Breathing and Gas Exchange Flashcards

1
Q

What happens when we breathe in, i.e. where does the air go?

A
  • Air enters our nsoe or mouth and passes down the trachea.
  • The trachea spilts into two tubes called the bronchi, one leading to each side of the lung.
  • Each bronchus divides into smaller and smaller tubes called bronchioles
  • And evtually ending at air scas, called alveoli.
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2
Q

What do the walls of the trachea contain and why?

A
  • Contain rings of cartilage
  • To support the airways and keep them open when we breathe in
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3
Q

What is the inside of the thorax spereated by?

A
  • By two thin, moist membranes called the pleural membranes
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4
Q

What is the trachea and larger airways lined with and what is its purpose?

A
  • Lined with goblet cells, which secrete mucus that traps particles of dirt or bacteria that we breathe in
  • Covered with cilia which beat back and forth, sweeping mucus and trapped particles out towards the mouth. This way, dirt and bacteria are prevented from entering the lungs where they could cause infection.
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5
Q

How does air enter the lungs?

A
  • The outer (external) intercostals contract and pull the ribs up.
  • At the same time the muscles of the diaphragm contract, pulling the diaphragm down into a more flattened shape.
  • Both these movements increase the volume of the chest and cause a slight drop of pressure inside the thorax and so air enters the lung
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6
Q

What happens when we breathe out?

A
  • The external intercoastals relax and the internal intercostals contract, pulling the ribs down and in.
  • At the same time, the diaphragm muscles relax and the diaphragm goes back to its normal dome shape.
  • the volume of the thorax decreases and the pressure in the thorax is raised slightly above atmospheric pressure.
    this forces air out of the lungs.
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7
Q

How are the alveoli adapted to their function?

A
  • Walls are extremely thin.
  • They have a large surface area in relation to volume.
  • They are fluid lined enabling gases to dissolve.
  • They are surrounded by numerous capillaries.
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8
Q

What happens to the cilia of smokers and what does this cause?

A
  • The cilia are destroyed by the chemcals in cigarette smoke
  • Reduced number of cilia mean that eh mucus is not swept away from the lungs, but clogs the air passages
  • Made worse that smoke irritates the lining of the airways, simulating the cells to secrete more mucus.
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9
Q

What does clogged mucus create and what is it?

A
  • Smoker’s cough
  • Irratation of the bronchial tree
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10
Q

What is bronchitis and what does it do?

A
  • Infection from bacteria in mucus
  • It blocks normal air flow, so the sufferer has difficulty properly
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11
Q

What is Emphysema?

A
  • Smoke damaging the walls of the alveoli which break down and fuse together again, forming enlarged irregular air spaces
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12
Q

What does Emphysema cause?

A
  • The surface area for gas exchange to be greatly reduced and this means the blood of the person carries less oxygen.
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13
Q

What does carbon monoxide do to the blood stream?

A
  • Intefers wth the ability of the blood to carry oxgen.
  • Carbon monoxide combines with the haemoglobin much more tightly than oxygen does forming carboxyhaemoglobin, with haemoglobin coming in preference with carbon monoxide.
  • The blood therefore carries much less oxgyen around.
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14
Q

What in cigarretes causes cancer?

A
  • Carcinogenic chemicals in tar cause mutations in the DNA of lung cells.
  • The cells multiply out of control forming a tumour.
  • The tumour blocks the airways or damages other tissues as it grows.
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