Term
|
Definition
|
|
Term
| some components of the digestive tract |
|
Definition
-oral cavity
–pharynx
-upper pharyngoesophageal sphincter
-esophagus
-lower gastroesophageal sphincter
-stomach
-pyloric sphincter
-small intestine
-ileocecal valve
-large intestine (cecum, colon, rectum)
-anus
-internal anal sphincter
-external anal sphincter
[image] |
|
|
Term
| divisions of the small intestine |
|
Definition
|
|
Term
| lenth of the GI tract in adults |
|
Definition
|
|
Term
| some accessory organs for the digestive system |
|
Definition
-teeth
-tongue
-salivary glands
-liver
-gall bladder
-pancreas |
|
|
Term
| the 4 general layers of the GI tract |
|
Definition
-mucosa
-submucosa
-muscularis
-serosa
[image][image] |
|
|
Term
|
Definition
-the layer closest to the lumen, where the food is
-lined with epithelial cells
-lamina propria below the epithelium
-muscularis mucosa below the lamina propria
[image][image] |
|
|
Term
|
Definition
muscular tissue that helps with folding of the gut in the small intestine and the stomach
[image][image] |
|
|
Term
|
Definition
-layer of connective tissue below the mucosa
-blood vessels and main lymphatics run thru it
-contains the submucosal plexus
[image][image] |
|
|
Term
|
Definition
within the submucosa
[image][image] |
|
|
Term
|
Definition
-in the muscularis layer
-between 2 muscular layers
-communicates with neurons
[image][image] |
|
|
Term
| the smooth muscle layers of the muscularis |
|
Definition
-inner circular layer
-outer longitudinal layer
they're governed by the autonomic and enteric nervous systems
[image][image] |
|
|
Term
|
Definition
An outer epithelial membrane that covers the surface of a visceral organ
-thinner outside layer
-adjacent to it is the abdominal cavity
[image][image] |
|
|
Term
|
Definition
| tissue that kinda lines the gut and is where the vessels, lymphatics, and most of the nerves run into the gut |
|
|
Term
| the most diverse layer of the GI tract |
|
Definition
| mucosa, especially the epithelial layer |
|
|
Term
|
Definition
| protrusions of the mucosa into the lumen |
|
|
Term
|
Definition
inpouchings down into the laminar propria
-their main job is to absorb nutrients |
|
|
Term
|
Definition
-characterized by squamous epithelium
-found in the oral cavity, pharynx, esophagus, and anal canal |
|
|
Term
|
Definition
-contains cells that are responsible for the secretion of digestive enzymes
-found only in the stomach |
|
|
Term
|
Definition
-contains crypts and villi
-responsible primarily for absorbing digested nutrients
-found along the entirety of the small intestine |
|
|
Term
| absorptive and protective mucosa |
|
Definition
-specializes in water absorption and mucous secretion
-found in the large intestine |
|
|
Term
| some general digestive activities in the GI tract |
|
Definition
-Motility
-Secretion
-Digestion
-Absorption
-Storage
-Elimination
-Regulation
[image] |
|
|
Term
| how the GI tract does Motility |
|
Definition
-mastication (chewing)
-deglutition (swallowing)
-peristalsis
-segmentation
-haustration
-defecation |
|
|
Term
| how the GI tract does Secretion |
|
Definition
-endocrine (hormones)
-paracrine
-exocrine (enzymes, electrolytes, HCl & water) |
|
|
Term
| how the GI tract does Digestion |
|
Definition
|
|
Term
| how the GI tract does Absorption |
|
Definition
| digested food enters blood or lymph |
|
|
Term
| how the GI tract does Storage |
|
Definition
|
|
Term
| how the GI tract does Elimination |
|
Definition
bile and indigestible food
-some substances are put into the bile to be eliminated |
|
|
Term
| how the GI tract does Regulation |
|
Definition
| neural (enteric nervous system ENS and ANS) and hormonal |
|
|
Term
|
Definition
| Waves of smooth muscle contraction in smooth muscles of the tubular digestive tract. It involves circular and longitudinal muscle fibers at successive locations along the tract and serves to propel the contents of the tract in one direction. |
|
|
Term
|
Definition
| segments of the gut constricting on food |
|
|
Term
|
Definition
|
|
Term
|
Definition
| kinda like peristalsis and segmentation in the colon |
|
|
Term
| endocrine functions in the GI tract |
|
Definition
|
|
Term
| paracrine and exocrine functions in the GI tract |
|
Definition
| enzymes, electrolytes, HCl & water |
|
|
Term
|
Definition
breaks down non-absorbable polymers (carbohydrates, fats, and proteins) into absorbable monomer (mostly) building blocks
-obtains basic organic molecules to make ATP, build tissues, and serve as cofactors and coenzymes.
[image] |
|
|
Term
| how digestion degrades non-absorbable molecules into smaller, absorbable molecules |
|
Definition
Hydrolysis into monomers, aided by specific enzymes
[image] |
|
|
Term
| what the basic molecules obtained by digestion are used for |
|
Definition
| to make ATP, build tissues, and serve as cofactors and coenzymes |
|
|
Term
| function of the oral cavity |
|
Definition
-chewing
-Mixes food with saliva which contains salivary amylase, mucus, growth factors.
