4.1 Digestive System Part 1 Flashcards
4 tissue layers of digestive tract
Mucosa Submucosa Muscularis Serosa Myenteric plexus
Mucosa Function
Absorption and secretion
Submucosa function
Secretion
Muscularis function
Motility
Myenteric plexus function
Innervation
-Motility
-Stretch detection
“Gut brain”
What does the myenteric plexus regulate?
Muscularis motility and secretions
How much CNS input does the myenteric plexus operate under?
Minimal due to pacemaker capacity
Enteric Nervous System (ENS)
Myenteric plexus and submucosal plexus
Is the myenteric plexus responsive to the sympathetic or parasympathetic branch?
BOTH
What is the submucosal plexus?
“Middle man,” regulates secretions by exocrine glands within submucosal layers
Is the submucosal plexus responsive to the sympathetic or parasympathetic branch?
Parasympathetic ONLY
Plexus
Bunch of neurons working together
Basal Electrical Rhythm (BER)
Some GI neurons have a pacemaker rhythm ~3-12 depolarizations / minute
How is BER spread?
Spread throughout the longitudinal smooth muscles in muscularis (via gap junctions)
BER stimulates motility in muscularis for…
Peristalsis and mixing
Peristalsis
Propulsive, unidirectional movement
Mixing
Back and forth
What is the BER pacemaker similar to?
SA node in heart
How does the BER pacemaker work?
Na+ leakage leads to firing of action potential.. Ca influx and muscle contraction
What in the BER determines the number of action potentials and then the force of contractions?
Resting membrane potential (hyper polarized -> fewer action potentials, etc)
What in the BER determines the number of action potentials and then the force of contractions?
Resting membrane potential (hyper polarized -> fewer action potentials, etc)
What does the parasympathetic division do to the RMP in BER pacemaker cells?
Depolarizes it
Easier activation of BER pacemaker cells leads to…
- Increased glandular secretions
- Increased peristaltic contraction
What does the sympathetic division do to the RMP in BER pacemaker cells?
Hyper polarizes it
