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173 Cards in this Set

  • Front
  • Back
function of the digestive system
-secretion (saliva, bile, enzymes, mucus)
-movement
-digestion (physical and chemical)
-absorption
process of digestion
-ingestion
-mechanical digestion (stomach, mouth, s. intestines)
-propulsion through gut
-chemical digestion (mouth, stomach, S+L intestines)
-defecation
gastrointestinal tract
mouth -> pharynx -> esophagus -> stomach -> [duodenum, jejunum, ilium] -> [ascending, transverse, descending colon] -> rectum -> anus
accessory organs
-teeth, tongue, salivary glands
-liver, gallbladder, pancreas (don't come in contact with food)
hypopharyngeal sphincter
-upper esophageal
-right below pharynx, controls if food enters digestive system or not
gastro esophageal sphincter
-lower esophageal
-between esophagus and stomach, keeps stuff in stomach
pyloric sphincter
-between stomach and s.intestines
-only opens when food is ready to leave stomach
ileo cecal valve
-between ilium and cecum
internal anal sphincter
-cannot be controlled
external anal sphincter
-skeletal muscle, you can control it
sphincters
-circular smooth muscle
-contracts, lumen is narrowed, nothing can move
histology of GI tract
-mucosa
-submucosa
-muscularis externa
-serosa
mucosa layer
-innermost layer
-epithelial: barrier
-lamina propria: blood vessels used for food to be absorbed into
-muscularis: smooth muscles, runs longitudinally
submucosa layer
-submucosal plexus controls muscles of mucosa layer
muscularis externa layer
-muslces run circular
-controlled by myenteric plexus
serosa layer
-secretes serus fluid
mixing
-alternating contractions of circular muscles (s.intestines and stomach)
propelling
-peristalsis
=circular muscles contract, constrict lumen
=longitudinal mucles contract, shorten muscle
peritoneum
-serous membrane surrounding organs
-parietal (lines abdominal cavity) and visceral (attached to organ)
-peritoneal cavity (space between layers filled with serous fluid, no organs in this cavity)
retroperitoneal
-if something goes wrong with that organ, it is secluded from other organs
-organ is located behind the peritoneum
intraperitoneal
-if organ is surrounded by visceral peritoneum and by cavity
mesenteries
-double fold of peritoneum
mesentery proper
-in s. intestines
-anchors s.intestines to back of wall
-how you get info. to and from organ (vessels)
lesser omentum
-superior portion of stomach to inferior portion of liver (has vessels connecting 2 organs)
greater omentum
-inferior portion of stomach, comes down front of cavity, comes back up and attaches to ascending colon
-all fat, no vessels
-insulation, protection
peritoneal ligaments
-alot smaller than mesentaries
-falciform: connects liver to diaphragm
mouth
-mastication
-initiation of swallowing reflex
-moisten food
-polysaccharide (starch) digestion begins
frenulum
-connects tongue to floor of mouth
papillae
-little bumps on tongue
-have taste buds on them
anchors of tongue
-hyoid bone, styloid process, hard palate, mandible
sublingual salivary glands
-secrete saliva onto floor of mouth
submandibular salivary glands
-secrete saliva towards back of mouth
parotid salivary gland
-secretes saliva in sides of mouth
bucal salivary glands
-intrinsic
-all of inside of mouth, keep mouth moistened
2 types of cells inside salivary glands
1) serous cells: make enzymes
2) mucous cells: make mucous
-made and secreted together as saliva
composition of saliva
-99% water
-HCO3 to maintain pH 7
-digestive enzymes (salivary amylase), antibodies, etc.
