Chapter 16- The digestive system Flashcards
what are the two main divisions of the digestive system?
- alimentary tube (extends mouth to anus)
2. accessory organs (teeth, tongue, salivary glands, liver, gallbladder, pancreas)
what are the two complementary process used in digestion?
- mechanical digestion (physical breakdown)
2. chemical digestion (break down of complex molecules into simplier compounds via enzymes)
what are the 3 types of complex organic molecules found in food, and what are their breakdown compounds?
carbohydrates > starch, disacharides, > glucose, fructose and galactose
proteins > amino acids
fats > fatty acids, glycerol
what is included in the oral cavity and what is the purpose of that organ?
- teeth- chewing, mixing *saliva
- tongue - taste, mixing, swallowing
- salivary glands > (parotid/submandibular/sublingual) > saliva via. ducts
- pharynx> (oropharyns/laryngopharynx) > food passageways for swallowing.
- esophagus > moves food from pharyxn > —-peristalsis—- >lower esophageal sphincter > stomach
what is the purpose of papillae on the tongue?
they contain taste buds.
what digestive enzyme is found in saliva?
amylase, which breaks down starch molecules > glucose molecules or to maltose (disaccharide)
where is the reflex centre that controls the voluntary action of swallowing located?
medulla.
what is happening to the LES during GERD?
when this smooth muscle doesnt close completely, acid juices move from the stomach up the esophagus. longterm exposure is bad.
describe the site of creation, function, and site of action for the enzyme: pepsin
organ created: stomach > cheif cells release, pepsinogen (needs HCI to > pepsin)
function: convert proteins to polypeptides
site of action: stomach
describe the site of creation, function, and site of action for the enzyme: HCI
organ created: stomach >parietal cells
function: changes pepsinogen to pepsin, and maintains pH 1-2 in the stomach to destroy pathogens
site of action: stomach
describe the site of creation, function, and site of action for the enzyme: bile salts
organ created: liver
function: emulsify fats
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: amylase (not salivary)
organ created: pancrease
function: convert starch to maltose
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: trypsin
organ created: pancreas
function: concert polypeptides to peptides
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: lipase
organ created: pancrease
function: convert emlsified fats to fatty acids and glycerol
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: peptidases
organ created: small intestine
function: convert peptides to amino acides
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: sucrase
organ created: small intestine
function: converts cucrose to glucose and fructose
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: maltase
organ created: small intestine
function:concerts maltose to glucose
site of action: small intestine
describe the site of creation, function, and site of action for the enzyme: lactase
organ created: small intestine
function: converts lactose to glucose and galactorse
site of action: small intestine
which enzymes are used in the breakdown of carbohydrates>
amylase, sucrase, maltase, lactase
which enzymes are used in the breakdown of proteins
trypsin, pepsin, peptidase
which enzymes are used in the breakdown of fats
bile
lipase
what are the four layers of the alimentary tube, and describe their puepose
- mucosa, > lining, made to secrete mucus to lubricate eh passage of food, and secrete the digestive enzymes
- submucosa > contains enteric nervous system (brain of gut) to innervate the mucosa to regulate secretions
- external muscle layer > 2 layers of smooth muscle, contract to help break up food/mix digestive juices, moves food using peristalsis
- serosa > above diaphragm outer most layer is firbous, below diaphragm it is the mesentery peritineum, (serous membrane)
what kind of digestion takes place in the stomach?
- mechanical (twisting of 3 layered muscle (longitudinal, circular, and oblique layer) sac)
- chemical
what is the pyloric sphinctor?
surronds the junction of the two organs. (stomach and duodenum)
what is the name of the folds in the stomach
rugae, caused by the wrinkled mucosa of an empty stomach)
how does the stomach prevent itself from erosion?
mucous cells, secret mucus to coat the stomach.
parietal cells release intrinsic factor, which is necessart for the absorption of?
vitamin B12,
enteroendocrine cells (called G cells) secrete what hormone in response to food in the belly, and what does it do?
gastrin, stimulates the secretion of greater amounts of gastric juices.
what nerve systems are found in the digestive tract and monitor/ control gastric movements of the muscle layers>
myenteric plexuses of the enteric nervous system.
what is a gastric ulcer?
an erosin of the mucosa of the stomach, as erosin reaches the submucosa , small blood vessels rupture and bleed, if not repaired can lead to perforation of stomach wall, and leak gastric content into abdomen cavity and peritonitis.
