The Digestive system Flashcards

Question

mastication

Answer 1

chewing muscles of jaw, lips, cheeks, tongue can be voluntary usually reflexive steps. intro of food bolus Jaw closes = inc P **jaw closing muscles = inh jaw opening = contracted mouth opens = dec P **jaw closing = contracted jaw closing = relax mouth closes

Answer 2

swalloeing after mouth = oropharynx, laryngopharynx to ego lining = strat squamous

Answer 3

muscular tube collapsed when empty (opens when needed) skeletal to smooth = loose voluntary control goes straight down mediastinum , through diaphragm at esophageal hiatus joins stomach at gastroesophageal sphincter

Answer 4

mucosa = throwing into folds when empty flatten when food enters submucosa = has mucus secreting glands muscular externa = 1/3 skeletal, 2/3 smooth circular and longitudinal layer = contract behind, open ahead adventitia = instead of slippery rosa bc want to be well anchored as goes down

Answer 5

coordination of 22 muscle groupes, 2 phases (tongue, soft palate, pharynx, + eso) buccal phase = voluntary contraction of tongue, pushing bolus into post of pharynx initiation of swallowing pharangyeal-eso phase involuntary phase = vagus nerve - controlled by swallowing centre in medulla and lower pons - close off resp pathway push food down into stomach (through oropharynx to eso)

Answer 6

storage tank round not tubular = can fill up initiation of protein digestion + convert content to chyme fixed (att) at either end but moves in bn collapses when empty regions cardia = entry to stomach fundus = part that extends above gastroeso sphincter body = majority of structure pyloric atrium as stomach narrows to meet small int pyloric canal = as getting closer to sphincter pyloric sphincter = carefully controls entry of acidic material into small int from stomach muscular gateway rugae = bumpy structures on stomach = wormy appearance indentation of mucosa of stomach allow to stretch to fill w food will flatten when filled has extra 3rd muscular layer= oblique helps w churning and mechanical digestion of food.

Answer 7

surface epi of stomach is entirely goblet cells product = mucus and a bicarb rich layer w/in layer = gastric pits = lead to gastric glands = make gastric juice concentrate depends on region of stomach

Answer 8

mucus neck cells at neck of glands, product type of acidic mucin parietal cells = secrete HCL and intrinsic factor HCL = to kill of micro orgs in lumen + denature proteins IF = important to absorb vit B12 (for RBC production, needs to be att to IF) chief cells = 1. secrete pepsinogen = precursors to active enzyme pepsin (activated in lumen when has contact w proetins, not in pits, so protects lining where it is made) 2. secretes = gastric lipase lipid digesting enzyme, does 15% of the digestion of lipids, rest is done my pancreatic lipase. enteroendocrine cells = secrete hormones including 1. gastrin= inc HCl, inc enzyme secretion, inc gut motility. 2. histamine= stimulates HCl prod in parietal 3. serotonin= inc gut motility 4. somatostatin= inhibits gastric secretion and digestion when not needed

Answer 9

bc of high conc of HCl and pepsin, it needs to protect itself from damaging environment created everytime you eat **pepsin = digests proteins + can damage cells in stomach** 1. thick bicarb rich mucosal layer + mucus = alkaline mucus layer + physical barrier bn lumen nad epi cells 2. tight junctions bn column epi cells keep acids away from underlying tissues 3. fast turnover, once every 3-6 days , by stem cells

Answer 10

controlled by long and short reflexes vagus nerves for long reflects (PNS) hormonal via gastrin and histamine long = if sitting down dn getting ready to eat short = as stomach is filling and stretching parietal cells have receptors for 3 chemicals = ACh, histamin adn gastrin, histaminę is key - histamine binds to receptor, activates a singaling pathway inside cells w cAMP as a messenger H pump get activated pump H+ into lumen, inc acidity gastrin and ACh use Ca signalling to activate pump

Answer 11

cephalic - prep gastric - most active intestinal - winding down

Answer 12

before food enters somtach trigger = smell, taste, sight, thought

Answer 13

lasts hours, provides 2/3 of gastric juices ACh and gastrin stimulate histamine secretion *in addition to binding to their own receptors, they stim histamine, which binds to its own receptors either we all have low gastric pH or SNS will reduce

