Physiology of Visceral Afferents and Referred Pain

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Questions and Answers

Which type of nerves carry unconscious physiological sensations to the CNS?

Motor nerves

Parasympathetic nerves (correct)

Somatic nerves

Sympathetic nerves

What is referred pain?

Pain sensation in the somatic region

Pain sensation in the location where the pain is occurring

Pain sensation in the visceral region

Pain sensation in a location different from where the pain is occurring (correct)

Which nerve is responsible for vasodilation and bronchoconstriction in the Pulmonary Plexus?

Somatic nerve

Vagus nerve (correct)

Sympathetic nerve

Parasympathetic nerve

What is the effect of the sympathetic nervous system on the heart rate?

Increase heart rate Signup and view all the answers

What is the effect of the parasympathetic nervous system on the force of heart contractions?

Decrease force of contractions Signup and view all the answers

Which spinal cord levels are associated with the cardiac plexus?

T1-T4 Signup and view all the answers

Which cranial nerve is responsible for transmitting parasympathetic signals for lacrimation?

CN VII Signup and view all the answers

What is the primary function of the parasympathetic nervous system?

Rest and digestion Signup and view all the answers

Which of the following is NOT a parasympathetic response?

Increased heart rate Signup and view all the answers

Which nerve carries visceral afferent fibers?

All of the above Signup and view all the answers

What is the effect of parasympathetic stimulation on the heart?

Decreased heart rate Signup and view all the answers

Which ganglion is responsible for transmitting parasympathetic signals for salivation?

Submandibular ganglion Signup and view all the answers

What is the primary function of the sympathetic nervous system?

Fight or flight response Signup and view all the answers

Which of the following organs is NOT innervated by the vagus nerve (CN X)?

Skeletal muscle Signup and view all the answers

Which spinal segments do sympathetics to body wall and limbs originate from?

T1-L2 Signup and view all the answers

What is the name of the nerves that exit the sympathetic chain to innervate abdominal viscera?

Splanchnic nerves Signup and view all the answers

What is the name of the response elicited by the sympathetic nervous system?

Fight, Fright, and Flight Signup and view all the answers

Where do preganglionics synapse before exiting the sympathetic chain?

In the sympathetic ganglia at the same spinal level Signup and view all the answers

What is the name of the nerves that innervate the thoracic viscera?

Cardiac nerves Signup and view all the answers

Which spinal segments do sympathetics to abdominal viscera originate from?

T5-T9 Signup and view all the answers

What is the name of the nerves that innervate the pelvic viscera?

Sacral splanchnic nerves Signup and view all the answers

Where do preganglionics originating from T1-T4 synapse?

In the sympathetic ganglia at the same spinal level Signup and view all the answers

What is the name of the type of nerves that innervate the body wall and limbs above T1 level?

Gray rami Signup and view all the answers

Where do preganglionics originating from T5-T9 exit the sympathetic chain?

To form the greater splanchnic nerves Signup and view all the answers

Study Notes

Visceral Afferents and Referred Pain

Visceral afferents traveling with parasympathetic nerves carry unconscious physiological sensations to the CNS
Visceral afferents traveling with sympathetic nerves carry pain sensations to the CNS
Referred pain occurs when sensory information comes from one location but is interpreted as coming from another location innervated by the same spinal cord level
Example: Heart attack pain is referred from the heart to the T1-T4 dermatomes

Pulmonary Plexus

Sympathetic nerves (T1-T4) cause vasoconstriction and bronchodilation
Parasympathetic nerves (Vagus nerve) cause vasodilation and bronchoconstriction

Cardiac Plexus

Sympathetic nerves (T1-T4) increase heart rate and force of contraction
Parasympathetic nerves (Vagus nerve) decrease heart rate and force of contraction

Parasympathetic Ganglia

Facial (CN VII) nerve:
- Preganglionic: CN VII, Greater petrosal nerve, Pterygopalatine (PT) ganglion
- Postganglionic: Pterygopalatine (PT) ganglion, Lacrimal gland (lacrimation)
Glossopharyngeal (CN IX) nerve:
- Preganglionic: CN IX, Lesser petrosal nerve, Otic ganglion
- Postganglionic: Otic ganglion, Auriculotemporal nerve, Parotid gland (salivation)
Vagus (CN X) nerve:
- Preganglionic: CN X, Ganglia in the target tissue
- Postganglionic: Targets include foregut to midgut, pharynx, larynx, trachea, lungs, esophagus, stomach, small intestine, and large intestine to 2/3 transverse colon

Sympathetic Motor Neuron Path

Sympathetic motor neurons have cell bodies in the lateral horn of spinal segments T1-L2
Preganglionic sympathetic neurons synapse in sympathetic chain ganglia
Postganglionic sympathetic neurons exit the chain via gray rami to spinal nerves T1-L2

Sympathetic Responses

Fight, Fright, and Flight response
3 increases:
- Increase heart rate
- Increase diameter of airways (bronchodilation)
- Increase diameter of pupils
3 decreases:
- Decrease heart rate
- Decrease diameter of airways (bronchoconstriction)
- Decrease diameter of pupils (constriction)

Parasympathetic Responses

Rest and Digest response
Stimulation (SLUDD):
- Salivation (S)
- Lacrimation (L)
- Urination (U)
- Digestion (D)
- Defecation (D)
3 decreases:
- Decrease heart rate
- Decrease diameter of airways (bronchoconstriction)
- Decrease diameter of pupils (constriction)

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Description

Quiz on the role of visceral afferents in carrying physiological sensations and pain to the CNS, and the concept of referred pain. Explore the relationship between spinal cord levels and pain interpretation.