A-Level PE AQA Respiratory System

The taking in of oxygen and the removal of carbon dioxide

. Ventilation
. External respiration
. Transport of gases
. Internal respiration
. Cellular respiration

Getting air into and out of the lungs

Gaseous exchange between the lungs and blood

Exchange of gases between the blood in the capillaries and the body cells

The metabolic precautions and processes that take place in a cell to obtain energy from fuels such as glucose

It is drawn in through the nose, and passes down the pharynx and larynx and down the trachea. It then moves through the right and left bronchus and as they move through each bronchus they (bronchus) subdivide into secondary bronchi and then into thinner structures called bronchioles. Finally these lead to alveoli

Exchange of gases between lungs and blood

Via diffusion, the movement of gas molecules from an area of high partial pressure to an area of low partial pressure

. Walls are very thin (one cell thick) -> short diffusion pathway
. Extensive capillary network -> excellent blood supply
. Large surface area -> millions of alveoli in each lung allowing for a greater uptake of oxygen

Due to air moving from an area of high pressure to an area of low pressure via diffusion, the greater the difference in pressure, the faster the air will flow

The pressure should be lower in the lungs than in the atmosphere

The pressure should be higher in the lungs than the atmosphere

It reduces the pressure in the lungs

It increases the pressure in the lungs

Diaphragm and external intercostals

Diaphragm
External intercostals
Sternocleidomastoid
Scalenes
Pectoralis major

It is passive so diaphragm is used whereas the external intercostals just relax

Internal intercostals and abdominals

. Rib cage moves upwards and outwards
. Diaphragm contracts and is pulled flat

. Rib cage falls
. Diaphragm relaxes and rises to dome shaped position

Volume of air breathed in or out per breath

Volume of air that can be forcibly inspired after a normal breath

Volume of air that can be forcibly expired after a normal breath

The amount of air that remains in the lungs after a maximal expiration

Volume of air breathed in or out per minute

A device that is used to measure the volume of air inspired and expired by the lungs

Increases

Decreases

Slightly decreases

Remains the same

Big increase

The pressure exerted by an individual gas when it exists within a mixture of gases

The movement of gas molecules from an area of high concentration to an area of low concentration

The partial pressure of oxygen needs to be successively lower

Oxygen is removed by the working muscles from the blood and so the concentration of oxygen becomes lower in the blood and so does it’s partial pressure

Due to the concentration gradient between the alveoli and the blood vessel in partial pressure, the oxygen diffuses from the alveoli to the blood vessel so that it can become equal

The partial pressure of oxygen has to be lower at tissues than in the blood for diffusion to occur. Capillary membranes surrounding the muscle has a partial pressure of 40mmHg and 100mmHg in the blood. This lower partial pressure allows oxygen to diffuse from the blood into the muscle until equilibrium is reached. Conversely, the partial pressure of carbon dioxide is lower in the blood (40mmHg) than in the tissues (46mmHg) so again, diffusion occurs and carbon dioxide moves into the blood to be transported to the lungs.

. Neural control
. Chemical control
. Hormonal control

Involves the brain and the nervous system

Concerned with blood acidity

They work towards the control of breathing. When blood acidity is too high the brain is informed and it sends impulses through the nervous system to increase breathing.

Prior to exercise, the brain sends impulses to the renal glands which respond and pump adrenaline into the blood in anticipation of the increased need for oxygen and carbon dioxide exchange.

. Irritation of the trachea and bronchi
. Reduces lung function
. Damages cells lining of trachea, bronchi and bronchioles
. Cilia damaged so leads to excess mucus build up in lung passages
. Damage alveoli as walls break down and join together reducing gaseous exchange due to larger air spaces than usual
. Increase risk of COPD