Answer 14

brief stimulatory followed by inhibitory stimulatory component food enters small int = breif release of intestinal gastrin = 2nd type of gastrin, encourages gastric glands of stomach to continue secretory activaties inhibitory component inh by entreogastric reflex = neuropathway + enterogastrones = reg hormones prod by small int. 4 factors = distension (expansion) of duodenum bc of chyme entry = presence of acidic, fatty and hypertonic chyme protects int from being overwhelmed by too much acidic chyme

Answer 15

Co2 and water = carbonic acid = bicarb and H+ H+ pumped out actively into stomach lumen, K+ into cell, K+ continues also out bc of leaky channels bicarb leaves the cell for incoming Cl from interstitial fluid, through mb channels, passes through cell, to stomach now H+ and Cl- from HCL in stomach

Answer 16

Co2 coming into cell = passive H+ pumped into lumen = active K+ pumped into cell = active K+ through leaky channels = passive bicarb into blood = active Cl- balancing charges = active Cl- into stomach = passive

Answer 17

needs protein to be digested pepsinogen is stored in zygmoen granules = vesicles sees proteins in stomach, is secreted, activated into pepsin in lumen of stomach pepsin = proteins to peptides HCl catalyzes it to active form, but once activated can self activate further primary stimulus = ACh

Answer 18

response of the stomach filling gastric contractile activity

Answer 19

stomach stretches to accommodate incoming good as filling, want walls to relax, open up for incoming food 1. receptive relaxation = happens in response to swallowing, stomach thinks material is coming in, relax in prep of what coming extrinsic bc = swallowing centre in Brian stem = activates swelling + relax smooth muscles of stomach 2. gastric accommodation as swallowing, there is material coming and take space, stretch of musculature of stomach so walls relax in response to being stretched, open up more

Answer 20

peristalsis = move in one direction, starts at upper part intel push against sphincter, then moves chyme into lumen of stomach, not emptying bc closed but mixing and exposing to HCl + pepsin Basic electrical rhythm = set by enteric pacemaker cells linked to rest of gastric muscles by gap ins so contracts as a whole distension/expansion + gastrin inc force not frequency as you go down pyloric region = stronger contractions = muscle is thicker now 3mL is into small int, rest goes back into stomach

Answer 21

control to have time to neutralize acidity + control V of material so walls don't get too stretched duodenum prevents overfilling by controlling how much chyme enters = responds to stretch and chemical signals (if fat heavy meal needs longer, ex). = enterogastric reflex + enterogastrones inh secretion slow down secretion + emptying, keep sphincter closed. carb heavy = faster = hungry sooner protein or fat = longer = later

Answer 22

liver, gallbladder, pancreas liver = produce bile bile = fat emulsifier = large droplets to smaller one = more accessible to lipase enzyme gallbladder = store bile pancreas = source of most enzymes need to digest all food groups, + provides bicarb to neut acid

Answer 23

largest glands 4 loves, L, R, caudate, quadrate falciform ligament sep L/R, suspends from diaphragm and ant body wall enclosed in visceral peritoneum (expect bare area, touching diaphragm)

Answer 24

hepatic artery = supplies liver tissue w O2 and nutrients hepatic vein = carry O2 poor away portal vein = coming from small int, brings absorbed products, is O2 poor since alr been circulated to small int. walls hepatic duct = collect bile made from liver L/R form common haptic duct, exit from liver merge w cystic duct = coming from the gall bladder from bile duct = carrying bile form gall + liver into duodenum

Answer 25

portal triad = cluster of 3 small vessels (blood vessels + bile duct) liver sinusoids = specialized capillaries that carry blood through the liver vessels flow towards central vein through sinusoidal caps ducts picking up pile and carry away from central veins blood to central to haptic away from liver tissue cannilucli = vessel found where bile is accumulating, goes towards brach of bile due that goes from small int to liver

Answer 26

yellow green, alkaline, has bile salts, pigments, cholesterol, neutral fats, phospholipids and electrolytes lipid digestion = bile salts and phosphor main bile salts = cholic acids, chenodeoxycholic acid = cholesterol derivatives that emulsifies fats

Answer 27

bile salts are conserved and recycled = enterohepatic circulation send bile to small int, do their job, reabsorb most of it, back to liver through blood stream if a lot of bile is being used up, a lot will be returning = signal to make more so in gen, inc after a fatty meal

Answer 28

bilirubin = most of bilirubin in bile converted to urobilinogen or sterdocoblin by intestinal bacteria

Answer 29

thin walled muscular sac stores and concentrates bile muscular contraction push bile into cystic duct => bile duct => hepatopancreatic sphincter => duodenumconcentrates it = cells lining the walls absorb water and salts, leaves being lipid soluble cholesterol material, bile salts + pigment

Answer 30

cells lining absorb water and salts leave behind = lipid soluble cholesterol material, bile salts + pigments if stays too long = gall stones, too much absorption of water,r cholesterol precipitates out of solution, if pushed out of sac = blocks path to small int.

