HLTH 2501: digestive system review Flashcards
function of the liver in the digestive system
reassembles the component nutrients into new materials as the body needs them; ex. amino acids are used by the liver to produce new proteins
upper tract of GI tract
mouth, esophagus, and stomach
lower tract of GI
intestines
5 continuous layers of the GI tract
mucosa and epithelial, submucosal layer, circulator smooth muscle, longitudinal smooth muscle, and the serosa
peritoneum and layers
large serous membrane in the abdominal cavity; parietal layer covers the abdominal wall and visceral encases the organs
peritoneal cavity
the potential space between the parietal and visceral layers
why may tumors develop in the adominal cavity
because the serous membrane in thin and permeable, allowing for the spread of infections and tumors from the general circulation
mesentery
a double layer of peritoneum that supports the intestines and coneys blood vessels and nerves to supply the wall of the intestine
what does the mesentry attatch
the jejunum and the ileum to the posterior wall
greater omentum
a layer of fatty peritoneum that hangs from the stomach like an apron over the anterior surface of the transverse colon and the small intestine
the lesser omentum
part of the peritoneum that suspends the stomach and duodenum from the liver
inflammation in the GI tract
tends to occur in the omentum and peritoneum and may lead to scar tissue and the formation of adhesions between structures in the abdominal cavity such as loops of intestine
retroperitoneal organs
pancreas and kidneys
3 salivary glands
parotoid, sublingual, and submandibular glands
what enzyme does saliva contain?
amylase which breaks down carbs in the mouth to glycogen and disaccharides
major digestive enzymes
salivary amylase, pepsin, pancreatic amylase, pancreatic lipase, trypsin, pancreatic nucleases, intestinal peptidase, and intestinal lipase
where is salivary amylase secreted from?
parotid gland
pepsin
secreted by gastric chief cells and splits proteins
pancreatic lipase
splits triglycerides into fatty acids and monoglycerides
pancreatic nucleases
split nucleic acids into nucleotides
intestinal peptidase
secreted from mucosa layer and converts peptides into amino acids
what cranial nerves are associated with swallowing
trigeminal and glossopharyngeal
how does swallowing occur?
soft palate is pulled upwards, the epiglottis covers the larynx, respiration ceases, and peristalsis occurs
anatomy of the stomach
muscosa folds into rugae when empty and 3 smooth muscle layers instead of 2 (additional oblique muscle)
what does chyme do?
initiates the digestion of proteins
role of hydrochloric acid
converts pepsinogen to pepsin
what is hydrochloric acid secreted by?
parietal cells
what is intrinsic factor secreted by?
parietal cells
what stimulates parietal and chief cells?
gatrin
where do pancreatic and liver secretions enter the small intestine?
via the ampulla of vater and the duodenal papilla
kupffer cells
remove and phagocytose any foreign material and bacteria from the GI tract before blood enters the circulation; found in the liver and line the sinusoids
what nutrients do hepatocytes store?
A, B6, B12, D, K, and folic acid
glycogenolysis
hepatocytes break down liver glycogen to glucose when blood glucose levels drop and glucagon secretion increases
gluconeogenesis
the formation of glucose from molecules that are not themselves carbohydrates
glycogenesis
converting glucose to glycogen via insulin when blood glucose levels are high; under hormonal influence such as cortisol or epinephrine
why does amino acid conversion take place?
to maintain the amino acid pool in the blood
what produces bile?
hepatocytes of the liver
what is bile?
a mixture of water, bile salts, bile pigment or bilirubin, cholesterol, and electrolytes including HCO3-
function of bile
to emulsify fats and fat-soluble vitamins before they are absorbed from the intestine
function of HCO3- in bile
assists in neutralizing the gastric acid to increase the pH of the small intestine
function of the pancreas
secretes digestive enzymes, electrolytes, and water into ducts that drain into the small intestine
major proteolytic enzymes in pancreatic secretions
trypsin, chymotrypsin, carboxypeptidase, and ribonuclease
major site of nutrient absorption
the ileum
enzymes produced in the small intestine mucosa
cholecystokinin, peptidase, nucleosidases, lipase, sucrase, matlase, and lactase
peyer patches
found in the ileum and limit the spread of of bacteria into the small intestine
vitamin K signficance
required for the production of clotting factors, such as prothrombin and fibrinogen
what nerve is responsible for peristalsis?
vagus nerve (X)
cholecystokinin
stimulates pancreatic enzyme secretion and stimulates the gallbladder contractions and release of bile; also inhibits gastric empyting
secretin
decreases gastric secretions and stimulates bile and pancreatic and pancreatic secretions with high HCO3- content
what nerves are associated with saliva production?
the facial and glossopharyngeal nerves
what are complex carbohydrates broken down to?
simple sugars or monosaccharides (glucose, galactose, and fructose)
protein breakdown
proteins are split into peptides or short chains of amino acids, then into single amino acids via peptidases
what substances move into the blood via simple diffusion?
water soluble vitamins (B and C) and iron, copper, and zinc
