GIT Physiology 5: Control of the digestive system Flashcards
What are the two types of control in the GIT?
Nervous and endocrine
What is the intrinsic control of the GIT?
within the gut walls, controlled by the enteric nervous system
What do the vagus and pelvic nerve do outside the intestine?
Receives input from the CNS, promotes digestion
Splanchic nerves function?
Extrinsic function, supplies input to the GIT and inhibits the functions of the intestine
What are the 2 plexus’s found in the gut?
Submucosal and myenteric
How do the two plexus’s communicate with each other?
via interneurons and with the CNS
What do the neurons within the plexus form synapses with?
each other, smooth muscle cells and neurons in other plexus’s
What changes effect the sensory neurones in the GIT?
content of the digestive tract (via chemoreceptors within mucosa)
degree of wall stretch (via mechanoreceptors within muscular layers)
What cells do the motor neurons in the GIT effect?
Smooth muscle cells, or
* Epithelial (secretory) cells that produce digestive juices or
hormones
Why is it important for reflex arcs to release inhibitory neurotransmitters
relaxation of sphincters which empties a portion of the tract
What other cells are found in the intrinsic system?
endocrine and paracrine cells
What are the criteria for gut hormones?
1) Must be secreted by one cell in the gut and affect another cell
2) Must be transported in the blood (endocrine)
3) Release must be stimulated by food
4) Secretion does not have to be controlled by neurones
5) A synthetic version of it must be able to mimic the natural hormone
What are vagal fibre types responsible for?
- Innervating the abdominal viscera (stomach)
- Carrying signals from the taste buds (to determine what animals eat)
- Projecting from the CNS to parasympathetic ganglia near organs and
to the pharynx (the afferents and efferents)
What is the function of the Splanchic nerve?
Carries signals to the CNS regarding presence of pathologies
What is Aldosterone and where is it secreted?
It is a steroid hormone, secreted by the adrenal cortex following low sodium levels