-1st stage of deglutition (oral stage, which is voluntary)
[image] |
|
|
Term
| the function of the pharynx |
|
Definition
| -2nd stage of deglutition (Pharyngeal stage, which is involuntary) |
|
|
Term
| function of the esophagus |
|
Definition
-Deglutition (swallowing)
-3rd stage of Deglutition (esophageal stage, which is involuntary) |
|
|
Term
| the stages of Deglutition (swallowing) |
|
Definition
1: Oral stage (voluntary) – bolus moved to pharynx
2: Pharyngeal stage (involuntary) – soft palate covers nasopharynx, vocal folds close and epiglottis covers them (larynx), upper esophageal sphincter relaxes.
3: Esophageal stage (involuntary) – peristalsis moves food down esophagus to stomach.
[image] |
|
|
Term
| the salivary glands in the oral cavity |
|
Definition
-parotid
-submandibular
-sublingual
[image] |
|
|
Term
| what the soft pallate does during swallowing |
|
Definition
covers the nasopharynx to keep food and liquid from going into your nasal passages
-the vocal folds close to cover the epiglottis
[image][image] |
|
|
Term
|
Definition
-voluntary
–bolus moved to pharynx
[image] |
|
|
Term
| Pharyngeal stage of swallowing |
|
Definition
involuntary – soft palate covers nasopharynx, vocal folds close and epiglottis covers them (larynx), upper esophageal sphincter relaxes
Bolus is moved out of pharynx --> through upper esophageal sphincter --> into esophagus.
[image] |
|
|
Term
| Esophageal stage of swallowing |
|
Definition
-involuntary
–peristalsis moves food down esophagus to stomach
[image][image] |
|
|
Term
| the movement of bolus through esophagus before it gets to the lower esophageal sphincter |
|
Definition
-*Upper third contains skeletal muscle, transitions to smooth m.
-Passes through diaphragm via hiatus.
[image] |
|
|
Term
| the movement of bolus through esophagus when it gets to the lower esophageal sphincter |
|
Definition
Lower esophageal sphincter
-Relaxes to allow bolus to pass.
-Closed to prevent regurgitation; heart burn – gastroesophageal reflux disease (GERD)
[image] |
|
|
Term
| heart burn (gastroesophageal reflux disease (GERD)) |
|
Definition
when stomach acid goes into the esophagus due to the failure of the lower esophageal sphincter to close properly
-it causes erosions
[image] |
|
|
Term
|
Definition
Series of localized reflexes in response to distention of wall by bolus.
-uses a peristaltic wave
[image] |
|
|
Term
|
Definition
coordinated, wave-like muscular contractions
[image] |
|
|
Term
| how the peristaltic wave occurs in the esophagus |
|
Definition
| -Circular smooth muscle contracts on the proximal side and relaxes on the distal side of the bolus --> followed by longitudinal contraction (shortening) of smooth muscle.
-After food passes into stomach, lower esophageal sphincter constricts.
-*These principles apply throughout the GI tract.
-this is a lot faster in the esophagus than in the small intestine
[image] |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| The state of being distended, enlarged, swollen from internal pressure |
|
|
Term
| depiction of how deglutition (swallowing) is neurologically controlled |
|
Definition
|
|
Term
|
Definition
-Cardia
-fundus
-body
-antrum
-pylorus
-pyloric sphincter
-Gastric glands (deeper in the mucosa)
[image]
[image] |
|
|
Term
|
Definition
-Stores food
-Churns food to mix with gastric secretions
-Initiates digestion of proteins via secretions
-Kills bacteria
-Moves food (chyme) into the small intestine |
|
|
Term
|
Definition
where the food enters the stomach
[image]
[image] |
|
|
Term
|
Definition
-in the stomach
-allow the stomach to expand
[image]
[image] |
|
|
Term
| chyme (pronounced "kyme") |
|
Definition
digested food in the stomach and intestines
-stops being chyme when it gets turned into feces |
|
|
Term
| the 3 muscle layers in the stomach |
|
Definition
1: inner Oblique
2: Circular
3: outer Longitudinal
[image] |
|
|
Term
| what the stomach does in terms of motility |
|
Definition
|
|
Term
| how the stomach does mixing during motility |
|
Definition
weak peristaltic constricting waves fundus to antrum
-Food + gastric secretions --> chyme
-Pyloric sphincter “closed”
[image] |
|
|
Term
| how the stomach does emptying during motility |
|
Definition
strong peristaltic waves starting in antrum to pylorus
-Pyloric sphincter “relaxed” --> chyme enters duodenum.
-Full duodenum --> pressure closes pyloric sphincter
[image] |
|
|
Term
| where gastric glands are found |
|
Definition
| gastric pits; the mucosa contains numerous gastric pits |
|
|
Term
|
Definition
line the pits and secrete exocrine molecules and water (gastric juice) into lumen, and endocrine and paracrine signaling molecules into interstitial space of mucosa.
