2. Physiology Flashcards
What are the 3 divisions of splanchnic nerves of the sympathetic nervous system that innervate the main portion of the GI tract? What vertebral level is each?
Greater (T5-9).
Lesser (T10-11).
Least (T12).
What are the two main parasympathetic nerves to the gut? What vertebral level is each from?
Vagus nerve (cranial). Pelvic splanchnic nerves (S2-4).
What nervous system stimulates the gut increasing motility?
Parasympathetic
What nervous system can operate completely independently?
Enteric
Where in the GI tract does the enteric nervous system exist?
From mouth to anus
One of the two main plexuses of the enteric nervous system is the mucosal (meissner’s) plexus. In which layer of the GI tract is it found and what does it control?
In the submucosa.
Secretions and blood flow.
One of the two main plexuses of the enteric nervous system is the myenteric (Auerbach’s) plexus. In which layer of the GI tract is it found and what does it control?
In the muscularis propria between circular and longitudinal muscle.
Motility.
What other nervous systems does the enteric nervous system communicate with?
Parasympathetic and sympathetic
What is the name of the 2 types of cells in the mucosa of the GI tract that secrete hormones?
Enteroendocrine cells (G,S,D). ECL cells (secrete histamine).
What are the two broad categories of gastrointestinal hormones?
Gastric family.
Secretin family.
Why do patients with abdominal pain first present with pain that is vague and not necessarily felt in the anatomical location of the cause of the pain?
If viscera becomes distended, then visceral peritoneum is involved. The visceral afferents accompany the sympathetic motor fibres, which go back to their spinal sensory ganglia and pain is felt in the corresponding dermatome.
What does the sympathetic nervous system mainly innervate?
Blood vessels
What type of pain is felt from foregut structures?
Epigastric pain.
What type of pain is felt from midgut structures?
Periumbilical pain.
What type of pain is felt from hindgut structures?
Suprapubic/hypogastric pain.
Where is pain from gallstones felt?
Right upper quadrant/right shoulder tip pain.
Where is pain from pancreatitis felt?
Back pain.
Where is pain caused by the oesophagus felt?
Retrosternal pain.
All muscle is smooth in the GI tract except in which 3 places?
Pharynx.
Upper third of oesophagus.
External anal sphincter.
What are the 5 types of phasic contractions of the GI tract?
Periodic. Tonic. Peristalsis. Segmentation. Mass movement.
What are periodic contractions of the GI tract for?
Propulsion and mixing.
What are tonic contractions of the GI tract? In what 3 places do they occur?
Constant level of contraction.
Upper stomach, ileocaecal valve, internal anal sphincter.
What is peristalsis of the GI tract? Where does contraction occur in relation of contents?
Propel contents in one direction.
Contraction proximal to contents (relaxation distal).
What is segmentation of the GI tract?
To and fro movements where contraction splits contents and then relaxes to mix contents.
