Gut and Immune System Flashcards
What is one thing we have learned that stimulates the immune system?
acute stress (maybe from HPA axis)
How does the gut increase the immune system as a result of stress
SNS nerve terminals are close to T cells, dendritic cells, macrophages and B cells which release NE and activate immune cells
What are the types of immune cells
peyer’s patches, Enterochromaffin epithelial cells and mast cells
Peyer’s patches
clusters of lymphoid nodules containing B and T cells in mucosa
What is found in running through peyer’s patches?
NE
Enterochromaffin epithelial cells
releases 95% of serotonin which binds to receptors and increases intestinal MOTILITY
- too much = diarrhea
mast cells
releases a range of cytokines (histamine) that stops release of NE
What happens when histamine from mast cells stop releasing NE?
blood vessels will dilate and more blood will enter gut and wash bad thing away
What neurotransmitter increases the activation of mast cells?
substance P
How does the gut respond when it wants to down regulate the immune system?
Ach will be released from vagus (PNS) nerve terminals and then bind to cholinergic receptors on immune cells to inhibit them
How does the gut make us feel good?
enterochromaffin epithelial cells releases serotonin
What do anti-depressants do?
= serotonin reuptake inhibitors = they stop serotonin from being sent back to cells and destroyed so there is more serotonin (feel good hormone) in the body and you won’t be depressed
what happens when you have too many anti-depressants in your system or the Enterochromaffin epithelial cells are overproducing serotonin?
increasing the amount of serotonin will cause overactive peristalsis and IBS
How does the gut respond to fear?
dorsal motor freeze response (PNS) –> even more serotonin in the gut –> diarrhea
How does the gut response to extreme stress?
brain signals mast cells in submucosal plexus –> mast cells secrete histamine –> inflammation of the gut (good) and diarrhea and cramping (bad)
