Regulation of the GI System - Basics & Neural Inputs
Regulation of the GI System:
- The GI system is
primarily regulated by
the volume and
composition of luminal
contents, along with
some external input.
- Various stimuli trigger
reflexes, which can be neural or hormonal in nature.
Neural Regulation of the GI System:
- Neural regulation is primarily carried out by the enteric nervous system (ENS),
which consists of two networks:
Submucosal plexus: Primarily influences secretory activity.
Myenteric plexus: Primarily influences motility.
Key Points about
ENS:
- The ENS is a self-
contained
system, with
input, output,
and interneurons
located in the
wall of the GI
tract.
, - Neurotransmitters such as acetylcholine (ACh), noradrenaline (NA), nitric oxide
(NO), ATP, and neuropeptides are involved in ENS signalling.
- The ENS can operate autonomously without involving the central nervous
system (CNS) but also receives input from the autonomic nervous system.
- The sympathetic division (fight or flight response) has inhibitory effects
mediated by NA, while the parasympathetic division (rest and digest response)
has stimulatory effects mediated by ACh.
Types of Neural Reflexes:
- Some reflexes are entirely contained within the walls of the GI tract, involving
the ENS as the stimulus triggers a response.
These are known as "short" reflexes.
- Other reflexes involve the CNS in addition to the ENS.
, These are referred to as "long" reflexes.
- Certain reflexes can originate from outside the GI tract, such as those
influenced by smell or emotions.
Regulation of the GI System - Hormonal Inputs
Hormonal Regulation of the GI System:
- Secretion and motility in the GI system are primarily controlled by three
important hormones: gastrin, cholecystokinin (CCK), and secretin.
- Other hormones, such as leptin (stimulates satiety) and ghrelin (stimulates
hunger), also have effects on the GI system.
Hormonal Regulation - Gastrin:
Regulation of the GI System:
- The GI system is
primarily regulated by
the volume and
composition of luminal
contents, along with
some external input.
- Various stimuli trigger
reflexes, which can be neural or hormonal in nature.
Neural Regulation of the GI System:
- Neural regulation is primarily carried out by the enteric nervous system (ENS),
which consists of two networks:
Submucosal plexus: Primarily influences secretory activity.
Myenteric plexus: Primarily influences motility.
Key Points about
ENS:
- The ENS is a self-
contained
system, with
input, output,
and interneurons
located in the
wall of the GI
tract.
, - Neurotransmitters such as acetylcholine (ACh), noradrenaline (NA), nitric oxide
(NO), ATP, and neuropeptides are involved in ENS signalling.
- The ENS can operate autonomously without involving the central nervous
system (CNS) but also receives input from the autonomic nervous system.
- The sympathetic division (fight or flight response) has inhibitory effects
mediated by NA, while the parasympathetic division (rest and digest response)
has stimulatory effects mediated by ACh.
Types of Neural Reflexes:
- Some reflexes are entirely contained within the walls of the GI tract, involving
the ENS as the stimulus triggers a response.
These are known as "short" reflexes.
- Other reflexes involve the CNS in addition to the ENS.
, These are referred to as "long" reflexes.
- Certain reflexes can originate from outside the GI tract, such as those
influenced by smell or emotions.
Regulation of the GI System - Hormonal Inputs
Hormonal Regulation of the GI System:
- Secretion and motility in the GI system are primarily controlled by three
important hormones: gastrin, cholecystokinin (CCK), and secretin.
- Other hormones, such as leptin (stimulates satiety) and ghrelin (stimulates
hunger), also have effects on the GI system.
Hormonal Regulation - Gastrin:
