Actual Last DI Flashcards
polysaccharides given examples
starch and glycogen
proteins splitters
polypeptides being split by such as pepsin, trypsin, chymotrypsin
effectors in gastrointeestinal regulation
smooth muscle contraction and epithelial cells
short reflexes
stimuli-receptor-pelxus-effector-response
long reflexes
afferent-receptors to cns
efferent-autonomic motor (sympathetic and parasympathetic) - cns to plexus
cephalic phase to stomach
-parasympathetic to stomach in preparation for food coming
-response: increase acid secretion and stomach motility
salivary amylase best in?
slight acidic enviornment (conditons from mouth to fundus of stomach)
lingual lipase best in?
highly acidic environment (condtitions from body to antrum of stomach)
limited absorption in mouth (can be absorbed a bit)
some vitamins and mineral, electrolytes, alcohol, drugs
goals of masticatin
physical digestion (expose more SA) - motility (mix with enzymes in mouth is start of chemical digesiton) - forming bolus
deglutition muscles?
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mastication invoves?
skeletal muscles plus activity of tongue, lips, and cheeks
-combination of voluntary and involuntary masticaiton patterns and reflexes (rhythmic jaw movements)
first point of pharyngeal stage of deglutition
oral pharynx RECEPTORS send signal to swallowing centre that bolus is present, stop signal once bolus in esophagus
lower esophageal sphincter contracts after what?
esophageal stage of deglutiton
stomach - filling and storage intitially
-expands during meals to accomodate foods and liquid
-need to slow down GI tract motility (ingestion faster than digestion/absorption)
gastric motility
-mixing waves that are propulsive and retropulsive
-pacemaker cells in smooth muscle set basic wave rate that can be altered by neural and hormonal
-stronger motility in body and antrum, minimal in fundus
-breaks down bollus into chyme
gastric emptying
small amount of gastric juice (stomach chyme + secretions) per mixing wave moves into duodenum
gastric phase
food arrives in stomach - receptors detect increased distension - increased amino acids and peptides - decreased acidity
gastric phase neural
-increase HCl secretion
-increase gastric motility - greater gastric emptying
gasric phase hormonal
-increase HCl secretion
-increase gastric motility/relax pyloric sphincter - greater gastric emptying
-increase contraction lower esophageal sphincter - regurgitation prevention
intestinal phase
food arrives in duodenum - receptors detect increase acidity, fats, amino acids, distetnion
intestinal phase neural
enterogastric reflex
-short refelxes: enteric changes - directly effect stomach
-long reflexes: CNS (parasympathetic and sympathetic) changes - indirectly effect stomach
intestinal phase hormonal
CCK and secretin secretion and release into bloodstream/bind target cells in stomach
intestinal phase responses
-decreased gastric motility and increase contraction of pyloric sphincter - decreased gastric emptying
-trying to mach gastric emptying to small intestine digestion and absorption rates
gastric empting other influences (add to intestinal phase shit)
emotions and exercise
bile produced where and composed of what?
you know this youre good
bile flows where when not needed?
gallbladder
process when bile is needed
fatty acids - CCK secretion into bloodstream - plasma CCK increase - gall bladder contraction (this leads to increase bile flow into common bile duct) and relaxation of sphincter of oddi - increased bile flow into duodenum
pancreas - bicarboonate
highly acidc chyme coing into duodenum from gastic emptying and we need this acid to be neutralized to create alkaline enviornement preferred by pancreatic enzymes relased in small intestine
key acid neutralizer - bicarbonate
-small - liver/gallbladder - bile
-large: pancrease - component of pancreatic juice (collective name for pancreatic secretions)
-pancreatic duct cell forms bicarbonate from water and CO2 - bicarbonate released into pacreatic duct lumen - pacreatic duct carries bicarbonate to duodenum
sphicnter of oddi
around opening of common bile duct and pancreatic duct, controls opening into duodenum
flow chart of pancreas - bicarbonate regulation
increaed acid in small intestine - increase secretin secretion by small intestine - increased plasma secretin - increased bicarbonate secretin by pancreatic duct cells - increase flow of bicarbonate into small intestine -neutralizatin of intestinal acid in small intestine
pancreas - digestive enzyme regulation
increaese intestinal fatty acids and amino acids - small intestiine increased CCK secretion - increased plasam CCK - increased enzyme secreton by pancreatic ACINAR cells - increase flow of enzymes into small intestine - increased digestion and basorption of fats and proteins in small intestine
intestinal juice collective name for
-pancrease,liver,gallbladder contributins
-stomach chyme
-intestinal secertions - water and mucus
*final digestion to reach absorable size
segmentation rate
parasympathetic and gastrin - increaes
sympathetic - decrease
paracellular goes to
blood capillary
transcellualr goes to
blood capillary and lacteal
disaccharide sucros
glucose and fructose by sucrase
disaccharide lactose
glucose and galactose by lactase (lactase limited = lactose intolerance)
disaccharide maltose
glucose and glucose by maltase
brush border enzymes attached to whree?
apical membrane
some carbohydrates indigestible
soluble and insoluble dietary fiber will see in large intestine
monosaccharides go where after crossing basolateral membrane by FD?
