Autonomic Nervous System Receptors and Drug Action Quiz

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Questions and Answers

Which nervous system is involved in the involuntary, unconscious control of functions?

Peripheral nervous system

Autonomic nervous system (correct)

Somatic nervous system

Central nervous system

What is the main contrast between the autonomic nervous system (ANS) and the somatic nervous system?

The ANS is unconscious and automatic, while the somatic nervous system is voluntary. (correct)

The ANS uses different neurotransmitters than the somatic nervous system.

The ANS is involved in brain and spinal cord functions, while the somatic nervous system is involved in peripheral tissues.

The ANS controls voluntary functions, while the somatic nervous system controls involuntary functions.

Which part of the nervous system innervates the gastrointestinal tract (GIT), pancreas, and gallbladder?

Autonomic nervous system (correct)

Somatic nervous system

Central nervous system

Peripheral nervous system

What type of neurons carry signals away from the central nervous system to the peripheral tissues?

Efferent neurons of ANS Signup and view all the answers

Which neurotransmitter chemistry is specifically discussed in the context of the autonomic nervous system?

Acetylcholine and norepinephrine Signup and view all the answers

Which nervous system is involved in the voluntary control of functions?

Somatic nervous system Signup and view all the answers

Which type of neurons bring information from the periphery to the central nervous system?

Afferent neurons of ANS Signup and view all the answers

Where do sympathetic preganglionic fibers originate?

Thoracic and lumbar segments of the cord Signup and view all the answers

Where are most sympathetic ganglia located?

Paravertebral chains along the spinal column Signup and view all the answers

Which receptors respond to acetylcholine?

Muscarinic and nicotinic receptors Signup and view all the answers

What determines the effect on the eye, such as pupil dilation or constriction?

Sympathetic or parasympathetic response Signup and view all the answers

What can pharmacologic ganglionic blockade cause changes in?

Pupil size and cardiac sinus node pacemaker rate Signup and view all the answers

Where do parasympathetic preganglionic motor fibers originate?

Cranial nerve nuclei III, VII, IX, and X and in sacral spinal cord segments Signup and view all the answers

What are the two major subdivisions of the autonomic nervous system?

Parasympathetic ANS (PANS) and sympathetic ANS (SANS) Signup and view all the answers

What type of receptors mediate the negative feedback of norepinephrine on its own release at nerve endings?

Alpha adrenoceptors Signup and view all the answers

Which receptors modulate transmitter release at nerve endings?

Presynaptic autoreceptors Signup and view all the answers

What does denervation supersensitivity refer to?

Increased sensitivity to denervation of tissues Signup and view all the answers

What occurs in autonomic effector tissues after administration of certain drugs?

Pharmacologic supersensitivity Signup and view all the answers

Which receptors primarily control the pupil and ciliary muscle in the eye?

Muscarinic receptors Signup and view all the answers

What effect does parasympathetic nerve activity and muscarinic cholinomimetics have on the circular pupillary constrictor muscle?

Causes miosis Signup and view all the answers

What is the result of alpha adrenoceptors mediating contraction of the pupillary dilator muscle fibers in the iris?

Causes mydriasis Signup and view all the answers

What do beta adrenoceptors on the ciliary epithelium facilitate?

Secretion of aqueous humor Signup and view all the answers

What is the therapeutic effect of blocking beta adrenoceptors on the ciliary epithelium?

Reduces intraocular pressure Signup and view all the answers

Which type of receptors are mainly found on autonomic effector cells, with evidence for 5 subtypes, 3 of which are essential in peripheral autonomic transmission?

Muscarinic receptors Signup and view all the answers

Where are nicotinic receptors primarily located?

Ganglia and skeletal muscle end plates Signup and view all the answers

Adrenoceptors, also known as adrenergic receptors, are divided into which subtypes?

Alpha and beta Signup and view all the answers

Which subclass of adrenoceptors have different distribution and function, with the D1 subtype being particularly important on peripheral effector-cells?

Dopamine (D) receptors Signup and view all the answers

Where may autonomic drugs act at various sites?

CNS centers, ganglia, postganglionic nerve terminals, effector cell receptors, and the mechanisms responsible for transmitter synthesis, storage, release, and termination of action Signup and view all the answers

What mainly provides functional integration in the ANS through negative feedback?

Modulatory pre- and postsynaptic receptors at the local level and homeostatic reflexes at the systemic level Signup and view all the answers

What do systemic reflexes regulate?

