Gas exchange and respiration
Gas exchange
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Breathing
Effects of Smoking on the Respiratory System
Gas exchange system
To make this process take place efficiently and quickly, some animals have evolved gas exchange surfaces called lungs
The lungs can absorb oxygen from the environment into the body as well remove carbon dioxide from the blood back into the environment
It is important that multicellular organisms can exchange substances with the outside such as nutrients as well as gases
Parts of gas exchange system
Lungs aren't the only part in the gas exchange system it contains all the bones and tubes that carry air around the body
The other parts are:
The left and right lung
Alveoli
Diaphragm
Bronchioles
Bronchi
Trachea
Breathing in
The volume of the chest increases
Pressure falls below that of the outside air
The ribs move up and out
Air moves into lungs from the outside air down the pressure gradient
The diaphragm contracts and moves upwards
Breathing out
The diaphragm relaxes and moves upwards
The ribs move down and in
The volume of the chest decreases
Pressure now increases above that of the outside air
Air moves out of the lungs to thee air down a pressure gradient
Factors
Negative factors
Positive factors
Exercise
Asthma
Smoking
Stomata
Each stomata can be closed or opened depending on two two guard cells which flank it
Gas exchange is mainly done through the lower surface of the leaf via small openings called stomata
Air breathed into the lungs through the trachea divides into two tubes called the bronchi
The bronchi divide to form bronchioles
The bronchioles divide until they divide until they end up in tiny air sacs called alveoli
The alveoli ae tiny air sacs and exchange oxygen with carbon dioxide in the blood and are surrounded by capillaries
Exchange surfaces
Ventilation
Large surface area
Kept clear
Thin membrane
Blood supply
Reduces diffusion distance
Alveoli are one cell thick
Alveoli create a large surface area of gas exchange in the lungs
A large surface area allow more of a substance to diffuse at the same time
In animals. if a gas is exchanged, the surface is ventilated to maintain a high concentration gradient and increase and increase the rate of exchange
Inspiration
Expiration
Diaphragm contracts and becomes flattened
The internal intercoastal muscles relax and the external intercoastal muscles contract, moving the rib cage up and out
The thorax volume increases, forcing air into the lungs because of decreased internal pressure
The internal intercoastal muscles relax and the external muscles contract, moving the ribcage downwards and in
The thorax volume decreases and the internal pressure increases
The diaphragm relaxes and becomes dome shaped
Air is forced out of the lungs
Bronchitis
Cancers
Emphysema
Heart diseases and strokes
Smoke damages the walls of the alveoli, reducing the surface area
This can cause emphysema, where gas exchange cannot happen efficiently, causing shortness of breath
This means that the cilia cannot waft away the mucus produced by goblet cells and the mucus builds up
This leads to bronchitis where the airways are partly blocked with mucus
When smoke is breathed in, it damages the cilia cells in the airway
The carcinogens can cause tumours to form in airways
Smoking can cause mouth, throat or lung cancer
Nicotine is very addictive and cause strain on the heart
Carbon monoxide reduces the ability of red blood cells to carry oxygen and also causes a strain on the heart
Both of these substances can cause heart attacks and strokes