Respiratory System

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Respiratory System
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I. Respiratory System

• A. Structures / Functions
• 1. Nasal Cavity warm, moisten and filter air
• Mucus, hairs trap dust, dirt and pathogens
• 2. Epiglottis prevents food from going into
  windpipe when swallowing
• 3. Larynx voice box, contains the vocal chords
• 4. Trachea wind pipe, passage for air to the
  lungs

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I. Respiratory System

• 5. Bronchi main branches to the trachea, lead
  to each lung
• Lined with cilia that move mucus up out of the
  lungs
• 6. Bronchioles smaller branches of the bronchi
• 7. Alveoli small grape-like clusters of air
  sacs where gas exchange occurs
• 8. Diaphragm large muscle that aids in breathing

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larynx
lung
Page 40 Unit 13
trachea
Cartilage rings
bronchus
bronchioles
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Nasal cavity
epiglottis
larynx
trachea
alveoli
bronchi
diaphragm
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I. Respiratory System
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• B. Mechanics of Breathing
• 1. Muscles diaphragm, intercostals (between
  ribs)
• 2. Inhalation
• Intercostals contract pulling ribs up and out
• Diaphragm contracts pushing abdomen down
• Both muscular contractions increase volume of
  thoracic cavity
• lowers air pressure w/in lungs
• Outside air pressure gt inside air pressure air
  moves in

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I. Respiratory System

• 3. Exhalation
• Intercostals relax
• Diaphragm relaxes
• Both decrease volume of thoracic cavity
• increases air pressure w/in lungs
• inside air pressure gt outside air pressure air
  moves out
• 4. Volumes of Breathing
• Vital capacity - maximum inhalation/exhalation
• Tidal volume - amount in normal breath
• Respiratory reserve - amount that can be exhaled
  forcefully after normal exhalation

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II. Exchange of Gases

• A. Diffusion
• movement of gases from high concentration to low
  concentration
• B. CO2 / O2 exchange
• Capillaries/Bloodstream CO2 high
• Alveoli O2 high
• O2 moves into blood, CO2 moves out of blood
• 300 million alveoli in a healthy lung

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Transport of O2 and CO2

• C. Hemoglobin molecule in red blood cell
• Red colored, oxygen carrying molecule
• Without it, the blood only carries about 2 of O2
  needed
• As blood flows through capillaries around
  alveoli, O2 is picked up by the hemoglobin of
  RBCs
• Oxyhemoglobin oxygen rich hemoglobin

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III. Respiratory Control

• How is breathing rate controlled?
• N.S. needs way to figure out if there is enough
  O2 in the blood
• Controlled by the level of CO2 in the bloodstream
• CO2 is an acid
• High levels of CO2 stimulate nerve cells to send
  message to MEDULLA OBLONGATA, which sends
  messages to respiratory muscles to increase
  breathing rate
• Try it! Hold your breath!
  Whats happening?

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IV. Respiration in Extreme Circumstances

• A. CO (carbon monoxide) poison
• Similar chemical reactions as oxygen
• Attaches to hemoglobin more strongly than oxygen
  gt RBC cannot deliver O2 cells
• Symptoms of CO poisoning
• Flushed appearance, tired, nauseous, aches/pains

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Extreme, contd.

• B. Extreme Altitudes
• At higher altitudes, atmospheric pressure drops
• Total amount of gases is much less, difficult to
  obtain enough oxygen (hypoxia)
• Try to compensate by hyperventilating or
  breathing more quickly or deeply
• Ex. Mountain climbers use oxygen masks to help
  them breathe
• Pulmonary edema low pressure causes lung
  capillaries to leak fluid that drowns the person
  in own secretions
• Ex. Native Andeans barrel shaped chests, large
  lungs, more capillaries around alveoli, strong
  diaphragms

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Extreme, contd.

• C. Diving
• At higher pressures below oceans surface, divers
  must carry tanks, which release oxygen-containing
  air at a pressure that matches the pressure of
  the ocean water on divers body
• Otherwise, it would be impossible for them to
  inhale/inflate lungs at such high external
  pressure
• D. Drowning
• Death from suffocation
• Water cuts off oxygen supply

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Extreme, contd.

• Mammalian Diving Reflex
• Slowing of breathing and pulse, triggered by
  exposure of cold water to face
• Blood is shunted from gut, skin, muscles and sent
  to brain, heart, lungs
• When face removed from water, MDR shuts down and
  CPR must be administered for survival
• CPR is administered for underwater exposure up to
  one hour!
• Younger people more apt to recover
• Example, Jimmy T (UP 43)

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V. Common Respiratory Diseases (UP 42)

• Bronchitis
• Emphysema
• Pneumonia
• Lung Cancer
• Asthma

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