Cell Signalling and Molecular Physiology

Principles of Cell Signalling and Membrane Transport

Cell signalling and membrane transport are fundamental to physiology. Cells must detect, respond to, and communicate with their environment in order to maintain homeostasis. This section explores how molecules move across selectively permeable membranes and how cells transmit signals through receptor-mediated pathways. Understanding these mechanisms is essential for interpreting normal physiology and disease processes.

Membrane Transport and Molecular Movement

Key topics include diffusion, osmosis, and active transport, which describe how substances cross cell membranes. These processes underpin fluid balance, electrolyte regulation, and nutrient exchange. You will also find detailed explanations of endocytosis and exocytosis, which allow cells to internalise and secrete larger molecules. Together, these mechanisms form the basis of cellular transport physiology.

Receptors, Enzymes and Intracellular Signalling

This section also covers cellular receptors, G-proteins, enzyme kinetics, and enzyme inhibition. These concepts are central to understanding pharmacology, hormone action, and metabolic regulation. Designed for medical students and healthcare professionals, the content links molecular physiology to clinical practice, supporting exam preparation and deeper conceptual understanding.

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Enzyme Kinetics

Diagram comparing competitive and non-competitive enzyme inhibition: substrate is blocked from Enzyme A’s active site by an inhibitor, while an inhibitor binds elsewhere on Enzyme B.

Enzyme Inhibition

G-proteins

Diagram showing small uncharged molecules diffusing across a plasma membrane from extracellular fluid into the cytoplasm over time.

Diffusion

Diagram showing osmosis across a semipermeable membrane: water moves from the dilute left side to the more concentrated right side, raising the liquid level on the right.

Osmosis

Diagram of active transport across a cell membrane, showing uniporter, symporter, and antiporter proteins with directional arrows and colored particles.

Active Transport

Diagram illustrating three types of endocytosis: phagocytosis forming a vacuole around a large particle, pinocytosis forming vesicles, and receptor-mediated endocytosis forming a coated vesicle.

Endocytosis and Exocytosis

Diagram of insulin activating a tyrosine kinase receptor: insulin binding induces receptor dimerization, tyrosine phosphorylation, and recruitment of intracellular signaling proteins.

Cellular Receptors

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