Processes such as blood pressure, gastrointestinal motility, bladder tone, and airway smooth muscle Signup and view all the answers

What is the total body water content of a 70 kg person?

~42 L Signup and view all the answers

Where is the majority of daily water intake derived from?

Fluids taken orally Signup and view all the answers

What term is used to describe the condition where fluid accumulates in body compartments?

Overhydration Signup and view all the answers

What is the clinical assessment of skin turgor, eyeball tension & the mucous membranes used for?

Assessment of hydration status Signup and view all the answers

What are the clinical features of intracellular fluid loss?

Lethargy, confusion & coma Signup and view all the answers

What are the effects of fluid depletion when the water loss is spread across both ECF & ICF compartments?

Signs of fluid depletion are not seen at first Signup and view all the answers

What percentage of filtered sodium is normally reabsorbed in the proximal tubule?

60-75% Signup and view all the answers

Which hormone stimulates sodium reabsorption in the distal parts of the distal convoluted tubules and collecting ducts?

Aldosterone Signup and view all the answers

What is the serum sodium concentration range for defining hyponatremia?

133–146 mmol/L Signup and view all the answers

What is the most common cause of hyponatremia due to water retention?

SIAD (syndrome of inappropriate antidiuretic hormone) Signup and view all the answers

What can hyponatremia result from, besides water imbalance?

Sodium loss Signup and view all the answers

What are the symptoms of hyponatremia?

Nausea, malaise, headache Signup and view all the answers

Which of the following is NOT a role of water in the human body?

Regulating blood glucose levels Signup and view all the answers

What is the principal extracellular cation in the body?

Sodium Signup and view all the answers

What is the role of antidiuretic hormone (ADH) in the kidneys?

Promotes water reabsorption Signup and view all the answers

What does hypernatremia primarily pose a concern for?

Unconscious patients Signup and view all the answers

What physical property is crucial for hypothalamic responses and is affected by sodium concentration?

Osmolality Signup and view all the answers

What does the osmolal gap indirectly indicate the presence of?

Osmotically active substances other than sodium, urea, or glucose Signup and view all the answers

What is the recommended maximal rate for correcting hypernatraemia to avoid cerebral edema and death?

0.5 mmol/L per hour Signup and view all the answers

What is the serum sodium level associated with a mortality rate of 60-75% in hypernatraemia?

Above 160 mmol/L Signup and view all the answers

What are the clinical features associated with hypernatraemia?

Altered mental status, seizures, and fever Signup and view all the answers

What is the urine osmolality related to hypernatraemia?

700 mOsm/kg Signup and view all the answers

What is the commonest and most serious electrolyte emergency that can cause muscle weakness, cardiac arrest, and ECG changes?

Hyperkalaemia Signup and view all the answers

What is the role of potassium (K) in determining the resting membrane potential of cells?

It maintains the resting membrane potential Signup and view all the answers

Which of the following is a cause of pseudohyperkalemia?

Movement of potassium out of cells during or after drawing blood Signup and view all the answers

Which treatment should not be given faster than 20 mmol/hour for hypokalemia, except in extreme cases and under ECG monitoring?

Intravenous potassium for severe depletion Signup and view all the answers

What is a symptom of hyperkalemia?

Muscle weakness Signup and view all the answers

Which condition is characterized by recurrent attacks of muscle weakness or paralysis?

Hyperkalemic periodic paralysis Signup and view all the answers

What is a common cause of hypokalemia?

Vomiting Signup and view all the answers

What is used to treat severe hyperkalemia by stimulating cellular uptake of potassium?

Insulin Signup and view all the answers

What is the total volume of interstitial fluid in a 70 kg person?

10.5 L Signup and view all the answers

What percentage of a 70 kg person's body weight is accounted for by water?

60% Signup and view all the answers

What is the daily water intake recommended for individuals?

1.5-2 L Signup and view all the answers

What is the term used to describe the condition where fluid accumulates in body compartments?

Overhydration Signup and view all the answers

What is the term for the assessment of volume of body fluid compartments?

Clinical assessment Signup and view all the answers

What clinical feature may not always be reliable in assessing a patient's state of hydration?

Skin turgor Signup and view all the answers

Which of the following is a cause of pseudohyperkalemia?

Potassium movement out of cells during or after drawing blood Signup and view all the answers

What is the recommended maximal rate for correcting hypokalemia to avoid complications?

20 mmol/hour Signup and view all the answers

What is a common cause of hyperkalemia?

Renal failure Signup and view all the answers

What is a symptom of hypokalemia?

