regulation of gut function Flashcards
- What are the divisions of the gut nervous system
Autonomic (extrinsic)
- Sympathetic
- Parasympathetic
Enteric (intrinsic)
- Where do sympathetic preganglionic neurons arise from?
Thoracic and Lumbar spinal cord
Stomach (T6-9) Colon (L2-5)
- What are the sympathetic postganglionic neurons innervating the stomach called?
- What are the sympathetic postganglionic neurons innervating the small intestine called?
- What are the sympathetic postganglionic neurons innervating the distal colon and rectum called?
Coeliac ganglion
Superior mesenteric ganglion Inferior mesenteric and pelvic ganglion
- What effect does the activation of the sympathetic nervous system have on the activities of the gastrointestinal tract?
- What is parasympathetic innervation to the stomach, small intestine and proximal colon supplied by?
Inhibitory
Vagus nerve
- Where do the preganglionic neurons originate from?
- What effect does the activation of the parasympathetic nervous system have on the activities of the gastrointestinal tract?
Dorsal vagal complex within brainstem from sacral spinal cord
Stimulatory
- What neurotransmitter is used in the sympathetic nervous system?
- What neurotransmitter is used in the parasympathetic nervous system?
Noradrenaline
Acetylcholine
- How are the neurones arranged in the enteric nervous system?
Myenteric (Auerbach’s) plexus- Between longitudinal and circular muscles
Submucosal (Meissner's) plexus- Inside of the circular muscles
- What is the overall function of the myenteric plexus?
To control the activity of the muscularis propria
Controls gut motility Tone velocity of contraction and intensity of contraction
- What are the functions of the submucosal plexus?
Senses local environment (gut lumen)
Controls secretion, blood flow, epithelial and endocrine cell function
- How do the myenteric and submucosal plexus work when food enters the gut?
Food stretches the intestinal smooth muscles
Distension of gut causes stimulation of sensory neurons in myenteric plexus Chemicals in food stimulates sensory neurons in submucosal plexus Sequential contraction/relaxation of circular and longitudinal muscles by inhibitory/excitatory neurotransmitter causes peristalsis, which allows food to move along GI tract
- Describe the contraction of muscle groups during peristalsis
Circular muscles behind the bolus of food contract
Longitudinal muscles ahead of the bolus of food contract causing it to shorten and widen to receive bolus
- Where do the sensory neurons from the epithelium send signals to?
Prevertebral ganglia, spinal cord and brainstem
Submucosal plexus Myenteric plexus
- Are the sympathetic neurons supplying the myenteric and submucosal plexuses, mainly pre or postganglionic?
- Are the parasympathetic neurons supplying the myenteric and submucosal plexuses, mainly pre or postganglionic?
postganglionic
all pre ganglionic
- Does sympathetic stimulation of the enteric nervous system have a stimulatory or inhibitory effect?
- Does parasympathetic stimulation of the enteric nervous system have a stimulatory or inhibitory effect?
Inhibitory, Reduces peristalsis, absorption, secretion and blood flow (via enteric nervous system and directly)
Stimulatory, Increases peristalsis, absorption, secretion and blood flow
- What disease is the most common cause of neonatal bowel obstruction?
- What happens in Hirschsprung’s diseases?
Hirschsprung’s disease
Congenital absence of ganglion of myenteric and submucosal plexuses
Tonal contraction without reciprocal relaxation Intestinal distension proximal to aganglionic segment of bowel