[image] |
|
|
Term
| some types of cells within the gastric glands |
|
Definition
(1) Goblet cells (mucous neck cells)
(2) Parietal cells
(3) Chief cells
(4) Enterochromaffin-like cells (ECL)
(5) G cells
(6) D cells
(7) Ghrelin cells
[image] |
|
|
Term
| Goblet cells (mucous neck cells) |
|
Definition
cells inside the gastric glands that secrete mucus & bicarbonate as protection against stomach acid
[image] |
|
|
Term
|
Definition
| cells inside the gastric glands that secrete gastric acid (HCl), which breaks down food, and intrinsic factor (IF), which helps absorb vitamin B12, which is used for making heme
[image] |
|
|
Term
|
Definition
cells inside the gastric glands that secrete pepsinogen, which is important for protein digestion
[image] |
|
|
Term
| Enterochromaffin-like cells (ECL) |
|
Definition
cells inside the gastric glands that secrete the paracrine molecules histamine and serotonin to trigger function of neighboring cells
[image] |
|
|
Term
|
Definition
cells inside the gastric glands that secrete gastrin endocrine hormone
[image] |
|
|
Term
|
Definition
cells inside the gastric glands that secrete somatostatin – paracrine and endocrine – inhibits secretion of multiple GI hormones
[image] |
|
|
Term
|
Definition
cells inside the gastric glands that secrete ghrelin – ↑ during fasting --> stimulate hunger
[image] |
|
|
Term
|
Definition
| the only essential function in stomach – polypeptide that promotes absorption of vitamin B12 in the ileum --> helps prevent pernicious anemia |
|
|
Term
| the reaction that produces H+ in the cytosol of the goblet cells in the stomach |
|
Definition
| CO2 + H2O --> H+ + HCO3- by carbonic anhydrase
[image] |
|
|
Term
| transport of ions at the apical membrane in the process of making gastric acid (HCl) |
|
Definition
| H+ is secreted into gastric lumen by primary active transport, through H+/ K+ ATPase (proton pump), Cl- is secreted through facilitated diffusion.
[image] |
|
|
Term
| concentration of H+ in lumen vs. that in parietal cells |
|
Definition
| 3 x 106 times more H+ in lumen than inside parietal cells
[image] |
|
|
Term
| transport of ions at the basolateral membrane in the process of making gastric acid (HCl) |
|
Definition
| HCO3- exits cells against its electrochemical gradient, by coupling its transport with Cl- following gradient – secondary active transport
[image] |
|
|
Term
| how gastric acid (HCl) secretion is regulated neurologically |
|
Definition
enteric and parasympathetic nervous systems (ACh) stimulates parietal & ECL cells.
-Binds muscarinic Rs.
[image] |
|
|
Term
| how gastric acid (HCl) secretion is regulated by endocrine means |
|
Definition
gastrin from G cells, carried to parietal & ECL cells by blood circulation
[image] |
|
|
Term
| how gastric acid (HCl) secretion is regulated by paracrine means |
|
Definition
| ECL cells secrete histamine --> binds H2 Rs on parietal cells
[image] |
|
|
Term
| Enterochromaffin-like (ECL) cells |
|
Definition
| Enterochromaffin-like cells
-secrete histamine --> binds H2 Rs on parietal cells
[image] |
|
|
Term
| the role of acetylcholine in the regulation of gastric acid (HCl) secretion |
|
Definition
| -binds muscarinic receptors
-ultimately triggers intracellular signaling, leading to activity of the H+ / K+ ATPase pump
[image] |
|
|
Term
| the 3 phases of regulation of stomach activities |
|
Definition
-Cephalic phase
-Gastric phase
-Intestinal phase |
|
|
Term
| Cephalic phase of regulation of stomach activities |
|
Definition
sight, smell, & taste of food --> ↑ vagal tone, gastrin and histamine activation --> ↑ secretion.
-increases tone to the vagus nerve
-"anticipating food" |
|
|
Term
| Gastric phase of regulation of stomach activities |
|
Definition
food in stomach --> physical distension and chemical nature of chyme (amino acids etc. ) --> ↑ secretion.
-Positive feedback– ↑ secretion of HCl and pepsinogen --> ↑ gastric secretion. |
|
|
Term
| Intestinal phase of regulation of stomach activities |
|
Definition
| gastric activity inhibited when chyme enters the small intestine. |
|
|
Term
|
Definition
| digestion and small amount of absorption |
|
|
Term
| function of HCl in the stomach |
|
Definition
HCl functions to provide an acidic gastric environment
-Denatures ingested proteins
-Activates pepsinogen to pepsin (pH = 2).
-Kills bacteria |
|
|
Term
| how digestion occurs in the stomach |
|
Definition
-Proteins denatured and partially digested by pepsin more digestible.
-Carbohydrate digestion by salivary amylase is soon inactivated by acidity. |
|
|
Term
| why carbohydrate digestion by salivary amylase stops in the stomach |
|
Definition
| because it gets inactivated by acidity |
|
|
Term
| some molecules that can get absorbed through the stomach lining |
|
Definition
-Alcohol (ethanol) – main absorption site is the small intestine.
-Aspirin and salicylates – unionized at gastric pH. |
|
|
Term
| why aspirin and salicylates can get absorbed through the stomach lining |
|
Definition
| because they're unionized at gastric pH |
|
|
Term
| how alkaline mucus functions as a chemical protective mechanism in the stomach |
|
Definition
| it contains HCO3- and forms a barrier against actions of pepsin & acid.
[image] |
|
|
Term
| some physical protective mechanisms in the stomach |
|
Definition
-Tight junctions
-Rapid rate of cell division
[image] |
|
|
Term
| how tight junctions function as a physical protective mechanism in the stomach |
|
Definition
between adjacent cells; keeps acid from getting between cells
[image] |
|
|
Term
| how rapid rate of cell division functions as a physical protective mechanism in the stomach |
|
Definition
entire epithelium replaced in 3 days
-they wear out fast
-the new cells work their way up from the gastric pits
[image] |
|
|
Term
| where the new cells for the stomach epithelium come from |
|
Definition
|
|
Term
| how prostaglandins help to protect the stomach epithelium |
|
Definition
| *Prostaglandins E2 (PGE2) and I2 (PGI2) --> ↓ gastric acid & ↑ mucus secretions, ↑ mucosal blood flow.
