
Which part of the SI opens up into the cecum?
The ileum
Describe some of the things that occur in the LI
Carbs are degraded to VFA’s (an energy source) and some of this gets lost in the faeces. Gases like CH4 and CO2 transported to the rectum. Most microbes in the LI are excreted in the faeces.
What happens when faeces reach the rectum?
The sensory receptors get stimulated, colon and rectum contract, inner & outer anal sphincter muscle contract