salivary amylase
-comes from salivary glands
-breaks down polysaccharides
-only chemical digestion in mouth
nervous control of salivary glands
-facial nerve
-parasympathetic NS
-sympathetic NS innervates glands (dry mouth)
esophagus
-pharynx to stomach
-through diaphragm (esophogeal hiatus)
-stomach starts just below opening
-no digestion, just transports food
hiatal hernia
-stomach gets pulled through esophageal hiatus, above diaphragm
buccal phase
-only part of swallowing you control
-food is chewed and mixed with saliva
-tongue rolls food into bolus and pushed back into pharynx
-tongue presses against palate sealing oral cavity
-soft palate pushed up by bolus
pharyngeal phase
-2nd phase of swallowing
-bolus triggers nerves (CN V and IX) medulla
-hyoid and larynx elevated so epiglottis covers top of larynx
-soft palate rises
esophageal phase
-3rd phase of swallowing
-muscles in pharynx relax to open and open the upper esophageal sphincter
-peristaltic wave begins to force food down esophagus
-when wave hits stomach lower esophageal sphincter relaxes and opens to let food in
heart burn
-failure of sphincter to close completely allows gastric juice into esophagus
esophageal ulcer
-erosion of wall due to chronic reflux of stomach acid
-occurs in esophagus, stomach, and duodenum
rugae
-bumps inside stomach
-incr. surface area, allow stomach to expand
greater curvature
-greater omentum goes from here to transverse colon
lesser curvature
-lesser omentum goes from here to liver
pylorus
-end where stomach goes into s. intestine
cardia
-top, where esophagus comes into stomach
lower esophageal sphincter
-between esophagus and stomach
pyloric sphincter
-between stomach and s. intestine
fundus
-space inside stomach
gastric pit
-has goblet cells
-secrete mucus with high pH to prevent acid from eating through lining
gastric glands
-produce gastric juice
=pH = 2
=digestive enzymes
=mucus
=hormones (get released into blood stream)
muscosal barrier
-alkaline mucus
-mucosa layer is made up of epithelial tissue (tightly bound)
-epithelial tissue is turned over every 3-6 days
chief cells
-found in the gastric glands
-release pepsinogen (inactive)
parietal cells
-found in the gastric glands
-HCl (low pH converts pepsinogen to pepsin and kills bacteria)(comes out of gland as H and Cl and comes together in lumen)
-intrinsic factor (absorbing vitamen B12)
metabolic alkolosis
-from CO2, H goes into stomach, bicarbinate goes into blood
-vomit, HCl leaves stomach, pH in blood incr.
gastrin
-made in stomach
-"get out of here" hormone
-released if pH rises or stomach stretches
-stimulates contraction of stomach muscles and secretion
-stimulates parietal and chief cells
-contracts lower esophageal sphincter
-relaxes pyloric sphincter
-stimulates gastric emptying
-stimulates contraction of s.intestine
-relaxes ileocecal valve
-stimulates mass movement (L. intestine)
enteroendocrine glands
-release hormones
mechanical digestion
-mixing waves help break down food into smaller particles
-chyme: mixture of food and gastric juices
chemical digestion
-produces chyme
-acid secreted by parietal cells breaks down bonds and activates pepsin
-pepsin: breaks down proteins
neural regulation of secretion
-parasympathetic increases contraction and secretion (vagus nerve)
-sympathetic decreases (splenic nerve)
Cholecystokinin (CCK)
-released from s.intestine
-released due to fat in s.intestine, stretch, pH lowering, hypertonic chyme
-inhibits contraction of stomach
-stimulates gallbladder to contract and relaxes sphincter
-stimulates acinar cells in pancreas to release digestive enzymes
-stimulates bile production in liver
Secretin
-released from s.intestine
-released due to fat in s.intestine, stretch, pH lowering, hypertonic chyme
-inhibits secretion
-stimulates liver to produce more bile
-stimulates pancreas to release bicarbinate
cephalic phase
-brain to stomach (vagus)
-excitatory (sight, smell, thought of food, stimulation of taste or smell receptors)
-inhibitory (loss of appetite or depression, decr. in stimulation of the parasympathetic (splenic, decr. vagus)
Gastric phase
-excitatory
=stretch receptors: if stretches stimulates contraction and secretion
=pH incr. more secretion to bring pH down
=caffeine, histamines cause more secretion
-inhibitory
=sympathetic
=pH of less than 2
Intestinal phase
-inhibitory (acidity of chyme and stretching of duodenum causes release of hormones that inhibit stomach)
-short reflex (run on interic NS, stretch of duodenum inhibits stomach)
-long reflex (stretch on duodenum sends a message to the brain to inhibit stomach)
gastritis
-inflammation of underlying layers of stomach wall
gastric ulcers
-erosion of stomach wall
-helicobacter infections cause 90% of all ulcers
-vomiting
vomiting
-caused by extreme stretching of stomach or small intestine or presence of irritants in the stomach
pancreatic islets
-produce insulin and glucagon
pancreatic acinar cells
-makes digestive enzymes
-put enzymes in pancreatic juice -> gets dumped into pancreatic duct -> merges with common bile duct from liver -> hepatopancreatic ampulla -> opens up into s. intestine (onto bump called major duodenal papilla)
