32 Questions
What is a partial agonist?
A substance that binds to a receptor but doesn’t activate it fully
Which receptor has a high affinity for isoproterenol?
Beta receptors
What does metoprolol selectively antagonize?
Beta-1 receptors
What is the typical synapsing pattern for sympathetic inputs to skin, blood vessels, heart, and lungs?
Neuron in the intermediolateral horn synapsing on a neuron in the paravertebral ganglion at the same spinal level
Where are the neuronal cell bodies located for the sympathetic nervous system?
Intermediolateral horn of T1 – L2
Which nervous system has long pre-ganglionic fibers and short post-ganglionic fibers?
Parasympathetic nervous system
Which cranial nerves are involved in controlling pupillary constriction, lacrimal gland and nasal mucous secretions, and salivary glands?
$VII$ (Facial), $IX$ (Glossopharyngeal), and $X$ (Vagus)
Which type of secretions are mainly under parasympathetic nervous system control?
$H_2O$-rich and more digestive enzymes
What is the function of white rami communicantes in the sympathetic nervous system?
To connect spinal nerves to paravertebral ganglia
What are the main pharmacological manipulations of the autonomic nervous system mentioned in the text?
Adrenergic agonists, adrenergic antagonists, and cholinergics
What is the main influence of the sympathetic nervous system on heart rate and cardiac output?
Increases heart rate and cardiac output
How does the parasympathetic nervous system mainly affect bodily systems according to the text?
Has limited effects outside the GI tract and reproductive organs
What are the major reflexes mentioned in the text related to the autonomic nervous system?
Baroreceptor, GI reflexes, and micturition reflex
What is influenced by the sympathetic nervous system leading to gluconeogenesis, glycogenolysis, and hyperglycemia?
Glucose metabolism
What can cause specific localized responses through reflexes and trigger a 'fight or flight' response according to the text?
Both sympathetic and parasympathetic systems
What is the main indication for phenylephrine?
Causes vasoconstriction and decreased secretions from the nasal mucosa
Why would dobutamine increase blood pressure the most?
It activates beta-1 receptors with less beta2 receptor effect
What is the main indication for clonidine?
Acts on presynaptic terminals to reduce adrenergic transmission in the central nervous system
What do albuterol and salbutamol primarily do when inhaled?
Activate beta-2 receptors in the bronchioles
What is the main action of metoprolol?
Selective beta-1 antagonist
What is the main action of isoproterenol?
Activates beta-1 and beta-2 receptors
Which part of the nervous system is responsible for controlling cranial skeletal muscles?
Somatic Motor
Which neurotransmitter is primarily associated with the Parasympathetic Nervous System?
Acetylcholine
Which part of the nervous system is responsible for stretch, pain, temperature, and chemical stimuli?
Visceral Sensory
Which division of the nervous system controls non-cranial skeletal muscles?
Somatic Motor, non-cranial
Which part of the nervous system is associated with Epinephrine and Norepinephrine as messengers?
Sympathetic Nervous System
Which neurotransmitters are primarily used by the sympathetic and parasympathetic nervous systems?
Acetylcholine and norepinephrine
Where is the nucleus responsible for most parasympathetic output found?
Dorsal motor nucleus of the vagus
What is the function of the sympathetic nervous system?
Triggers 'fight or flight' response
Where do sacral efferents, located in the S2-S4 levels, travel to supply?
Rectum, bladder, and male and female reproductive organs
What happens to 50-80% of secreted norepinephrine?
Taken up again into the presynaptic terminal
What are the major types of receptors involved in the autonomic nervous system?
Nicotinic, adrenergic, and muscarinic receptors
Study Notes
Autonomic Nervous System Anatomy and Physiology Overview
- The vagus nerve is responsible for most parasympathetic output, with its nucleus found in the dorsal motor nucleus of the vagus.
- The sacral efferents, located in the S2-S4 levels, travel with pelvic splanchnic nerves to supply the rectum, bladder, and male and female reproductive organs.
- The sympathetic and parasympathetic nervous systems use specific neurotransmitters and receptors at particular sites, with acetylcholine and norepinephrine being the main neurotransmitters.
- The sympathetic nervous system triggers the "fight or flight" response, increasing heart rate, decreasing digestive function, and increasing glucose availability.
- The parasympathetic nervous system induces the "rest and digest" response, decreasing heart rate, increasing digestive function, and increasing blood flow to the digestive tract.
- Acetylcholine is synthesized in presynaptic nerve terminals and then stored in vesicles, while norepinephrine synthesis is a slightly more complex process.
- 50-80% of secreted norepinephrine is taken up again into the presynaptic terminal, and it can be broken down by monoamine oxidase and catechol-O-methyltransferase.
- Major types of receptors include nicotinic, adrenergic, and muscarinic receptors, each with specific agonists, antagonists, and G protein signaling pathways.
- Sympathetic stimulation leads to increased heart rate and contractility, as well as vasoconstriction in the skin and most vascular beds.
- Parasympathetic stimulation mainly results in decreased heart rate and vasodilation in skeletal muscles.
- Acetylcholinesterase is widely distributed in connective tissue throughout the body and in the synapse of cholinergic terminals.
- The adrenal glands lack post-ganglionic innervation and "are" the ganglion.
Test your knowledge of the vagus nerve and its role in parasympathetic output as described in Clinical Neuroanatomy, 29th ed. and Moore’s Clinically-Oriented Anatomy. Learn about the nucleus, course, and division of the vagus nerve responsible for supplying plexuses in the abdominal cavity.
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