Muscle weakness and paralysis Signup and view all the answers

What treatment is used for severe hyperkalemia to stimulate cellular uptake of potassium?

Insulin Signup and view all the answers

What is a cause of hypokalemia?

Vomiting Signup and view all the answers

What plays a crucial role in regulating water reabsorption in the kidneys?

Antidiuretic hormone (ADH) Signup and view all the answers

What is the principal extracellular cation?

Sodium Signup and view all the answers

What physical property is crucial for hypothalamic responses and is affected by sodium concentration?

Osmolality Signup and view all the answers

What percentage of filtered sodium is normally reabsorbed in the proximal tubule?

70-80% Signup and view all the answers

What does the osmolal gap indirectly indicate the presence of?

Osmotically active substances other than sodium, urea, or glucose Signup and view all the answers

What is the serum sodium concentration range for defining hyponatremia?

133–146 mmol/L Signup and view all the answers

What is the most common cause of hyponatremia due to water retention?

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) Signup and view all the answers

Which hormone stimulates sodium reabsorption in the distal parts of the distal convoluted tubules and collecting ducts?

Aldosterone Signup and view all the answers

What primarily determines plasma osmolality?

Sodium concentration Signup and view all the answers

What is the most common cause of hyponatremia due to water retention?

SIAD Signup and view all the answers

What are the symptoms of hyponatremia?

All of the above Signup and view all the answers

What does ECF volume depend on?

Total body sodium content Signup and view all the answers

What is the recommended maximal rate for correcting hypernatraemia to avoid cerebral edema and death?

0.5 mmol/L per hour Signup and view all the answers

What is the serum sodium level associated with a mortality rate of 60-75% in hypernatraemia?

160 mmol/L Signup and view all the answers

What are the clinical features of hypernatraemia?

Altered mental status, seizures, and fever Signup and view all the answers

What is the role of potassium (K) in determining the resting membrane potential of cells?

It maintains the resting membrane potential Signup and view all the answers

What is the reciprocal relationship between potassium and hydrogen ions in acidosis and alkalosis related to?

Urinary loss of potassium Signup and view all the answers

What is the commonest and most serious electrolyte emergency, which can cause muscle weakness, cardiac arrest, and ECG changes?

Hyperkalemia Signup and view all the answers

What is the total amount of water in liters in a 70 kg person's body?

42 L Signup and view all the answers

What is the volume of interstitial fluid in the body of a 70 kg person?

10.5 L Signup and view all the answers

What is the daily water intake recommended for an individual?

1.5-2 L Signup and view all the answers

What is the term used to describe the condition where fluid accumulates in body compartments?

Overhydration Signup and view all the answers

What clinical feature may not always be reliable in assessing a patient's state of hydration?

Skin turgor Signup and view all the answers

What are the clinical manifestations of intracellular fluid loss?

Lethargy, confusion & coma Signup and view all the answers

What is the primary role of antidiuretic hormone (ADH) in the kidneys?

Stimulating water reabsorption in the kidneys Signup and view all the answers

What is the principal extracellular cation in the body?

Sodium Signup and view all the answers

What is the physical property crucial for hypothalamic responses and affected by sodium concentration?

Osmolality Signup and view all the answers

What is the difference between measured and calculated osmolality used to indirectly indicate the presence of osmotically active substances other than sodium, urea, or glucose?

Osmolal gap Signup and view all the answers

What plays a crucial role in determining cell volume and regulating body temperature through sweating?

Water Signup and view all the answers

What is the most common route for water and sodium output from the body?

Kidneys Signup and view all the answers

What is the maximal recommended rate for correcting hypernatraemia to avoid cerebral edema and death?

0.5 mmol/L per hour Signup and view all the answers

What is the serum sodium level associated with a mortality rate of 60-75% in hypernatraemia?

160 mmol/L Signup and view all the answers

What is the commonest and most serious electrolyte emergency that can cause muscle weakness, cardiac arrest, and ECG changes?

Hyperkalemia Signup and view all the answers

What is the recommended maximal rate for correcting hypokalemia to avoid complications?

20 mmol/L per hour Signup and view all the answers

What is the reciprocal relationship between potassium and hydrogen ions in acidosis and alkalosis related to?

Urinary loss of potassium Signup and view all the answers

What are the clinical features of hypernatraemia?

Altered mental status, seizures, fever, nausea, vomiting Signup and view all the answers

What percentage of filtered sodium is normally reabsorbed in the proximal tubule?

60-75% Signup and view all the answers

What is the definition of hyponatremia?