hepatopancreatic sphincter
-prevents pancreatic juice from flowing into s.intestines
pancreas structure
-head connected to duodenum
-just below stomach
-horizontal, posterior wall
pancreatic juice
-pH 7-8 : buffers pH from stomach
-clear
-water, salts, HCO3 (bicarbinate, keeps pH up)
-contains 6 enzymes
neural regulation of the pancreas
-parasympathetic nerves
-vagus nerve stimulates pancreas to release juice
pancreatitis
-inflammation of the pancreas
-retroperitoneal, so if pancreas was ruptured and enzymes released, they would activate and just break down pancreas
location of liver
-liver connected to stomach by lesser omentum
-inside lesser omentum is portal triad
portal triad
-hepatic portal vein, hepatic artery, common bile duct
round ligament
-what was left over of the umbilical vein
gluconeogenesis
-making glucose from new sources (fatty acids)
liver functions
-glucose to glycogen (CHO metabolism)
-making and breaking down lipids (lipid metabolism)
-making and breaking down proteins (protein metabolism)
-destroy damaged RBC
-detoxification (removing substances from blood stream that aren't supposed to be there)
-secrete bile
urea
-waste product of breaking down proteins
blood supply to liver
-hepatic portal vein and hepatic artery drop into capillary known as liver sinusoid
-go to central vein (still inside liver) then into hepatic vein, then inferior vena cava
hepatocytes
-fuctional unit of the liver, actually doing the functions
lobules
-liver lobes broken up into smaller portions
-consist of 6 portal triads and one central vein
-bile formed here and put into bile caniculi (run opposite direction, to outside of lobule)
bile ducts
-merge until you have a right and left hepatic duct
-merge to form a common hepatic duct leaving liver
-merges with cystic duct from gallbladder (form common bile duct)
-merges with common pancreatic duct to form ampulla (opens into s.intestines, controlled by sphincter, bile backs up into gallbladder)
gallbladder
-stores bile
-reabsorbs water from bile
-secretes bile into s.intestines
-when sphincter is closed, liver-produced bile backs up into cystic duct into gallbladder to be stored
bile
-water, bile salts, bile pigment, cholesterol, electrolytes
-pH 7.6-8.6
-bile salts stimulate liver to make more bile
bile salts
-mostly cholesterol
-functions: emulsification (mechanical digestion)
-enhance absorption
gallstones
-crystallized bile salts (high cholesterol forces them out of solution)
neural control of bile release
-parasympathetic NS can contract gallbladder, relax sphincter, stimulate liver to produce bile
VIP
-released from s.intestine
-released due to fat in s.intestine, stretch, pH lowering, hypertonic chyme
-inhibits smooth muscles in capillaries of s.intestines (vasodialate, more blood, more places to absorb things)
-stimulates s.intestine to release an alkaline mucus
GIP
-released from s.intestine
-released due to fat in s.intestine, stretch, pH lowering, hypertonic chyme
-stimulates pancreas to release insulin
-inhibits secretions and contractions of stomach
pancreatic amylase
-released from pancreas
-breaks down starch
-active
pancreatic lipase
-released from pancreas
-breaks down lipids
-active
pancreatic nuclease
-released from pancreas
-breaks down nucleic acids
-active
tripsinogen
-released from pancreas
-inactive (so you don't break down organ itself)
-activated to tripsin (converts other 2 enzymes to active
enterokinase
-found in lining of s.intestine
-activates tripsinogen to tripsin
chymotrypsinogen
-released from pancreas
-inactive (so you don't break down organ itself)
-activated to chymotripsin
-breaks down protein
procarboxypeptidase
-released from pancreas
-inactive (so you don't break down organ itself)
-activated to carboxypeptidase
-breaks down protein
pyloric sphincter
-between s.intestines and L.intestines
function of s. intestines
-completes digestion of nutrients in chyme
-absorbs the products of digestion
-transport to L.intestine
peyer's patch
-lymphatic tissue located in submucosa
blood supply of s.intestine
-superior mesenteric aretery, superior mesenteric vein (into hepatic portal vein)
intestinal villi
-tiny projections
-contain blood vessel, lymphatic capillary called lacteal, nerve
microvilli
-specialized portion of plasma membrane (increases surface area)
-part of the cell
-contains brush border enzymes
intestinal glands
-duodenal glands: secrete alkaline mucous
-secrete intestinal juice
-first secrete to buffer, then to lubricate
plicau circularis
-circular fold in mucosal and submucosal layers
-incr. surface area and forces chyme to move in circular motion down s.intestine
goblet cells
-secrete alkaline mucous
paneth cells
-secrete antibacterial protein
brush border enzymes
-peptidases
-sucrase
-maltase
-lactase
-intestinal lipase
peptidases
-brush border enzyme
-peptides to aminto acids
sucrase, maltase, lactase
-brush border enzymes
-disaccharides to monosaccharides
intestinal lipase
-brush border enzyme
-fat into fatty acid and glycerol
migrating myoelectric complex (MMC)
-weak peristaltic waves
