Nervous and hormone

Question 1

Function of the digestive tract

Answer 1

1. ingestion
2. secretion of water, acid, buffers and enzymes
3. mixing and propulsion
4. digestion- mechanical, chemical, fermentive
5. absorption
6. defecation

Question 2

Regulation of the digestive system is done with integration of two systems

Answer 2

central (extrinsic) nervous and endocrine system

local (intrinsic) nervous and endocrine components in the GI tract

Question 3

Enteric NS consists of neurons in the gut wall, cell bodies of ENS are arranged in 2 systems of ganglia

Answer 3

1. myenterix plexus
   - ganglia arranged between circular and longituidinal layers
   - contrls GI tract motility
2. Submucosal plexus
   - ganglia within submucosal layer
   - controls GI secretions

Question 4

Is there a direct synapse between enteric nerve endings and the structures they innervate?

Answer 4

NO

instead NT is released diffusely within the tissue

Question 5

ENS motor axons end in branching ?

Answer 5

arborizations called varicosities

Question 6

Excitatory enteric neurotransmitters

Answer 6

Acetylcholine
-stim SM contraction
-increases intestinal secretions
-causes release of enteric hormones
-dilates BV
Substance P
-peptide involved in pain perception (among other functions) 
-in CTZ of medulla- vomiting

Question 7

Inhibitory enteric neurotransmitters

Answer 7

peptides
-somatostatin (inhibits gastrin release)
-PACAP 
non peptide
-NO
-ATP

Question 8

Most of the GI tract is supplied by which parasympathetic efferent nerves?

Answer 8

vagus nerve

Question 9

Intrinsic gut hormones

Answer 9

are regulatory peptides released from APUD cells –> contribute to regulation of gut function

Question 10

Mucosal imune system

Answer 10

also regulates gut function
direct effects on GIT on secretion and motility
major immune roles : tolerance and defence