digestive system Flashcards
what are the 4 functions of the gut?
- ingestion= intake of food into the body through the mouth
- digestion= breakdown of large insoluble food molecules into soluble molecules via enzyme action
- absorbtion= passage of digested food through gut wall into blood.
- egestion= elimination from body of food that cannot be ingested.
what are the 2 types of digestion & their function?
-
mechanical=
* cutting/crushing
* peristalsis- movement of food through digestive system using muscles. -
chemical=
* enzyme action
* e.g. in the mouth- salivery amylase from salivery glands
what is the serosa’s function in the gut
- a protective coat (connective tissue)
- reduces friction
what is the longitudinal and circular muscles function in the gut
peristalsis
what is peristalsis
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward
what is the function of mucosa in the gut?
- lines the gut wall- often folded to increase surface area
- often worn away by friction so has to be replaced
what is the purpose of sub-mucosa in the gut
connective tissue with nerves/blood/lymph/lymph vessels
what are the 6 specialised roles in the digestive system?
- the mouth
- the oesophagus
- the stomach
- small intestine
- pancreatic juice
- Bile
function of the mouth during digestion?
- mechanical digestion- teeth & tongue
- enzymatic digestion- lubrication and salivery glands (contains amylase)
what is the oesophagus?
the tube connecting the mouth to the stomach
what are features of the oesophaus which help it to carry out its function?
- epiglottus (prevents food from entering trachea)
- allows peristaltic movement of food towards the stomach using muscle layers
- longitudinal & curcular muscles (peristalsis)
longitudinal and curcular muscles function & what is the proccess called?
peristalsis
* behind bolus of food- circular muscle contracts & longitudinal muscle relaxes
* infront of bolus of food- circular muscle relaxes & longitudinal muscle contracts
function/specialisation of stomach during digestion.
- when food enters stomach- - 2 rings of muscle seal both ends
- circular and longitudinal muscles rythmetically contract & mix the food with gastric juice
what are the 3 types of cells in gastric glands + function
-
mucous cells-
* secrete mucous
* coats and protects stomach from self-digestion
* helps with movement of food -
parietal/oxyntic cells-
* secrete acid of PH2
* kills bacteria
* optimum ph for peptidases (protein digesting enzymes) -
cheif cells-
* secrete peptidases
what is specialised in the small intestine to help process of digestion?
mucosa in small intestine is folded and on the folds are smaller folds called villi (increase surace area)
what is in the mucosa in the small intestine
- crypt of lieberkuhn
- brunners glands
what are crypt of lieberkuhn?
- found in the mucosa in the small intestine
- paneth and endocrine cells- produce enzymes and hormones
- stem cells- divide continuously to replace columar and goblet cells
what are brunners glands
- found at the top end of the duodenum
- produce a mucas rich alkaline secretation in order to…
1. provide an alkaline condition for intestinal enzymes to be active & absorbtion to take place
2. lubricate intestinal walls
3. protect duodenim from the acidic content of chyme
function of pancreatic juice in the digestive system
- secreted from exocrine glands in the pancreas & contains
1. endopeptidases
2. amylase
3. lipase
(they all hydrolyse protein, starch & lipids)
function of bile in the digestive process
- produced by liver and stored in gall bladder
- they attach to lipids/fat in the intestine & lowers the surface tension and splits them into smaller molecules
what are the enzymes involved with digestion
- lipase (pancreas)- hydrolise lipids to fatty acids & glycerol
- amylase (pancreas)- hydrolises starch to maltose
- maltose, sucrose, lactose- hydrolises disaccharides into 2 monosaccharides.
what are the 3 disaccharides
- sucrose (sugar)
- lactose (milk sugar)
- maltose (malt sugar)
sucrose
- a disaccharide
- energy transport and storage in plants & part of the human diet
- breakdown= sucrase
- formation= sucrose synthase
lactose
- a disaccharide
- energy storage in mammal milk
- breakdown= lactase
- formation=lactose synthase
maltose
- intermediate in starch digestion
- breakdown=maltase
- formation= maltose synthase
- a disaccharide which hydrolises into 2 alpha glucose molecules by breaking a glycosidic bond
what are the 2 digestion peptidases
- endopeptisases
- exopeptidases
function of endopeptidases
digest polypeptide into smaller poypeptides (breaks polypeptide up)
function of exopeptide
digest terminal peptide bond releasing individual amono acids
features of the villus
- surface consists of a single layer of epithelial cells
- goblet cells produce a mucus which keeps the environment moist & lubricated
- capillaries & lymph vessels take away absorbed molecules.
where do waste/end products of digestion go?
in the IIeum- amino acids, sugars, fatty acids & glycerol
* ALL are aborbed into the blood via epethelial cells
* glucose is transported by co-transport
* amino acids are absorbed by active transport then facilitated diffusion
