Digestive System Flashcards
The digestive system includes
the muscular digestive tract
Various accessory organs
What is part of the muscular digestive tract in the digestive system
Esophagus
Stomach
Intestine
What are the accessory organs in the digestive system
Liver
Pancreas
Oral cavity
Functions of the digestive system
Ingestion
Mechanical processing
Digestion (mechanical breakdown, and chemical breakdown)
Secretion
Absorption
Excretion
Storage
What are the four layers of the digestive tract
Mucosa
Submucosa
Muscularies
Serosa
Which layers lines the digestive tract
Mucosa
Lamina propria and epithelium form_____ in the ____(digestive tract layer)_____
Mucosa
Mucous epithelium
Which layer of the digestive tract is moistened by glandular secretions
Mucosa
Which is the layer of the digestive tract that has dense irregular connective tissue
Submucosa
Which layer of the digestive tract contains blood vessels and nerves
Submucosa
Peristalsis
Waves or contractions that move and propel food (volumes) along the digestive tract toward the anus
Segmentation
Segmentation is the contraction that is produced in small intestine and some part of the large intestine
THIS LEADS TO MIXING OF FOOD AND FRAGMENT A BOLUS
Mixes with digestive juices
Goes back and forth in the small intestine
Functions of the oral cavity
Analysis of material before swallowing
Mechanical processing by the teeth tongue and palatial surfaces
Lubrication
Limited digestion
(SALIVA STARTS DIGESTING COMPLEX CARBOHYDRATES)
Primary functions of the tongue
Mechanical processing
Assistance in chewing and swallowing
Sensory analysis by touch temperature and taste receptors
What are the 3 pairs of the salivary glands
Parotid
Sublingual
Submandibular
Components of saliva
99.4% water
.6% electrolytes, buffers, glycoproteins, antibodies (IgA), and enzymes (salivary amylase: breakdown of carbohydrates)
Functions of saliva
Lubrications
Moistening
Dissolving
initiation of digestion of complex carbohydrates
Help to control bacterial population in the oral cavity
The function of the esophagus
Carries solids and liquids from the pharynx to the stomach
The wall of the esophagus contains _____ layers
Mucosal
Submucosal
Muscularis
Functions of the stomach
Storage: bulk storage of undigested food
Mechanical processing of the food
Chemical processing of the food: disruption of chemical bonds via acids and enzymes
Secretion: production of intrinsic factor, HCl, pepsinogen, and gastric
Cardia of the stomach
Superior medical portion that connects to the esophagus
Fundus
Portion superior to stomach - esophageal junction
Gastric pits
Contain gas here all the time
Body of the stomach
Area between the fundus and the curve of the J
Pylorus of the stomach
Antrum and pyloric Canal adjacent to the duodenum(part of the stomach that connects to the duodenum)
Pyloric sphincter of the stomach
Guards exit from stomach
Regulates entry of food to the small intestine (duodenum) from the stomach
Rugae of the stomach
Ridges and folds in relaxed stomach
Allows the stomach to stretch
Temporary folds that are gone when here’s no food in the stomach
How long does it take to empty the stomach
4 hours
Gastric pits are found
In fundus and body of the stomach
Function of gastric pit
Communicates with several gastric gland
2 types of secretary cells
Parietal cells
Chief cells
Parietal cells
Secrete intrinsic factor, and HCl
HCl (THAT COMES FROM OUR FOOD) kill most bacteria, denature proteins, inactivate food enzymes, breakdown plant cells and connective tissue in meat, activate pepsinogen to pepsin
Pepsinogen ——> pepsin——> protein breakdown
chief cells
secrete pepsinogen that converts to popsin in the presence of acid
PEPSIN BREAKS DOWN PROTEINS
in kids, they also produce lipase and rennin (to help with milk digestion)
pyloric glands
produces mucous containing several hormones
enteroendocrine cells
G cells secrete gastrin
gastrin stimulates parietal cells and chief cells to secrete HCl and popsinogen
D cells secrete somatostatin
somatostatin inhibits gastrin secretion
pepsin
enzyme that digests proteins
stomach permits digestion of carbohydrates by lipase until
the pH falls to 4.5
why doesnt absoprtion occur in the stomach
epithelial cells are no exposed to chime
epithelial cells lack transport mechanism
gastric lining is impermeable to water
digestion is not completed (some drugs are absorbed)
role of small intestine in digestion and absorption
mucosa of SI produce few enzymes, and buffer to neutralize chyme
what are the 3 parts of the small intestine
duodenum
jejunum
ileum
duodenum
recieves chyme from stomach, bile from gall bladder, and digestive secretion from pancreas
digestion continues in here
jejunum
digestion and absoprtion takes place here
ileocecal sphincter
transition between small intestine and large intestine
gastroenteric reflexes are initiated by
stretch receptors in stomach
gastroileal reflex triggers
relaxation of ileocecal valve
what are the endocrine functions of pancreas
secretes insulin and glucagons
what are the exocrine functions of pancreas
produces majority of pancreatic secretions
pancreatic juice secreted into the small intestine contains
carbohydrases: to digest carbohydrates
lipases: to digest lipids
nucleases
proteolytic enzymes
functions of the liver
performs metabolic and hematological regulation and produces bile
bile canaliculi
carry bile to bile ductules
bile ductules
lead to portal areas
functions of gall bladder are
stores bile
modifies bile
concentrates bile
TOO MUCH BILE CONCENTRATION CAUSES GALLSTONE
bile salt break large droplet of fat for digestion
which mechanisms coordinate glands
neural
hormonal
GI activity is stimulated by
parasympathetic innervation
GI activity is inhibited by
sympathetic innervation
what are the three divisions of the large intestine
cecu,
colon
rectum
cecum
collects and stores material from ileum
what are the 4 regions of the colon
ascending colon, transverse colon, descending colon, and sigmoid colon
functions of the large intestine
absorption of water
absoprtion of vitamins produced by bacteria
storage of fecal material prior to defecation
carbohydrate digestion and absorption begins in
the mouth
salivary and pancreatic enzymes
disaccharides and trisaccharides
brush border enzymes
monosaccharides
absorption of monosaccharides occurs across the
intestinal epithelia
lipid digestion and absorption
utilizes pancreatic lipases
bile salts imrpove chemical digestion- EMULSIFIES LIPID DROPS
MICELLES (lipid bile salt complexes ) ARE FORMED
micelles diffues into intestinal epithelia THIS RELEASES LIPIDS INTO BLOOD AS CHYLOMICRONS
protein digestion and absorption
low pH destroys tertiary and quarternary structure
uses pepsin, trypsin, chymotrypsin, and elastase
free amino acids are absorbed
absorption
water (ALL THAT IS INGESTED IS REABSORBED BY OSMOSIS)
ions (ABSORBED BY DIFFUSION, COTRANSPORT, AND ACTIVE TRANSPORT)
vitamins (water soluble vitamins are absorbed by diffusion,
fat soluble vitamins are absorbed as part of micelles,
vitamin B12 requires intrinsic factor)
movement of materials along the digestive tract is controlled by
neural mechanisms (parasympathetic and local reflexes)
hormonal mechanisms (enhance or inhibit smooth muscle contraction)
local mechanisms (coordinate response to changes in pH or chemical stimuli
