1C: Neuroanatomy

Question 1

What are the two autonomic motor system neurons?

Answer 1

Σ (Sympathetic) and РΣ (Parasympathetic)

They function as unconscious motor neurons.

Question 2

What is the primary function of the sympathetic nervous system?

Answer 2

Reactions to stress, increased heart function, decreased digestive function, pupillary dilation, and vasodilation in skeletal muscle

It also involves vasoconstriction in other vessels.

Question 3

What is the primary function of the parasympathetic nervous system?

Answer 3

Recovery of rest, increased digestion, pupillary constriction, and bowel and bladder emptying

It promotes vegetative functions.

Question 4

What is the origin of sympathetic preganglionic neurons for heart innervation?

Answer 4

T1 to T4-5 intermediolateral nucleus (IML)

Preganglionic neurons exit the spinal cord at these levels.

Question 5

What is the pathway for sympathetic innervation of the heart?

Answer 5

Ventral root → white ramus → sympathetic chain → cardiopulmonary ganglion

It synapses on postganglionic neurons in the chain ganglia.

Question 6

What is the origin of parasympathetic preganglionic neurons for heart innervation?

Answer 6

Nucleus Ambiguus in the open medulla

They exit as the vagus nerve (CN-X).

Question 7

What neurotransmitter do sympathetic postganglionic neurons release?

Answer 7

Norepinephrine (NE)

It binds to β1 receptors in the heart.

Question 8

What are the actions of beta-1 receptors in the heart?

Answer 8

• Increased heart rate (positive chronotropic activity)
• Increased strength of contraction (positive inotropic activity)
• Increased conduction velocity (positive dromotropic activity)

These effects enhance cardiac performance.

Question 9

What neurotransmitter do parasympathetic postganglionic neurons release?

Answer 9

Acetylcholine (ACh)

It binds to M2 receptors in the heart.

Question 10

What are the actions of M2 receptors in the heart?

Answer 10

• Decreased heart rate (negative chronotropic activity)
• Decreased strength of contraction (negative inotropic activity)
• Decreased conduction velocity (negative dromotropic activity)

These actions oppose the effects of beta-1 receptors.

Question 11

What is the origin of sympathetic innervation for the vasculature?

Answer 11

All levels of the intermediolateral nucleus from T1 to L2,3

This includes the entire sympathetic chain.

Question 12

What neurotransmitter is primarily used in sympathetic innervation of blood vessels?

Answer 12

Norepinephrine (NE)

Exceptionally, ACh is used in vessels perfusing skeletal muscle.

Question 13

What are the sympathetic receptors involved in vascular innervation?

Answer 13

• Alpha-1 Receptors: excitatory action on most vessels
• Beta-1 Receptors: mainly in the heart
• Beta-2 Receptors: inhibitory in bronchial and GI smooth muscle

These receptors have distinct physiological effects.

Question 14

What is the role of nitric oxide (NO) in vasodilation?

Answer 14

NO increases vascular diameter by inhibiting smooth muscle contraction

It is released from sympathetic cholinergic postganglionic axons in skeletal muscle.

Question 15

True or False: Both sympathetic and parasympathetic systems can be influenced by antagonists.

Answer 15

True

Atropine is an antagonist for M2 receptors, while propranolol is for beta-1 receptors.

Question 16

Fill in the blank: The sympathetic system has an endocrine homologue in the _______.

Answer 16

adrenal medulla

It releases epinephrine into the bloodstream.

Question 17

What are the key outcomes of studying this unit?

Answer 17

• Recognize autonomic innervation of the heart
• Demonstrate peripheral vasculature innervation
• Apply knowledge to case studies

Understanding of neuropharmacological features is also emphasized.

Question 19

What are the two autonomic motor system neurons?

Answer 19

Sympathetic (Σ) and Parasympathetic (РΣ)

These systems function as unconscious motor neurons.

Question 20

What is the anatomical structure shared by sympathetic and parasympathetic systems?

Answer 20

Pre- and postganglionic neurons

They connect the CNS to the effector organs.

Question 21

What is the primary function of the sympathetic system during stress?

Answer 21

Increased oxygen supply for ATP production

This is crucial for the oxidative phosphorylation system.

Question 22

What is the effect of sympathetic innervation on bronchial smooth muscle?

Answer 22

Dilation of bronchial smooth muscle

It also inhibits mucous secretions.

Question 23

What is the role of the parasympathetic system during rest?

Answer 23

Bronchoconstriction and increased mucous secretion

This helps humidify dry air and capture particulates.

