TRANSPORT OF RESPIRATORY

GASES

Shows the affinity of hemoglobin for oxygen

The degree to which O₂ binds to hemoglobin is determined by the partial pressure of O₂ in the blood

OXYGEN DISSOCIATION CURVES

Hemoglobin saturated at very

high pO₂

At low pO₂ few heme bound to oxygen.

Hemoglobin does not carry much oxygen

Easier for more oxygen to be picked

up

Carbon dioxide is carried in three forms in blood plasmaDissolved as carbon dioxideReversibly converted to bicarbonate

(hydrogencarbonate) ions that are dissolved in plasma

Bound to plasma protein

CARBON DIOXIDE TRANSPORT IN BLOOD

Majority is converted to more soluble and less toxic bicarbonate (hydrogencarbonate) ion

Occurs in red blood cells

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-

Enzyme carbonic anhydrase

When cells release CO₂, bicarbonate ion and hydrogen ion are generated

pH of the blood become lowerIn lungs, when CO₂ leaves the blood, the reaction is driven to the left and

converted back to CO₂ (exhale)

CO₂ → HCO₃⁻

Metabolism ↑, more CO₂ released into blood, pH of blood ↓Low pH indicates high acidity in bloodHigh blood acidity shift the O₂ dissociation curve to the right (Low affinity of hemoglobin for O₂)Greater release of O₂ from hemoglobin

This ensures respiring tissues have enough O₂ In lungs, pCO₂ is lower, so saturation of hemoglobin can occur at lower pO₂

THE BOHR SHIFT

Hyperventilation that occurs in response to exercise

Chemoreceptors in medulla, aorta and carotid artery are able to detect changes in concentration of CO₂ in blood

High level of CO₂ triggers an increase in ventilation rate for the body to remove the CO₂ build-up

CO₂ diffuses into alveoli and ventilation expels the CO₂ from body

EFFECT OF CO₂ ON VENTILATION RATE

Medulla Oblongata(brain

stem)

Intercostal nerveStimulate the

intercostal muscle in the

thorax

Phrenic nerve Stimulate the diaphragm

REGULATION OF VENTILATION RATE

When lungs expand, stretch receptors in the walls of the chest and lungs send signals to the respiratory center

This triggers a cessation of the signals leading to inspiration until the animal exhales

Then a new signal is sent

Blood CO₂ increase

pH of blood decrease

Chemoreceptors in carotid artery and aorta sends signals to breathing center in medulla

oblongataNerve impulse sent from medulla oblongata to

diaphragm and intercostal muscle

Ventilation rate increase

CHEMORECEPTORS AND BLOOD PH

Allows the transfer of oxygen in the placenta onto the fetal

hemoglobin

Fetal hemoglobin has a higher affinity for oxygen at

all partial pressures

This ensures that oxygen is transferred to the fetus from

the maternal blood across the placenta

DIFFERENCES IN OXYGEN AFFINITY BETWEEN FETAL AND ADULT

HEMOGLOBIN

Analysis of dissociation curves for hemoglobin and myoglobin

ANALYSIS OF DISSOCIATION CURVES

INTERPRETING MICROGRAPHS OF LUNG TISSUE

Identification of pneumocytes, capillary endothelium cells and blood cells in light micrographs and electron micrographs of

lung tissue.

D.6 TRANSPORT OF RESPIRATORY GASES (AHL)

APPLICATION

pH of blood regulated to stay within the narrow range of 7.35-7.45

Blood pH falls below 7.35Chemoreceptors send signal to respiratory centre to increase the

rate of ventilationHyperventilation withdraws CO2 from the blood driving the

carbonic acid rxn to the left. Hence, this action of withdrawing Hydrogen ions from blood raising the pH

CO2+H2O=H2CO3=H++HCO3-

In the kidney, H+ ions can be secreted into the urine bound to buffers to raise the pH. Greater amounts of bicarbonate will be

reabsorbed from the tubules to neutralize the acidIf blood to basic, bicarbonate ions can be secreted into the distal

convoluted tubule of the kidneyChemical buffers exist within the extracellular fluid and these

can’t remove the acids or bases, but can minimize effect.

REGULATION OF BLOOD PH

High altitudes, amount of O2 decreased. Because pressure decreased

Volume of gases cover large area and spread further So partial pressure of O2 is reduced

Decreases hemoglobin affinity for oxygen Results is less oxygen in body tissues used for

metabolism Can cause altitude sickness- fatigue, nausea,

headaches Severe altitude sickness, loss of coordination, coma,

death

GAS EXCHANGE AT HIGH ALTITUDES

lung condition- alveoli become damaged and cannot efficiently carry out gas exchange

How? Fragile alveoli overinflate with trapped air and lose their elasticity

So? Without elasticity, gas exchange becomes difficult between alveoli and capillaries.

Enhance by? Scar tissue will build up to cover up the damaged alveoli, hence, alveoli will thicken, so gas exchange becomes more difficult

Cause? Cigarette smoking and exposure to air pollutants , genetic defect

Treatment? Cessation of smoking, avoiding air pollutants, use of chemical therapies, delivery of low levels of oxygen directly to the lungs

EMPHYSEMA