Digestive System Flashcards
involves the breakdown of food into its constituent organic molecules; two types (intracellular and extracellular) and two methods (mechanical and chemical)
digestion
involves the oxidation of glucose and fatty acids to make energy
intracellular digestion
process by which glucose and fatty acids are obtained from food, occurs in the lumen of the alimentary canal
extracellular digestion
the physical breakdown of large food particles into smaller food particles
mechanical digestion
the enzymatic cleavage of chemical bonds, such as the peptide bonds of proteins or the glycosidic bonds of starches
chemical digestion
pathway of digestive tract:
accessory organs of digestion:
include salivary glands, pancreas, liver, and gallbladder
involves the transport of products of digestion from the digestive tract into the circulatory system for distribution to the body’s tissues and cells
absorption
a collection of neurons in the wall of the alimentary canal that govern the function of the gastrointestinal system and controls peristalsis; its activity is upregulated by the parasympathetic nervous system and downregulated by the sympathetic nervous system
enteric nervous system
the rhythmic contractions of the gut tube, in order go move materials through the system
perstalsis
regulate feeding behavior
hormones
hormones that promote thirst
ADH (antidiuretic hormone or vasopressin) and aldosterone
hormones that promote hunger
glucagon and ghrelin
hormones that promote satiety
leptin and cholecystokinin
site where mastication (chewing) starts the mechanical digestion of food, while salivary amylase and lipase start the chemical digestion of food; food is formed into a bolus and swallowed
oral cavity
connects the mouth and posterior nasal cavity to the esophagus
pharynx
propels food to the stomach using peristalsis
esophagus
allows food to enter the stomach from the esophagus
lower esophageal (cardiac) sphincter
has four parts: fundus, body, antrum, and pylorus; has a lesser and greater curvature; lining is thrown into folds called rugae; lined by many types of secretory cells
stomach
type of secretory cell lining stomach:
produce bicarbonate-rich mucus to protect the stomach
mucous cells
type of secretory cell lining stomach:
secrete pepsinogen, a protease activated by the acidic environment of the stomach
chief cells
type of secretory cell lining stomach:
secrete hydrochloric acid and intrinsic factor, which is needed for vitamin B(12) absorption
parietal cells
type of secretory cell lining stomach:
secrete gastrin, a peptide hormone that increases HCl secretion and gastric motility
G-cells
term for food particles after mechanical and chemical digestion in the stomach
chyme
consists of three segments: the duodenum, jejunum, and ileum
small intestine
allows food to pass into the duodenum from the stomach
pyloric sphincter
the first part of the small intestine and is primarily involved in chemical digestion
duodenum
present on the luminal surface of cells lining the duodenum and break down dimers and trimers of biomolecules into absorbable monomers
brush-border enzymes
brush-border enzymes that break down disaccharides such as maltose, isomaltose, lactose, and sucrose into monosaccharides; include maltase, isomaltase, lactase, and sucrase
disaccharidases
brush-border enzymes that break down proteins (peptides); include aminopeptidase, dipeptidase, and enteropeptidase
peptidases
activates the trypsinogen and procarboxypeptidases, initiating an activation cascade that leads to release of pancreatic enzymes into duodenum
enteropeptidase
a peptide hormone that causes pancreatic enzymes to be released into the duodenum
secretin
a peptide hormone that stimulates bile release from the gallbladder, release of pancreatic juices, and satiety in the brain; secreted in response to the entry of chyme into the duodenum
cholecystokinin (CKK)
a complex fluid composed of bile salts (emulsify fats and cholesterol into micelles), pigments (especially bilirubin), and cholesterol
bile
a complex mixture of several enzymes in a bicarbonate-rich alkaline solution (helps neutralized acidic chyme to provide an ideal working environment for digestive enzymes)
pancreatic juices
cells in the pancreas that produce pancreatic juices that contain bicarbonate, pancreatic amylase, pancreatic peptidases (trypsinogen, chymotrypsinogen, and carboxypeptidases A and B), and pancreatic lipase
acinar cells
component of pancreatic juices:
responsible for carbohydrate digestion
pancreatic amylase
component of pancreatic juices:
responsible for protein digestion
pancreatic peptidase
component of pancreatic juices:
responsible for lipid (fat) digestion
pancreatic lipase
processes nutrients (through glycogenesis and glycogenolysis, storage and mobilization of fats, and gluconeogenesis), produces urea, detoxifies chemicals, activates or inacitvates medications, produces bile, and synthesizes albumin and clotting factors
liver
stores and concentrates bile
gallbladder
second and third portion of the small intestine, primarily involved in absorption
jejunum and ileum
line the small intestine; covered with micro____ which increase surface area for absorption; contain a capillary bed and a lacteal
villi
a vessel of the lymphatic system
lacteal
flow of material in villi:
water soluble compounds, including monosaccharides, amino acids, water-soluble vitamins, small fatty acids, and water
enter the capillary bed
flow of material in villi:
fat-soluble compounds, including fats, cholesterol, and fat-soluble vitamins
enter the lacteal
where blood flows first from small intestine; regulates nutrient distribution and removes toxins from the blood
liver
absorbs water and salts, forming semisolid feces
large intestine
an outpocketing of the large intestine that accepts fluid from the small intestine through the ileocecal valve and is the site of attachment of the appendix
cecum
part of large intestine divided into ascending, transverse, descending, and sigmoid portions; absorbs water and salts from undigested material left over from small intestine
colon
stores feces, which consists of indigestible material, water, bacteria, and certain digestive secretions not reabsorbed
rectum
opening through which wastes are eliminated, consists of two sphincters: the internal sphincter (under involuntary, autonomic control) and the external sphincter (under voluntary somatic control)
anus
produce vitamin K and biotin (vitamin B(7)) in symbiotic relationship
gut bacteria