-they're "housekeeping" prostaglandins
[image] |
|
|
Term
| how Prostaglandins E2 and I2 |
|
Definition
-helps decrease gastric acid and increase mucus secretions
-nutritive
-helps remove metabolic waste products |
|
|
Term
|
Definition
Erosions of mucosa of stomach or duodenum
[image] |
|
|
Term
| chemicals that can damage lining to produce an ulcer |
|
Definition
|
|
Term
| some causes of peptic ulcers |
|
Definition
| -gastrin-secreting tumor
-Helicobacter pylori
-NSAIDs (aspirin, ibuprofen, etc.) |
|
|
Term
| how NSAIDs (aspirin, ibuprofen, etc.) cause peptic ulcers |
|
Definition
| by inhibiting paracrine secretion of PGE2 & PGI2 |
|
|
Term
| some treatments for ulcers |
|
Definition
| -Proton pump inhibitors such as omeprazole (Prilosec)
-Histamine receptor (H2) blockers such as famotidine (Pepcid) and ranitidine (Zantac)
-Antibiotics |
|
|
Term
| the 3 sections of the small intestine |
|
Definition
-Duodenum
-Jejunum
-Ileum
[image] |
|
|
Term
|
Definition
–short
-Bile and pancreatic duct empty here
[image][image] |
|
|
Term
|
Definition
2/5 length of small intestine
[image] |
|
|
Term
|
Definition
3/5 length of small intestine
-Ileocecal valve into colon
[image][image] |
|
|
Term
|
Definition
the valve through which the chyme goes from the ileum into the colon
[image] |
|
|
Term
| some structural components of the small intestine |
|
Definition
-Folds (plicae circulares)
-villi
-microvilli (aka the brush border)
-Epithelial cells (enterocytes)
-goblet cells
-intestinal crypts
-Lamina propria
+lymphocytes
+capillaries
+central lacteal
[image] |
|
|
Term
| the structures in the small intestine that increase surface area to let it do its job more efficiently |
|
Definition
| Folds (plicae circulares) --> villi --> microvilli (also known as the brush border)
[image] |
|
|
Term
| Epithelial cells (enterocytes) interspersed with... |
|
Definition
|
|
Term
|
Definition
| epithelial cells of the small intestine |
|
|
Term
| how the epithelial cells at the tips of villi are maintained |
|
Definition
-exfoliated
-replaced by mitosis in intestinal crypts |
|
|
Term
| where the new enterocytes (epithelial cells of the small intestine) come from |
|
Definition
|
|
Term
| Lamina propria contains... |
|
Definition
-lymphocytes
-capillaries
-central lacteal |
|
|
Term
| functions of the small intestine |
|
Definition
| complete digestion and absorption of carbohydrates, proteins, and fats |
|
|
Term
| enzymes needed for digestion in the small intestine |
|
Definition
-pancreatic enzymes
-brush border enzymes |
|
|
Term
| why absorption in the small intestine is very rapid |
|
Definition
|
|
Term
|
Definition
| attached to surface of microvilli – not secreted |
|
|
Term
| advantage of the brush-border enzymes being attached to the surface of the microvilli instead of floating around |
|
Definition
makes them last longer due to negating the need to continue synthesizing them
[image] |
|
|
Term
| what the duodenum and jejunum absorb |
|
Definition
| -carbohydrates
-amino acids
-lipids
-iron
-Ca2+
-H2O |
|
|
Term
|
Definition
| -bile salts
-vitamin B12
-electrolytes
-H2O |
|
|
Term
| some ways water gets into the GI tract |
|
Definition
-Diet
-saliva
-gastric secretions
-bile
-pancreatic juice
-SI secretions
-colonic secretions
[image] |
|
|
Term
| some ways water gets out of the GI tract |
|
Definition
-SI reabsorption
-colonic reabsorption
[image] |
|
|
Term
| water that enters the GI tract, but does not get reabsorbed, is lost in... |
|
Definition
|
|
Term
| where water gets absorbed in the GI tract |
|
Definition
| -mostly small intestine (all but ~2L) |
|
|
Term
| how water absorption occurs in the small intestine |
|
Definition
| absorbs all but ~ 2 L of ingested H2O, and H2O from GI secretions
-Absorbs Na+ and Cl- via facilitated diffusion.
-Na+ cotransported with glucose.
-Na+, K+ ATPase pump moves Na+ out of enterocytes into interstitial fluid.
-Water follows Na+ by osmosis.
[image] |
|
|
Term
| how water absorption occurs in the large intestine |
|
Definition
| -absorbs Na+ via facilitated diffusion
-H2O follows by osmosis
+Roughly 100+ mL H2O remains in feces daily. |
|
|
Term
| the 2 major types of motility patterns derived from contractions in the small intestine |
|
Definition
-Peristalsis
-Segmentation |
|
|
Term
|
Definition
-Movement of chyme through the small intestine.
-Slow and weak movement – avg. 1 cm/min.
[image] |
|
|
Term
|
Definition
-Major contractile activity of the small intestine 2-3x/min.
-Strong contraction of circular smooth muscle to mix chyme.
