Importance

CO2 dissolves in blood to form weak acid, lowering pH of blood and tissue fluid, affect metabolic rate and enzymatic activity

Factors:

• respiration rate
• ventilation rate
• blood circulation

Control of breathing

Voluntary/involuntary

Ventilation rate= berathing rate* tidal volume
Respiratory center in medulla oblongata connects
nerve impulses --> respiratory muscles --> contract

When ph too low, chemoreceptors in carotid bodies, aortic bodies and repiratory centre are stimulated and send nerce impulses to the respiratory centre in medulla oblongata. more nerve impulses to intercostal muscles and diaphragm muscles , contract more frequently and forcefully. rate and depth increase

Control of heartbeat

1. SA generates electrical impulse which spread to both atria contract simultaneously.
2. Electrical impulse passes to the atrioventricular node whih
3. AV node relays impulses to ventricles along septum in Bundle of His
4. Ventricles contract bottom up

Nervous control

conc. CO2
BP
movement of limbs --> stretch receptors

--> cardiovascular centre in medulla --> SA node
sympathetic nerve: stimulate
vagus nerve: inhibit

Hormonal control

adreanal glands: secrete adrenaline in blood to stimulate SA node and cardiac muscle contract more forcefully and frequently

exercise