Mechanics of breathing

What is tidal volume? What happens to it during exercise?

Volume of air breathed in or out per breath. Increase

What is residual volume? What happens to it during exercise?

Volume of air left in the lungs after maximum expiration. Stays the same

What is inspiratory reserve volume? What happens to it during exercise?

Volume of air that can be forcibly inspired above resting tidal volume. Decrease

What is expiratory reserve volume? What happens to it during exercise?

Volume of air that can be forcibly expired above resting tidal volume. Slight decrease

What is minute ventilation? What happens to it during exercise?

Volume of air breathed in or out per minute. Big increase

What is breathing?

A mechanical process through which muscles contract to cause a movement of the rib cage and sternum. This causes changes in the volume and pressure of the thoracic cavity. Air is then rushed into or out of the lungs.

Where is the respiratory centre and what does it do?

It is in the medulla oblongata and controls the rate and depth of breathing through neural and chemical control through the sympathetic and parasympathetic nervous system.

How does the body respond to an increase in CO2?

Chemoreceptors detect a change in blood acidity and send impulses to the respiratory centre. The sympathetic nervous system is triggered, sending an impulse down the phrenic nerve to the diaphragm and external intercostals to increase breathing rate.

How does the body respond to a change in blood pressure?

Baroreceptors detect a decrease in blood pressure in the aorta and carotid arteries and send impulses to the respiratory centre. The sympathetic nervous system is triggered, sending an impulse down the phrenic nerve to the diaphragm and external intercostals to increase breathing rate.

How does the body respond to changes in muscle movements?

Proprioceptors are sensory receptors located in joints and muscles that detect an increase in muscle movement and send impulses to the respiratory centre. The sympathetic nervous system is triggered, sending an impulse down the phrenic nerve to the diaphragm and external intercostals to increase breathing rate.

What do stretch receptors do?

During exercise the lungs stretch more. Stretch receptors prevent over inflation of the lungs by sending impulses to the respiratory centre, which sends the impulse down the intercostal nerve to the expiratory muscles (abdominals and internal intercostals) to increase expiration.

What is adrenaline?

A natural stimulant made within the adrenal gland of the kidney.

What does adrenaline do?

It is transported in the blood and affects the nervous system. Prior to exercise, an impulse is sent to the adrenal gland which pumps adrenaline into the blood in anticipation of the increased need for oxygen and removal of CO2. This acts on the medulla oblongata, causing the respiratory system to send an impulse down the phrenic nerve to the diaphragm and external intercostals to increase breathing rate. This relaxes the airways around the lungs, increasing air flow.

Where and how does gaseous exchange occur?

At the alveoli. The partial pressure of oxygen is higher in the alveoli than in the capillaries because oxygen has been removed from the blood by the muscles. This is the opposite for carbon dioxide. This difference in partial pressure creates a large concentration gradient meaning faster diffusion.