Blood (UNIT 5 BIOLOGY)

Straw coloured liquid

Transports dissolved substances around body (hormones, nutrients (water, glucose, amino acids), waste products (CO2, urea))

Found in RBC

Carries oxygen

Quaternary structure (4 polypeptide chains)

Each chain has haem group containing iron giving red colour

(in the lungs) oxygen bonds with iron -> oxyhaemoglobin (which is reversable)

Coloured by pigment in haemoglobin

Made in bone marrow

Life span of 4 months (120 days)

Diameter of 7 micrometers

Biconcave structure = larger surface area = more oxygen transported

Have a nucleus

Larger than RBC, irregular or spherical in shape

Two basic types:

Granulocytes - granular cytoplasm and lobed nucleus

Agranulocyes - smooth looking cytoplasm and nucleus is round or horseshoe

Phagocytes

> Can escape capillaries and enter intersitial fluid

> Collect at site of infection, ingest harmful bacteria and cell debris

Lymphocytes

> Produces antibodies - chemicals that kill pathogens or stick to them for ingestion by phagocytes

Formed in bone marrow, fragments of larger cells

No nucleus

Reactions take place in cytoplasm

Roles:

Blood clotting, producing prostaglandins (regulate the degree of constriction or dilation in vessels)

Blood has several vital functions:

> Transport - oxygen, food, hormones, nutrients, etc.

> Defence - WBC - pathogens, toxins

> Form of lymph and tissue fluid

> Regulation - pH, temperature (homeostasis)

O- is a universal donor. Any blood type can accept O-

AB- can accept any blood type as it has no antibodies

Mothers often have blood group tests to see whether they are Rh positive or negative.

If mother is negative, and baby inherits fathers positive blood the mother may be exposed to babys blood during birth

Mothers blood develops antibodies, in later pregnancys if baby is positive, mothers blood may attack babys blood cells causing anaemia and possibly still birth