Biology: The blood and blood vessels

Blood is a tissue with 3 things suspended in plasma?

• red blood cells

• white blood cells

• platelets

What is Plasma and what does it do? State 5 points.

• A yellow liquid

• It transports cells and platelets around the body through the blood vessels

• It transports dissolved substances including carbon dioxide from respiring cells

• It transports soluble products of digestion, such as glucose & amino acids

• It transports urea - a waste product when the liver breaks down excess protein

MOST of the cells in blood are RED blood cells. They transport OXYGEN round the body & have 4 adaptations for this function. What are they?

• Contain a red pigment (HAEMOGLOBIN) which binds reversibly to oxygen.

• NO NUCLEUS - provides more space for the cell to contain Haemoglobin.

• DISC SHAPE - increases the surface area to volume ratio for diffusion.

• The flexible shape allows them to fit through narrow blood vessels.

White blood cells are LARGER than red blood cells. They have a NUCLEUS and are part of the body's immune system. Two types which are.....

• PHAGOCYTES - engulf and destroy PATHOGENS (disease-causing organisms).

• LYMPHOCYTES - produce ANTIBODIES to bind to PATHOGENS and lead to their destruction.

What are PLATELETS?

• They are fragments of cells with NO NUCLEUS.

• They are involved in causing a blood clot at a wound or cut.

• They are much smaller than red blood cells.

How do platelets protect the body from infection?

• Platelets respond to a cut or wound by TRIGGERING CLOTTING.

• Platelets are TRAPPED in a meshwork of fibrin/protein.

• The clot PREVENTS PATHOGENS from entering.

The body contains 3 different types of blood vessels called....

• Arteries

• Veins

• Capillaries

What do arteries do? How are arteries adapted to fit the purpose?

• Arteries carry blood AWAY from the heart.

• Blood in arteries is under high pressure.

• The pressure increases each time the heart pumps.

• Arteries have thick walls containing muscles and elastic fibres.

• They can stretch without bursting as blood is pumped through them. They regain their shape afterwards.

What do veins do? How are they adapted for this purpose?

• Veins carry blood TOWARDS the heart.

• Blood in veins is under the lowest pressure & is not pumped by the heart.

• Veins have thinner walls than arteries.

• Veins have a large LUMEN (space inside).

• Veins have VALVES to prevent blood flowing backwards.

What are CAPILLARIES?

• The smallest blood vessels & contain blood at low pressure.

• They form capillary beds & supply blood to the body's tissues & organs.

• Substances are exchanged between the blood in the capillaries and the cells around them.

• One blood cell wide & have thin walls so substances can diffuse through them.