IB MYP Integrated Science- Biology - Blood components -Study Notes - New Syllabus

Blood Components

🌟 Introduction

Blood is the body’s transport system.
It carries oxygen, nutrients, hormones, wastes and helps in defense, clotting, and maintaining internal balance.

It has two main parts:

• Plasma (liquid)
• Formed elements (cells + platelets)

🌊 Plasma (Fluid Part)

Pale yellow fluid, 55 percent of total blood.
Made of 90 percent water plus dissolved substances.
It helps in transport, maintaining pH, and maintaining fluid balance.

What plasma carries:

• Nutrients: glucose, amino acids, fatty acids.
• Gases: carbon dioxide (mostly as bicarbonate).
• Wastes: urea, uric acid.
• Proteins:
  • Albumin (maintains osmotic pressure)
  • Globulins (antibodies)
  • Fibrinogen (clotting)
• Hormones, salts, vitamins.

🔴 Red Blood Cells (RBCs) / Erythrocytes

• Most abundant blood cells.
• Biconcave discs to increase surface area.
• No nucleus (in mammals).
• Packed with hemoglobin that binds oxygen.

Functions

• Carry oxygen from lungs to tissues.
• Carry carbon dioxide from tissues to lungs (small amount).

Life span: About 120 days, destroyed in liver and spleen.

Made in: Bone marrow (red bone marrow).

⚪ White Blood Cells (WBCs) / Leukocytes

Have nucleus, fewer in number than RBCs.
Defend the body against pathogens.

📌 Types of WBCs

A. Granulocytes

• Neutrophils
  Most abundant.
  First responders.
  Kill bacteria by engulfing them (phagocytosis).
• Eosinophils
  Fight parasitic infections.
  Involved in allergies.
• Basophils
  Release histamine and heparin.
  Important in inflammation.

B. Agranulocytes

• Lymphocytes
  B-cells: make antibodies.
  T-cells: kill infected cells.
  Memory cells: long-term immunity.
• Monocytes
  Largest WBC.
  Turn into macrophages and eat dead cells, bacteria.

🟡 Platelets (Thrombocytes)

• Fragments of big cells called megakaryocytes.
• No nucleus.
• Essential for blood clotting.

Role in clotting:

• Stick to damaged blood vessels.
• Release chemicals that turn fibrinogen into fibrin threads.
• Fibrin forms a mesh trapping RBCs → clot is formed.

📋 Summary Table

🧠 Quick Recap 
Plasma = transport liquid.
RBCs = oxygen carriers, no nucleus.
WBCs = body’s defense army.
Platelets = clot makers.
WBC order: N L M E B.