Traffic - week 15 Flashcards
function of digestive (amazon)
transfer nutrients, H2O and electrolytes from food to body
food is…(blocks)
an energy source and contains basic building blocks of body tissues
4 digestive processes (DAMS)
motility, secretion, digestion and absorption
motility
muscular contractions that move food through digestive tract (propulsive) and mix food
secretion (BEHM - bile)
digestive juices (enzymes, bile, mucus, hormones)
digestion (catabol)
breaking down large molecules into smaller units
absorption - substances moved from…(nymph)
digestive tract to blood or lymph. major and accessory organs
intrinsic nerve plexuses (stomach - tv wall)
- network of nerves in digestive tract wall (enteric nervous system)
- influence all digestive tract activity a. mainly coordinate activities
- influenced by extrinsic nerves
extrinsic nerves (ANS) (motor bike)
- influences motility and secretion
a. modify activity of intrinsic plexuses
b. act directly on glands and smooth muscle
digestive tract contains (COM - receptors)
a. chemoreceptors
b. mechanoreceptors
c. osmoreceptors
stimulation of receptors initiates reflexes (short - in..long - different)
a. short reflexes - entirely within intrinsic nerves
b. long reflexes - also involve ANS
gastrointestinal hormones (bloody nose-hormones)
produced in mucosa, released to blood in response to local chemical changes or nerve stimulation
mastication
mixes and breaks down food
saliva produced by salivary glands (amyl - kitchen counter)
begins digestion of carbohydrate with salivary amylase
- moistens food with mucus for easy swallowing
- lysozyme lyses bacteria
- produced in response to stimulation from chemoreceptors and pressure receptors in mouth, or seeing/smelling food
Pharynx and Esophagus - pathways to…
stomach
3 major functions of stomach (closet - oates)
store duodenum, Hcl and enzymes, mix to chyme
- store food and release to duodenum at the appropriate rate
- secrete HCl and enzymes to begin protein digestion (continue carbohydrate digestion with salivary enzymes)
- mix food with gastric secretions to make chyme
4 aspects of motility (pie)
gastric filing, gastric storage, gastric mixing, gastric emptying
gastric filling (stretch - stress ball)
a. plasticity-stomach can stretch without
increasing tension
b. receptive relaxation - eating triggers reflex relaxation
gastric storage (body)
food stored mainly in body of stomach
gastric mixing (perry ant)
mostly in antrum (thicker muscle layer) b. peristaltic contractions
gastric emptying - influencing factors (stomach) (chyme full- house - body builder)
amount of chyme - more chyme increases
emptying via direct effect on smooth muscle, intrinsic and extrinsic neurons, hormone gastrin
gastric emptying (perry - wave)
peristaltic waves push some chyme into duodenum
gastric emptying - influencing factors (duodenum) (SNH)
(1) stimuli
(2) neural response
(3) hormonal response
gastric secretions come from…(pit)
gastric pits/gastric glands
oxyntic mucosa (body and fundus) (elk stomach - couch)
a. surface epithelial cells secrete thick alkaline mucus that protects stomach from acid and digestive enzymes
b. mucous neck cells produce watery, lubricating mucus, also divide rapidly and differentiate into other cell types (entire mucosa replaced every 3 days)
parietal cells secrete…(parietal eskimo)
HCl, activates digestive enzymes and produces optimal pH for protein digestion; breaks down connective tissue and muscle; kills bacteria
chief cells secrete pepsinogen (flat pepsi chief)
(inactive so cells won’t be digested), which is converted to protein digestive enzyme pepsin
pyloric gland area (antrum) (pylon - g - doorway)
a. secretes mucus and some pepsinogen (not HCl)
* b. G cells secrete hormone gastrin
(1) stimulates parietal and chief cells
(2) stimulates growth of mucosa in stomach and small intestine
control of gastric secretions (CIG secretions)
cephalic phase, gastric phase, intestinal phase
cephalic phase (eat epi)
thinking about food and eating increases gastric secretion via parasympathetic stimulation
gastric phase (PDAC) - caffeine
protein, distention, caffeine and alcohol initiate both short and long reflexes that trigger gastrin secretion
intestinal phase (intestines -protein - ric and stone - cat tree - me)
(1) protein stimulates release of intestinal
gastrin (excitatory component)
*(2) enterogastric reflex and enterogastrones suppress
secretory activity (inhibitory component)
Small Intestine (major)
major organ of digestion and absorption
