Definition of Centrally Acting Muscle Relaxants: Centrally acting muscle relaxants are a class of drugs that reduce muscle tone and help relieve muscle spasms through actions on the central nervous system (CNS) rather than directly on skeletal muscles. Mechanism of Action: These drugs work primarily by: Depressing neuronal activity in the brain and/or spinal cord. … Read more
Definition of Sedatives and Hypnotics: Sedatives: Drugs that reduce anxiety and exert a calming effect without inducing sleep at low doses. Hypnotics: Drugs that induce and maintain sleep at higher doses. The same drug can act as both a sedative and a hypnotic depending on dose. Mechanism of Action Most act by potentiating GABA-A receptors … Read more
Pre-anesthetics are drugs given before anesthesia to reduce anxiety, pain, and side effects during surgery. Pre-anesthetics Pre-anesthetics are drugs administered before the induction of anesthesia to improve the quality and safety of anesthesia and surgery. They are used to: Calm the patient (anxiolysis) Reduce pain (preemptive analgesia) Decrease secretions Prevent reflex responses (bradycardia, salivation) Reduce … Read more
Pharmacokinetics Absorption: Via lungs → alveoli → blood → brain Distribution: Depends on blood-gas partition coefficient Low B/G coefficient = faster induction/recovery (e.g., Desflurane) High B/G coefficient = slower induction/recovery (e.g., Halothane) Elimination: Mostly exhaled unchanged; some undergo hepatic metabolism (e.g., Halothane) Potency – Minimum Alveolar Concentration (MAC) MAC: Concentration required to prevent movement in … Read more
Definition of General Anesthetics: These are central nervous system (CNS) depressants that induce a reversible state of unconsciousness, analgesia, amnesia, muscle relaxation, and loss of reflexes to enable surgical procedures. Stages of General Anesthesia (Guedel’s Classification for Inhaled Agents) Stage I – Analgesia Patient is conscious but drowsy Perception of pain is reduced Stage II … Read more
Below we have described about the Dopamine (DA) which is a neurotransmitter that regulates movement, reward, mood, and plays a role in neurological disorders. Function of Dopamine (DA): Controls movement, reward, emotion, and endocrine regulation. Pathways: Nigrostriatal → movement control (degenerates in Parkinson disease). Mesolimbic/mesocortical → reward, salience (hyperactive in schizophrenia). Tuberoinfundibular → tonic inhibition … Read more
Serotonin (5-HT) is a neurotransmitter that regulates mood, sleep, appetite, and cognitive functions in the CNS. Function Serotonin (5-HT): Regulates mood, appetite, sleep, pain perception, and cognition. Receptors: Multiple subtypes (5-HT1 to 5-HT7) with distinct actions: 5-HT1A: mood, anxiety. 5-HT2A: hallucinations, platelet aggregation. 5-HT3: vomiting center (only ionotropic receptor). 5-HT4: GI motility. Synthesis Pathway: Tryptophan … Read more
Glycine is an inhibitory neurotransmitter in the CNS that regulates motor and sensory pathways. Function of Glycine: Inhibitory neurotransmitter, especially in spinal cord and brainstem. Facilitates Cl⁻ influx, similar to GABA-A. Receptors: Glycine receptor (ionotropic Cl⁻ channel) Also co-agonist for NMDA glutamate receptor (excitatory role there) Synthesis Pathway of Glycine: Serine → Glycine Enzyme: Serine … Read more
Glutamate is the primary excitatory neurotransmitter in the CNS, crucial for learning, memory, and brain function. Function of Glutamate: Primary excitatory neurotransmitter. Crucial for synaptic plasticity, learning, and memory. Receptors: Ionotropic: NMDA (N-Methyl-D-Aspartate) AMPA Kainate Metabotropic: mGluRs (G-protein-coupled) Synthesis Pathway of Glutamate: Glutamine (from astrocytes) → Glutamate Enzyme: Glutaminase Glutamate is packed into vesicles by … Read more
γ-Aminobutyric Acid (GABA) is the main inhibitory neurotransmitter in the CNS, reducing neuronal excitability and promoting relaxation. Function of γ-Aminobutyric Acid (GABA): Primary inhibitory neurotransmitter in the CNS. Reduces neuronal excitability and prevents overstimulation. Maintains balance with excitatory glutamate. Receptors: GABA-A (ionotropic): Ligand-gated Cl⁻ channels → fast inhibition. GABA-B (metabotropic): G-protein-coupled → opens K⁺ channels, … Read more
