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11-respiration and gas exchange - Coggle Diagram
11-respiration and gas exchange
energy and respiration
every living cell needs energy
human cells use energy to
contract muscles
synthesize proteins by linking together amino acids
divide cells for growth and repair damaged tissue
enable active transport
transmit nerve impulses
produce heat inside the body
energy comes from the food eaten
cells release energy from glucose
when glucose is combined with oxygen, aerobic respiration takes place and energy is released
glucose+oxygen--->carbon dioxide+water C₆H₁₂O₆+6O₂--->6CO₂+6H₂O
glucose can also be broken down without oxygen during anaerobic respiration, but it is less efficient than aerobic respiration
in yeast, glucose--->alcohol+ carbon dioxide C₆H₁₂O₆--->2C₂H₅OH+2CO₂; however, in muscle cells anaerobic respiration produces lactic acid and not alcohol
gas exchange surfaces
they are special areas where oxygen enters and carbon dioxide leaves
they are thin and permeable as to enable gases to move easily
they are close to an efficient transport system
they have a large surface area to enable lots of gas to diffuse at the same time
they have a good supply of oxygen
the human breathing system
the nose and mouth
air can enter trough either of them
inside the nose there are thin bones covered in cells
some of these cells, the "goblet cells", make a liquid containing mucus and water, which evaporates inside the nose and moistens it
other cells have tiny hair-like projections called "cilia"
they are always moving and bacteria and particles of dust get trapped in them and in the mucus
cilia are also found all along the trachea and bronchi, too
these sweep mucus up to the throat so that it does not block the lungs
the trachea
it is also called the "windpipe"
it contains the larynx, or "voice box"
here there are the vocal cords, which can be tightened by muscles to make sounds when air passes over them
it has rings of cartilage around it, which prevent the trachea from collapsing when the pressure inside it is lower than the pressure outside it
pressure changes due to breathing in and out
it goes down the neck and into the thorax
there, it divides into 2
the bronchi
they are the two parts in which the trachea divides
each bronchus goes to each lung
there, it branches out into smaller tubes, the "bronchioles"
alveoli
they are tiny air sacs
there are many of them at the end of each bronchiole
it is where gas exchange takes place, precisely their walls
tiny capillaries are wrapped around the outside of the alveoli and there oxygen diffuses into the blood and carbon dioxide diffuses outside the blood
the walls are only one cell thick
the walls have a large surface area
the walls have a good supply of oxygen thanks to "ventilation" (the continuous movement of air into and out of the lungs
breathing movements
they change the volume of the thorax, thus enabling air to move in and out of the lungs
breathing in (inspiration)
the volume of the thorax increases and thus the pressure inside it falls below atmospheric pressure. Air therefore flows in
the external intercostal muscles contract, pulling the rib cage upwards and outwards and increasing the volume
the muscles of the diaphragm contract, pulling it downwards and increasing its volume
breathing out (expiration)
air can also forcefully be expelled, for example when coughing
the external intercostal muscles relax and the rib cage drops down again into its normal position, decreasing the volume in the thorax
the muscles of the diaphragm relax, making it acquire its original shape and decreasing the volume in the thorax