Digestive System Flashcards
Passage of food
Oral cavity, pharynx, esophagus, stomach, small intestine, large intesine, rectum
Enteric nervous system
peristalsis, rhythmic contractions of the cut, heavily regulated by autonomic nervous system
all glands of the body except for sweat glands are
parasympathetically innervated
Salivary amylase
breaks starch into smaller sugars
Lipase
Breaks down lipids
Stomach
Highly muscular, 2 L capacity, upper left quadrant, under diaphram
4 main anatomical divisions of stomach
fundus, body, antrum, pylorus
Gastric glands
fundus and body
Pyloric glands
Andrum and pylorus
Gastric glands respond to
signals from vagus nerve of parasym. activated by brain in response to light taste, smell of food.
Three types of gastric gland cells
Mucus cells (bicarb rich mucus that protects wall from acidic/ proteolytic environment) 2 Chief cells (secrete pepsinogen) 3 Parietal cells- secrete H ions as HCL that cleave pepsinogen to pepsin. They also secrete intrinsic factor which helps in proper absorbtion of B12. Pepsin= digests proteins by cleaving peptide bonds
Pyloric glands
G cells - secrete gastrin (a peptide hormone, it induces parietal cells to secrete more HCL) chyme- semifluid mixture of food and hcl that enters the small intestine
Small intestine parts
duodenum, ilieum, jejunum
Duodenum
Majority of chemical digestion and some absorption
The presence of chyme in duodenum stimulates
release of brush border enzymes on luminal surface of cells to break down dimer and trimers. also in duodenum there is secretion of enteropeptidase and hormones secretin and cholecystokinin (CCK)
Lack of a certain enzyme means that bacteria will breakdown and release
methane
Peptidases
Break down proteins. Aminopeptidase glands in the duodenum secrete this to remove n terminal from peptide. also there are dipeptidases which cleave bonds of dipeptides to release free amino acids.
enteropeptidase (enterokinase)
Activates trypsinogen (pancreatic protease) to trypsin. Can also activate procarboxypeptidases A and B into active forms
Secretin
Peptide hormone, causes pancreatic enzymes to be released into duodenum. Can reduce HCL secretion by parietal cells. and can increase bicarb from pancreas. It is considered an enterogastrone which is a hormone that slows motility through digestive tract to increase absorption
CCK cholecytokinin
Secreted in response to entry of chyme in the duodenum
Bile salts
made from cholesterol. not enzymes but play a mechanical role by emulsifying fat and cholesterol into michelles.
without bile what what happen
fats would seperate out of an aq mix and become inaccessible to pancreatic lipase which is water soluble. Improtant to note michelles increase surface area and increase abs rate
Pancreatic juices
several enzymes in bicarb rich alkaline solution. bicarb can reduce acidic chyme
Pancreas
Exo and endocrine functions. the endocrine side- release of insulin, glucagon and somatostatin. Hormona cells reside in islets of langerhans . The exocrine cells are called acinar cells and produce pancreatic juices
Pancreatic amylase
Break down large polysaccharides to small disaccharides. takeaway= CARBS
Pancreatic peptidases
Protein digestion. Trypsinogen, chymotripsinogen and carboxy peptidases A and B. all activated by enteropeptidases
Pancreatic Lipase
Fats broken into free fatty acids and glycerol.
Liver
Upper right quadrant. Bile ducts connect liver to the small intestine and the gallbladder. Bile stored in gallbladder.
Liver receives nutrient rich blood via the
hepatic portal vein.
glycogenesis and gluconeogenesis occurs in the
liver
Urea is produced from ammonia in the
liver
Bile
Made up of bile salts, pigments and cholesterol. the major pigment is bilirubin which is a byproduct of hemoglobin breakdown.
Bilirubin
travels to the liver where it is conjugated (attached to a protein) and secreted into bile for secretion. The inability to process or excrete bilirubin could be due to liver damage, rbc destruction, or bile duct blockage.
albumin is synthesized in the
liver. this protein maintains plasma oncotic pressure, serves as a carrier, clotting factor during blood coagulation
absorption and defacation
jejunum and ileum. lg intestine is for h20 absorption
Larger fats, glycerol and cholesterol
can move seperately into intestinal cells but then reform into triglycerides.
Chylomicrons
contain triglycerides and cholesterol and travel via lymphatic system via lacteals to thoracic duct to left subclav vein
The large intestine
It is larger in diameter but shorter in length. Consists of cecum, colon (ascending, transverse, descending, sigmoid) and retum.
Cecum
outpocketing that accepts fluid exiting small intestine through ileocecal valve. site of appendix.
fat soluble vitamins that are transported in chylomicrons
adek
water soluble
b complex and c
