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Questions and Answers
Where do the nerves of the sympathetic nervous system primarily originate?
Where do the nerves of the sympathetic nervous system primarily originate?
What is the primary action of the preganglionic neurons in the sympathetic nervous system?
What is the primary action of the preganglionic neurons in the sympathetic nervous system?
Which ganglion is responsible for innervating the stomach and small intestine?
Which ganglion is responsible for innervating the stomach and small intestine?
Which neurotransmitter is primarily released by chromaffin cells in the adrenal medulla during sympathetic activation?
Which neurotransmitter is primarily released by chromaffin cells in the adrenal medulla during sympathetic activation?
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What is the action of α1 adrenoreceptors in vascular smooth muscle?
What is the action of α1 adrenoreceptors in vascular smooth muscle?
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Which of the following best describes the function of the hypothalamus in the autonomic nervous system?
Which of the following best describes the function of the hypothalamus in the autonomic nervous system?
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Which ganglion is NOT part of the sympathetic ganglia associated with the autonomic nervous system?
Which ganglion is NOT part of the sympathetic ganglia associated with the autonomic nervous system?
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What role does Neuropeptide Y (NPY) play in the sympathetic postganglionic adrenergic nerves?
What role does Neuropeptide Y (NPY) play in the sympathetic postganglionic adrenergic nerves?
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Which medication is primarily used to treat chronic asthma when combined with steroids?
Which medication is primarily used to treat chronic asthma when combined with steroids?
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In which condition is terbutaline primarily indicated for use?
In which condition is terbutaline primarily indicated for use?
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What is the primary clinical use of methylphenidate?
What is the primary clinical use of methylphenidate?
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Which α1 antagonist is primarily used to manage pheochromocytoma?
Which α1 antagonist is primarily used to manage pheochromocytoma?
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What is the effect of propranolol in treating hyperthyroidism symptoms?
What is the effect of propranolol in treating hyperthyroidism symptoms?
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What initiates the activation of α1 adrenoreceptors?
What initiates the activation of α1 adrenoreceptors?
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What is the primary effect after the activation of α1 adrenoreceptors?
What is the primary effect after the activation of α1 adrenoreceptors?
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How does the α2 adrenoreceptor affect adenylyl cyclase activity?
How does the α2 adrenoreceptor affect adenylyl cyclase activity?
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Which of these correctly describes the activation mechanism of α1 adrenoreceptors?
Which of these correctly describes the activation mechanism of α1 adrenoreceptors?
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What are the primary locations of β1 receptors in the body?
What are the primary locations of β1 receptors in the body?
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What is the effect of noradrenaline binding to α2 adrenoreceptors?
What is the effect of noradrenaline binding to α2 adrenoreceptors?
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Where are α1 adrenoreceptors primarily located?
Where are α1 adrenoreceptors primarily located?
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What molecule is produced by activated phospholipase C after α1 receptor activation?
What molecule is produced by activated phospholipase C after α1 receptor activation?
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Which subunit of the G protein is involved in the activation of adenylyl cyclase by α2 adrenoreceptors?
Which subunit of the G protein is involved in the activation of adenylyl cyclase by α2 adrenoreceptors?
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What is the role of calcium ions in the signaling mechanism of α1 adrenoreceptors?
What is the role of calcium ions in the signaling mechanism of α1 adrenoreceptors?
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Which type of receptor is responsible for the stimulation of adenylyl cyclase and the increase of cAMP in the heart?
Which type of receptor is responsible for the stimulation of adenylyl cyclase and the increase of cAMP in the heart?
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What physiological mechanism is associated with β2 adrenoreceptors in vascular smooth muscle?
What physiological mechanism is associated with β2 adrenoreceptors in vascular smooth muscle?
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Which neurotransmitter primarily interacts with adrenoreceptors?
Which neurotransmitter primarily interacts with adrenoreceptors?
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What is the mechanism of action for the α1 adrenoreceptor in vascular smooth muscle?
What is the mechanism of action for the α1 adrenoreceptor in vascular smooth muscle?