Question 24

What is the origin of sympathetic preganglionic neurons for the bronchi?

Answer 24

T1 to T4-5 IML

This indicates the spinal cord segments involved.

Question 25

What is the path of sympathetic preganglionic neurons to the bronchi?

Answer 25

Ventral root → white ramus → sympathetic chain ## Footnote They ascend via interganglionic branches to synapse on postganglionic neurons.

Question 26

Where do postganglionic sympathetic neurons project in the bronchi?

Answer 26

To smooth muscle and glands of the bronchial tree ## Footnote They travel through the cardiopulmonary ganglion.

Question 27

What is the origin of parasympathetic preganglionic neurons for the bronchi?

Answer 27

Dorsal Motor Nucleus of X, open medulla ## Footnote This indicates the brainstem origin.

Question 28

How do parasympathetic preganglionic neurons reach the pulmonary ganglia?

Answer 28

Exiting the jugular foramen as the vagus nerve (CN-X) ## Footnote They pass through the carotid sheath and thoracic outlet.

Question 29

What is the role of high threshold GVA innervation?

Answer 29

Path: Dorsal root ganglion → spinal cord grey matter ## Footnote It is involved in sensory input from the bronchi.

Question 30

What neurotransmitter is released by sympathetic postganglionic neurons?

Answer 30

Norepinephrine (NE) ## Footnote This binds to β2 receptors in the bronchi.

Question 31

What is the action of beta-2 receptors in the bronchi?

Answer 31

Dilation of the bronchial tree and decreased mucous secretion ## Footnote They are activated by norepinephrine.

Question 32

What neurotransmitter do parasympathetic postganglionic neurons release?

Answer 32

Acetylcholine (ACh) ## Footnote It binds to M3 receptors in the bronchi.

Question 33

What is the function of M3 receptors in the bronchial tree?

Answer 33

Increased smooth muscle contraction and mucous secretion ## Footnote This occurs via a second messenger system.

Question 34

What are the expected outcomes after studying the autonomic innervation of the bronchial tree?

Answer 34

Recognize, recite, and demonstrate autonomic innervation ## Footnote Also, understand neuropharmacological features and apply knowledge to case studies.

Question 35

What is the primary focus of Module 1C?

Answer 35

Innervation of the Heart and Bronchi ## Footnote This module is part of the CFS-6300 Integrative Anatomy of the Thorax and Abdomen course.

Question 36

What will students be able to do after this lesson?

Answer 36

Trace the innervation of the heart and bronchi, both sympathetic and parasympathetic pathways and the afferent innervations ## Footnote This includes understanding the neuropharmacology of the sympathetic and parasympathetic inputs.

Question 37

What are the components of sympathetic innervation?

Answer 37

Preggl Origin, Preggl Synapse, Postggl Origin, Postggl Synapse ## Footnote These components are crucial for understanding the sympathetic nervous system's influence on the heart and bronchi.

Question 38

What are the components of parasympathetic innervation?

Answer 38

Preggl Origin, Preggl Synapse, Postggl Origin, Postggl Synapse ## Footnote These components are essential for understanding the parasympathetic nervous system's role.

Question 39

What is the origin of High Threshold GVA Innervation?

Answer 39

Dorsal root ganglion ## Footnote This indicates the source of sensory information related to high threshold stimuli.

Question 40

Where does High Threshold GVA Innervation synapse?

Answer 40

Spinal cord grey matter ## Footnote This is where the sensory input is processed in the spinal cord.

Question 41

What is the origin of Low Threshold GVA Innervation?

Answer 41

Nodose ganglion of X ## Footnote This refers to the vagus nerve's ganglion involved in low threshold sensory input.

Question 42

Where does Low Threshold GVA Innervation synapse?

Answer 42

Medullary gray (nucleus solitarius) ## Footnote This is the processing center for visceral sensory information from the vagus nerve.

Question 43

What type of input do all arterioles and arteries receive?

Answer 43

Sympathetic input ## Footnote This input can come via peripheral nerves or the endocrine sympathetic system homologue.

Question 44

How does the heart receive its sympathetic input?

Answer 44

Via the cardiopulmonary nerves ## Footnote This pathway is critical for the heart's response during stress or physical activity.

Question 45

From where do the body wall and limbs receive sympathetic input?

Answer 45

VPR and DPR ## Footnote VPR stands for ventral primary rami and DPR stands for dorsal primary rami.

Question 46

How does the abdominopelvic system receive its sympathetic input?

Answer 46

Via the splanchnic nerves and visceral branches ## Footnote This input follows the vascular pattern of the abdominopelvic viscera.