pathophys2 final: Autonomic Nervous System ppt

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Questions and Answers

What is the primary function of the autonomic nervous system?

To transmit sensory information from the skin

To control voluntary actions

To regulate skeletal muscle movement

To maintain steady state among organs (correct)

Which of the following is NOT a target tissue of the autonomic nervous system?

Cardiac muscle

Skeletal muscle (correct)

Smooth muscle

Glands

What type of receptors measure wall tension and thus pressure in blood vessels and viscera?

Chemoreceptors

Baroreceptors

Mechanoreceptors (correct)

Nociceptors

Where are the cell bodies of sensory neurons in the autonomic nervous system located?

Dorsal root ganglia of the spinal cord Signup and view all the answers

Which cranial nerve is most prominent in the autonomic nervous system?

Vagus nerve Signup and view all the answers

What is the characteristic of the autonomic nervous system that distinguishes it from the somatic nervous system?

Two-neuron system Signup and view all the answers

Where are paravertebral ganglia located in the sympathetic division of the autonomic nervous system?

In two longitudinal chains on either side of the spinal column Signup and view all the answers

Which type of receptors relay signals interpreted as pain when viscera are damaged and/or overdistended?

Nociceptors Signup and view all the answers

What is the primary function of the parasympathetic nervous system?

To conserve and restore energy Signup and view all the answers

What is the anatomical location of the sympathetic ganglia?

Along the spinal cord in a chain Signup and view all the answers

What is the neurotransmitter released by the adrenal medulla into the bloodstream?

Epinephrine and Norepinephrine Signup and view all the answers

What is the receptor type for sympathetic postganglionic fibers?

Adrenergic Signup and view all the answers

Which of the following receptors is primarily associated with relaxation and inhibition?

α2-adrenergic receptors Signup and view all the answers

What is the primary neurotransmitter for the entire peripheral nervous system?

Acetylcholine Signup and view all the answers

What is the primary function of β1-adrenergic receptors in the heart?

Increase heart rate and contractility Signup and view all the answers

What is the characteristic of postganglionic fibers in the parasympathetic nervous system?

Short and with little branching Signup and view all the answers

Which of the following is NOT a function of α1-adrenergic receptors?

Increase heart rate Signup and view all the answers

Where do the cell bodies of sympathetic preganglionic neurons originate?

In the thoracolumbar region of the spinal cord Signup and view all the answers

What is the primary mechanism of action of nicotine in the body?

Acts as a nicotinic receptor agonist Signup and view all the answers

What is the function of the celiac ganglion?

To innervate the abdominal viscera Signup and view all the answers

Which of the following medications is used to treat bradycardia by blocking parasympathetic nervous system input to the cardiac conduction system?

Atropine Signup and view all the answers

What is the result of G-protein coupled receptor signaling in the sympathetic nervous system?

Signal amplification through a cascade of effects Signup and view all the answers

Which of the following receptors is primarily associated with skeletal muscle paralysis?

Nicotinic receptors Signup and view all the answers

Which of the following organs is not innervated by the parasympathetic nervous system?

All of the above Signup and view all the answers

What is the primary function of β2-adrenergic receptors in the lungs?

Relax bronchial muscles Signup and view all the answers

Which of the following medications is used to help individuals quit smoking?

Varenicline Signup and view all the answers

What is the primary mechanism of action of organophosphates?

Inhibit acetylcholinesterase Signup and view all the answers

Which of the following receptors is primarily associated with glands, eyes, bladder, and GI smooth muscle?

Muscarinic receptors Signup and view all the answers

Study Notes

Autonomic Nervous System (ANS)

Maintains steady state among organs; regulator of cardiac muscle, smooth muscle, glands
Targets:
- Smooth muscles (blood vessel walls, alimentary canal, urinary bladder)
- Glands (sweat glands, respiratory and GI tract)
- Cardiac muscle and cardiac electrical conduction system
Peripheral nerves gather information from target tissues through special sensory receptors:
- Chemoreceptors (send signals about pH, oxygen partial pressure)
- Mechanoreceptors (measure wall tension and pressure in blood vessels and viscera)
- Nociceptors (relay signals interpreted as pain when viscera are damaged and/or overdistended)

Sensory Component (Afferent)

Long processes go from specialized receptors in peripheral tissues to cell bodies in the dorsal root ganglia of the spinal cord
Information is transmitted to the spinal cord by short axons for processing, integration with other signals, and autonomic reflexes

Motor Component (Efferent)

Two-neuron system (preganglionic and postganglionic neurons)
Preganglionic (myelinated) neurons synapse with postganglionic neurons in ganglia
Postganglionic (unmyelinated) neurons transmit signals to target organs

Autonomic Nervous System Divisions

Sympathetic (Fight or Flight)
- Paravertebral ganglia (chains along the spinal column)
- Prevertebral ganglia (around the aorta branches)
- Neurotransmitters: epinephrine and norepinephrine
Parasympathetic (Conservation/Restoration of Energy)
- Ganglia located near or embedded in target organs
- Neurotransmitters: acetylcholine

Sympathetic Nervous System

Thoracolumbar (T1-L2)
Longitudinal set of ganglia lying next to the spinal cord
Short preganglionic neurons originate at the spine, synapse with post-ganglionic neurons, and head to effector organs

Parasympathetic Nervous System

Craniosacral (cell bodies originate in cranial nerve nuclei and sacral spinal cord)
Ganglia exist in the periphery, close to organs they innervate
Most travel out to the periphery via the VAGUS and pelvic nerves
Affects cardiac conduction

Anatomical Differences

Sympathetic: ganglia close to the spinal cord, long postganglionic fibers, lots of branching
Parasympathetic: ganglia close to target organs, short postganglionic fibers, little branching

Adrenal Medulla

Endocrine gland that behaves like a sympathetic ganglion
Sympathetic nerve fibers from the sympathetic trunk → Adrenal Medulla → Epi/Norepi released directly into the bloodstream

Autonomic Nervous System Neurotransmitters

Sympathetic PREGanglionic fibers: acetylcholine (cholinergic receptor)
Sympathetic POSTganglionic fibers: norepinephrine (adrenergic receptor)
Parasympathetic PREGanglionic and POSTganglionic fibers: acetylcholine (cholinergic receptor)

Adrenergic Receptors

G-protein coupled receptors
α-adrenergic receptors:
- α1 (excitation/stimulation, most common)
- α2 (relaxation/inhibition)
β-adrenergic receptors:
- β1 (increase heart rate, contractility, and renin release)
- β2 (relaxation of bronchi, bladder, and other muscles)
- β3 (lipolysis and thermogenesis)

Clinical Correlation

Vasopressors/Inotropes: Norepinephrine, Epinephrine, Dopamine, and inotropic drugs (Dobutamine, Milrinone)
Smoking: Nicotine acts as a nicotinic receptor agonist, involved in reward pathways with dopamine
Quitting smoking: Use a nicotinic receptor antagonist (Varenicline, Chantix)
Muscarinic receptor antagonist (Atropine): blocks PSNS input to the iris (pupil dilation), cardiac conduction system (treats bradycardia), and GI smooth muscle

Comparing Receptors

Nicotinic receptors:
- Ion-gated channels
- Found in muscles, CNS, autonomic, and more
Muscarinic receptors:
- G-protein coupled receptors
- Found in glands, eyes, bladder/GI smooth muscle, and more

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Description

Learn about the Autonomic Nervous System, its functions, and target tissues including smooth muscles, glands, and cardiac muscles.