Blood. A 70kg adult has about 5.5L of blood consisting of: - Plasma (fluid) 55% total volume -...

Blood A 70kg adult has about 5.5L of blood

consisting of:- Plasma (fluid) 55% total volume- Blood cells – 45% total volume


consisting of:- Plasma (fluid) 55% total volume- Blood cells – 45% total volume The most common type of blood cells

are red blood cells (5 million per mL)



are red blood cells (5 million per mL) White blood cells (7500 per mL)



are red blood cells (5 million per mL) White blood cells (7500 per mL) Platelets (7000 per mL)

Red Blood cells Are biconcave discs – this shape

increases surface area: volume ratio = rapid uptake and release of oxygen.

Red Blood cells Are biconcave discs – this shape

increases surface area: volume ratio = rapid uptake and release of oxygen.

Capillaries have similar diameter to that of a RBC and the shape of a RBC can alter as it squeezes along it = further reducing the diffusion distance further increasing rate of oxygen movement into cells.

Red Blood cells Are biconcave discs – this shape increases

surface area: volume ratio = rapid uptake and release of oxygen.

Capillaries have similar diameter to that of a RBC and the shape of a RBC can alter as it squeezes along it = further reducing the diffusion distance further increasing rate of oxygen movement into cells.

Contain haemoglobin – a large molecule that binds oxygen and transport it through the blood.

Red Blood Cells Have no nucleus so they can’t replicate

or repair themselves.


or repair themselves. Have an average survival of about 120

days.


or repair themselves. Have an average survival of about 120

days. Constantly broken down in the spleen

and liver, and constantly made in the bone marrow.

Red Blood Cells Have no nucleus so they can’t replicate or

repair themselves. Have an average survival of about 120

days. Constantly broken down in the spleen and

liver, and constantly made in the bone marrow.

People with insufficient numbers of RBC lack energy, look pale, and are said to be anaemic.

White blood cells (leucocytes) Made in the bone marrow.

White blood cells (leucocytes) Made in the bone marrow. Contain a nucleus and protect the body

against disease.


against disease. Lymphocytes are white blood cells that

produce antibodies.



produce antibodies. Antibodies are proteins that ‘tag’ foreign

objects, and when these are tagged they can be recognised and destroyed by other WBC’s called phagocytes.



produce antibodies. Antibodies are proteins that ‘tag’ foreign

objects, and when these are tagged they can be recognised and destroyed by other WBC’s called phagocytes.

Phagocytes can alter their shape and move to sites of infection where they engulf pathogens.

White Blood cells (leucocytes) The specific region on a foreign object

that the antibody recognises is called an antigen – these are usually proteins.

White Blood cells (leucocytes) The specific region on a foreign object

that the antibody recognises is called an antigen – these are usually proteins.

Each different antigen stimulates the production of a specific antibody that will only recognise that particular antigen.

White Blood cells (leucocytes) The specific region on a foreign object that

the antibody recognises is called an antigen – these are usually proteins.


WBC’s are not confined to blood vessels – they can leave and travel through the lymph and tissue fluid around cells, seeking out pathogens.

White Blood cells (leucocytes) The specific region on a foreign object that the

antibody recognises is called an antigen – these are usually proteins.


WBC’s are not confined to blood vessels – they can leave and travel through the lymph and tissue fluid around cells, seeking out pathogens.

When leucocytes fail to mature properly, a person suffers from leukaemia.

Platelets (thrombocytes) Involved in blood clotting.

Platelets (thrombocytes) Involved in blood clotting. Release a chemical at the injury site

that converts soluble blood protein fibrinogen into insoluble fibrin.

Platelets (thrombocytes) Involved in blood clotting. Release a chemical at the injury site

that converts soluble blood protein fibrinogen into insoluble fibrin.

Fibrin forms a tangle of fibres at the clot, trapping further blood cells to form a permanent clot.

Transport of blood gases As blood passes through the lungs,

oxygen from the lungs binds to haemoglobin (Hb) in RBC’s to form oxy-haemoglobin (oxy-Hb)



Oxy-Hb releases oxygen in regions of the body low in oxygen.




Hb is a large, complex protein containing a few Fe (iron) atoms.

Transport of blood gases As blood passes through the lungs, oxygen

from the lungs binds to haemoglobin (Hb) in RBC’s to form oxy-haemoglobin (oxy-Hb)


Hb is a large, complex protein containing a few Fe (iron) atoms.

Carbon dioxide is transported from tissues to the lungs as bicarbonate ions (HCO3-) in the blood plasma.

The lymphatic system This works like a drainage system.

The lymphatic system This works like a drainage system. Lymph capillaries and lymph vessels,

similar to veins, drain excess tissue fluid from around the cells.



Lymph fluid is similar to blood, except that it contains no RBC’s and little protein.



Lymph fluid is similar to blood, except that it contains no RBC’s and little protein.

Lymph returns to the blood system via two large lymph vessels which empty into the superior vena cava – the large vein that connects to the right atrium of the heart.

Blood. A 70kg adult has about 5.5L of blood consisting of: - Plasma (fluid) 55% total volume -...

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