Answer 31

acing cells produce enzymes = packages in zymogen granules small duct, fuses to => main pancreatic duct => lumen of small int cells lining duct = source of bicarb imp to neutralize pancreatic juice so can neut acidity of chyme

Answer 32

pancreatic duct fuses with one coming from liver and gallbladder = at hepatopancreatic ampulla opens into small int via major duodenal papilla opening of hepatopancreatic sphincter stim by cholecystokinin (CCK) accessory = some people have, others not, if gallstones block main pancreatic duct, has another way to get to small int.

Answer 33

electrolytes (moslty bicarb) proteases (inactive form) amylase lipases nucleases (If digesting cellular foods, material will have nucleic acid that need to be digested as well)

Answer 34

brush border enzymes = activates trypsinogen = leads to activation of chymotrypsinogen and procarboxypeptidase trypsinogen = embedded in microvilu of epi cells lining beginning of small int = catalyzes first step in activating protein digesting enzymes coming from pancreas

Answer 35

no digestion = hepatopancreatic sphincter = closed cholecystokinin responds to fatty chyme in duodenum 1. stim gallbladder contraction 2. stim secretion of pancreatic juice (acinar cells) 3. relaxes hepatopancreatic sphincter secretin = also stim bile secretion stim secretion of bicarb rich fluid

Answer 36

stomach => pyloric sphincter => duodenum =>jejunum =>ileum => iléocaecal valve => large int. superior mesenteric artery brings blood veins=> superior mesenteric veins => hepatic portal veins

Answer 37

lots of SA = more transporters to move the breakdown product of digestion + more presence of brush border enzymes (last step of digestion mods circular folds = perm folds of mucosa and submucosa = slows down and spirals food, vili = finger like projections microvilli = where brush border enzymes are found

Answer 38

intestinal crypts found in bn villi 5 main cells 1. enterocytes = most common, linked by tight jns and microvilli, absorb breakdown products (w trasnporters or passively) in crypts = secrete mucus rich juice = protect from acid and enzymes 2. goblet cells = produce mucus in villi and crypts 3. enteroendocrine cells = source of enterogastrone hormones including secretin and CCK 4. Paneth cells = deep in crypts = secrete anitmicrobirla agents = protect against bacteria backflow from large defensin and lysozyme 5. stem cell = protection from 1. is not perfect, we replace lining frequently

Answer 39

MALT = protects against micro organ 1. individual lymphoid follicles 2. Peyers patch = in lining of small in times, inc as we get closer to large intestine 3. plasma cells that secrete IgA= present in secretions submucosa = areolar CT = has duodenal glands = secrete basic mucis to neut acidity muscular externa = typical 2 layers circ + longitudinal

Answer 40

segmentation, mixing back and forth movement, moving slightly forward along length of small int. intirated by intrinsic pacemaker cells, frequency of contr = region associated. net effect = more mixing in beginning, less at end, gives time for enzymes to break molecs down to subunits once aborption is done = segementation replaced by peristalsis, get this shit out, very directional, push from back, open in front. migrating motor complex=when first peristaltic wave happens, won't go all the way down small int, will fizzle down, so second starts a little further down to fizzle a little further down, making minuscule progress Motility = hormone prod by small int, stimulates pattern of peristalsis a second round to clean up follows

Answer 41

iloececal sphincter usually closed, pushed open by ileal content sphincter relaxes and opens by these signals (message = empty the small int bc another meal is coming) = gastroileal reflex = long reflex due to inc of secretion and contraction of stomach = gastrin = inc motility of ileum, relaxes leocecal sphincter once chyme passes into large int, backwards pressure closes valves, preventing back flow

Answer 42

most digestible is starch, smaller amounts of disacc, monosaccharides, and glycogen we don't have enzymes to digest cellulose, so is a fibre salivary amylase kicks ito off in small int, pancreatic amylase picks up where left off BBE = dextrine + glucoamylase (for 3+ glucose) , maltase, sucrase, lactase

Answer 43

monos = glucose, fructose, galactose dis= maltose = Glucose + glucose lactose = glucose + galactose sucrose = glucose + fructose)

Answer 44

absence of deficiency in lactase, which breaks down lactose (made of glucose and galactose). no lactose, can't digest lactose acts like a fibre since can't be digested, tells us = we have to have monos, we can't absorb dis.

