The respiratory system

Inspiration - Diaphragm and External intercostal muscles 

Inspiration (during excerise) - Diaphragm, External intercostal muscles, SCM, pectorialis minor. 

Expiration - Diaphragm and External intercoastal muscles just relax. 

Expiration (during excerise) - Internal intercoastals and abdominals. 

Tidal volume - volume breathed in or out per breath (inc. during excerise)

Inspiratory reserve volume - volume of air that can be forcibly inspired after a normal breath (dec. during excerise) 

Expiratory reserve volume - volume of air that can be forcibly expired after a normal breath (dec. during excerise)

Residual volume - air that remains in lungs after maximum expiration (stays same). 

Minute ventiallation - volume breathed in or out in per min ( huge increase during excerise). 

-Neural and chemical regulation;

-neural control involes the brain and nervous system and chemiacl control is concerned with blood acidicty. When blood acidity is high the brain is informed and sends impulses to through thye nevcrous system to increase breathing. 

Hormonal regulation during excerise;

-as adrenaline is released which engages the sympoathetic nervous system and increases heart rate. 

-Smoking;

-can damage the cells lining the trachea, bronchi and bronchiholes which can disrupt thier ability to shift mucus and lead to smokers cough trying to clear the mucus out. 

-can damage the alveoli, breaking thier walls down and joing them togther to from larger air spaces which can reduce efficceny of gaseous exchange. 

-increased risk of COPD (chronic obstructive pulmonary disease).

-Carbon monoxide combines with haemoglobin in red blood cells which can reduce capacity to carry oxygen and cause breathelessness.  

Baroreceptors, Chemoreceptors, Proprioceptors ----> Inspiratory centre --->                    Respiratory centre (MO) ---> Phrenic nerve ---> Diaphragm , external intercostals ---> increased breathing rate. 

Sretch receptors ---> Expiartory centre ---> Respiratory centre ---> Intercostal nerve ---> Abdominals, Intercostals ---> Increased expiration. 

Slow twitch fibres (Type 1)    

• Slow contarction speed 
• Low force produced
• Very high aerobic content 

 Fast twitch oxidative glycolytic fibres (Type 2a) 

• Fast contraction speed
• High forced produce 
• High anaerobic content

Fast twitch glycolytic (Type 2b 

• Fast contraction speed
• High force produced
• Very high anaerobic capacity 

-a motor unit consists of a motor neurone and its muscle fibres, working with the nervous system so that a contraction can occur. Individually, each unit contains one type of muscle fibre. 

-The all or none law - here a 'threshold' has to be met for all muscle fibres to contract otherwise if the threshold is not met no muscle action will occur.