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Local anesthetics suppress pain by:

A.

Blocking (Sodium) Na channels

B.

Increasing impulse conduction

C.

Blocking (Calcium) Caz" channels

D.

Blocking (Potassium) K channels

Answer and Explanation

The Correct Answer is A

A. Local anesthetics work by reversibly binding to voltage-gated sodium channels on the neuronal cell membrane. By blocking sodium influx, they prevent the generation and propagation of action potentials, which interrupts the transmission of pain signals from the peripheral nerves to the central nervous system. This is the primary mechanism by which local anesthetics provide analgesia.

B. Local anesthetics do the opposite of increasing impulse conduction. They inhibit nerve impulse transmission to prevent the sensation of pain, not enhance it.

C. Calcium channels are important for neurotransmitter release at synaptic terminals, but local anesthetics do not primarily target calcium channels to suppress pain. Calcium channel blockers are a different class of medications used for cardiac and vascular effects.

D. Potassium channels help in repolarization of neurons. Local anesthetics do not block potassium channels as their main action. Their analgesic effect is specifically due to sodium channel blockade.


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Related Questions

Correct Answer is ["50"]

Explanation

Step 1: Use the formula
Flow rate (gtt/min) = (mL/hr × Drop factor) ÷ 60

Step 2: Insert values
Flow rate = (150 × 20) ÷ 60

Step 3: Calculate
Flow rate = 3,000 ÷ 60
Flow rate = 50 gtt/min

Step 4: Round to nearest whole number
50 → 50 gtt/min

Final Answer: 50 gtt/min

Correct Answer is A

Explanation

A. Topical anesthetics are applied directly to the skin or mucous membranes (via spray, cream, gel, or ointment) to desensitize a localized area. They work by blocking nerve endingsat the surface, reducing pain for minor procedures such as IV insertion, suturing, or minor dermatologic procedures.

B. This involves injecting anesthetic near a nerve or group of nervesto block sensation in a larger region of the body, such as an arm or leg. It is more invasive than a topical spray and is used for surgical procedures requiring regional anesthesia.

C. In this type, the anesthetic is injected directly into the tissuearound a surgical site to numb a small area. Unlike topical anesthesia, it involves needle injection and is not simply applied to the surface.

D. General anesthesia induces a loss of consciousness and systemic analgesia, usually through inhalation agents or IV medications. Topical sprays are not systemicand do not cause unconsciousness, so this is not applicable.

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