digestive systems- topic 1 Flashcards
What is the gastrointestinal system?
GIT and accessory digestive organs
What are the four major functions of the GIT?
- motility
- diggestion
- secretion
- absorption
what essential is the GIT?
hollow tube of musculo-membranous from the mouth to the anus
what are the accessory digestive organs (4)
- salivary glands
- gall bladder
- liver
- pancreas
What are the 3 types of digestive systems?
- mongastric
- ruminants (fore gut fermentors)
- hind gut fermentors
What is an example of a hindgut fermenter?
horse and rabbit
What is an example of a foregut fermenter?
ruminants - cow, sheep, goat
What is an example of a monogastric fermenter?
dogs and cats
What is the function of the oral cavity (6)?
prehension, mastication, insalivation, bolus formation, weapon, taste
What is the role of the tungue?
prehensile organ (PICKING UP FOOD) aids in chewing, mixing and bolus formation
what (4) types of papillae covers the tongue?
- filiform papillae
- fungiform papillae
- foliate papillae
- vallate papillae
where are taste buds found (5)?
on the tongue (papillae), epiglottis, larnyx, pharanyx and soft palate
What are the two types of lips and which animals have them?
soft- sheep and horse
hrad- pig and cow
what is the role of cheecks?
muscular, covered in mecous membrane, aid in
chewing.
what are the (2) components of the jaw?
upper- maxilla
lower- mandible
What is the hard palate?
roof of mouth
what is the soft palate?
caudal to the hard palate on roof of mouth
what are the (2) types of teeth?
hypsodont and brachydont
what is the difference between a hypsodont and brachydont tooth? give an example of each
hypsodont erupt continuaslly - horse
brachydont- low crowned teeth, stuop growing once erupted- dog
what are the 3 layers to the tooth?
pulp (inner) dentin enamel (outer)
what holds the tooth in place?
cementum and periodontal ligament
what are the 4 types of teeth?
incisor (cutting), canine (tearing), premolar and molar (grinding)
what are the tonsils?
mass of lympoid tissue
what is the pharynx?
common passage for food and air in 3 parts (oropharny, naso pharynx and hypopharynx)
what 2 muscles types surrond the oesophagus?
inner circular and outer longitudinal
what is the small intestine important for?
digestion and absorption of fats, carbs and proteins
what are the 3 components of the small intetines?
duodenum, jejunum (long) and ileum (short)
iluem joins the small intetines to the caecum
what are the 3 components of the large intetines?
caecum, colon and rectum
what is the peritoneum and where is it found?
membrane lingin the abdominal cavity and covers all visceral organs within the abdomen
what are the 4 components of the peritoneum
- parietal ( lining abdominal wall)
- visceral (lining organs)
- mesentery (supports intestines and suspends them from dorsal abdominal wall)
- omentum ( covers stomach and other structures)
what are the 4 layers covering the GIT?
- mucosa (inner)
- submucosa
- muscularis
- serosa (outer) (visceral peritonuem)
which animal has a crop and what is its role?
bird, acts as a food storage
what is a proventriculum and what is its role?
in birds, similar to grandular stomach. grinds and mixes food. `
which animal can have paired caeca?
bird
what is a cloaca?
in birds, similar to anus
what is the exterior portions of the monogastric stomach (4)?
cardiac, fundic, pyloris and body
what are the 4 internal regions of the monogastic stomach?
oesophageal- no glands
cardiac- glands
fundic- glands
pyloric- glandular
what are the 2 major parts of the ruminant (foregut)?
- forestomach
- reticulum, rumen and omasum - true stomach
- abosmasum
what is the forestomach of the rumen and waht happens there?
rumen, recticulum and omasum
food is soaked, mixed and undergoes microbial digestions
where does microbial digestion take place?
forestomach of ruminants
where is the glandular part of the ruminant stomach?
abomasum (true stomach)
describe the passage of food through the ruminant (7)
reticulum/rumen, omasum, abomasum, small intestines, caecum, large intestines
what are the 4 components of the rumen?
- dorsal sac
- dorsal blind sac
- ventral sac
- ventral blind sac
what divides the sacs of the rumen?
grooves externally, muscular pillars internally
what is the role of the rumen?
- storage
- enviro for fermentation
- mixing
- transport
- eructation (burping)
- rumination
- absorption of VFA (product of fermentation)
what are the two types of digestion and where do they take part in the ruminant?
microbial- foregut (rumen, reticulum and omasum
enzymatic- true stomach (abomasum)
what 2 nerves control the GIT?
mysenteric and submucosal plexus
what is the difference between extrinsic and intrinsic control? how do they interact?
extrinsic- external
intrinsic- local
extrinsic systems communicate to the intrinsic through the mysenteric and submucosal plexus
what is the function of motility (4)?
- propel ingesta
- retain ingesta (enables digestion, absorption or storage)
- physical break down of food
- circulate/mix food (increases contact with absorptive surfaces
what is the first act of digestion?
mastication, mechanical breakdown of food
what does chewing stimulate (4)?
secretion of saliva, gastric juices, pancreatic juices and bile
define deglutition
swallowing
what is the role of the epiglottis?
a flap of cartilage which covers the oesophagus when swallowing
what is segmentation and where does it occur?
random localised contractions of the circular smooth muscle. occurs in the small and large intestines, mixing ingesta
what are the 3 types of motility in the large intesetine?
peristalsis/antiperistalsis (peristalsis in reverse) and segmentation (random localised mixing) and mass movement (waves or peristalsis contractions sweeping undigested material along)
what are the two types of rumen motility?