-this is to mix the contents; these muscles can squish forward, backwards, up, and down
[image] |
|
|
Term
| some ways by which humoral regulation of intestinal activity is done |
|
Definition
-Endocrine regulation
-Paracrine regulation |
|
|
Term
| some things secreted by the enterocytes for endocrine regulation of intestinal activities |
|
Definition
-Secretin
-Cholecystokinin (CCK), a.k.a. pancreazymin
-Gastric inhibitory peptide or glucose-dependent insulinotropic peptide (GIP)
-Motilin |
|
|
Term
| how paracrine regulation of the intestinal activities is done |
|
Definition
| filling --> ↑ intestinal pressure --> ↑ secretion of serotonin (ECL cells) in intestinal mucosa --> ↑ muscle contractions |
|
|
Term
|
Definition
| stimulus: drop in pH.
-Stimulates HCO3- and H2O secretion in pancreatic juice.
-Inhibits gastrin secretion. |
|
|
Term
| Cholecystokinin (CCK), a.k.a. pancreazymin |
|
Definition
| stimulus: presence of partially digested fats and proteins.
-Stimulates contraction of gallbladder, thus secretion of bile.
-Stimulates enzymatic and HCO3- secretion in pancreatic juice. |
|
|
Term
| Gastric inhibitory peptide or glucose-dependent insulinotropic peptide (GIP) |
|
Definition
stimulus: proteins, fats, CHOs.
-Stimulates insulin secretion from endocrine pancreas.
-Inhibits gastric motility & HCl secretion --> slows emptying. |
|
|
Term
|
Definition
| released from M cells during fasting --> stimulates motility |
|
|
Term
| the parts of the small intestine in order |
|
Definition
cecum --> ascending colon --> transverse colon --> descending colon --> sigmoid colon --> rectum --> anal canal --> anus
[image] |
|
|
Term
| how motility occurs in the large intestine |
|
Definition
Outer surface bulges outward to form haustra (bag-like structure).
1) Haustrations
2) Mass propulsive movements.
[image] |
|
|
Term
|
Definition
part of the outer surface of the large intestine that bulges outward to form a bag-like structure
[image] |
|
|
Term
|
Definition
| mixing movements in the large intestine triggered by chyme |
|
|
Term
| the histological makeup of the large intestine |
|
Definition
-No plicated folds or villi.
-Thin brush border on epithelial cells.
-Many goblet cells.
[image] |
|
|
Term
|
Definition
| roughly the 1st half of the colon
-H2O (most of remaining 10-15%) and electrolytes (Na+, Cl-).
-HCO3- secreted to neutralize acidic products of bacterial metabolism.
-Production of vitamin B complexes and vitamin K via microbes. |
|
|
Term
|
Definition
| roughly the 1st half of the colon
-Feces with residual H2O |
|
|
Term
| what the microbes in the absorbing colon do |
|
Definition
| -make vitamin K and some B vitamins (riboflavin, thiamin, biotin, pantothenic acid, folic acid)
-make short-chain fatty acids (FAs) from cellulose
+FAs help absorb Na+, Ca2+, HCO3-, Mg2+, Fe2+ (much less absn. in colon vs. SI).
-Beneficial (mutualism) vs. harmful species of bacteria |
|
|
Term
| diversity of microbes in the large intestine |
|
Definition
| > 400 different species of microbes |
|
|
Term
| Disruption of normal microflora leads to... |
|
Definition
|
|
Term
| what causes the defecation reflex? |
|
Definition
| Waste material passes to the rectum |
|
|
Term
| the amount of your feces that's composed of bacteria |
|
Definition
|
|
Term
| the pathway of the defecation reflex |
|
Definition
Distension of rectum by fecal material --> signals sent to the sacral region of the spinal cord --> induction of defecation reflex --> relaxation of internal anal sphincter (involuntary) and external anal sphincter (voluntary), aided by contractions of abdominal and pelvic muscles which push feces from rectum --> defecation
[image] |
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Term
| why the defecation reflex is called a reflex |
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Definition
because part of it goes through the spinal cord and back without going to the brain
[image] |
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Term
| some functions of the liver |
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Definition
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Term
|
Definition
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Term
| why the liver is so good at regenerating |
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Definition
| Active hepatocytes undergo mitosis --> amazing regenerative abilities |
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Term
| some groups of blood vessels in the liver |
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Definition
-hepatic artery
-hepatic portal system
-hepatic veins
[image][image] |
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Term
|
Definition
-brings oxygenated blood to liver
-Branches off aorta
[image][image] |
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Term
|
Definition
-brings nutrients and deoxygenated blood from abdominal organs to liver
-Venous return for the abdominal organs
[image][image][image] |
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Term
|
Definition
multiple hepatic veins take deoxygenated blood from liver to inferior vena cava
[image][image] |
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Term
| depiction of how the hepatic portal system works |
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Definition
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Term
| why the liver is organized the way it is |
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Definition
| Organized to filter the blood. Blood percolates through endothelium-lined sinusoids between cords or plates of hepatocytes into the central vein, which then drains into the hepatic vein. |
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Term
| how the liver is organized |
|
Definition
Lobes --> lobules --> hepatic cords or plates --> hepatocytes
[image] |
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Term
| the histology of the lobule |
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Definition
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Term
| portal triad in the liver |
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Definition
corners at the liver's lobules where the branches of hepatic artery, portal vein, and bile ductules run together
[image] |
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Term
| after the portal triad, the fluid empties into the... |
|
Definition
central vein, which leads to the bile duct
[image] |
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Term
| Perimeter of each lobule is defined by... |
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Definition
| portal triads at the corners |
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Term
| the direction everything flows in the portal triad |
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Definition
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Term
| the flow of oxygen-rich and nutrient-rich blood in the portal triad |
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Definition
Oxygen-rich blood from hepatic artery and nutrient-rich blood from hepatic portal vein mix and flow through sinusoids toward central vein in center of each lobule.
