Visceral Afferents T. Smith Flashcards
(blank) refers to a condition with microbial imbalances on or inside the body. It is most prominent in the digestive tract or on the skin, but can also occur on any exposed surface or mucous membrane such as the vagina, lungs, mouth, nose, sinuses, ears, nails, or eyes. It has been associated with different illnesses, such as inflammatory bowel disease, as imbalances in the intestinal microbiome may be associated with bowel inflammation and chronic fatigue syndrome.
Dysbiosis (also called dysbacteriosis)
What do parasympathetics do for the gut?
What do symapthetics do for the gut?
stimulates peristalsis and secretion
inhibits peristalsis and secretion
Where are the ganglion for the cell bodies of vagal afferents?
nodose ganglion
Inside the gut wall in the submucous plexus we have (blank) neuron that sense what is happening in the mucosa.
intrinisic primary afferent neurosn (IPANs)
Visceral afferents will have cell bodies in the (blank) and will travel through the prevertebral and paravertebral ganglia to the spinal cord.
dorsal root ganglion
What percentage of the vagus is made up of sensory nerve fibers?
80%
The distal colon is represented in thoracolumbar and lumbosacral spinal segments by (blank and blank)
least splanchnic and pelvic nerve inputs.
Gastric input to the CNS is represented in the brainstem and thoracic spinal cord by (blank and blank)
vagal and splanchnic inputs.
Extrinisic afferents reach the gut via (blank, blank, blank, and blank)
vagal, splachnic, pelvic, and pudendal
What are the three pathways that connect the gut to the CNS?
vagal afferents-> upper GI regions
Pelvic afferents-> Colorectal region
Splachnic afferents-> throughout GI, thought to be nociceptive
What do pelvic afferents regulate?
regulate colon, rectum and internal anal sphincter
What are the splachnic afferents thought to be?
nociceptive
Afferent neurons or their nerve terminals may be sensitized or inhibited by (blank) released from several cell types.
chemical mediators
Are all the afferents chemosensitive?
no some are and some arent
A bolus of food in the pharynx stimulates (blank) in the wall of the pharynx
tension receptors
Pharyngeal contraction coincides with relaxation of the (Blank)
upper esophageal sphincter (UES)
What follows pharyngeal contraction and UES relaxation?
sequential (peristaltic) phasic contraction along the esophageal body, which propels the swallowed bolus toward the stomach.
What follows the peristaltic/phasic contractions along esophageal body?
LES relaxes and remains relaxes until the peristaltic wave arrives
Is a generator potential different than an action potential? How?
Yes
Generator potentials do not propagate and are local
Action potentials propagate
A generator potential is (blank); it is small when few transmitters are coupled to their receptors and become larger when a lot of transmitters are attached. (so not all or none)
graded
If you have a weak stimulus what will happen to your generator potental?
Strong stimulus?
weak stimulus-> small generator potential-> low frequency action potential
Strong stimulus-> large generator potential-> high frequency action potentials
The basic spinal reflex arc that changes activity in an effector consists of what five things?
1) visceral afferent neuron plus sensory receptor
2) interneuron
3) preganglionic neuron
4) postganglionic neuron
5) effector
Which is faster, reflexes in ANS or reflexes in skeletal muscle?
Reflexes in skeletal muscle
What will microbial signals and antigens stimulate?
immune and tissue defense signals; local, systemic and neural
Information about luminal factors and conditions of the gut are signalled through (blank and blank) to the brain stem and spinal cord, respectively.
extrinsic vagal and spinal afferents
Mechanical stimuli (stretch, pressure, distortion and shearing forces) can activate spinal, vagal and intrinsic primary afferents (IPANs) directly, without (blank) such as the enteroendocrine (EE) cells.
intermediary cells
Signalling molecules (including proteases, histamine, serotonin and cytokines) that are produced by immune cells in Peyer’s patches and within the gut epithelium can activate their respective receptors on (blank and blank).
vagal and spinal afferents
Enterochromaffin (EC) cells signal to both (blank and blank).
IPANs and vagal afferents
Different classes of EE cells are interspersed between (blank) throughout the gastrointestinal tract.
gut epithelial cells
EE cells, Upon luminal stimulation (or upon activation by postganglionic sympathetic or vagal nerves), these cells can release up to 20 different gut peptides from their basolateralsurface.
EE cells
Released peptides can activate closely adjacent vagal afferent nerve terminal, in a (blank) fashion, or when released into the circulation they can exert an (blank) effect, signalling to various sites in the brain and other parts of the gastrointestinal tract.
paracrine
endocrine
(blank) function as detectors that analyze luminal contents, survey the mucosal status and activate afferent neurons.
Endocrine cells in the GI tract
(blank) release CCK in response to fat and protein digestion.
I cells in the duodenum
(blank) is involved in satiation, reflex inhibition of gastric motility and emptying, reflex increase in gastric blood flow and mucosal protection.
CCK
(blank) cells, in response to duodenal acidification, release secretin from endocrine cells in the proximal small intestine to enhance pancreatic exocrine secretion and bile flow.
S cells in stomach and intestine
(blank) release ~20 different neuropeptides that can stimulate vagal afferents in a paracrine fashion, or when released into the circulation they can exert an endocrine effect signaling to various sites in the brain and other parts of the GI tract.
EE cells throughout the gut
(blank) cells via mechanical and chemical stimulation, releases 5HT to activate both intrinsic (peristalsis) and extrinsic afferent neurons to cause receptive relaxation of the stomach.
Enterochromaffin cells (EC)
(blank) includes antigen-sampling M cells, macrophages, eosinophils, neutrophils and mast cells (mainly aggregated in Peyer’s patches)
Lymphoid tissue
The enteric nervous system and central nervous system communicate with each other via (blank)
epithelial cells
enteroendocrine cells
immune cells
intrinsic and extrinsic sensory neurons
The enteric nervous system and central nervous system communicate with each other via (blank)
epithelial cells
enteroendocrine cells
immune cells
intrinsic and extrinsic sensory neurons
Most visceral afferent nerve fibers mediating sensation and nociception (pain) accompany the (blank)
sympathetic nerves (splachnic nerves)
(blank) stimulation elicits severe pain in conscious humans, whereas vagal nerve stimulation doesn’t produce pain.
splachnic nerve stimulation
Chronic visceral pain (e.g. cancer, severe peripheral vascular disease) relieved by surgically sectioning (blank).
sympathic nerve trunk by not parasympathetic nerve trunks
Chronic visceral pain (e.g. cancer, severe peripheral vascular disease) relieved by surgically sectioning (blank).
sympathic nerve trunk by not parasympathetic nerve trunks
About (blank)% of the total nerve fibers running with sympathetic nerves are afferent. In contrast, (blank)% of all fibers in the vagus nerve and (blank)% of all fibers in the pelvic nerves are afferent.
20%
80%
50
Because of the relative lack of visceral sensory neurons compared to mechanosensory neurons (x10),visceral sensations are (blank)
diffuse and difficult to localize.
Vagal and spinal primary afferent neurons are (blank) and have collaterals that run to enteric ganglia.
pseudounipolar
The cell bodies of spinal primary afferent neurons are in dorsal root ganglia, their central processes end in the (blank) of the spinal cord and their peripheral axons pass via sympathetic ganglia to the intestine.
dorsal horns