Smith: Visceral Affarents 2014

Question 1

The gut communicates with the (blank)

Answer 1

CNS

Question 2

(blank) innervation inhibits peristalsis and secretion, while (blank) innervation stimulates peristalsis and secretion

Answer 2

sympathetic; parasympathetic

Question 3

a condition with microbial imbalances on or inside the body

Answer 3

dysbiosis

Question 4

Vagal affarents synpase in the (blank), while pelvic afferents synapse in the (blank)

Answer 4

nodose; dorsal root ganglia

Question 5

Gastric input to the CNS is represented in the brainstem and thoracic spinal cord by (blank) and (blank) inputs

Answer 5

vagal; splanchnic

Question 6

(blank) percent of nerve fibers in the vagus nerve are sensory

Answer 6

80%

Question 7

Three pathways connecting the gut to the CNS

Answer 7

1. vagal afferents
2. pelvic afferents
3. splanchnic afferents

Question 8

Make up 80% of nerve fibers, signal mainly from upper GI regions

Answer 8

vagal afferents

Question 9

Regulate colon, rectum and internal anal sphincter

Answer 9

pelvic afferents

Question 10

Throughout the GI tract, many are thought to be nociceptive

Answer 10

splanchnic afferents

Question 11

Extrinsic afferents reach the gut via these four nerves

Answer 11

vagus
splanchnic
pelvic
pudendal

Question 12

Differences between a generator potential and an action potential.

Answer 12

1. generator potential does not propagate
2. generator potential is “graded”–>larger when more transmitters are attached
3. no refractory period

Question 13

The spinal reflex arc that changes activity in an effector (5 steps)

Answer 13

1. visceral afferent neuron plus sensory receptor
2. interneuron
3. preganglionic neuron
4. postganglionic neuron
5. effector

Question 14

Information about conditions of the gut are signaled through extrinsic (blank) afferents to the brain stem and (blank) afferents to the spinal cord

Answer 14

vagal; spinal

Question 15

Mechanical stimuli (stretch, pressure, distortion and shearing forces) can activate spinal, vagal and intrinsic primary afferents (IPANs) (blank) without intermediary cells.

Answer 15

directly

Question 16

Function as detectors that analyze luminal contents, survey the mucosal status and activate afferent neurons

Answer 16

endocrine cells in the GI tract

Question 17

release Cholecystokinin (CCK) in response to fat and protein digestion

Answer 17

I cells in the duodenum

Question 18

release secretin from EC cells in response to duodenal acidification to enhance pancreatic exocrine secretion and bile flow

Answer 18

S cells of the stomach and intestine

Question 19

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

Answer 19

EE cells

Question 20

Mechanical and chemical stimulation releases 5-HT to activate both intrinsic (peristalsis) and extrinsic afferent neurons to cause receptive relaxation of the stomach

Answer 20

EC cells

Question 21

includes antigen-sampling M cells, macrophages, eosinophils, neutrophils, and mast cells

Answer 21

lymphoid tissue

Question 22

(blank) nerve stimulation elicits severe pain in conscious humans, whereas (blank) nerve stimulation doesn’t produce pain

Answer 22

splanchnic; vagal

Question 23

Afferents regulating visceral tone, distension, motility and secretion accompany the (blank) efferent nerves

Answer 23

parasympathetic

Question 24

Most visceral afferent nerve fibers mediating sensation and nociception (pain) accompany the (blank) nerves

Answer 24

sympathetic

Question 25

Bottom line: (blank) afferent nerve fibers cause pain, (blank) afferent nerve fibers do not.

Answer 25

sympathetic; parasympathetic

Question 26

There are many more mechanosensory neurons than visceral sensory neurons, so visceral sensations are (blank) difficult to (blank).

Answer 26

diffuse; localize

Question 27

(blank) afferents are considered to convey to the CNS the sensations of discomfort and pain.