IF to blood capillary by simple diffusion
brush border enzyymes for proteins
small peitides broken down to signle amino acids by brush border peptidases
very first step of protein absorpitn
pancreatic proteases and peptidases included with proteins to be either small peptides or single amino acids
single amino acids cross basolateral membrane by
FD involving amino acid transporters (around 10 dif in humans)
why are large fat globules fortmed
fats not very soluble in watery intestinal juices so form to minimize surface area
fat globule to ED leads to
more SA exposed to pancreatic lipase digestive action
small intestine absorption for electrolytes
-sodium mmoves largely coupled to glucose and amino acids
-most negative charge ions like chloride and bicarbonate move following positive sodium ions (electrical gradient)
-other ions move by concetration gradients created by water movement
-most ions that reach small intestine will be absorbed (not based on nutrient needs)
2 ions that move based on nutrient needs
calcium
-based on blood levels
-transcellualr active transport involving release of parathyroid hormone (converts vitamin D to calcitrol) to increase caclium absorpiton
-paracellular passive transport based on concentration gradient
iron
-based on stroed levels in epithelial cells
-transcellular active transport with specific iron transporters
-women have more than men due to mentrsual cycle leading to loss of epithelial cells
fat soluble vitamins
follow into micells and cross into epithelial cells with fats by simple diffusion
-need fat to absorb fat soluble vitamins
water soluble vitamins
-some SD plus some active and passive transproters
-some will cross in large intestine (vitamin k and vitamin b)
-vitamin B12 needs to bind intrinsic factor from stomach
-intrinsic factor B12 complex absorbed in ileum (last section of small intestine) by endocytosis
absroption small intesine water
-95% water absrobed by osmosis
-following changes in osmotic pressure created by solute movement
-when water moves it creates concentration gradients for many other substances to follow
absrobed carbohydrates
move from IF - blood capillaries - smaller blood vesseels join to form portal vein circulating to liver
absorbed fats (chylomicrons)
move from IF - lacteal (lymphatic capillary with large pores)
-once in lacteal - other lymphetic vessels - eventually enter bloodstream near subclavian vens circulating to liver
migrating myoelectrical complex
occurs after segmentaiton and absorption
-peristalsis migrates from stomach antrum down small intestine in series of perstalsis steps
-at end of ileum, if chyme still present in small iintestine, return back to stomach antrum and start migration again
releaxation of ileocecal valve
-for movement from small to large intestine triggered by
1. gastroilieal reflex (neural) - signal from stomach along nerve plexus to valve
2. gastrin (hormonal) release and binding valve
Gi tract - large intestine chemical digestion
secretins are minimal and lack digestive enzymes, most mucus and water secretion for lubrication and formation of feces
gi tract - large intestine bacterial digestion
bacterial population in large intestine (microbiome, 10m different types)
-ferment some carbohydrates that were not absorbed to produce gases
-small amonts of vitamins (vitamin B complex and vitamin K) synthesized
-some undigeseted fiber converted to short chain fatty acids for fuel (brain likes these)
ultimately in large intestine
-absorption of some water and electrolytes/bacterial products (aorund 10% of absorption in large intestine)
-feces formation: to solid or semisolid mass, mainly unabsorbed material, indigestible food, water, bacteria
-storage: non-absorbed material in distal large intestine until defecation
hasutral churning
segmentation of large intestine
-motility: mix and bring contents into contact with absorptive surfaces
-haustra filling causes distension of walls until reach certain volume - smoooth muscle ocntraction - push material to adjacent haustra (back and forth)
-weakly propulsive
peristalsis in long intestine
-mostly weak version
-has mass movement
mass movement
3-4 times per day, an intense peristalsis from transverse colon to rectum (sweeping material along like MMC)
-often stimulates urge to defecate as material moved into rectum
mass movement triggered by
- gastrocolic reflex (neural) signal from stomach along nerve plexus to large intestine
- gastrin (hormonal) release and binding in large intestine
metabolic rate
amount of energy expended over given period of time
reactions with metabolic rate
anabolism: build reactions
catabolism: breakdown reactions
basal metabolic rate
energy needed for most minimal essential physiological activities
total metabolic rate
total daily energy expenditure composed of:
1. BMR: 60%
2. physical activity: 30-35%
3. food induced thermogenesis (digestion, absorption, storage): 5-10%
core temperature decreases
steps to produce or conserve heat
-vasocontriciton of skin vessels
-release epinephrine/norephinephrine/thyroid hormones to stimulate metabolic rate
-shivering for muscular activity
behavioural such as clothing, hot fluids, increased activity
core temperature increases
seps to lose heat
-vasodilation skin blood vessels
-enhanced sweating for greater evaporative loss
-behavioural such as clothing, reducing activity, finding colder locaiton