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How do muscarinic receptors affect cAMP levels?
How do muscarinic receptors affect cAMP levels?
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What is the primary physiological response mediated by β2 adrenoreceptors?
What is the primary physiological response mediated by β2 adrenoreceptors?
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Which enzyme is likely affected by β adrenergic stimulation leading to increased second messenger levels?
Which enzyme is likely affected by β adrenergic stimulation leading to increased second messenger levels?
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Which of the following is a function of nicotinic receptors?
Which of the following is a function of nicotinic receptors?
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What roles do adrenergic receptors play in pharmacological contexts?
What roles do adrenergic receptors play in pharmacological contexts?
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In which tissue would you find α2 adrenergic receptors predominantly?
In which tissue would you find α2 adrenergic receptors predominantly?
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What occurs first after acetylcholine binds to nicotinic receptors?
What occurs first after acetylcholine binds to nicotinic receptors?
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What is the primary effect of activated phospholipase C in muscarinic receptors?
What is the primary effect of activated phospholipase C in muscarinic receptors?
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Which type of receptors are located in the sweat glands?
Which type of receptors are located in the sweat glands?
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In the activation of β2 receptors, what is the first step that occurs?
In the activation of β2 receptors, what is the first step that occurs?
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Which of the following describes the mechanism of action of indirect-acting adrenoceptor agonists like amphetamine?
Which of the following describes the mechanism of action of indirect-acting adrenoceptor agonists like amphetamine?
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What is a key clinical application of epinephrine?
What is a key clinical application of epinephrine?
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How do muscarinic receptors activate protein kinase C?
How do muscarinic receptors activate protein kinase C?
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Which receptor type binds to acetylcholine in chromaffin cells?
Which receptor type binds to acetylcholine in chromaffin cells?
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What characterizes the action of cocaine in the nervous system?
What characterizes the action of cocaine in the nervous system?
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Which agonist is used in cases of acute hypotension to provide cardiovascular support?
Which agonist is used in cases of acute hypotension to provide cardiovascular support?
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Study Notes
Sympathetic Nervous System
- The sympathetic nervous system (SNS) originates in the thoracic and lumbar spinal cord (T1 to T12 and L1 to L3)
- SNS nerves do not travel directly to the target organs.
- Instead, they synapse with neurons in ganglia located near the spinal cord.
- Two main categories of ganglia:
- Paravertebral ganglia (sympathetic chain)
- Prevertebral ganglia (celia, superior mesenteric and inferior mesenteric)
- Ganglia relay signals to effector organs.
Autonomic Nervous System
- The autonomic nervous system has both sympathetic (fight or flight) and parasympathetic (rest and digest) branches.
- This system controls involuntary bodily functions like heart rate, digestion, and pupil dilation.
Fight or Flight Response
- The fight or flight response is a physiological response to stress or perceived threat.
- The sympathetic nervous system is activated, leading to increased heart rate, blood pressure, and breathing rate; pupils dilate, slowing digestion.
- This response prepares the body for action.
Structure of the sympathetic nervous system
- SNS nerves originate in the thoracic and lumbar spinal cord (T1 to T12 and L1 to L3)
- SNS nerves do not travel directly to the organs. There are intermediary ganglia.
- Two main types of ganglia are involved:
- Para-ventral ganglia (sympathetic chain ganglia)
- Prevertebral ganglia (celia, superior mesenteric and inferior mesenteric ganglia)
Sympathetic ganglia
- Located near the spinal cord (paravertebral ganglia and the prevertebral ganglia)
- Ganglia are connected to specific target organs:
- Superior cervical ganglion → eyes and salivary glands
- Celiac ganglion → stomach and small intestine
- Superior mesenteric ganglion → small and large intestine
- Inferior mesenteric ganglion → lower large intestine, anus, bladder, and genitalia.
Receptors and Neurotransmitters of SNS
- Preganglionic neurons release acetylcholine (ACh). ACh binds to nicotinic receptors.
- Postganglionic neurons release either noradrenaline or adrenaline.
