6.6 Structure of human gas exchange system Flashcards
Why do aerobic organisms need a constant supply of oxygen
What needs to be removed from the body after this
Aerobic organisms need oxygen for aerobic respiration which produces energy in the form of ATP
This process produces CO2 which is harmful to the body when it builds up
The volume of oxygen that has to be absorbed, and the volume of CO2 that must be removed are large in mammals because…
. Mammals are relatively large organisms with a large volume of living cells
. They maintain a high body temperature which is related to them having a high metabolic and respiratory rate
What is the gas exchange surface of humans
Lungs ensure sufficient gas exchange between air and their blood
Why are lungs located inside the body of mammals
. Air is not dense enough to support and protect these delicate structures
. The body would lose lots of water and dry out
What protects the lungs
The ribcage is a body box
How can the ribs be moved
There are intercostal muscles between the ribs which can be internal or external and can contract or relax to make ribs expand
Describe function and structure of the lungs
. A pair of lobed structures made up of a series of highly branched tubules called bronchioles, which end in tiny air sacs called alveoli
Describe function and structure of the trachea
It is a flexible airway containing rings of cartilage
This cartilage prevents the trachea collapsing as the air pressure inside falls when breathing in (as the diaphragm and intercostal internal muscles relax)
The tracheal walls are made of muscle lined with ciliated epithelium and goblet cells
Describe function and structure of the bronchi
What do they contain
. These are two divisions of the trachea, each leading to one lung
The larger bronchi are supported by cartilage, although the amount of cartilage is reduced as bronchi get smaller
. They are similar in structure to trachea, and also produce mucus to trap dirt particles, and have cilia that can sweep this mucus up to the throat
Describe function and structure of the bronchioles
These are a series of branching subdivisions of the bronchi
Their walls are made of muscle lined with epithelial cells.
This muscle allows them to constrict so they can control the flow of air in and out of the alveoli
Describe function and structure of the alveoli
They are tiny air sacs with a diameter of between 100qm and 300qm
They are found at the end of bronchioles
Between them, collagen and elastic fibres are found .
These elastic fibres allow them to stretch as they fill with air when breathing in , and then they can spring back when breathing out to expel the CO2 rich air
They are lined with epithelium (layer of cells)
It is the alveolar membrane that is the gas exchange surface
