The Blood How many litres of blood do

The Blood • How many litres of blood do you have in your body? • 4 -6 L • Blood has four main components – Plasma – Red blood cells – White blood cells – Platelets

Plasma (55%) • Straw coloured solution containing – Water with dissolved salts (90%) – Plasma proteins (10%) – Nutrients, metabolic wastes, hormones, O 2, CO 2 • Plasma proteins help transport vitamins and fight viral and bacterial infections

Red Blood Cells (41%) • Carry oxygen (hemoglobin) • Produced in bone marrow (2 million/second) • No nuclei – Life span of ~100 days – Gives them a flat disk shape – Increased surface area for O 2 molecules – Flexibility to squeeze through different sized blood vessels

Sickle Cell Anemia

White Blood Cells (3%) • Fight infection, parasites, and bacteria • Can move through blood vessel walls • Your WBC count increases when you have an infection • Pus is WBCs and dead bacteria • Produced in the bone marrow • Life span of years

Platelets (1%) • Help with blood clotting • Release clotting factors • Scab forms

Blood Type

Blood Vessels • Arteries • Capillaries • Veins

Arteries: – Carry blood away from the heart to the body tissues – Smaller diameter – High pressure Capillaries: – Exchange of nutrients and wastes (diffusion gradient) – Tiny tubes with large surface area Veins: – – Carry blood back to the heart Larger diameter Low pressure Valves allow blood to only flow in one direction