name the 3 sections of the small intestine, and describe its purpose
- duodenum
- jejunum
- ileum
> complete digestion, and products absorbed into the blood and lymph.
what is the purpose of lymph nodes called peyers’ patches found along the small intestine
destroy absorbed pathogens.
what is the purpose of the liver in the digestive system?
liver cells (hepatocytes) produce bile. Bile > bile ducts (bile canaliculi) > hepatic duct > + cystic duct (gallbladder) > common bile duct > duodenum
what is emulsification?
breakdown of large fat globules into small globules, via mechanical digestion.
what is the gallbladders purpose to the digestive system?
stores bile until it is needed in small intestine, it can [bile] by removing water.
what is the purpose of the hormone cholescystokinin, released by the enteroendocrine cells, when fatty foods enter the duodenum.
stimulated the contaction of the smooth muscle in the wall of the gallbladder, which forces bile into the cystic duct, then into the comon bile duct and into the duodenum.
what is the purpose of the pancreas? (exocrine functions)
exocrine glands are called acini
what are gallstones>
crystals formed by high concentrations of cholesterol in the bile, when water is absorbed.
what procedure is used to remove gallstones if too large to pass through the bile duct
lithotripsy - shock wave therapy to pulverize the stone into smaller pieces
what is the purpose of the bicardonate juice, alkaline, produced by the pancreas?
contains sodium bicarbonate, to help neutralize the gastric juices that enter the duodenum
what hormones regulate the secretion of the pancreatic juices?
secretin (stimulates bicarbonate juice) and cholescystokinin (secretes pancreatic enzymes)
what gives the small intestine the velvet appearance (name the fold layers) ?
plica circulares (circular folds) > villi > micro-villi > villus > capillary network + lacteal
where does absorption take place in the intestine?
in the lumen of the intestine into the vessels within the villi.
what is absorbed via active transport?
monosaccharides, amino acids, +ve ions, and water soluble ions,
how is B12 absorbed?
requires intrinsic factors produced by the parietal cells of the gastric mucosa,
how is calcium absorbed?
efficient absorption of calcium ions requires parathyroid hormone and vitamin D.
how are fat soluble nutrients absorbed?
into the lyph in the lacteal of the vili, bile salts are required for the absorption of fatty acids and fatty soluble vit ( A,D,E,K)
-when abosorbed> +glycerol > triglycerides >globules with (+cholesterol+protien) >form chylomicrons >lymph transport > blood system into L subclavian vein. > liver.
descrive the pathway of the large intestine starting from the illeum.
illeum >ileocecal valve > cecum (+apendix duct connect) >transverse colon> descending colon > sigmoid colon> rectum > anal canal > Anus
name 4 disorders of the intestine and define each
- duodenal ulcers - erosions of deodenal wall
- paralytic ileus - cessation of contraction of smooth muscle layer,- tx with suctioning intestinal colon to eliminate an obstruction for it to regain its normal motility
- lactose intolerance- inability to digest lactose d/t deficiency of the enzyme lactase.
- diverticulosis - presence of diverticula ( small outpouchings through weak areas of intestine wall)
diverticulitis- inflammation of diverticula (usually d/t entrapment of feces and bacteria)
what is the function of the colon?
absoprtion of water, minerals, and vitamins and the elimination of undigestible material. 80% of water that enters the colon is absorbed.
what is the purpose of the normal colon flora?
- provide vitamins made from the body, and inhibit the growth of pathogens.
name the 8 additional features of the liver.
- carbohydrate metabolism
- amino acid metabolism
- lipid metabolism
- synthesis of plasma proteins
- formaiton of bilirubin
- phagocytosis by Kupffer cells
- storage vit A, D, E, K, and B12, minerals, copper,
- detoxification
what is hepatitis
inflammation of the liver causes by any or several viruses
define hep A
intestinal virus that is spread by feces to oral.
mild,
tx with lifelong immunity,
vacine exist, but people already exposed can recieve gamma globulin by injection to prevent the idease
define hep B
contracted by body fluids
severe/ fatal (10% of recoveres become carriers)
chronic hepatitis > cirrhosis or primary liver-ca
-vaccine avail.
define hep C
contracted via body fluid, and blood or mucous memebrane contact
may be chronic disease, most people are asymptomatic
when active- causes liver failure
tx with liver transplant.
