Intro to GI Phys DSA Flashcards
What sphincter is associated with the major duodenal papilla?
Sphincter of Oddi
What sphincters/valves are associated with the GI tract in order to restrict the passage of intestinal content and optimize digestion/absorption? (There are 7)
UES LES Pyloric sphincter Sphincter of Oddi Ileocecal valve Internal anal sphincter External anal sphincter
4 functional layers of small intestine wall
Mucosa
Submucosa
Muscularis (Circular + longitudinal)
Serosa
2 enteric nervous system components associated with the GI tract and their location within the functional layers of the gut tube
Submucosal plexus - at the base of submucosal layer
Myenteric plexus - between circular and longitudinal muscle layers of muscularis
The myenteric and submucosal plexuses are innervated by the ______ autonomic nervous system. They make up an integrating center that can exert its functions without ____ input
Extrinsic; CNS
The ENS receives information from what branches of the nervous system?
Parasympathetic
Sympathetic
CNS
The ENS receives sensory info from _____ and _____ in the mucosa
Mechanoreceptors
Chemoreceptors
Contraction, secretion, and endocrine function of the GI tract are controlled by what specific nervous system?
ENS
What some examples of roles of CNS in regulation of GI function?
Vasovagal reflex (gastric receptive relaxation reflex)
Modulation of ENS responses
Centers that control food intake
The vasovagal reflex associated with GI function is based around vagal efferents from the ______ in the brain, and vagal afferents from the sensory ganglion of the vagal nerve, aka the ____ ganglion
NTS (nucleus of the tractus solitarius)
Nodose
Parasympathetic innervation modulates GI function via the ____ and _____ nerves.
Preganglionic cell bodies are located in the ____ or _____ spinal cord
Postganglionic neurons lie in the ____ of the organ
Synapse between pre and post ganglionic cell is _______
Vagus; pelvic
Brainstem; sacral
Wall
Nicotinic (nAChRs)
Sympathetic innervations modulate GI functions via nerves running between the _______ and the prevertebral ganglia, and between these ganglia and _______
Preganglionic efferent fibers arise in _____ ______ and end in the ______ ______
Postganglionic fibers from the __________ innervate ____ and _____ plexuses
Spinal cord
Spinal cord; prevertebral ganglia
Prevertebral ganglia; myenteric; submucosal
Mostly, sympathetic preganglionic efferent fibers release _____, while postganglionic efferents release ____
ACh; NE
Cellular communication is key in the regulation of GI function. ______ regulation involves LOCAL action of peptides (e.g. somatostatin) or other messenger molecules (e.g. histamine), wherein signals reach their target cells by diffusion over short distances
Paracrine
_______ is secreted by D cells of GI mucosa
Somatostatin
Stimulus of somatostatin secretion from D cells of GI mucosa
Decreased luminal pH
Actions of somatostatin
Inhibits gastric H secretion
Inhibits secretion of other GI hormones
Somatostatin is secreted by D cells of the GI mucosa. Where else in the body is somatostatin secreted?
Hypothalamus
Delta cells of exocrine pancreas
_______ in the stomach is stored and secreted by enterochromaffin-like cells (ECLs) in gastric glands
Histamine
Target of histamine in the stomach
Parietal cells
Action of histamine in the stomach
Stimulates acid production
Enteroendocrine cells contain secretory granules filled with hormones that are released upon stimulation. What path do these hormones take to get to their target cells upon their release?
First they enter portal circulation, then travel to the liver, then into systemic circulation, then to their target cell which has a specific receptor for that hormone
Hormone family and site of secretion of gastrin
Family: gastrin-CCK
Site of secretion: G cells of stomach
Stimulus for gastrin secretion
Small peptides and amino acids
Distension of the stomach
Vagal stimulation (via GRP)
