Neuronal & hormonal regulation of GIT Flashcards Preview

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Flashcards in Neuronal & hormonal regulation of GIT Deck (20):
1

2 levels of control?

Intrinsic (enteric)
Extrinsic

2

Intrinsic properties?

GIT has own NS - self regulatory
Intrinsic nervous & endocrine components
As many neurons as spinal cord
Some info from ANS but mostly independent

3

Extrinsic properties?

ANS
Endocrine

4

What is a plexus?

nerve network

5

2 major plexuses & characteristics?

Submucosal plexus - regulates gut blood flow & ion/water transport
Myenteric plexus - regulates gut motility & enzyme secretion

6

Plexus contains what?

Sensory neurons (chemo-, mechanoreceptors)
Interneurons
Motor neurons

7

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

8

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

9

Endocrine peptides...?

Gastrin
Secretin
CCK
GIP
Motilin

10

Neurocrine peptides...?

Vasoactive intestinal peptide (VIP)
Gastrin-releasing peptide (GRP)
Enkephalins

11

Paracrine peptides...?

Somatostatin
Histamine

12

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

13

Regulation of appetite occurs where?

At the satiety & appetite centre within the hypothalamus

14

3 main hormones that control long-tern appetite?

Leptin - long term hunger suppression
Ghrelin - appetite stimulant
Peptide YY (PYY) - reduces appetite

15

Short-term regulation of feed intake?

Balances hunger vs satiety

16

Short-term satiety factors?

Insulin
CCK
Neural input from mechano-, chemoreceptors in GIT wall

17

Immune sys & GIT protection...?

Immune cells line gut mucosa (PP's, mesenteric lymph nodes)
Monitors antigenic environment

18

What monitors chemical & physical environment in the GI?

Enteric NS & GI endo/paracrine sys

19

2 key immune cell functions in GIT?

Antigenic memory (synthesise antibodies)
Inflam mediators (PGEs, histamine, cytokines)

20

Cascade of events following exposure to antigen?

Antigen ingested -> lymphocytes -> cytokines-> Inflammatory response + intrinsic NS & endocrine systems