767379
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Mapa Mental por leonie1997, actualizado hace más de 1 año
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Creado por leonie1997
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Human health and physiology -
Gas exchange
- The need for gas exchange and ventilation in humans.
- Cell respiration happens in the cytoplasm and
mitochondria of cells and releases energy in
the form of ATP for use inside the cell.
- In humans oxygen is used in cell respiration
and carbon dioxide is produced.
- Human therefore must take in oxygen from their
surrounding and release carbon dioxide. This process of
swapping one gas for another is called gas exchange.
- Gas exchange happens in the
alveoli of human lungs.
- Oxygen diffuses from the air in the alveoli to
the blood in capillaries. Carob dioxide
diffuses in the opposite direction.
- Oxygen diffuses from the air in the alveoli to
the blood in capillaries. Carob dioxide
diffuses in the opposite direction.
- Diffusion of oxygen and carbon dioxide
happens because there are concentration
gradients of oxygen and carbon dioxide
between the air and the blood.
- To maintain these concentration gradients, the air in the
alveoli must be refreshed frequently. The process of
bringing fresh air to the alveoli and removing stale air is
called ventilation.
- To maintain these concentration gradients, the air in the
alveoli must be refreshed frequently. The process of
bringing fresh air to the alveoli and removing stale air is
called ventilation.
- Cell respiration happens in the cytoplasm and
mitochondria of cells and releases energy in
the form of ATP for use inside the cell.
- Adaptions of the alveolus to gas exchange
- Although each alveolus is very small, the lungs
contain hundreds of millions of alveoli in total, giving
a huge overall surface area for gas exchange.
- The wall of the elveolus consists of a single
layer of very thin cells. The capillary wall also is
a single layer of very thin cells, so the gasses
only have to diffuse a very shot distance.
- The alveolus is covered by a dense network of
blood capillaries with low oxygen and high
carbon dioxide concentrations. Oxygen therefore
diffuses into the blood and carbon dioxide
diffuses out.
- Cells in the alveolus wall secrete a fluid which keeps the
inner surface of the alveolus moist, allowing the gases to
dissolve. The fluid also contains a natural detergent, which
prevents the sides of the alveolus from sticking together.
- Although each alveolus is very small, the lungs
contain hundreds of millions of alveoli in total, giving
a huge overall surface area for gas exchange.
- Ventilation of the lungs
- Air is inhaled into the lungs through the
trachea, bronchi and bronchioles.
- It is exhaled via the same route.
- Muscles are used to lower and raise the
pressure inside the lungs to cause the
movements of air.
- Inhaling
- 1. The external intercostal muscles
contract, moving the rib cage up and out.
- 2. The diaphragm contracts,
becoming flatter and moving down.
- 3. These muscle movements
increase the volume of the thorax.
- 4. The pressure inside the thorax therefore
drops below atmospheric pressure.
- 5. Air flows into the lungs from outside
the body until the pressure inside the
lungs rises to atmospheric pressure.
- 1. The external intercostal muscles
contract, moving the rib cage up and out.
- Exhaling
- 1. The intercostal muscles contract,
moving the ribcage down and in.
- 2. The abdominal muscles
contract, pushing the diaphragm
up into a dome shape.
- 3. These muscle movements
decrease the volume of the thorax.
- 4. The pressure inside the thorax therefore
rises above atmospheric pressure.
- Air flows out from the lungs to outside
the body until the pressure inside the
lungs falls to atmospheric pressure.
- 1. The intercostal muscles contract,
moving the ribcage down and in.
- Air is inhaled into the lungs through the
trachea, bronchi and bronchioles.
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