Serum sodium concentration below 133 mmol/L Signup and view all the answers

What is the most common cause of hyponatremia?

SIAD (syndrome of inappropriate antidiuretic hormone secretion) Signup and view all the answers

What are the symptoms of hyponatremia?

Nausea, malaise, and headache Signup and view all the answers

What is the treatment for hyponatremia dependent on?

Patient's volume status Signup and view all the answers

What is the role of aldosterone in regulating urinary sodium output?

Stimulates sodium reabsorption in the distal convoluted tubules and collecting ducts Signup and view all the answers

What is the treatment for severe hyperkalemia that involves stimulating cellular uptake of potassium?

Insulin and glucose Signup and view all the answers

Which condition results from potassium movement out of cells during or after drawing blood, especially if the sample is delayed in separation or refrigerated, often due to haemolysis?

Pseudohyperkalemia Signup and view all the answers

What is a common cause of hypokalemia?

Chronic laxative abuse Signup and view all the answers

What is the plasma potassium level range for defining hypokalemia?

2.5 - 3.5 mmol/L Signup and view all the answers

What is the recommended maximal rate for correcting hypokalemia to avoid complications?

20 mmol/hour Signup and view all the answers

What is the most common cause of hyperkalemia?

Renal failure Signup and view all the answers

Study Notes

Autonomic Nervous System Receptors and Drug Action

Muscarinic receptors are mainly found on autonomic effector cells, with evidence for 5 subtypes, 3 of which are essential in peripheral autonomic transmission, all G-protein-coupled.
Nicotinic receptors respond to acetylcholine and nicotine, located in ganglia and skeletal muscle end plates, and are the primary receptors for transmission at these sites.
Adrenoceptors, also known as adrenergic receptors, are divided into alpha and beta subtypes, each with distinct locations and G-coupling proteins.
Dopamine (D) receptors, a subclass of adrenoceptors, have different distribution and function, with the D1 subtype being particularly important on peripheral effector-cells.
Autonomic drugs may act at various sites, including CNS centers, ganglia, postganglionic nerve terminals, effector cell receptors, and the mechanisms responsible for transmitter synthesis, storage, release, and termination of action.
Functional integration in the ANS is mainly provided through negative feedback, using modulatory pre- and postsynaptic receptors at the local level and homeostatic reflexes at the systemic level.
Central integration at the highest level involves the integration of the two divisions of the ANS and the endocrine system with sensory input and information from higher CNS centers.
Systemic reflexes regulate processes such as blood pressure, gastrointestinal motility, bladder tone, and airway smooth muscle, with the control of blood pressure being especially important.
Homeostatic mechanisms have evolved to maintain mean arterial blood pressure at a level determined by the vasomotor center and renal sensors, with any deviation causing a change in ANS activity and renin-angiotensin-aldosterone levels.
Compensatory responses, such as increased sympathetic activity and renin release in response to decreased blood pressure caused by hemorrhage, are important in determining the response to conditions or drugs that alter blood pressure.
The treatment of hypertension with a vasodilator may be unsuccessful if compensatory responses, such as tachycardia and salt and water retention, are not prevented through the use of additional drugs, highlighting the importance of understanding the homeostatic system.
The text provides a comprehensive understanding of the different receptor types in the autonomic nervous system, their distribution, function, and the sites at which autonomic drugs may act, as well as the mechanisms and importance of functional integration and systemic reflexes in maintaining homeostasis.

Hyperkalemia and Hypokalemia: Causes, Symptoms, and Treatment

Insulin is used to treat severe hyperkalemia by stimulating cellular uptake of potassium
Hyperkalemic periodic paralysis is a rare autosomal dominant disorder causing recurrent attacks of muscle weakness or paralysis
Pseudohyperkalemia results from potassium movement out of cells during or after drawing blood, especially if the sample is delayed in separation or refrigerated, often due to haemolysis
Causes of hyperkalemia include decreased excretion due to renal failure and hypoaldosteronism, which can be seen with the use of certain medications
Symptoms of hyperkalemia include muscle weakness, tingling, numbness, mental confusion, cardiac arrhythmia, and fatal cardiac arrest at high concentrations
Treatment of hyperkalemia includes infusion of calcium gluconate, bicarbonate, insulin, and glucose, loop diuretics, sodium polystyrene sulfonate enema, and dialysis
Hypokalemia is a plasma potassium level below the lower limit of the reference range and can result from GI or urinary loss or increased cellular uptake of potassium
Common causes of hypokalemia include vomiting, diarrhea, diuretics, metabolic alkalosis, insulin treatment, refeeding, β-agonism, treatment of anemia, and hypokalemic periodic paralysis
Increased gastrointestinal and urinary losses are common causes of hypokalemia, with chronic laxative abuse as a less frequent cause
Symptoms of hypokalemia range from mild (asymptomatic) to muscle weakness and paralysis, particularly dangerous for patients with cardiovascular disease
Treatment of hypokalemia includes prophylactic oral potassium salts, intravenous potassium for severe depletion, and diet rich in potassium for mild chronic hypokalemia
Intravenous potassium should not be given faster than 20 mmol/hour except in extreme cases and under ECG monitoring