[image] |
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Term
| one advantage of the liver's endothelium being fenestrated |
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Definition
hepatocytes directly exposed to blood
-this makes it easier for hepatocytes to secrete albumin into the blood stream |
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Term
| the flow of bile through the bile canaliculi in the portal triad |
|
Definition
collect waste products --> flow in opposite direction (away from central vein) to bile ductules in portal triads --> gall bladder
[image] |
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Term
|
Definition
part of the portal triad
-collect waste products --> flow in opposite direction (away from central vein) to bile ductules in portal triads --> gall bladder
[image] |
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Term
| how bile secretion is triggered, and then occurs |
|
Definition
Bile stored in gall bladder until signaled to release:
-Cholecystokinin – primary signal
-Parasympathetic and enteric nervous system (ACh)
[image] |
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Term
|
Definition
primary signal for bile secretion
[image] |
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Term
| Enterohepatic (re)circulation |
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Definition
95% of bile from ileum reabsorbed --> portal vein --> reused
-whatever doesn't get recirculated winds up in the stool
[image] |
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Term
|
Definition
| a collective term, it contains
-bile acids
-bile salts
-Bile pigment – bilirubin (heme without Fe)
-Electrolytes
-cholesterol
-HCO3-
-water
[image] |
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Term
| Bile acids and bile salts |
|
Definition
-Precursor – cholesterol.
-Aids digestion of fat.
[image] |
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Term
| Bile pigment aka bilirubin |
|
Definition
heme without Fe
-Aged RBC --> engulfed by phagocytes mainly in spleen and bone marrow --> … --> liver --> conjugated bilirubin.
[image] |
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Term
| Jaundice or icterus caused by... |
|
Definition
↑ in blood bilirubin levels
[image] |
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Term
| endocrine functions of the pancreas |
|
Definition
Islets of Langerhans secrete...
-insulin
-glucagon
-somatostatin |
|
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Term
| exocrine and digestive function of pancreas |
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Definition
| pancreatic juice secreted from acinar cells in acini --> pancreatic ducts.
-*Contains H2O, HCO3- and digestive enzymes.
-Complete digestion of food requires action of both pancreatic and brush border enzyme. |
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Term
| some things that signal for pancreatic juice to be released |
|
Definition
-Secretin
-Cholecystokinin
-Parasympathetic and enteric nervous systems (ACh) |
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Term
| Most pancreatic enzymes are produced as... |
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Definition
| inactive precursors called zymogens |
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Term
|
Definition
(when activated by enterokinase in the small intestine)
-triggers the activation of other pancreatic enzymes
-breaks peptide bonds within the aino acid chain |
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Term
| Pancreatic trypsin inhibitor |
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Definition
| inhibits activation of trypsin in the pancreas |
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Term
| the 3 main enzymes that the pancreas secretes |
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Definition
|
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Term
| depiction of the duct of the pancreas that releases enzymes |
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Definition
|
|
Term
|
Definition
the enzyme that activates trypsinogen into trypsin
[image] |
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Term
| what would happen if the pancreas did not use trypsin inhibitor? |
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Definition
| trypsinogen could possible turn into trypsin while still in the pancreas |
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Term
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Definition
| removes FAs from glycerol |
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Term
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Definition
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Term
| the role of bicarbonate in the small intestine |
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Definition
| helps neutralize gastric acid to prevent gastric acid reflux back into the pancreatic ducts |
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Term
| some types of regulation that regulate the digestive system |
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Definition
-neural regulation
-hormonal regulation |
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Term
| differences between neural and hormonal regulation of the digestive system |
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Definition
-neuronal occurs faster and lasts shorter
-hormonal occurs slower and lasts longer |
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Term
| extrinsic component of the neuronal regulation of the GI activity |
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Definition
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Term
| how the extrinsic parasympathetic component of the nervous system regulates GI activity |
|
Definition
–generally stimulatory
–vagus nnerves and sacral nerves |
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Term
| how the extrinsic sympathetic component of the nervous system regulates GI activity |
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Definition
| generally inhibitory (inhibits peristalsis and secretion, stimulates contraction of sphincters) |
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Term
| intrinsic division of the neuronal regulation of the GI system |
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Definition
| domain of the enteric nervous system (enteric or visceral brain) |
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Term
| Submucosal & myenteric plexi |
|
Definition
where extrinsic and intrinsic divisions of neuronal regulation of the GI system meet
[image] |
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Term
| depiction of the enteric nervous system (ENS), showing the sympathetic and parasympathetic divisions |
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Definition
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Term
|
Definition
input to ENS, ANS, brain
[image] |
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Term
| Myenteric or Auerbach’s plexus |
|
Definition
between longitudinal and circular smooth m. – controls GI movements.
-innervates smooth m. of muscular layer from esophagus thru entire GI tract.
(1) ↑ tone (tonic)
(2) ↑ intensity of contractions (phasic)
(3) ↑ rate of contractions (phasic)
(4) ↑ conduction rate of excitatory waves.
[image] |
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Term
| Submucosal or Meissner’s plexus |
|
Definition
within submucosa – controls GI secretions and local blood flow.
-in SI and LI.
-Innervates mucosal layer.
