Digestive 2 Flashcards
Are all the fibers involved in the ANS part of the ENS passing through other ENS fibers?
NO
The efferent synapse directly from the gut onto ANS neurons before reaching the CNS
Explain a long reflex loop starting at the stimulis
Stimulus, Receptors, afferent neurons (from gut, smell, emotion, etc), CNS, SANS and PANS efferent, ENS plexus, smooth muscle, response
What are non-GIT hormones?
hormones that influence growth and development (GH)
What are GIT hormones? Give 2 examples
hormones that influence activities outside of the GIT
- Fasting: GHRELIN production reaches the hypothalamus to stimulate hunger
- Overeating: LEPTIN production reaches the hypothalamus to induce satiety
What is the main endocrine system of the digestive tract? What are the 5 important hormones?
DES: Diffuse Endocrine system
Gastrin
CCK
Secretin
GIP
VIP
What is the pathway of the GIT regulatory hormones?
Released by mucosa into portal blood
Goes through the liver
to the heart
reaches systemic circulation and then target cell
Why do regulatory hormones have to pass through the liver?
To get filtered
What are the possible targets of regulatory hormones?
excitatory or inhibitory
What can GIT regulatory hormone interact with?
one another or neurotransmitters
What are the possible interactions of hormones and NT (GIT)?
Synergistically
Antagonistically
What are two important elements of propulsion (flow) in the GIT?
Pressure gradient
Resistance
What creates the most pressure in the GIT?
Coordinated contraction of the GIT wall by segmentation and peristalsis
What is segmentation and peristalsis?
s: allows mixing (contractions of diameter)
p: allows moving (a same contraction moving along the wall
What could create resistance in the GIT (but shouldn’t)?
The sphincters
Which two sphincters have to relax to allow the esophageal phase?
the upper and lower esophageal sphincters
What happens during the oral phase?
food gets covered in salive to create the bolus
Which parts of deglutition are controlled by the cortex?
voluntary phases (oral)
Which parts of deglutition are controlled by the medulla?
the involuntary phases (pharyngeal and esophageal)
Explain the steps of the pharyngeal phase.
Bolus causes stretch
Reflexes bring it downwards
Presses on epiglottis and closes it to cover glottis
Larynx moves forward and up to protect further (brief apnea)
Muscles contract and UES relaxes
