Biology: Chapter 9: The Digestive System Flashcards
What is intracellular digestion
involves the oxidation of glucose and fatty acids to make energy
What is extracellular digestion
occurs in the lumen of the alimentary canal
What is mechanical digestion
physical breakdown of large food particles into smaller food particles
what is chemical digestion
enzymatic cleavage of chemical bonds such as the peptide bonds of proteins or the glycosidic bonds of starches
what is the pathway of the digestive tract
oral cavity -> pharynx -> esophagus -> stomach -> small intestine -> large intestine -> rectum
what are the accessory organs of the digestive system
salivary glands, pancreas, liver, and gall bladder
what is the enteric nervous system
in the wall of the alimentary canal and controls peristalsis; activity is upregulated by parasympathetic NS and downregulated by sympathetic NS
which hormones promote thrist
ADH and Aldosterone
which hormones promote satiety
Leptin and Cholecystokinin
which hormones promotes hunger
glucagon and Ghrelin
What is the first step in digestion
mastication (mechanical)/salivary amylase + lipase (chemical) forms a bolus which is swallowed
what is the esophagus
propels food to the stomach using peristalsis and enters the stomach through the lower esophageal sphincter
what are the four parts of the stomach
fundus, body, antrum, and pylorus
what are the mucus cells of the stomach
produce bicarbonate rich mucus to protect stomach lining
what are the chief cells of the stomach
secrete pepsinogen, a protease activated by the acidic environment of the stomach
what are the parietal cells of the stomach
secrete HCl and intrinsic factor which is used for B12 absorption
what are G cells of the stomach
secrete gastrin, a peptide hormone that increases HCl secretion and gastric motility
What is the second step of digestion
Further mechanical and chemical digestion in the stomach which produces chyme; passes into the duodenum through the pyloric sphincter
what is the duodenum
first part of the small intestine + chemical ingestion
what is Disaccharidases in the duodenum
brush border enzymes that break down maltose, isomaltose, lactose, and sucrose into monosaccarides
what are peptidases in the duodenum
aminopeptidase and dipeptidase
what is enteropeptidase in duodenum
activates trypsinogen and procarboxypeptidases initializing an activation cascade
what is secretin in duodenum
stimulates the release of pancreatic juices into the digestive tract and slows motility
what is cholecytokinin in the duodenum
stimulate bile release from the gall bladder, release of pancreatic juices, and satiety
How is the pancreas related to the digestive system
acinar cells produce pancreatic juices that contain bicarbonate, pancreatic amylase, pancreatic peptidases, and pancreatic lipase
how is the liver related to the digestive system
synthesizes bile which can be stored in the gall bladder or secreted into the duodenum directly; processes nutrients, produces urea, detoxication, activation/inactivation of medication, synthesizes albumin and clotting factors
what is the function of bile
bile emulsifies fats making them soluble and increasing their surface area
what is bile made of
biles salts, pigments, and cholesterol
what is the function of the gall bladder
stores and concentrates bile
what is the jejunum and ileum
part of small intestine are primarily involved in absorption
how is surface area in the small intestine increased
lined with villi which are covered with microvilli
How is absorption conducted in the small intestine
1) water soluble compounds (monosaccarides, amino acids, small fatty acids, water) enter capillary bed
2) fat soluble compounds (fats, cholesterol, and fat soluble vitamins) enter the lacteal
*lacteal is a vessel of the lymphatic system
what is the function of the large intestine
absorbs water and salts forming semisolid feces
what is the cecum
outpocketing of large intestine that accepts fluid from the small intestine through the ileocecal valve and is the site of attachment of the appendix
what is the colon
divided into ascending, transverse, descending, and sigmoid portions
what is the rectum
stores feces which is excreted through the anus