- Adrenaline is released from the adrenal medulla.
Co-transmitters in the SNS
- Sympathetic postganglionic adrenergic nerves release:
- Norepinephrine (NA)
- ATP
- Neuropeptide Y (NPY)
- These substances together affect the intensity of the response.
Brain control of ANS
- Important areas of the brain that regulate the ANS include:
- Hypothalamus
- Midbrain
- Pons
- Medulla
Classification of Receptors (Mechanism of Action)
- Adrenoreceptors and cholinergic receptors have different effects on various tissues. This is due to their mechanism of action.
A bit of Pharma...
- Drugs can have physiological and pharmacological effects on the body.
- Physiologic response: effect of the drug on the target organ/tissue.
- Pharmacological effect: effect of the neurotransmitters or drugs on the receptors, often based on the drug being antagonist or agonist.
Adrenoreceptors
- Noradrenaline and adrenaline act on adrenergic receptors in target organs.
- Two types:
- Alpha receptors (α1, α2)
- Beta receptors (β1, β2, β3)
α1 Adrenoreceptors
- Location: vascular smooth muscle of the skin, skeletal muscle, sphincters of the GI tract, radial muscle of the iris.
- Mechanism: activate a different G-protein, that leads to contraction of smooth muscle
- Effect after activation: contraction (vasoconstriction)
α2 Adrenoreceptors
- Location: presynaptically and postsynaptically in neurons, gastrointestinal tract.
- Effect after activation: inhibitory.
- Mechanisms: involve G protein, leading to inhibition of adenylyl cyclase.
β1 Adrenoreceptors
- Location: heart, salivary glands, adipose tissue, kidney.
- Mechanism: activation of adenylyl cyclase. This enzyme converts ATP to cAMP which leads to increased activity in the target tissue.
β2 Adrenoreceptors
- Location: vascular smooth muscle of skeletal muscle, walls of GI tract, bladder, and bronchioles.
- Mechanism: Same as beta 1
Cholinoreceptors
- Acetylcholine acts on the cholinergic receptors in the SNS.
- Two types:
- Nicotinic receptors
- Muscarinic receptors
Nicotinic Receptors
- Location: postganglionic neurons, chromaffin cells of the adrenal medulla.
- Mechanism: Ion channel that leads to depolarisation.
Muscarinic Receptors
- Location: sweat glands (in the sympathetic system)
- Mechanism: G-protein coupled receptor.
Indirect-Acting Adrenoceptor Agonists
- Amphetamine-like drugs
- Cocaine: blocks the DAT, inhibiting reuptake of DA.
- Mechanism: inhibit reuptake of released neurotransmitters
Clinical applications of adrenoreceptor agonists
- Used for conditions like acute hypotension, cardiac arrest or inducing local vasoconstriction, as well as pulmonary applications and ophthalmic conditions.
Clinical applications of alpha-receptor antagonists
Conditions like pheochromocytoma, hypertensive emergencies.
Beta-receptor antagonists drugs
- Propranolol and Metoprolol are nonselective and ẞ1-selective, respectively.
Clinical Applications (Various Conditions)
- These drugs can be used in treating hypertension, ischemic heart disease, glaucoma, hyperthyroidism, and several neurological conditions.
CNS control of the ANS
- The CNS, and certain structures in it, regulate the activities of the ANS
Reflex Mechanisms (e.g., blood pressure, micturition)
- Explain the importance of sympathetic and parasympathetic systems in responding to certain stimuli.
- For instance blood pressure regulation or micturition (urination)
Reflex Mechanisms (Pupil diameter)
- The pupil size is controlled by two muscles, the pupillary dilator and constrictor.
- These muscles are controlled by sympathetic and parasympathetic nervous system branches, which regulates their contraction and relaxation.
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Description
This quiz explores the sympathetic nervous system and its role within the autonomic nervous system. You will learn about the origins of the SNS, the types of ganglia involved, and how it contributes to the fight or flight response. Test your understanding of these essential physiological processes.