Answer 45

glucose + galactose = co transported w Na, secondary active transport fructose = facilitated

Answer 46

sources of proteins = dietary, secreted enzymes, shedded epi cells in stomach = pepsin activated by HCl, unwinds large proteins by breaking peptide bonds small int = 3 enzyme that continue, to get shorter and shorter chains carboxypeptidase + aminopeptidase = works at protein from either side 1) works from carboxyl end 2) words from amino end dipeptide = splits dipeptides into indv aa

Answer 47

mostly aa but can absorb di or tripeptides aa transport = secondary active transport (w Na) + some carriers that recognize some aa) di and tri = linked to H+, split into aa w/n enterocyte

Answer 48

some lingual and gastric lipase make a small effort, but not much small int = bile emulsifies + lipase breaks bond bn glycerol and 3 fatty acid chains formation of micelle = fatty acid = monoglyceride and bile salts (to have enough density + prevent from clumping so get close enough to mb so can be absorbed into epi cells. now that were in, we undo and resynth = packaged with anything else fat soluble (fatty substances and proteins) = forms chylomicrons = enter intestinal lacteals (lymphatic vessels of intestine) enter blood stream at thoracic duct in blood = lipoprotein lipase hydrolyzes fats into free fatty acids and glycerol so can pass through cap walls

Answer 49

pancreatic ribonuclease and deoxyribonuclease + w BBE in small int, picked up, into blood stream towards hepatic portal

Answer 50

fat soluble vitamins (ADEK) w fats water soluble (B and C) absorbed easily like sugars, B12 w IF biome of late int will make K and B, absorbed by large int. Na = coupled w glucose and aa, + w NA/K pump (-) charged ions follow Na electrical grad Cl, active exchange for HCO3- K = simple diffusion, when water is absorbed, K follows conc grad. iron = entry into blood reg by body's need, lost when shedded cells **Iron get into epitherlial cells, att to ferritin, held there, if neded, travels in blood stream, transferin picks up and to bone marrow, if not needed, stays in int epi cells, if that cell dies, will be carried out w the dying cells Calcium = vit D helps w absorption of calcium, if blood levels drop, gonna trigger hormone secretion, activation of vit d so can pick up calcum in small int to bloodstream.

Answer 51

most absorbed in small int by osmosis can move in both directions active uptake of Na, moves water from chyme to blood

Answer 52

gut microbiome bacteria comes from small int and anus here we ferment indigestible carbs + make some B and K vitamins

Answer 53

small intestine => ileocecal valve =>ascending colon =>transverse colon =>descending colon => sigmoid colon =>rectum =>anal canal ( => external anal sphincter) strips of longtidunal muscle = tenia coli tension of muscle = pull into pockets called hastrum = bumps and ridges yellow bumps/appednages = mesentery w fat cells hanging off strips of muscles rectum = longitudinal muscles all around, so can push rectal valve = indentation extending to lumen of large int. block feces from getting out if passing gas 2 sphincters = internal = smooth muscles external = skeletal muscle = voluntary control levator ani = pull anus up so easier to push out hemaroidal veins = vasculartion family close to exit point

Answer 54

small amount, not much left pull back more salt and water not essential for life, major fn of organ is defecation takes time to get along length

Answer 55

usually not very active, sluggish and short contractions haustral contractions = push content from one haustrum to another mass movement = move anything fairly quickly towards terminal parts, w fibre = inc strength of colon contractions + softens stool, too little fibre = volume is small, contr inc P on walls, lead to diverticulosis = small herniations = become infected.

Answer 56

ParaSNS = rectum takes up space, stimulates stretch receptor to CNS, Motor output to internal sphincter (not voluntary), gonna want to go valsalvas maneuver = inc P in abdo cavity to help push levator ani = pulls anus up

Answer 57

food passes too quickly, not enough water reabsorbed, = dehydration and electrolyte imbalance

Answer 58

too much water absorbed, difficult to pass, not enough fibre, lack of expertise