gastrointestinal system Flashcards
what is the gastrointestinal system
a group of specialised organs responsible for the digestion & absorption of food and excretion of waste products
what are the organs involved in the gastrointestinal system?
- mouth
- pharynx
- oesophagus
- stomach
- small intestine
- large intestine
- rectum
- anus
what glands are associated in the GI tract?
- salivary glands
- liver
- pancreas
what are the three functions of the GI tract?
- the digestion of food
- the absorption of food
- the elimination of wastes
What ways does digestion break down food
- mechanical
- chemical
- microbial
what is the mouth compromised of?
- lips
- tongue
- cheeks
- hard palate
- soft palate
- teeth
- salivary glands
what is the function of the tongue
helps with the process of moving food around and presenting it for swallowing
function of teeth
break down good into smaller particles
what are the four types of teeth
- incisors
- canines
- premolars
- molars
features of incisors
- the very front teeth
- used for nibbling & biting food from its origin
- dogs & cats have 6 upper and lower incisors
dental pad features
- tough thickened pad
- cattle & sheep only have 8 lower incisors opposed against the dental pad
- crop food by exposing teeth against dental pad
features of horse & rabbit teeth
- grow continuously
- need a diet to wear them down appropriately
features of canine teeth
- long fang-like teeth located behind the incisors
- used for holding the food to tear into smaller pieces in carnivores
- teeth are less well developed in herbivores
- 2 upper & 2 lower
pre-molars and molars features
pre molars
- located behind canines and in front of molars
- used for grinding in herbivores & shearing in carnivores
molars
- located in cheek area
- for grinding food
- herbivores spend considerable time chewing food with molars
functions of salivary glands
produce saliva which:
- lubricates food to assist swallowing
- contains some enzymes which commence digestion
- local anti-bacterial properties
- moistens and protects tissues of mouth
features of the pharynx
- connects back of nasal cavity to top of trachea
- connects oral cavity to oesophagus
- common passage way for air & food
how does the pharynx reduce the chance of food entering the airways?
the epiglottis and soft palate move to close the airway.
features of the oesophagus
- smooth muscular tube connect pharynx to stomach
- functions to transfer or move food to the stomach
what is peristalsis
the process of rhythmical, coordinated waves of muscular contraction and relaxation to propel food down the digestive tract
features of the stomach
- hollow organ with strong muscular wall of several layers of smooth muscle
- located in the cranial abdomen
- stomach lined with tough epithelium to protect it from stomach acid
functions of the stomach
- stores ingested food
- mechanical digestion or breakdown of food
- start of chemical digestion of protein by digestive enzymes and stomach acid
what is the purpose of mucus, HCI and pepsin
mucus: lubricates food and protects stomach lining
HCI: kills most pathogenic bacteria
pepsin: breaks down proteins
features of simple stomachs
- single chamber
- function is primarily for mechanical digestion.
- includes dogs & cats
complex stomach or ruminant features
- usually four chambered
- function is for microbial digestion in herbivores - gut breaks down plant material
- cows, sheep and goats
features of hindgut fermenters
- microbial digestion of food occurs
- in large intestine
- single chambered stomach
- horses & rabbits
what is the band of muscle at the opening of the stomach called and what does it prevent?
the gastro-oesophageal sphincter and it prevents reflux of food or acid
features of stomach lining
- highly folded and compacted to help with mechanical breakdown of food
features of stomach wall
- thick muscular smooth muscle wall
- permits churning and expulsion of ingesta
what are the 4 chambers of a complex stomach?
- rumen
- reticulum
- omasum
- abomasum
features of the rumen
- largest compartment
- for storage and fermentation of food
features of the reticulum
- where chemical breakdown of food occurs
features of omasum
- where absorption of water and fatty acids occur
features of abomasum
- glandular stomach (produces acid and enzymes)
- similar to simple stomach of dogs & cats
what is fermentation
a metabolic process that uses enzymes to cause chemical changes to ingested food
what is rumen fermentation
a process that converts ingested food into energy sources for the host
features of small intestine
- long, thin walled muscular tube
- runs from stomach to large intestine
- contains smooth muscle divers to propel ingests along by peristalsis
the small intestine is divided into three parts called?
