Peripheral Nervous System (PNS) is the part of the nervous system outside the brain and spinal cord, consisting of cranial nerves, spinal nerves, and peripheral ganglia. It connects the central nervous system (CNS) to limbs and organs, enabling sensory input and motor responses. The PNS includes all nerves outside the brain and spinal cord. It … Read more
Transmembrane Enzyme-Linked Receptors are cell-surface receptors that activate intracellular enzymes upon ligand binding, regulating growth, metabolism, and cell signaling. These receptors have intrinsic enzymatic activity (often kinase activity). Most Common Type: Receptor Tyrosine Kinases (RTKs) Structure of Transmembrane Enzyme-Linked Receptors: Single transmembrane domain Extracellular ligand-binding site Intracellular tyrosine kinase domain Mechanism: Ligand binds to the … Read more
Transmembrane JAK-STAT Binding Receptors are receptors that activate JAK kinases on ligand binding, triggering STAT pathways to regulate gene expression. These receptors lack intrinsic kinase activity but associate with cytoplasmic enzymes, specifically Janus Kinases (JAKs). Structure of Transmembrane JAK-STAT Binding Receptors: Single transmembrane receptor No intrinsic enzymatic domain Mechanism: Ligand (e.g., cytokine) binds to receptor … Read more
Intracellular Receptors Regulating Transcription Factors are receptors inside cells that bind ligands and directly influence gene expression. These receptors are located inside the cell, either in the cytoplasm or nucleus. They bind lipid-soluble ligands that cross the plasma membrane. Structure of Intracellular Receptors Regulating Transcription Factors: Ligand-binding domain DNA-binding domain (zinc finger motifs) Transcriptional regulatory … Read more
Dose-Response Relationship describes how the magnitude of a drug’s effect changes with different doses, showing potency and efficacy. The dose-response relationship explains how a drug’s effect changes with varying doses—central to pharmacodynamics. Graded Dose-Response Measures the intensity of response in an individual as dose increases. Displayed as a sigmoidal (S-shaped) curve on a semi-log graph. … Read more
Therapeutic Index (TI) is the ratio between a drug’s toxic dose and effective dose, indicating its safety margin. Definition of Therapeutic Index (TI): The Therapeutic Index is a measure of drug safety. It compares the dose that causes toxicity to the dose that produces a therapeutic effect. Formula: $TI = \frac{LD_{50}}{ED_{50}}$ TD₅₀ = dose causing … Read more
Combined Effects of Drugs describe how two or more drugs interact, producing additive, synergistic, or antagonistic effects on the body. Combined Effects of Drugs When two or more drugs are used together, they may interact in different ways: Synergism Definition: Two drugs given together produce a greater effect than the sum of their individual effects. … Read more
Factors Modifying Drug Action include age, body weight, genetics, sex, disease, diet, and drug interactions that influence a drug’s effects. Factors Modifying Drug Action Several factors can influence how a drug acts in the body: Age Neonates: Immature liver/kidneys → slower metabolism and excretion. Elderly: Reduced organ function → altered drug response. Body Weight & … Read more
Adverse Drug Reactions (ADRs) are harmful or unintended effects of medicines occurring at normal therapeutic doses. Definition of Adverse Drug Reactions (ADRs): An adverse drug reaction is an unintended and harmful response to a drug that occurs at normal therapeutic doses used in humans for prophylaxis, diagnosis, or treatment. Classification of ADRs: Type A (Augmented) … Read more
Drug interactions occur when one drug affects the action of another, altering effectiveness or causing side effects. Drug Interactions Drug interactions occur when the effect of one drug is altered by the presence of another drug, food, or substance. These can be classified as pharmacokinetic or pharmacodynamic. Pharmacokinetic Interactions These involve changes in the Absorption, … Read more