-only travel a few inches, slowly move chyme through s.intestines, come in contact with enzymes, digest and absorb
segmentation
-local mixing of chyme w/intestinal juice
-alternating contraction and relaxation
-mechanical digestion
enteric reflex
-stretch of duodenum intitiates segmentation and MMC
gastroileal reflex
-stomach to ileum
-contract ileum, relax ileocecal valve, empty s.intestine
-started by stretch of stomach, incr. pH, undigested substances
enterogastric reflex
-s.intestine to stomach
-ingibit secretions and contractions, inhibit emptying
-started by stretch of s.intestine, hypertonic chyme, decr. pH
gastrocolic reflex
-stomach to L.intestine
-mass movement, large peristaltic waves
-started by stretch of stomch, incr. PH, undigested substances
lipid digestion
-lipid to fatty acid and monoglyceride
protein digestion
-protein to amino acid
carbohydrate digestion
-carbs to monosaccharide (glucose, fructose, galactose)
nucleic acid digestion
-nucleic acid to nucleotide to sugar and phosphate and nitrogen base
sucrase
-breaks down sucrase to glucose and fructose
maltase
-breaks down maltose to glucose and glucose
lactase
-breaks down lactose to glucose and galactose
lactose intolerance
-cells fail to produce lactase
-can't digest lactose sugar in milk
-lactose stays in s.intestine, hypertonic solution, water gets pulled in
-diarrhea, gas, bloating, cramps
function of L.intestine
-no digestive function
-form, store, concentrate, and excrete feces
-not essential to life
hepatic flexture
-where ascending colon turns into transverse colon
splenic flexure
-where transverse colon becomes descending colon
mesocolon
-mesentary that anchors L.intestine to posterior wall
appendix
-hangs off of cecum
-if cecum gets backed up, appendix can become enflamed and rupture, rupturing cecum (contents can enter abdominal cavity)
rectal valve
-allows gas to pass without allowing feces
anal canals
-folds of mucosa, has mucous and stretch receptors (defecation reflex)
levator ani muscle
-skeletal muscle, when it contracts, rectum and anus shorten, incr. pressure, helps reflex
deeper crypt
-produce more mucous, lubricate feces
teniae coli
-longitudinal muscle along center of L.intestine, ends with sigmoid colon
-constantly contracted, causes wall to have pouches call HAUSTRAS
haustral churning
-segmentation in L.intestine
-very slow, moves food into next haustrum
mass movements
-3-4 times per day, have large contraction of transverse and descending colon to push everything into rectum
-stimulated by valsalva manuever, gastrin, gastrocolic reflex
bacterial flora
-breaks down stuff not broken down in s.intestine
-undigested carbs = CO2 and methane gas
-undigested proteins = odor
-bilirubin = color
feces
-materials not digested
-water, electrolyte, muscus
-dead epithelial cells
-75% water
metabolism
-sum of all the chemical processes occurring in the body
anabolism
-building process
-use energy and heat
-take water out
catabolism
-break things down
-release energy and heat
-hydrolysis
glycolysis
-breakdown of glucose
gluconeogenesis
-making glucose from new sources
glycogenesis
-glucose to glycogen (stored form)
glycogenolysis
-take glycogen and break it down to glucose
ATP generated by triglyceride
400 ATP
ATP generated by 16 C fatty acid
129 ATP
ATP generated by glucose
36 ATP
beta oxidation
-take fatty acids, end up with acetly CoA (2C molecule)
-every time you do this, clip off an Acetyl CoA (goes into Kreb cycle)
lipolysis
-breaking down lipid into glycerol and fatty acid
-if need energy, take glycerol and convert it to Acetyl CoA and dump into Kreb cycle
-if you don't need energy, take glycerol and do gluconeogenesis
ketogenesis
-occurs in liver only
-2 Acetyl CoA to acid to ketones
-ketones can be used for energy
ketosis
-accumulation of ketones in the blood (can only use so many for energy)
-change pH of blood (acidosis)
lipogenesis
-formation of lipids
-can make fat from anywhere
-from Acetyl CoA can make lipids
-stimulated by insulin
lipoprotein
-wrap protein around a lipid (or anything else fat soluble)
-how u transport lipids and cholesterol
chylomicron
-absorb fat and dump into blood stream, low density lipoprotein (very little protein)
VLDL
-mostly triglyceride, formed in liver, transport triglycerides from liver to adipose sights
LDL
-mostly cholesterol, made in liver, transport cholesterol from liver to other cells of body
HDL
-take cholesterol from cells of body and bring in back to liver
IDL
-VLDL drops off triglycerol at adipose site, as it is returneing to liver it is called IDL
total cholesterol #
< 200 mg
LDL #
< 130 mg
HDL #
> 40 mg
heart attack risk
-look at ratio between TC and HDL
-should be below 4
deamination
-removal of nitrogen group from AA
-need to get rid of amine group in order to use
-end up with keto acid (goes into kreb cycle, makes ATP, lipid, glucose, ketones) and amonia (have to get rid of, liver combines it with water to make urea and dumps it into bloodstream - comes out via secretion)
jaundice
-accumulation of urea in the tissues
transamination
-start with one AA and a keto acid
-take one amine group from AA and transfer to keto acid
-results in a new AA and a different keto acid