- duodenum (chemical digestion)
- jejunum ( absorption of nutrients)
- ileum ( absorption of nutrients)
what is the mesentery
- transparent curtain like membrane that the intestine are suspended from.
- contains blood supply to and from intestines
- absorber food molecules are transported from here to liver
function of the small intestine
most chemical digestion and absorption of nutrients occur in small intestine
what is the duodenum
the site of chemical digestion by digestive enzymes
- enzymes break down large molecules of food to smaller particles for absorption
what are the digestive enzymes present in the duodenum called?
- trypsin
- lipase
- amylase
purpose of trypsin
break down proteins into amino acids
purpose of lipase
breaks down lipids into fatty acids
purpose of amylase
breakdowns complex carbohydrates into simple sugars
what is jejunum and ileum
sites of nutrient absorption
what is absorption
the passage of digestive food molecules through the mucous membrane lining and into the bloodstream
what is bile
a fluid produced by the liver and is released into the small intestine to work like a detergent to turn fat into smaller droplets
purpose of villi
- to increase surface area available for absorption
- richly supplied with capillaries for absorption of digested food molecules
- contain mucous glands to assist with lubrication
- contain lymphatic tissues to protect body from infection
the large intestine is divided into what parts?
- colon
- caecum
then followed by
- rectum
- anus
features of the colon
- wide in diameter but shorter in length
- main site of water absorption and absorption of water-soluble vitamins
features of the caecum
- varies in size between species
- blind sac at start of colon where it attaches to the ileum
- in hindgut fermenters, caecum is very large and plays an important role
features of the rectum
- storage area for faeces prior to elimination via the anus.
- produces mucous for lubrication
features of the anus
- last part of GIT
- set of two muscular bands controlling defaecation
- under conscious control
functions of large intestine in dogs & cats
- absorb water
- absorb water soluble vitamins
- form faeces
what are hindgut fermenters
species that have a greatly enlarged caecum and colon that acts similarly to the rumen as its like a large microbial fermentation vat.
what are foregut fermenters
animals with complex 4-chambered stomachs are called foregut fermenters
features of the liver
- performs many vital functions
- second largest organ
- located in cranial abdomen
- has tremendous regenerative capacity & repair well if damaged.
functions of the liver
- produces bile
- processes food
- manufacture proteins
- detoxifying substances
- removal of old rbc from circulation
- storage of minerals and the fat suluble vitamins A, D, E, K
where is bile stored
the gall bladder
absorbed food molecules are transferred via the?
hepatic portal system
what does the hepatic portal venous system do
collects absorbed nutrients from the gut and gets them ready for use by the body
what are the vessels entering and leaving the liver?
- arterial (entering)
- venous (entering)
- venous (leaving)
features of the hepatic artery
- branches off aorta and enters the liver
- delivers oxygenated blood to liver cells - main blood supply to liver
hepatic portal venous system features
- delivers nutrient rich DEOXYGENATED blood to liver from intestine
hepatic vein features
- delivers oxygenated blood full of processed nutrients
- from liver to vena cabs then back to heart
what is detoxifying
the breakdown of toxins that may be absorbed by the intestines
what is glucose metabolism
the body breaking down glycogen to glucose to release to the body when required
what is fat metabolism
when fats may be broken down or made into more complex structures required by body tissues.
pancreas features
- small l shaped structure
- located between stomach and duodenum
pancreas functions
- produces digestive enzymes
- produces hormone insulin
what are the two parts of the pancreas that performs vital functions
endocrine and exocrine pancreas
exocrine pancreas functions
- produces and secretes digestive enzymes to break down components of food
what are the three digestive enzymes
- amylase
- lipase
- protease
endocrine pancreas function
- produces hormone insulin
- secretes insulin into the bloodstream to make its way to every cell
- insulin is required by every cell to control uptake of glucose
