2.1 d - Circulatory system (blood)

Parts of blood

plasma, erythrocytes, white blood cells and platelets

Features of plasma

fluid-matrix of blood, clear straw coloured liquid, mostly water

What does plasma transport?

blood cells, glucose/amino acids, mineral ions, urea

Features of erythrocytes

contain haemoglobin, no nucleus, biconcave shape, destroyed in spleen/liver, made in red bone marrow, small/thin

What does no nucleus in erythrocytes do?

more room to carry haemoglobin

Types of white blood cells

polymorphs, monocytes, lymphocytes

Polymorphs features

most common, lobed nucleus, granular cytoplasm, phagocytosis

Monocytes features

largest, kidney shaped nucleus, phagocytosis, mature into macrophages

Lymphocytes features

large round nucleus, little cytoplasm, B lymphocytes make antibodies, T lymphocytes destroy infected cells

Platelets features

cell fragments in blood clotting

Blood clotting explanation

tissue damage activates platelets release thromboplastin forming plug and catalyses prothrombin to thrombin (with Ca2+/vitamin K. Thrombin catalyses fibrinogen to fibrin

What is haemophilia?

X-linked recessive gene mutation causing lack of clotting factors so can’t clot

Why doe blood not normally clot?

smooth lining, heparin acts as anticoagulant

Structure of haemoglobin

conjugated quaternary protein

How is conjugated quaternary protein structure of haemoglobin arranged?

4 globin polypeptide chains with iron containing haem group, binding up to 4 O2

Oxyhaemoglobin equation

Hb + 4O2 = HbO2 (reversible)

Define loading tension

partial pressure haemoglobin 95% saturated with O2

Define unloading tension

partial pressure haemoglobin 50% saturated with O2

Why is haemoglobin oxygen dissociation curve an s-shape?

difficult for 1st O2 to bind, then shape changes so easier to bind with 2nd/3rd O2, high saturation makes it hard for 4th O2 to bind

Myoglobin features

muscle O2 store with high O2 affinity. Only releases O2 at low partial pressure

Why is myoglobin curve steep then plateaus?

single polypeptide chains. Loads above 1kPa instantly unloads below 1kPa.

What is the Bohr effect?

high CO2 levels lower haemoglobin affinity for O2

Why is the CO2 Bohr Effect useful?

high CO2 indicates respiration, O2 released more readily

What factors other than CO2 have Bohr Effect?

temp, pH

Effect of altitude on O2 conc and change in O2 affinity

at high altitudes O2 conc low so blood needs higher affinity

What happens after time at high altitude

acclimation. Increase no. of erythrocytes so more efficient O2 transport and increases ventilation to improve O2 diffusion