-Controls local secretion, local absorption, and local contraction of muscularis mucosa.
[image] |
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Term
| Autonomic nervous system (ANS) |
|
Definition
mainly works through influencing ENS neurons.
[image] |
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Term
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Definition
| maintaining tone over time |
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Term
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Definition
| briefer, short-term changes in firing of neurons |
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Term
| types of smooth muscle electrical activity in the GI system |
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Definition
(1) Slow Waves
(2) Spike Potentials |
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Term
|
Definition
not action potentials
-Interstitial cells of Cajal pacemakers.
-Slow, rhythmic, low intensity gradually bring smooth muscle to threshold.
[image][image] |
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Term
|
Definition
action potentials
-Slow waves that reach approx. – 40 mV.
-Last longer than neuronal APs.
-Stretch and parasympathetic NS trigger depolarization.
-Sympathetic NS triggers hyperpolarization.
[image][image] |
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Term
| some details about how neural regulation of peristalsis occurs |
|
Definition
-Presence of food bolus induces contraction and relaxation simultaneously in the same muscle bundles.
-Stretch triggers mechanoreceptors.
-Potential role for chemoreceptors.
[image][image] |
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Term
| the pathway by which neural regulation of peristalsis occurs |
|
Definition
Stretch triggers mechanoreceptors. Potential role for chemoreceptors. Afferent sensory neurons --> Cholinergic interneurons in ENS --> ACh triggers release of ACh and substance P proximal to bolus --> smooth muscle contraction behind bolus.
-ACh triggers release of NO, VIP, and ATP distal to bolus --> smooth muscle relaxation in front of the bolus.
[image][image] |
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Term
| some short reflexes within the GI tract mediated by ENS |
|
Definition
-Gastroileal reflex
-Ileogastric reflex
-Intestino-intestinal reflex
[image] |
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Term
|
Definition
↑ gastric activity --> ↑ motility of ileum --> ↑ movement of chyme through ileocecal sphincter.
[image] |
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Term
|
Definition
↑ distension of ileum --> ↓ gastric motility.
[image] |
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Term
| Intestino-intestinal reflex |
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Definition
↑ distension in one GI segment --> relaxation throughout the rest of intestine.
[image] |
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Term
| Long reflexes in the GI system |
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Definition
involve communication through CNS to mediate ENS function.
[image] |
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Term
| table summarizing the GI hormones |
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Definition
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Term
| some GI hormones you should not forget |
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Definition
|
|
Term
| endocrine mediators target... |
|
Definition
-epithelial cells
-smooth muscle |
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Term
| Paracrine mediators target... |
|
Definition
-epithelial cells
-neurons |
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Term
| some paracrine mediators involved in the GI system |
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Definition
|
|
Term
| sequence of how carbohydrates get digested |
|
Definition
-Salivary amylase – begins starch digestion.
-Pancreatic amylase – digests starch to oligosaccharides.
-Brush border enzymes – hydrolyzes oligosaccharides into monosaccharides.
[image] |
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Term
|
Definition
begins starch digestion.
[image] |
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Term
|
Definition
digests starch to oligosaccharides.
[image] |
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Term
|
Definition
hydrolyzes oligosaccharides into monosaccharides.
[image] |
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Term
| the carbohydrates that get absorbed |
|
Definition
only monosaccharides, such as...
-Glucose
-galactose
-fructose
[image] |
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Term
|
Definition
| -by secondary active transport
-co-transporting glucose with Na+.
[image] |
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Term
| Absorbed monosaccharides goes to... |
|
Definition
blood (via portal vessel to the liver).
[image] |
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Term
|
Definition
the transporter through which glucose exits enterocytes to interstitial fluid
-this is facilitated transport
[image] |
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Term
| lactose intolerance caused by... |
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Definition
|
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Term
| Digestion of proteins begins in the stomach when... |
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Definition
| pepsin digests proteins to form polypeptides. |
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Term
| how digestion of polypeptides occurs in the duodenum and jejunum |
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Definition
-Endopeptidases cleave peptide bonds in the interior of the polypeptide
-Exopeptidases cleave peptide bonds from the ends of the polypeptide
[image] |
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Term
| how digestion of polypeptides occurs in the enterocytes |
|
Definition
Di- and tripeptides --> amino acids.
[image] |
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Term
|
Definition
-in the duodenum and jejunum
-cleave peptide bonds in the interior of the polypeptide
+Trypsin
+chymotrypsin
[image] |
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Term
|
Definition
-in the duodenum and jejunum
-cleave peptide bonds from the ends of the polypeptide
+Carboxypeptidases
+aminopeptidases
[image] |
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Term
| the endopeptidases in the duodenum and jejunum |
|
Definition
-Trypsin (pancreatic)
-chymotrypsin (pancreatic)
[image] |
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Term
| the exopeptidases in the duodenum and jejunum |
|
Definition
-Carboxypeptidases (pancreatic)
-aminopeptidases (brush-border)
[image] |
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Term
|
Definition
-cleaves proteins at the amino end
-brush border enzyme in the duodenum and jejunum that helps digest polypeptides.
-The other 3, trypsin, chymotrypsin, and carboxypeptidase, are pancreatic.
[image] |
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Term
|
Definition
-pancreatic enzyme in the duodenum and jejunum
-cleaves proteins at the carboxy end
[image] |
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Term
| how proteins are absorbed |
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Definition
| 1: free amino acids absorbed by co-transport with Na+ (secondary active transport)
2: Di-peptides and tri-peptides transported by secondary active transport using a H+ gradient to transport them into the cytoplasm
3: Facilitated transport of amino acids into interstitial fluid --> portal system --> liver.
