AS level PE Respiratory system

Discus mechanics of breathing Inspiration Expiration Air is distributed to the lungs by way of the Trachea Primary bronchi (Also secondary/tertiary) Bronchioles alveoli

Respiratory system – 3 main processes Pulmonary respiration The breathing of air into and out of the lungs External respiration Exchange of O2 and CO2 between the lungs and the blood Internal respiration Exchange of O2 and CO2 between the blood and muscle tissues

RESPIRATORY VOLUMES AT REST Tidal volume Amount of air inhaled and exhaled with each breath (approx 500ml) Frequency (f) Rate of breathing Minute Ventilation VE = TV X f Residual volume Volume of air remaining in the lungs (1200ml)

RESPIRATORY VOLUMES AT REST (Cont’d) Inspiratory reserve vol Expiratory reserve volume

LUNG CAPACITIES Inspiratory capacity = IRV + TV Expiratory capacity = ERV + TV Vital capacity Maximal vol of air that can be expired after maximal inspiration Total lung capacity Maximal volume of air contained in the lungs after a maximal inspiration TLC = TV + IRV + ERV + RV

ALVEOLI

Gaseous Exchange Gaseous exchange refers to the exchange of gases, namely O2 and CO2 and relies on a process called diffusion What is Diffusion?? PP – partial pressure of a gas is the pressure it exerts within a mixture of gases Gases always move from an area of high pressure to an area of low pressure

Inspired air – PO2 -159 , PCO2 -0.3 Trachea – PO2 – 149, PCO2 – 0.3 Pulmonary veins – PO2-100, PCO2 -40 Heart Body tissues – PO2 – 40, PCO2 - 46

MYOGLOBIN – RED PIGMENT IN MUSCLES THAT STORES O2 AND TRANSPORTS O2 TO THE MITOCHONDRIA 02 – muscle cells (hb – myoglobin) -- by product – CO2 CO2 travels in blood as carbonic acid (70%), Carbaminohaemoglobin(20%) & 7% plasma

TASK IN GROUPS OF 3-4 YOU HAVE 5-10MINS TO DISCUSS AND PRESENT THE MECHANICS OF RESPIRATION DURING EXERCISE MECHANICS LUNG VOLUME CHANGES DURING EXERCISE SKIPPING ROPES CONES & PAPER

MECHANICS OF RESPIRATION DURING EXERCISE What muscles are involved? Inspiration – SCOM(sternocleidomastoid), scalenes & pec minor Expiration – internal intercostals & rectus abdominals / obliques See p.96 Discuss the ventilatory response to light, moderate and heavy exercise

LUNG VOLUME & EXERCISE Tidal volume – 500ml 3-4litres Frequency – 12-15 40-60 VE – 6-7.5l 120-180l IRV – 3100ml  decreases ERV – 1200ml  slightly decreases Vital capacity – 4800ml  slight decrease Residual volume – 1200ml  slight increase Total lung capacity – 6000ml  slight decrease

EXERCISE CHANGES TO GASEOUS EXCHANGE BOTH EXTERNAL & INTERNAL RESPIRATION INCREASE DURING EXERCISE IN ORDER TO INCREASE THE SUPPLY OF O2 TO THE WORKING MUSCLES

OXYGEN-HAEMOGLOBIN DISSOCIATION CURVE