IMMUNOLOGY

Detailed explanation-1: -Receptors on the cell surface bind ligand molecules on the target, such as a pathogen, dead cell, or bead. As receptors bind more and more ligand molecules, the cell membrane progressively engulfs the target. Upon full engulfment, a phagosome is formed, which fuses with lysosomes, leading to digestion of the target.

Detailed explanation-2: -Phagocytosis: Engulfment of bacteria by white blood cells and engulfment of food particles by cells are examples for phagocytosis. Pinocytosis: Uptaking of enzymes and hormones from the extracellular fluid is an example for pinocytosis.

Detailed explanation-3: -Activation. Resting phagocytes become activated by inflammatory mediators (e.g. bacterial proteins, capsules, peptidoglycan, prostaglandins, complement proteins). Chemotaxis. Margination, Rolling and Adhesion. Diapedesis. Recognition-Attachment. Phagocytosis.