Chapter 36 Flashcards
The digestive system is responsible for
intake, digestion of food, absorption of nutrients and elimination of solid waste.
what are the functions of the digestive system
- ingestion of food
- storage and sythesis of vitmains
- propulsion of food and wastes from the mouth to anus
- secretion of mucus, water, enzymes and hormones
- mechanical digestion of food particles
GI tract function
- chemical digestion of food particles
- absorption of digested food
- elimination of waste products by defecation
the process of digestion and absorption of nutrients requires
intact and healthy gastrointestinal tract epithelial lining that can resist the effects of own digestive secretions. the presence of enzymes for the digestion and absorpiton of nutrients
the process of digestion and absorption of nutrients involves the movement of
materials through the gastrointestinal tract at a rate that facilitates absorption
List the components of the the upper part of the digestive tract
mouth, esophagus, and stomach
what is the function of the upper part of the digestive tract?
acts as an intake source and receptacle through which food passes and in which initial digestive processes take place
List the components of the middle portion of the digestive tract?
small intestine, duodenum, jejunum, and ileum
Where does most of the digestive and aborption take place?
in the small intestine
List the components of the lower segment of the digestive tract?
cecum, colon and rectum
What is the function of the lower segment of the digestive tract?
serves as a storage channel for the efficient elimination of waste
List the components of the fourth part of the digestive tract?
accesory organs- the salivary glands, liver, and pancreas
what is the function of the fourth part of the digestive tract?
produce digestive secretions that help dismantly foods and regulate the use and storage of nutrients
What structures are involved in swallowing?
esophagus, peristaslsis, upper esophageal sphincter, lower esophageal sphincter
the functions of the stomach
reservoir and mixer. start digestion of protein, nucleic acids and fats. activates some enzymes. destory some bacteria-acid. makes intrinsic factor (B12 absorption)
What are the phases of digestion?
- ingestion
- movement
- digestion
- absorption
- further digestion
where does digestion start?
with saliva
______ cleans the mouth and contains the enzyme lysozyme, which has an antibacterial action.
Saliva
mucus-secreting cells (prostoglandins) are the
protectors and lubricators
parietal cells secrete:
HCl anf intrinsic factor
G cells secrete
gastrin; stimulates HCl
Chief cells secrete
release pepsinogen
what are the two major gastrointestinal hormones
cholecystokinin and secretin
stimulates contraction of the gall bladder. stimulates secretion of pancreatic enzymes. slows gastric emptying
cholecystokinin
stimulates secretion of bicarbonate- containing solution by the pancreas and liver
secretin
digestion is completed in
the small intestine
what is digested and absorbed in the small intestine?
proteins, carbohydrates, fats, 80% ingested water, electrolytes
what are the functions of the large intestine?
recieve fluid waste products and store until released from body. excess water absorbed. feces, stools. defecation or bowel movement.
bile acid secretion, motility and antibody production keep bacterial numbers in the duodenum to a
minimum
How would fat digestion be affected if bile levels decreased?
it would decrease
absorption and digestion of carbohydrates
- mouth: salivary amylase
- duodenum: pancreatic amylase ( polysachharides –> disacchrides)
- brush border enzymes: disacchrides –> monosacchrides.
- monosachrides absorbed into blood
absorption and digestion of fats
- duodenum: bile (breaks down fat)
- duodenum: pancreatic lipase (breaks fat/triglycerides into glycerol)
- jejunum: packages fat as chylomicron, passed to the lymph or absorbed in the blood.
absorption and digestion of proteins:
- stomach: pepsinogen (breaks proteins into polypeptides)
- duodenum: pancreatic tryspinogen (breaks proteins into polypeptides)
- brush border enzymes: break polypeptides into 2-3 amino acids peptides and then those peptides are absorbed into the blood