Answer 27

spinal

Question 28

Types of vagal, pelvic and spinal afferents

Answer 28

intramuscular arrays intraganglionic endings mucosal intravillous arbors

Question 29

Located within the submucosal and myenteric plexuses | Activate enteric reflexes that regulate motility, secretion, and blood flow

Answer 29

intrinsic primary afferent neurons (IPANs)

Question 30

Two types of extrinsic primary afferent neurons

Answer 30

Vagal afferents | Spinal afferents

Question 31

Activated by mechanical, thermal and chemical stimuli | Cell bodies in nodose ganglion and central terminals to brainstem nucleus tractus solitarius

Answer 31

vagal afferents

Question 32

Activated by low and high intensity chemical stimuli Cell bodies in DRG and central terminals in superficial dorsal horn of spinal cord Convey info about painful stimuli

Answer 32

spinal afferents

Question 33

EC cells can release (blank) which can activate the vomiting center via vagal afferents directly, vagal afferents to the area postrema, or through the bloodstream to the area postrema

Answer 33

5HT

Question 34

a type of chronic inflammatory bowel disease. It involves the formation of areas of patchy inflammation, primarily in the small intestine (terminal ileus) but sometimes in other parts of the digestive tract

Answer 34

Crohn's disease

Question 35

a form of IBD in which the inflammation is limited to the large intestine

Answer 35

Ulcerative colitis

Question 36

T/F: irritable bowl syndrome = IBD

Answer 36

FALSE, While IBS can be painful, it doesn’t lead to other health problems or damage the GI tract

Question 37

Inflammation sensitizes responses to gastric distension

Answer 37

visceral hyposensitivity

Question 38

Following injury, there is complex sensitization of pain (nociceptive) fibers caused by a (blank)

Answer 38

inflammatory soup (bradykinins, histamine, prostaglandins, substance P)

Question 39

Sensory (blank) channels sense how hot or mild different foods are.

Answer 39

TRP

Question 40

exaggerated pain in response to a painful stimulus

Answer 40

hyperalgesia

Question 41

pain in response to an innocuous stimulus

Answer 41

allodynia

Question 42

Sensitization of peripheral visceral sensory neurons is defined by an increase in the number of (blank) triggered by a stimulus, a decrease in the (blank) required for AP generation, and a lowering of the (blank) for AP generation

Answer 42

action potentials; stimulus intensity; threshold

Question 43

Sensitization of peripheral visceral sensory neurons may be associated with increase or change in (blank) release at central synapses or enhanced response of postsynaptic neurons

Answer 43

transmitter

Question 44

Sensitization of central visceral sensory neurons is associated with (blank) in response magnitude of central neurons, (blank) in size of are of referred sensation, and (blank) excitability of spinal neurons.

Answer 44

increase

Question 45

both somatic sensory fibers and visceral sensory fibers have the cell bodies in the same dorsal root ganglion and synapse on the same second-order neurons in the spinal cord causing (blank)

Answer 45

referred pain

Question 46

T/F: Visceral organs, such as the bladder and colon, can become cross-sensitized

Answer 46

True

Question 47

Theory attempting to explain why thoughts and emotions influence pain perception

Answer 47

gate control theory of pain

Question 48

Used to manage gut pain and can relieve diarrhea

Answer 48

opioids

Question 49

Some patients with inflammatory bowel disease (IBD) anecdotally report that they experience relief by smoking marijuana. What endogenous ligand is at work here?

Answer 49

cannabinoids

Question 50

T/F: Low innervation density and polymodal character of visceral sensory neurons explain the poor discriminatory ability of sensory input

Answer 50

true

Question 51

Convergence of different afferent input to higher order sensory neurons is responsible for (blank) pain

Answer 51

referred

Question 52

(blank) of sensory pathways during acute episodes of gastroenteritis contributes to the development of postinfectious functional GI disorders

Answer 52

sensitization

Question 53

Most gastric ulcers caused by a bacterial infection, usually (blank)

Answer 53

H. pylori

Question 54

Emesis occurs as a result of (blank) acting on nerves from the intestines to the vomiting center in the brain

Answer 54

5HT

Question 55

Detect stretch; are supplied by vagal afferents and innervate the smooth muscle layers of the GI tract

Answer 55

intramuscular arrays

Question 56

Detect mechanical changes; are supplied by vagal afferents and innervate

Answer 56

intraganglionic endings

Question 57

Sensitive to luminal chemicals and selective responses to fine tactile stimulation

Answer 57

vagal mucosal afferents