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 510MINS TO DISCUSS AND PRESENT
THE MECHANICS OF RESPIRATION
DURING EXERCISE
1. MECHANICS
2. 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