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