PARTIAL PRESSURES

When we see this picture we must think of High to Low.

You must include where the pO2 (partial pressure of Oxygen) or pCO2 (partial pressure of carbon dioxide) is high or low.

Where being: Atmosphere Alveolus Pulmonary Artery Pulmonary Capillary Pulmonary Vein

Use the figures in your answer

For Diffusion to occur: requires a difference in

partial pressures; Oxygen from alveolus to pulmonary artery; Because of 103 compared to 35; Carbon dioxide from artery to alveolus; Because 44 compared to 38;

To explain exercise changes: Reduced pO2 in artery – Why? O2 used; Reduced pO2 in alveolus – Why? O2 used; Increased pCO2 in artery – Why? Waste product; Increased pCO2 in alveolus – Why? Waste product ; Reduced transit time;

Breathing Rate Control

Start to exercise

Movement generates

Levels of acidity in blood

Detected by (in carotid arteries/aortic arch/medulla)

Movement detected by

Nerve sent to Respiratory Centre in of brain

Impulses to muscles/ /

output from Centre – deeper and breathing

Breathing Rate Control

Start to exercise

Movement generates Carbon Dioxide

Levels of acidity increase in blood

Detected by Chemoreceptors (in carotid arteries/aortic arch/medulla)

Movement detected by Muscle Receptors

Nerve impulses sent to Respiratory Centre in medulla of brain

Impulses to breathing muscles/ diaphragm/ intercostals

Increased output from Respiratory Centre – deeper and faster breathing