Final answer:
Local anesthetics like lidocaine are used to temporarily numb specific areas by blocking nerve impulses, which is achieved through injection directly into the tissue where pain relief is desired. Their effect is reversible and provides targeted pain relief without affecting consciousness or causing nerve damage.
Step-by-step explanation:
Administration of a local anesthetic such as lidocaine or procaine (Novocain) involves injecting the medication directly into the tissue where pain relief is desired. When applied to nerve tissue, local anesthetics temporarily block the initiation and transmission of nerve impulses. For instance, in dental procedures, a local anesthetic may be used to numb the area around a tooth to prevent pain during treatment. The local anesthetic does this by inhibiting voltage-gated sodium channels necessary for the generation and conduction of action potentials in neurons. As a result, sensory impulses from that area do not reach the brain, effectively causing a reversible loss of sensation in the targeted area without affecting consciousness.
The mode of administration of local anesthetics is critical. They can be applied through various methods, such as injectable solutions into or around the site of pain, leading to a localized effect. This differs from general anesthetics, which are administered via inhalation or intravenously to induce unconsciousness and are often used during surgical procedures to provide a broader scope of pain relief and sedation. It is essential to understand that the action of a local anesthetic is reversible, with complete recovery in nerve function after the drug wears off, and no evidence of structural damage to nerve fibers or cells.