This definitions covers Key Definitions within Blood Components and Vessels for GCSE Biology. Blood composition, red and white blood cells, platelets, plasma, blood vessel structure and function, adaptations for transport It is section 9 of 16 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 9 of 16
Practice
18 questions
Recall
24 flashcards
Key Definitions
Plasma: The pale yellow liquid component of blood (90% water) that transports dissolved substances including glucose, urea, hormones, and proteins such as fibrinogen and antibodies.
Red blood cell (erythrocyte): A biconcave, enucleate cell packed with haemoglobin, specialised for transporting oxygen from the lungs to respiring tissues.
Haemoglobin: An iron-containing protein in red blood cells that reversibly binds oxygen, forming oxyhaemoglobin in the lungs and releasing oxygen in tissues.
White blood cell (leucocyte): A nucleated blood cell that defends the body against pathogens, either by engulfing them (phagocytes) or by producing antibodies (lymphocytes).
Phagocytosis: The process by which phagocytes engulf and digest pathogens or debris by surrounding them with their cell membrane and forming an internal vesicle.
Platelet: A small, anucleate cell fragment produced from megakaryocytes in bone marrow that triggers blood clotting by releasing chemicals at the site of vessel damage.
Fibrinogen: A soluble plasma protein that is converted into insoluble fibrin threads during blood clotting, forming the mesh that strengthens a clot.