Breathing system
Group of organs that work to take air into and out of the body
Oxygen
Gas found in the air that is taken into the blood in the lungs as it is needed for respiration
Carbon dioxide
Gas found in air that is passed out of the blood into the lungs as it is produced in respiration
Lungs
Gas exchange organs found in the thorax of the body
Thorax
Upper part of the body above the diaphragm
Ribcage
Bones in the upper body that protect the lungs
Abdomen
Lower part of the body below the diaphragm
Diaphragm
Muscle which separates the thorax above from the abdomen below. During inhalation it contracts and flattens whilst during exhalation it relaxes and springs up.
Trachea
Tube connecting the mouth to the lungs.
Bronchi
2 branches of the trachea each of which goes to one lung.
Bronchioles
Smaller branches of the bronchi
Alveoli
Small air sacs at the end of bronchioles where gas exchange occurs
Intercostal muscles
Muscles between ribs which contract and pull the ribs up during inhalation and then relax and the ribs fall inwards passively
Pleural membranes
Thin membranes around the edge of the lungs
Ventilation
The movement of air into and out of the lungs
Inhalation
The action of breathing in air
Exhalation
The action of breathing out air
Volume of thorax
This determines whether the pressure in the lungs is greater than the outside in which case air is forced out of the lungs or if the pressure in the lungs is less than the outside in which case air is sucked into the lungs
Surface area
The total area that is available for absorption
Surface area to volume ratio
The size of the area available for absorption relative to the size of the organism
Blood supply
This transports gases around the body. It maintains the concentration gradient in the lungs to ensure that the diffusion of gases
Diffusion
The movement of particles from an area where they are in high concentration to an area where they are in low concentration.
Concentration gradient
The difference in concentration between 2 areas. The greater the gradient the faster diffusion occurs
Nicotine
Addictive substance found in cigarettes
Addictive
Feature of a substance which means that it is difficult to give up. The person may suffer withdrawal symptoms if they do not have this substance
Carbon monoxide
Gas found in cigarette smoke which combines irreversibly with haemoglobin in red blood cells and so reduces the amount of oxygen carried in the blood.
Haemoglobin
Oxygen-carrying substance found in red blood cells
Carcinogens
Substances that cause cancer
Cancer
The uncontrolled growth of cells which can be caused by carcinogens
Emphysema
Condition where the walls of the alveoli breakdown decreasing the surface area for oxygen absorption
Atherosclerosis
Disease of the heart and blood vessels that can be caused by cigarette smoke. It can cause a heart attack