GI 3 Flashcards
hormone families
gastrin family
secretin family
“other”
gastrin family
gastrin, cholecystokinin
secretin family
secretin, vasoactive intestinal peptide, gastric inhibitory peptide, glucagon like peptide
other hormone
motilin
what are the 3 phases that describe integrated function of digestive system
- cephalic/oral phase
- gastric phase
- intestinal phase
cephalic/oral phase
digestive processes occurring before food enters the stomach
- long reflexes beginning in brain
gastric phase
digestive processes in the stomach
intestinal phase
digestive processes in the intestines (split in small and large)
what causes long reflexes beginning in brain known as cephalic phase
sight, thought, smell of food will start long reflexes that start motility and secretions in stomach and mouth
what is cephalic phase driven by
increased parasympathetic output from medulla to salivary glands and to ENS (via vagus nerve)
where does chemical and mechanical digestion begin
mouth
what does mechanical digestion begin with
mastification (chewing) of food by teeth
tongue and lips also manipulate food and saliva joins
what type of secretion is saliva
exocrine from epithelial cells
how much saliva is secreted per day
1.5 L/day: 99.5% water, 0.5% solutes
what is saliva made up of
Na, Cl, K, HCO3, P04
amylase, lysozyme, mucus, immunoglobulin A
where are secretory cells found
clusters known as acini
what cells exist in the glands
mucous and serous cells
what does parotid glands secrete
watery solution with amylase (serous cells)
what do submandilbular glands secrete
similar to parotid plus some mucus (serous with some mucous)
what do sublingual glands secrete
mainly mucus (mucous)
what are glands controlled by
parasympathetic control
what is deglutition (swallowing)
reflex that pushes a bolus of food or liquid into esophagus
how is deglutition activated
pressure agaisnt soft palate and back of mouth (voluntary) activate sensory neurons going to medulla
what is the swallowing center
medulla
what does the medulla output after deglutition activated
somatic motor outputs to pharynx and upper esophagus and autonomic outputs to lower esophagus
what does soft palate do when bolus of food is moving through
closes off nasopharynx
what happens in pharynx as bolus moves down
peristaltic contractions
what does contraction do to larynx
moves up and forward
what does epiglottis do
closes trachea (covers airway) and upper esophageal sphincter relaxes and opens
last step of swallowing
lower esophageal sphincter tension relaxes
what causes gastroesophageal reflex disease (heartburn)
- churning action of stomach contraction can cause backflow
- negative intrapleural pressure during inspiration can esophagus to expand drawing gastric acid and pepsin
why does heartburn happen
lower esophageal sphincter is not true sphincter
- not thickened, high continuous contraction
