A Level Eduqas Biology: Component 3: "Adaptations for the Transport of Gases in Animals"

Just Hb

What is blood?

An aqueous medium which allows the exchange and delivery of important molecules

What is plasma comprised of and what colour is it?

Glucose, amini acids, urea, antibodies, water

Straw coloured

How much of plasma is water?

90%

Name the 3 types of blood cells and what are their roles?

Erythrocytes; transport of oxygen

Leucocytes; immune response

Thrombocytes; platelets for clotting

Of the three types of blood cells, which is the most abundant?

Erythrocytes (red blood cells)

What is the role of plasma?

Distributing heat around the body

The transport of hormones, proteins, antibodies

What pigment is found in erythrocytes?

Haemoglobin

Which features of erythrocytes allow for efficient transport of oxygen?

Biconcave disc, no nucleus and flexibility

Why does having a biconcave shape allow for efficient transport of oxygen in erythrocytes?

The surface area increases and the diffusion distance decreases so theres a higher rate of diffusion

Why does a lack of nucleus aid the function of an erythrocyte?

It creates more room for haemoglobin to maximise the amount of oxygen that can be carried

Why do erythrocytes need to be flexible?

So they can fit through the narrow lumen of capillaries

Name the two groups of leucocytes and their functions.

Granulocytes; engulf pathogens

Agranulocytes; produce antibodies

Explain the differences in structure of granulocytes and agranulocytes.

G: lobed nuclei to avoid taking too much space, granular cytoplasm containing lysosomes w/ digestive enzymes

AG: spherical nucleus and a large number of RER

Describe the structure of haemoglobin

Complex globular protein with a quaternary structure of 4 polypeptide chains, containing a haem group at the centre of each polypeptide chain.

What is the role of the haem group in haemoglobin?

A binding site for one oxygen molecule

What is the equation for the reaction between haemoglobin and oxygen?

Hb + 4O2 >< Hb.O8

Define affinity

One molecule having a chemical attraction for another

Define saturation

The percentage of oxygen bound to haemoglobin

Define association/loading

The uptake of oxygen by haemoglobin to form oxyhaemoglobin at the lungs

Define dissociation/unloading

The release of oxygen at the respiring tissues to form haemoglobin

Define cooperative binding

The increasing ease with which haemoglobin binds to its second and third oxygen molecules, as the conformation of the haemoglobin changes

What do we measure the concentration of oxygen by?

Partial pressure

Where is the ppO2 high and what occurs because of this?

The lungs

Oxygen associates with haemoglobin

Where is ppO2 low and what occurs because of this?

Respiring tissues

Oxygen dissociates from oxyhaemoglobin, forming haemoglobin

What is the shape of the oxygen dissociation curve?

Sigmoidal

In terms of haemoglobin affinity, what is the difference between low ppO2 and high ppO2?

low- low affinity

high- high affinity for oxygen

What are the title axes for the oxygen dissociation curve?

pp02 and oxygen saturation of haemoglobin

Oxygen affinity decreases as ppO2 does. What is this significant in humans?

Oxygen is readily released to meet respiratory demands. A small pp02 reduction leads to a rapid dissociation of oxygen.

Why is ppO2 low in respiring tissues?

Oxygen is being used up in aerobic respiration

Compared to the normal oxygen dissociation curve, what does the foetal curve look like?

It shifts to the left

Why is the foetal oxygen dissociation curve shifted to the left?

It means the foetus has a higher affinity for oxygen and can associate with oxygen from the mothers blood at all ppO2.

Why do animals who live at high altitude have more red blood cells?

They will have more haemoglobin for carrying oxygen

Describe llama haemoglobin, referring to its habitat.

Llama at high altitudes, so theres a drop in atmosphere pressure and ppO2. Llama haemoglobin has a higher affinity for oxygen and picks up oxygen more readily

Describe lugworm haemoglobin with reference to its haemoglobin.

They live in sand burrows on the seashore so they obtain oxygen from seawater, which has a low ppO2. Their haemoglobin has a higher affinity for oxygen.

What is myoglobin?

An oxygen store in muscle tissue

What is the oxygen dissociation curve of myoglobin like?

Far to the left of normal haemoglobin.

What does the myoglobin oxygen dissociation curve show about the way it works in different ppO2?

At every ppO2, myoglobin has a higher % oxygen saturation than haemoglobin. At very low ppO2, oxymyoglobin unloads all of its oxygen

What causes the Bohr effect?

When ppCO2 is high, the conditions become more acidic causing haemoglobin to change shape and have a lower affinity for oxygen.

What does the oxygen dissociation curve of the Bohr effect look like?

Shifted to the right

Why is the Bohr effect beneficial?

The high ppCO2 is caused by actively respiring tissues. The lowered affinity of haemoglobin means oxyhaemoglobin dissociates more readily at respiring tissues.

What is the lymphatic system involved in?

The absorption of lipids in the small intestine.

The formation if lymphocytes and the prevention of disease

How does lymph return to the venous system?

Via the thoraic duct to the left subclavian vein above the heart.

What is lymph?

The remaining tissue fluid that doesnt return to capillaries at the venous end of a capillary bed

How much of tissue fluid becomes lymph?

10%

How much of CO2 in the blood is converted to HCO3- ions and transported in plasma?

85%

How much CO2 dissolves in plasma?

5%

Explain the process of CO2 being converted to HCO3-

CO2 from respiring cells diffuses into red blood cells in the plasma

It reacts with water to form carbonic acid, catalysed by carbonic anhydrase

Carbonic anhydrase is unstable to immediately dissociates into H+ ions and hydrogen carbonate ions

What happens to the HCO3- ions after they form in the red blood cells from CO2?

They diffuse down their conc gradient into the plasma

They combine with Na+ ions to form sodium hydrogen carbonate

What happens to the H+ ions formed from CO2 ions in red blood cells?

It causes a fall of pH and reduces the haemoglobin affinity for oxygen. They do this by reacting with oxyhaemoglobin to form haemoglobinic acid and oxygen. This oxygen diffuses back into respiring tissues.

What is the equation between H+ ions and oxyhaemoglobin?

H+ + Hb.O8 = HHb + 4O2

Why is the process of CO2 reactions in the red blood cells called the chloride shift?

The movement of HCO3- iobs out of red blood cells is balances by Cl- ions moving in from the tissue fluid by facilitated diffusion. They do this to maibtain the electrochemical neutrality.

What causes kwashiokor?

Lack of protein due to malnutrition there less plasma protein. The blood has a higher water potential so osmotic pressure is greater than hydrostatic pressure. Tissue fluid then remains in the tissue,making them swell.

How does tissue fluid form?

The blood has high hydrostatic pressure which is greater than osmotic pressure. There is a net flow of fluid out of the blood, forced through gaps in the capillary so plasma becomes tissue fluid, just without plasma proteins

In terms of capillaries, what is osmotic pressure?

Water trying to get into the blood

Where does plasma become tissue fluid?

Arteriole end of a capillary bes

What happens at the venous end of a capillary bed?

Tissue fluod contains waste substances and diffuses back into the capillary down a conc gradient. Friction between the blood and the capillary results in a smaller volume of fluid and therefore lower hydrostatic pressure. The osmotic pressure is greater so theres a net movement of water back into the blood.

What helps decrease the water potential and therefore hydrostatic pressure of the blood in the venous end of a capillary bed?

The presence of plasma proteins