Breathing by mikesanye



Anatomy and Physiology
• Respiration is the
  exchange of gases
  between the
  atmosphere and the
• Breathing is a part of
  it; only in medicine is
  breathing called
 Organs of the Respiratory System

• Nose—air enters and
• Nasal cavity—hollow
  space lined with
  mucous membrane
• Sinuses– air filled
  spaces which reduce
  the weight of the skull
Organs of the Respiratory System
• Pharynx—behind the
  mouth; passageway
  for air (and food)
• Larynx-enlargement
  of the trachea;
  passageway for air and
  houses vocal cords
• Epiglottis closes this
  off when swallowing
Organs of the Respiratory System
• Trachea—is the
• Primary bronchi—the
  two branches off the
• Secondary bronchi-
  branches off the
  primary bronchi
• Bronchioles: smaller
  Organs of the Respiratory System

• Bronchioles end in the
• Alveoli are small air
  sacs surrounded by
• Gas exchange occurs
  here between the air in
  the alveolus and the
Alveoli (air sacs)

              ―Bathed‖ in capillaries
Organs of the Respiratory System
• Lungs are large,
  spongy organs in the
  thoracic cavity
• Right and left lungs
• The bronchi and
  smaller bronchioles
  are inside
• Covered by two
  membrane layers:
  visceral pleura and
  parietal pleura
•   Is a mechanical action
•   Moving air in and out
•   Inhalation and Exhalation
•   Is a result of pressure changes due to
    change in size of the thoracic cavity
• Diaphragm contracts
  and moves down
• The ribs move up and
• This expands the size
  of the chest cavity
• Pressure inside cavity
  is now lower than
  outside; air rushes in
• Diaphragm relaxes,
  moving back up
• The ribs move down and
• This decreases the size of
  the chest cavity
• Pressure inside the cavity
  is now higher than
  outside, forcing air out
        Control of Breathing
• Rhythmic, involuntary, will continue even if
  person is unconscious
• Respiratory muscles are under voluntary
• Respiratory center is in the pons and
  medulla oblongata
• Nerve impulses stimulate the diaphragm
  and inspiratory muscles
                    Control of Breathing
• Chemoreceptors monitor levels of CO2 and
    hydrogen ions
•   When these concentrations rise, respiration rate
    and volume are increased.
•   Low oxygen has little effect—must be very very
    low to trigger respiration
•   If you hold your breath, CO2 and H+ increase,
    stimulating breathing
•   Hyperventilation gets rid of CO2, so no stimulus to
Gas Exchange in Alveoli
              • Wall of alveolus is a
                thin layer of simple
                squamous epithelium
              • Each cell is near a
Gas Exchange in Alveoli
            • By diffusion
            • With gases, we talk
              about regions of
              higher pressure and
              lower pressure instead
              of higher and lower
            • Gas molecules will go
              from high to low
Gas Exchange in Alveoli
          Diffusion of Gases
• In the alveolus, oxygen moves from the
  alveolus into the capillary
• At the body cells, oxygen moves from the
  capillary into the cell
• In the alveolus, carbon dioxide moves from
  the capillary into the alveolus to be exhaled
• At the body cells, carbon dioxide moves the
  cell into the capillary
Transporting the gases
           • Most oxygen is carried
             by hemoglobin
           • A small amount is
             dissolved in the
           • CO2 is carried three
             ways: dissolved in
             plasma, carried by
             hemoglobin, or in the
             form of a bicarbonate
             ion HCO3-
Carbon Monoxide CO
           • Is deadly because it
             combines more
             effectively with
             hemoglobin than
             oxygen does
           • Takes oxygen’s place,
             and cells become
             oxygen deficient
Carbon Monoxide CO

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