Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The concentration of Na+ is highest in the cytosol, and the concentration of K+ is highest in the extracellular fluid.
Ch. 11 Introduction to the Nervous System and Nervous Tissue
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
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Amerman 2nd EditionCh. 11 Introduction to the Nervous System and Nervous TissueProblem L3.1
Amerman 2nd EditionCh. 11 Introduction to the Nervous System and Nervous TissueProblem L3.1Chapter 11, Problem L3.1
The drug neostigmine blocks the actions of acetylcholinesterase in the synaptic cleft. What effect would this have on synaptic transmission? What effects might you expect to see as a result of this drug?
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Understand the role of acetylcholinesterase: Acetylcholinesterase is an enzyme that breaks down acetylcholine (ACh) in the synaptic cleft, terminating the signal transmission between neurons or between a neuron and a muscle cell. Blocking this enzyme would prevent the breakdown of ACh.
Analyze the effect of neostigmine on acetylcholine levels: Since neostigmine inhibits acetylcholinesterase, acetylcholine would accumulate in the synaptic cleft, leading to prolonged stimulation of postsynaptic receptors.
Consider the impact on synaptic transmission: The increased presence of acetylcholine would enhance synaptic transmission, causing the postsynaptic neuron or muscle cell to remain activated for a longer period than normal.
Evaluate physiological effects: Prolonged activation of acetylcholine receptors could lead to effects such as increased muscle contraction, improved communication at neuromuscular junctions (useful in conditions like myasthenia gravis), or potential overstimulation of muscles, which might result in muscle cramps or spasms.
Relate to clinical applications and side effects: Neostigmine is often used to treat conditions like myasthenia gravis by improving muscle strength. However, excessive accumulation of acetylcholine could also lead to side effects such as bradycardia (slow heart rate), excessive salivation, or gastrointestinal disturbances due to overstimulation of parasympathetic pathways.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acetylcholinesterase Function
Acetylcholinesterase is an enzyme that breaks down the neurotransmitter acetylcholine in the synaptic cleft. By hydrolyzing acetylcholine, it terminates the signal between neurons and muscle cells, allowing for precise control of muscle contraction and synaptic transmission. Inhibition of this enzyme leads to prolonged action of acetylcholine.
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Functional Groups
Synaptic Transmission
Synaptic transmission is the process by which signaling molecules, or neurotransmitters, are released from one neuron and bind to receptors on another neuron or muscle cell. This process is crucial for communication within the nervous system and involves the release of neurotransmitters, receptor activation, and subsequent cellular responses. Disruption of this process can lead to various physiological effects.
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Effects of Neostigmine
Neostigmine, by inhibiting acetylcholinesterase, increases the concentration of acetylcholine in the synaptic cleft, enhancing synaptic transmission. This can lead to increased muscle contraction and potential overstimulation of the neuromuscular junction, resulting in symptoms such as muscle twitching, cramps, or even paralysis if excessively administered. It is often used in the treatment of conditions like myasthenia gravis.
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Related Practice
Textbook Question
During a surgical procedure, an anesthesiologist administers to the patient an inhaled anesthetic agent that opens Cl− channels in the postsynaptic membranes of neurons in the brain. Explain why this would put the patient 'to sleep' for the duration of the surgical procedure.
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Textbook Question
Predict the effect that tetrodotoxin would have on Albert's muscle fiber action potentials (see question 3). Would it affect end-plate potentials at the motor end plate? Why or why not?
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Textbook Question
Albert accidentally ingests the poison tetrodotoxin from the pufferfish, which you know blocks voltage-gated Na+ channels. Predict the symptoms Albert will experience from this poisoning.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The resting membrane potential refers to the voltage difference across the membranes of excitable cells at rest.
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Textbook Question
Albert, the patient in question 3, takes the drug lithium, which reduces the permeability of the neuronal axolemma to Na+ (that is, it allows fewer Na+ to enter the axon). Predict the effect this would normally have on his neuronal action potentials. Do you think this drug would be beneficial or harmful, considering his condition?
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