Neuromuscular blocking agents cause muscle relaxation by blocking transmission at neuromuscular junctions. Neuromuscular Blocking Agents (NMBAs) These are drugs that interfere with transmission of nerve impulses at the neuromuscular junction (NMJ). They cause paralysis of skeletal muscles by blocking the action of acetylcholine (ACh), the neurotransmitter that mediates nerve impulses to muscles. They do not … Read more
Sympatholytic drugs block adrenergic activity, lowering blood pressure and reducing heart rate. (Also called Adrenergic Antagonists) Definition of Sympatholytic Drugs: These drugs block the effects of the sympathetic nervous system by inhibiting adrenergic receptors. Classification with Mechanism: Alpha-blockers: Non-selective: Phenoxybenzamine, Phentolamine Selective α1 blockers: Prazosin, Terazosin Beta-blockers: Non-selective: Propranolol Selective β1 blockers: Atenolol, Metoprolol Centrally … Read more
Sympathomimetic drugs stimulate adrenergic receptors, increasing heart rate, blood pressure, and bronchodilation. (Also called Adrenergic Agonists) Definition of Sympathomimetic Drugs: These drugs mimic the effects of the sympathetic nervous system by activating adrenergic receptors (alpha and beta receptors). Classification with MOA: Direct-acting: Act directly on adrenergic receptors (e.g., epinephrine, dobutamine) Indirect-acting: Increase release or prevent … Read more
Parasympatholytic Drugs block acetylcholine action in the parasympathetic system, reducing secretions, relaxing smooth muscles, and increasing heart rate (Also called Anticholinergics or Cholinergic Antagonists) Definition of Parasympatholytic Drugs: These drugs block the effects of the parasympathetic nervous system by inhibiting acetylcholine at muscarinic receptors. Examples of Parasympatholytic Drugs: Atropine – prototype drug Scopolamine – used … Read more
Co-transmission occurs when neurons release multiple neurotransmitters to regulate complex physiological responses. Definition of Co-transmission: It is the simultaneous release of more than one neurotransmitter from a single neuron, usually from the same synaptic vesicle or nearby vesicles. Key Features: Neurotransmitters can be classical (e.g., acetylcholine) and peptides (e.g., substance P) or amines (e.g., dopamine). … Read more
Parasympathomimetic Drugs (Cholinergic Agonists) are agents that mimic acetylcholine, stimulating parasympathetic activity to control functions like smooth muscle contraction, gland secretion, and reduced heart rate. Definition of Parasympathomimetic Drugs: Parasympathomimetics are drugs that mimic the action of the parasympathetic nervous system. They enhance the effects of acetylcholine (ACh) at muscarinic or nicotinic Classification with MOA: … Read more
Neurotransmitters are classified as excitatory, inhibitory, or modulatory, based on their role in nerve signaling. Excitatory Neurotransmitters These promote depolarization of the postsynaptic membrane, increasing the likelihood of an action potential. Glutamate: Main excitatory neurotransmitter in the CNS Aspartate: Excitatory amino acid in the CNS Acetylcholine: Excitatory at the neuromuscular junction (nicotinic receptors) Norepinephrine (Noradrenaline): … Read more
Neurohumoral transmission is the process where nerve impulses release chemical messengers to transmit signals. Definition: Neurohumoral transmission refers to the process by which a nerve impulse leads to the release of a chemical substance (neurotransmitter), which then acts on a target cell (neuron, muscle, or gland) to produce a specific physiological response. Steps of Neurohumoral … Read more
The autonomic nervous system regulates vital functions like heart rate, digestion, respiration, and glandular activity. Sympathetic Nervous System (Fight or Flight) Prepares the body for emergency or stressful situations. Physiological effects: Heart: ↑ heart rate and force of contraction (β1) Blood vessels: Vasoconstriction (α1) in skin and viscera; vasodilation (β2) in skeletal muscle Lungs: Bronchodilation … Read more
Organization of the autonomic nervous system (ANS) includes sympathetic and parasympathetic divisions controlling involuntary functions. What is the Autonomic Nervous System (ANS)? The Autonomic Nervous System (ANS) is a part of the Peripheral Nervous System (PNS) that controls involuntary body functions—those that happen without conscious thought. It regulates: Heart rate, Breathing rate, Digestion, Pupillary response, … Read more