- primary contractions
- mix ingesta - secondary contractions
- cause eruction (burping)
what are the 3 stages of rumination and what happens during each phase?
- regurgiation
- floating fiborous material regurgitated - remastication
- only rechewing of fiborous material - reswallowing
- moves reticulum to omasum
what is the difference between secretions and excretions?
secretion- release of useful substances
excretion- elimination of waste from the body
what are the two types of secretions of gastric juices and which cells secrete them?
exocrine cells
- chief cells
- parietal cells
endocrine
- ECL cells (Enterochromaffin-like cells)
- G cells
- D cells
what does the chief cell secrete and what does it do?
secrete pepsinogen- protein break down
what does the parietal cell secrete and what does it do?
secrete HCL- activates pepsinogen which becomes pepsin, denatures proteins and kills micro organisms
what does the ECL (Enterochromaffin-like cells) cell secrete and what does it do?
secrete histamine which stimulates parietal cells
what does the G cell and D cell secrete and what does it do?
g cells secrete gastrin which stimulates parietal, chief and ECL cells
d cells secrete somatostatin which inhibits parietal, G and ECL cells
what secretes intestinal juices and what does this do?
crypts of lieberkuhn between the villi
secrets watery bicarb fluid into lumen and intestinal hormones
what glands are in the duodenum?
brunners glands secrete mucus
what are peyers patches and where are they found?
aggregation of lymph nodes- immune response
intestines and commonly in ileum
define digestion
breakdown of complex nutrients into simple molecules for absorption
what are the 3 types of digestion and give an example of each
- mechanical
chewing - chemical
enzymes - microbial
microflora in rumen
define absorption
transport of simple molecules across the intestinal wall
what does pepsin break down and where does this occur?
proteins, stomach
what occurs most in the small intestines?
digestion and absorption of soluble carbs, proteins and fats
what is the role of mechanical digestion?
reduce particle size to increase SA
what is the role of chemical/glandular digestion?
reducing nutrients to simpler components
what is the simple form of carbs and what enzyme do this?
simple sugars, amylase (from pancreas and saliva)
what is the simple form of protein and what enzyme do this?
AA and simple peptides, pepsin and pancreatic proteolytic enzymes
what is the simple form of fats and what enzyme do this?
monoglycerides and free FA, bile salts and pancreatic lipases
In ruminants and horses, what do carbs become due to microbial digestion (fermentation)?
VFA- important energy source
where are proteins transported to for processing?
liver
where does fat digestion absorb into?
lymphatic system
what are the 3 types of salivary gland classification?
serous, mucous or mixed
what are the 3 major salivary glands?
parotid, mandibular and sublingual
why is saliva not essential for non ruminants?
enzymes produced by the pancreas and small intestines can digest food
what are the two nervous controls to the salivary glands and what do they do?
sympathetic
- decreases blood flow- saliva more sticky
parasympathetic
- increases blood flow- makes saliva watery
what is the difference between exocrine and endocrine
endocrine secretes hormones directly into blood
exocrine secretes hormones ducts opening onto epithelium
what is the pancreas?
compound gland with endocrine and exocrine portions producing sodium bicarb, digestive enzymes and hormones
what is the exocrine portion of the pancreas and what is its function?
produces sodium bicarb and digestive enzymes
what are the three exocrine digestive enzymes produced by the pancreas?
proteolytic enzymes- protein digestion
lipase- fats
amylase- carbs
what is the endocrine portion of the pancreas and what is its function?
islets of langerhan produce insulin (beta cells) and glucagon (alpha cells)
what are the four major vessels associated with the liver and what are their functions?
hepatic artery- arterial blood
portal vein- venous blood from all parts of digestive tract
vena cava- livers venous drainage
bile duct- releases bile
what is gluconeogenesis
synthesis of glucose from compounds
what is glycolysis
breakdown of stored glycogen to release glucose
what are the 3 general functions of the liver?
metabolic regulation
- composition of circling blood, metabolism of carbs and fats, waste product removal and storage of fat soluble vitamins
haematological regulation
- remove old rbc
syn and release of plasma proteins
removing circulating hormones
bile production
- stored in gall bladder
what is the gall bladder and where is it located?
near liver, empties into duodenum via bile duct
not in horses
stores bile
what is the function of the bile?
secreted as bile salts and pigments
breakdown fats and increase fat solubility (aids digestibility)
list in order the principal parts of the digestive system
oral cavity, oesophagus, stomach, duodenum, jejunum, ileum, ceacum, colon, rectum, anus
what is the role of the salivary gland?
breakdown of carbs, solvent, lube, buffer, immune
what are the ruminant stomach compartments and what are their functions?
rumen - storage, mixing, transport eructation (burping) reticulum - reticulo rumen = fermentation vat omasum -grinding roughage and squeezing out fluid abomasum -gastric juices digest
