PHGY 216 - Module 6 Questions And
Answers.
nutrient breakdown stages - Answer 1. ingestion (eating)
2. digestion (breakdown)
3. absorption (into blood)
4. distribution
5. usage
circular vs longitudinal muscle action - Answer circular: decreases lumen diameter
longitudinal: shortens the tube
-between them is myenteric plexus
serosa - Answer continous with mesentery
factors regulating digestive function (just names) - Answer autonomous smooth muscle
function, intrinsic nerve plexuses, extrinsic autonomic nerves, gastrointestinal hormones
Autonomous smooth muscle function - Answer -pacemaker like rhythmic changes (slow-wave
potentials)
-from non-contractile interstitial cells of Cajal
moving closer and further from threshold - if reached then AP and contraction
-mechanical, hormonal and neural factors modulate membrane potential
intrinsic nerve plexuses - Answer (enteric NS)
-submucosal plexus and myenteric plexus
-some input from ANS but also self-regulated
-secretory neurons, smooth muscle neurons, exocrine glands, endocrone glands innervation...
extrinsic autonomic nerves - Answer sympathetic and parasympathetic
, -modifies activity of ENS, regulates GI hormone secretion, some dirrect innervation on smooth
muscle/glands
-PNS postganglionic are part of intrinsic NS
digestion phases - Answer cephalic (thought, sight, smell - gastric secretions)
oral (saliva proteins: amylase-carbs, mucus-facilitate swallowing, lysozyme)
-saliva important: need to have things dissolved...has bicarb buffers for acids (food, bacteria)
gastric
parasympathetic vs sympathetic saliva - Answer parasympathetic: watery, rich in enzymes
sympathetic: less volume, rich in mucus, thick
salivary reflexes - Answer simple: chemoreceptors, mechanoreceptors
conditional: thinking, smelling, seeing, hearing food
swallowing is all in one response - Answer once initiated it can't be stopped
swallowing phases - Answer oropharyngeal: rapid
-tongue positions against palate to prevent backflow of food
-uvula covers nasal passage
-respiratory centre in brain stem inhibited
-larynx: vocal cords tighten
esophageal:
-UES closed, oropharyngeal structures returned to normal, breathing continues
-peristalsis circular smooth muscle contractions
-peristalsis relaxes LES
-mucus secreted to lubricate esophagus movement
stomach functions - Answer 1. store food
2. secrete HCl and enzymes for protein digestion
Answers.
nutrient breakdown stages - Answer 1. ingestion (eating)
2. digestion (breakdown)
3. absorption (into blood)
4. distribution
5. usage
circular vs longitudinal muscle action - Answer circular: decreases lumen diameter
longitudinal: shortens the tube
-between them is myenteric plexus
serosa - Answer continous with mesentery
factors regulating digestive function (just names) - Answer autonomous smooth muscle
function, intrinsic nerve plexuses, extrinsic autonomic nerves, gastrointestinal hormones
Autonomous smooth muscle function - Answer -pacemaker like rhythmic changes (slow-wave
potentials)
-from non-contractile interstitial cells of Cajal
moving closer and further from threshold - if reached then AP and contraction
-mechanical, hormonal and neural factors modulate membrane potential
intrinsic nerve plexuses - Answer (enteric NS)
-submucosal plexus and myenteric plexus
-some input from ANS but also self-regulated
-secretory neurons, smooth muscle neurons, exocrine glands, endocrone glands innervation...
extrinsic autonomic nerves - Answer sympathetic and parasympathetic
, -modifies activity of ENS, regulates GI hormone secretion, some dirrect innervation on smooth
muscle/glands
-PNS postganglionic are part of intrinsic NS
digestion phases - Answer cephalic (thought, sight, smell - gastric secretions)
oral (saliva proteins: amylase-carbs, mucus-facilitate swallowing, lysozyme)
-saliva important: need to have things dissolved...has bicarb buffers for acids (food, bacteria)
gastric
parasympathetic vs sympathetic saliva - Answer parasympathetic: watery, rich in enzymes
sympathetic: less volume, rich in mucus, thick
salivary reflexes - Answer simple: chemoreceptors, mechanoreceptors
conditional: thinking, smelling, seeing, hearing food
swallowing is all in one response - Answer once initiated it can't be stopped
swallowing phases - Answer oropharyngeal: rapid
-tongue positions against palate to prevent backflow of food
-uvula covers nasal passage
-respiratory centre in brain stem inhibited
-larynx: vocal cords tighten
esophageal:
-UES closed, oropharyngeal structures returned to normal, breathing continues
-peristalsis circular smooth muscle contractions
-peristalsis relaxes LES
-mucus secreted to lubricate esophagus movement
stomach functions - Answer 1. store food
2. secrete HCl and enzymes for protein digestion