small intestine - motility segmentation (chyme - oates - illiana - kitchen)
- mixes chyme and exposes chyme to absorptive surfaces
- slowly moves chyme forward
- duodenum segments in response to distention
- ileum segments in response to gastrin when chyme is in the stomach (gastroileal reflex)
pancreas secretes digestive…(pan - elk - duo)
enzymes and protective alkaline fluid (NaHCO3) into duodenum
proteolytic enzymes (king meditating)
secreted in inactive forms
pancreatic amylase (secreted in active form) (poly amethyst)
polysaccharides➝disaccharides
pancreatic lipase (active) (lips - 3 to 1)
triglycerides ➝ monoglycerides + fatty acids
liver’s digestive function is…(bile waiting)
to produce bile that can be stored in gall bladder until needed in the duodenum
bile salts (hippo)
cholesterol and lecithin are produced by hepatocytes (other fluids come from bile duct cells)
other liver functions - hepatic portal…(mario - vein)
circulation brings venous blood from digestive tract directly to liver
small intestines adapted for…(small sponge)
absorption (lots of surface area)
Na+ (salt - pump - bed)
a. active and passive
b. Na+-K+pump at basolateral side establishes gradients for passive movement
c. H2O and Cl- follow
d. also involved in secondary active transport of sugars and amino acids
large intestine actively absorbs..(large - desk)
Na+, H2O and Cl- follow
- no digestion except bacteria digest cellulose for themselves
large intestine secretes…(large elk)
alkaline, lubricating mucus
Leptin (lepra - window)
made by fat cells, tells hypothalamus you have enough energy stored and suppresses appetite (molecular satiety signal)
Ghrelin (growling)
made by stomach, signals hunger and activates reward system
PYY (pi - full)
released by intestines as food moves through (satiety signal)
fiber
- insoluble helps food move faster and generate
satiety signal sooner - soluble delays stomach emptying making you feel more full
gastric emptying - fat… - duodenum (oates -pool)
fat, acid, increased osmolarity and distention in duodenum. trigger slowing of gastric emptying via neural and hormonal responses
gastric emptying - neural response (short and)
short and long reflexes (enterogastric reflex)
gastric emptying - hormonal response (SCG) (CCK) (empty stones lake)
SCG
enterogastrones released to blood act on stomach (secretin, cholecystokinin or CCK, gastric inhibitory peptide or GIP)
parietal cells secrete…(parent take vitamins)
intrinsic factor allows absorption of vitamin B12
control of pancreas secretions (CIG) (16)
CIG
a. cephalic phase
b. gastric phase
* c. intestinal phase
proteolytic enzymes - trypsinogen becomes… (trip w/ kinase and moon)
➝trypsin, with enterokinase in luminal border of mucosa
proteolytic enzymes - trypsin (convert) (road trip)
digests protein and converts other enzymes to active forms. each enzyme breaks different peptide bond
bile salts emulsify…(ax)
fats - break up fat into droplets to expose more surface area for digestion
bile salts form (mines)
micelles that carry non-water soluble products of fat digestion to absorption sites on mucosa
bile salts are released in response to…(epi is vile)
parasympathetic stimulation, secretin, *bile use
liver functions - processing (warehouse sun)
(1) processing/storage of nutrients
(2) detoxification of wastes, drugs, etc.
b. makes plasma proteins
c. activates vitamin D
liver functions - macrophages…(mac - fridge)
d. macrophages (Kupffer cells) eat bacteria and old RBCs
e. excretes cholesterol
f. excretes bilirubin (from breakdown of Hb)
large intestine also synthesize (micro)
vitamin K, which we absorb (important in clotting)
large intestine - bacteria can’t go..
backward to small intestine (ileocecal valve and sphincter)
large intestine motility (runway)
- haustral contraction (similar to segmentation but slower) - mostly short reflex control
- mass movements (gastrocolic reflex)
a. strong contractions move contents to rectum for storage until defecation reflex occurs (triggered by distention)
small intestines secrete…(brush)
mucus, but digestive enzymes are in epithelial cell membranes (brush border)
small intestines absorb…(best of…gym)
most nutrients to its full ability (iron and Ca2+ regulated)
pancreas secretions - cephalic phase (epi)
parasympathetic stimulation
pancreas secretions - gastric phase
gastrin
pancreas secretions - intestinal phase (the secretary phase - w/ test soda CK)
secretin ➝ NaHCO3 (sodium bicarbonate), CCK ➝ enzymes
(trypsin converts) chymotrypsinogen ➝
chymotrypsin
(trypsin converts) procarboxypeptidase ➝(just lose the pro)
carboxypeptidase
