The surface area of the lungs isroughly the same size as a tennis court.
The large surface area of the lungs is provided by……….
Which structure is located behind the trachea? trachea
The rings of cartilage keep the trachea open at all times During swallowing.During exhaling.
Three things happen to the airbreathed in as it passes through the nasal passages:Cilia Mucus Cell membrane
It is better to breathe through thenose rather than the mouth. Why?
What prevents food from entering the trachea? Epiglottis closes the trachea .trachea
Sequence air takes to enter the lungs:2. pharynx 1. nasal passages4. trachea 3. larynx lung 5. bronchi 6. bronchioles 7. alveoli
The lungs are placed in an air-tight chamberWhat happens to the lungs if air enters this chamber? Lung collapses
Fun FactsAt rest, the body takes in and breathes out about 10 liters of air each minute.* The right lung is slightly larger than the left.* The highest recorded "sneeze speed" is 165 km per hour.* The capillaries in the lungs would extend 1,600 kilometers if placed end to end.* We lose half a liter of water a day through breathing. This is the water vapor we see when we breathe onto glass.* A person at rest usually breathes between 12 and 15 times a minute.* The breathing rate is faster in children and women than in men.
CHANGES IN THE COMPOSITION OF BREATHED AIR Gas Inhaled % Exhaled % Oxygen 21 16 Carbon dioxide 0.03 4 Nitrogen 79 79 Water vapour variable saturated Why is exhaled air always saturated with water vapour?
Due to evaporation of film of moisture lining the alveoli
Gaseous exchange occurs in alveolipulmonaryartery pulmonary vein bronchiole alveolus
Question: SEP, 2008a) Explain why humans breathe out:i) more carbon dioxide than is breathed in, (2) A waste product that is made all the time by respiration.ii) as much nitrogen as is breathed in. (2) Not used by the body.
b) Compare the amount of water vapour in inhaled and exhaled air. (2) More present in exhaled air due to evaporation from film of moisture inside alveoli.
Question: MAY, 2010Draw a clear well labelled diagram showinghow gaseous exchange takes place in thealveolus. (4)
Fig. 4 A small part of a human lung. Give TWO features of alveoli that aid diffusion of gases.1. Thin epithelium2. Dense capillary network3. Provide a large surface area
A lighted cigarette produces many harmful chemicals
Chemicals incigarette smoke:1. NICOTINE2. CARBON MONOXIDE3. TAR
1. NICOTINE increases heart rate and blood pressure person becomes addicted
2. CARBON MONOXIDE combines with haemoglobin in red blood cells so reducing the level of oxygen in the blood
3. TAR a black sticky material that remains in the lungs
3. TAR contains over a thousand chemicals, some of them are carcinogens (substances that cause cancer)
Some effects of cigarette smoke:1. Irritate the membrane lining the upper respiratory tract.2. Cilia stop beating.3. Extra mucus forms in the trachea and bronchi causing ‘smoker’s cough’.
Non- smoker Smoker Note more mucus present compared to a non-smoker.
4. Smoking weakens the walls of the alveoli and repeated coughing can destroy some of them.This breakdown of alveoli is called emphysema.
Question: MAY, 2007Why do people who suffer from emphysemabecome breathless on minimal physical activitye.g. walking upstairs? (3)Emphysema results in a reduction in lungvolume.Less surface area to absorb oxygen.Person cannot produce enough energy.
Question: MAY, 2010Explain why:i) patients suffering from emphysema absorb less oxygen; (3)Emphysema is a condition caused by thedeterioration of the alveolar wall. This decreasesthe surface area for absorption therefore there isdecreased gaseous exchange (less oxygen uptake). Award half a mark if they mention alveoli burst.
Question: MAY, 2010Explain why:ii) emphysema patients tend to hyperventilate (rapid breathing); (3)Emphysema patients try to compensate for thedecrease oxygen uptake by taking quick rapidbreaths. This increases oxygen concentration inthe lungs and therefore increases oxygenabsorption.
Question: MAY, 2010Explain why:iii) emphysema patients are more prone to pulmonary infections such as bacterial bronchitis. (3)Emphysema is mainly caused by smoking.Cigarette smoke stops the cilia in the breathingsystem from beating, leading to an accumulationof mucus and microbes in the lungs. Microbesremain in lungs and can infect , bringing aboutpulmonary infections.
5. Babies born to mothers who smoke: are generally lighter than babies born to non-smoking mothers are at a risk of premature birth
Question: SEP, 2011Explain why pregnant females areencouraged to avoid smoking. (3)Higher risk for miscarriages.Higher risk for premature birth.Less oxygen reaches embryo – baby isborn smaller than average.Chemicals in smoke affect the brain ofthe embryo and baby is born mentallyretarded.
What is ‘passive smoking’? When people breathe in thesmoke from other people’s cigarettes.
Examples of lung diseases: Asthma Lung cancer Bronchitis Emphysema
Examples of lung diseases: Pneumonia Normal alveoli [inflammation of alveoli] Pneumonia
Feature Function1) alveoli present a large to absorb oxygen surface area to allow oxygen to diffuse2) alveolar lining is very thin into the blood easily3) alveolar surface is moist to allow oxygen to dissolve4) a dense capillary network to pick up and transport surrounds the alveoli oxygen5) a mechanism to renew the to keep a high concentration air in contact with the gradient between the alveoli alveoli and the blood