Flashcards in Neuronal & hormonal regulation of GIT Deck (20):
2 levels of control?
GIT has own NS - self regulatory
Intrinsic nervous & endocrine components
As many neurons as spinal cord
Some info from ANS but mostly independent
What is a plexus?
2 major plexuses & characteristics?
Submucosal plexus - regulates gut blood flow & ion/water transport
Myenteric plexus - regulates gut motility & enzyme secretion
Plexus contains what?
Sensory neurons (chemo-, mechanoreceptors)
3 main influences of Extrinsic NS on GIT motility & secretion?
1. Modifies ongoing activity in intrinsic plexus
2. Alters levels of GIT hormone secretion
3. Acts on SM & muscle cells
4 types of hormones?
1. Endocrine - via blood
2. Paracrine - to neighbouring cells
3. Autocrine - out then back onto itself
4. Neurocrine - via enteric NS to nearby muscles & glands
Vasoactive intestinal peptide (VIP)
Gastrin-releasing peptide (GRP)
3 digestion regulation phases?
1. Cephalic - rapid, feed forward
2. Gastric - slower than ceph, food in stomach
3. Intestinal - slowest, in response to factors in duodenum
Regulation of appetite occurs where?
At the satiety & appetite centre within the hypothalamus
3 main hormones that control long-tern appetite?
Leptin - long term hunger suppression
Ghrelin - appetite stimulant
Peptide YY (PYY) - reduces appetite
Short-term regulation of feed intake?
Balances hunger vs satiety
Short-term satiety factors?
Neural input from mechano-, chemoreceptors in GIT wall
Immune sys & GIT protection...?
Immune cells line gut mucosa (PP's, mesenteric lymph nodes)
Monitors antigenic environment
What monitors chemical & physical environment in the GI?
Enteric NS & GI endo/paracrine sys
2 key immune cell functions in GIT?
Antigenic memory (synthesise antibodies)
Inflam mediators (PGEs, histamine, cytokines)