[image] |
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Term
| the result of lipids entering the duodenum |
|
Definition
Arrival of lipids in duodenum --> ↑ secretion of bile
[image][image] |
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Term
| Functions of bile acids/salts |
|
Definition
-Emulsification
-Micelle formation
[image][image] |
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Term
|
Definition
forms smaller fat molecules from big fat droplets --> ↑ surface areas for lipid-lipase contact.
[image][image] |
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Term
|
Definition
transports digested fat in micelles --> move to brush border for absorption.
[image][image] |
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Term
| how digestion of lipids occurs in the small intestine |
|
Definition
-Pancreatic lipase + colipase --> triglycerides --> fatty acids + monoglycerides.
-Pancreatic phospholipase digests phospholipids into fatty acids.
[image][image] |
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Term
|
Definition
Pancreatic lipase + colipase --> triglycerides --> fatty acids + monoglycerides.
[image][image] |
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Term
|
Definition
digests phospholipids into fatty acids.
[image][image] |
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|
Term
| how lipids are transported in the gut |
|
Definition
|
|
Term
|
Definition
-bile salts
-free fatty acids
-monoglycerides
-phospholipids
-cholesterol
[image] |
|
|
Term
| the role of micelles in absorption of fat |
|
Definition
Micelles allow diffusion of constituents through unstirred water layer on enterocytes -> absorption through apical membranes of epithelium.
[image] |
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|
Term
| what happens to micelles after they enter the cell? |
|
Definition
Resynthesize triglycerides and phospholipids within cell --> combine with apolipoprotein to form chylomicrons.
[image] |
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Term
| what happens to chylomicrons after they get secreted out of the cell? |
|
Definition
chylomicrons --> secrete into central lacteals --> larger lymphatic vessels --> thoracic duct --> mix with venous blood at vena cava --> blood circulation
-indirect trip to the liver
[image][image] |
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Term
| general depiction of what happens with micelles and lipids in lipid absorption |
|
Definition
indirect trip to the liver
[image] |
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Term
|
Definition
| In blood, lipids + apolipoproteins = lipoproteins |
|
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Term
|
Definition
| hydrolyzes triglycerides --> free fatty acids + glycerol supplied to tissues |
|
|
Term
| what happens to chylomicrons in the bloodstream? |
|
Definition
| In capillary endothelium of adipose tissue, LPL hydrolyzes triglycerides in chylomicrons --> free fatty acids and glycerol to store in the fat cells |
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Term
| what happens to what's left of the chylomicrons after hydrolysis? |
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Definition
| After hydrolysis, chylomicron remnants containing cholesterol are taken to the liver. Liver synthesizes and adds cholesterol and triglycerides. |
|
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Term
| Very low-density lipoprotein (VLDL) |
|
Definition
| triglycerides and cholesterol + apolipoproteins leave liver to deliver triglycerides to organs. |
|
|
Term
| how VLDL gets converted to LDL |
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Definition
| As triglycerides are removed, VLDLs --> intermediate-density lipoprotein (IDL) --> low-density lipoprotein (LDL). ↓ in triglyceride and ↑ in cholesterol and apolipoproteins content. |
|
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Term
| low-density lipoprotein (LDL) |
|
Definition
transport cholesterol to organs. “Bad cholesterol.”
[image] |
|
|
Term
| what happens to excess cholesterol? |
|
Definition
| returned to liver on HDL to prevent atherosclerosis |
|
|
Term
| high-density lipoprotein (HDL) |
|
Definition
Excess cholesterol is returned to the liver on high-density lipoproteins (HDL), thus preventing atherosclerosis. “Good cholesterol.”
[image] |
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Term
| the types of lipoproteins that can be in chylomicrons |
|
Definition
|
|
Term
| the lipoproteins with the most triglycerides |
|
Definition
|
|
Term
| table summarizing the lipoproteins involved in transport of lipids |
|
Definition
|
|
Term
| the structure of a lipoprotein |
|
Definition
|
|
Term
| depiction of the major pathways of lipid metabolism |
|
Definition
|
|
Term
|
Definition
hardening of arteries
-the most common form is atherosclerosis
[image] |
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Term
|
Definition
the most common form of arteriosclerosis (hardening of the arteries)
[image] |
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Term
| the pathway that leads to atherosclerosis |
|
Definition
| Arterial endothelial cells contain LDL Receptors --> LDL-LDL R’ --> endocytosis --> oxidized LDL --> oxidative damage and inflammatory response --> formation of atheroma --> atherosclerosis
[image] |
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Term
|
Definition
localized plaques of fat that protrude into lumen of arteries
[image] |
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|
Term
| how atheromas clog arteries |
|
Definition
Atheromas (localized plaques of fat) protrude into lumen of arteries --> ↓ blood flow --> … --> ↑ clot formation
[image] |
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Term
| substances that can reduce the oxidation of LDL |
|
Definition
| Antioxidants, such as vit C, E, and beta-carotene |
|
|
Term
| do arterial endothelial cells contain HDL or LDL receptors? |
|
Definition
|
|
Term
| the pathway explaining what HDL does with cholesterol |
|
Definition
| HDL carries cholesterol to liver --> formation of bile in liver that contains bile salts and cholesterol --> eliminates excessive cholesterol from the body |
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