OrganisationDefinitions

Key Definitions

Part of Blood Components and Vessels · GCSE GCSE Biology revision

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

21 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 and antitoxins (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.

Keep building this topic

Read this section alongside the surrounding pages in Blood Components and Vessels. That gives you the full topic sequence instead of a single isolated revision point.

How It Works: Why Red Blood Cells Are Shaped That Way Common Misconceptions The River of Life Blood Composition and Components

Practice Questions for Blood Components and Vessels

What is the main function of red blood cells?

A. To fight infection
B. To help blood clot
C. To transport oxygen
D. To carry hormones

1 markfoundation

Explain how red blood cells are adapted for their function of transporting oxygen.

4 marksstandard

Quick Recall Flashcards

What is hemoglobin?

A protein in red blood cells containing iron that binds reversibly with oxygen to transport it around the body.

What are platelets?

Small cell fragments with no nucleus that help blood clot by sticking to damaged vessels and releasing clotting factors.

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How It Works: Why Red Blood Cells Are Shaped That Way

Common Misconceptions