Hypernatraemia and Hyperkalaemia: Key Points

Hypernatraemia is defined as a serum sodium level above the reference interval of 133–146 mmol/L, developing due to water loss or sodium gain.
Causes of hypernatraemia include excess water loss, decreased water intake, and increased sodium intake or retention (salt poisoning).
Clinical features of hypernatraemia include altered mental status, seizures, fever, nausea, vomiting, lethargy, restlessness, and muscle twitching.
Hypernatraemia with a serum sodium level of more than 160 mmol/L is associated with a mortality rate of 60-75%.
Urine osmolality of 700 mOsm/kg, loss of thirst, insensible loss of water, GI loss of hypotonic fluid, and excess intake of sodium are related to hypernatraemia.
Treatment of hypernatraemia involves correcting pure water loss with oral or IV water, administering sodium for dehydration, and using diuretics and natriuresis for salt poisoning and sodium overload.
The maximal rate for correcting hypernatraemia should be 0.5 mmol/L per hour to avoid cerebral edema and death.
Sodium can be measured in serum, plasma, urine, and sweat, and hemolysis does not significantly affect serum or plasma values of sodium.
Potassium (K) disorders are important due to K's role in determining the resting membrane potential of cells, and changes in plasma K levels can cause fatal consequences such as arrhythmias.
Factors affecting plasma K concentration include intracellular K reservoir, K intake and excretion routes, and redistribution of potassium.
There is a reciprocal relationship between potassium and hydrogen ions in acidosis and alkalosis, affecting urinary loss of potassium.
Hyperkalaemia, the commonest and most serious electrolyte emergency, can cause muscle weakness, cardiac arrest, and ECG changes that mimic other conditions, warranting serum potassium checks after cardiac arrest.

Hyperkalemia and Hypokalemia: Causes, Symptoms, and Treatment

Insulin is used to treat severe hyperkalemia by stimulating cellular uptake of potassium
Hyperkalemic periodic paralysis is a rare autosomal dominant disorder causing recurrent attacks of muscle weakness or paralysis
Pseudohyperkalemia results from potassium movement out of cells during or after drawing blood, especially if the sample is delayed in separation or refrigerated, often due to haemolysis
Causes of hyperkalemia include decreased excretion due to renal failure and hypoaldosteronism, which can be seen with the use of certain medications
Symptoms of hyperkalemia include muscle weakness, tingling, numbness, mental confusion, cardiac arrhythmia, and fatal cardiac arrest at high concentrations
Treatment of hyperkalemia includes infusion of calcium gluconate, bicarbonate, insulin, and glucose, loop diuretics, sodium polystyrene sulfonate enema, and dialysis
Hypokalemia is a plasma potassium level below the lower limit of the reference range and can result from GI or urinary loss or increased cellular uptake of potassium
Common causes of hypokalemia include vomiting, diarrhea, diuretics, metabolic alkalosis, insulin treatment, refeeding, β-agonism, treatment of anemia, and hypokalemic periodic paralysis
Increased gastrointestinal and urinary losses are common causes of hypokalemia, with chronic laxative abuse as a less frequent cause
Symptoms of hypokalemia range from mild (asymptomatic) to muscle weakness and paralysis, particularly dangerous for patients with cardiovascular disease
Treatment of hypokalemia includes prophylactic oral potassium salts, intravenous potassium for severe depletion, and diet rich in potassium for mild chronic hypokalemia
Intravenous potassium should not be given faster than 20 mmol/hour except in extreme cases and under ECG monitoring

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Description

Test your knowledge of autonomic nervous system receptors and drug action with this quiz. Explore the distribution, function, and subtypes of muscarinic, nicotinic, adrenoceptors, and dopamine receptors, as well as the sites where autonomic drugs may act. Gain insights into the mechanisms and significance of functional integration, systemic reflexes, and homeostatic regulation in maintaining physiological balance.