EX 23. FACTORS INFLUENCING THE RESPIRATORY CENTER

• Apnea


  Absence of breathing
• Anoxemia


  Deficiency of oxygen in the blood
• Cyanosis


  Bluish discoloration of the skin and mucous membranes due to deoxygenated hemoglobin
• Procedure 1


  1. Subject breathes very deeply for 1 or 2 minutes with open mouth

  2. It becomes increasingly more difficult to breathe deeply; one must finally force himself to continue

  3. Subject may experience dizziness

  4. Immediately and for a few seconds after the forced breathing, the individual experiences no desire to breathe (apnea)
• Forced deep breathing


  Causes apnea
• Procedure 2


  1. Subject breathes with a large paper bag lightly over the mouth and nose

  2. Deep breathing can be carried on for a longer length of time and with greater ease with a paper bag than without

  3. Role of CO2 in the mechanism of this phenomenon
• Breathing with a paper bag

  Allows for longer and easier deep breathing
• Procedure 3


  1. Place about 30 gms of soda lime in the bag and repeat procedure 2

  2. Purpose of soda lime and effect of its presence in the bag that produces changes in results
• Procedure 4


  1. Subject sits quietly for 4 minutes to eliminate any muscular activity

  2. Subject inspires quietly and then holds breath

  3. Repeat 3 times and take the average
• Procedure 5


  1. Repeat procedure 4, this time after a deep inspiration

  2. Explain the difference in result obtained
• Procedure 6


  1. Repeat procedure 4, after breathing for one minute from a paper bag

  2. Explain any difference in result
• Procedure 7


  1. Subject runs in place for 2 minutes

  2. Determine how long the breath can be held immediately after this exertion

  3. Rest for 5 minutes and repeat

  4. Explain result
• Procedure 8


  1. Subject breathes quietly for 2 minutes, then takes a deep breath and at the end of inspiration holds the breath

  2. Determine if the resulting urge is for inspiration or expiration

  3. Role of the vagus nerve and what stimulates it

  4. Effect of vagus nerve stimulation
• Procedure 9


  1. Repeat procedure 8, but hold the breath at the end of expiration

  2. Note the results and explain
• Procedure 10


  1. Subject holds breath with end of glass tubing in mouth and outer end dipped into beaker of water

  2. As soon as discomfort ensures and the breaking point is almost reached, begin to sip water

  3. Explain results

  4. Afferent nerve concerned and its importance
• Procedure 11


  1. Subject blows steadily through a narrow glass tube

  2. Note appearance of cyanosis or feelings of dizziness

  3. Note the rate, fullness and force of the pulse during and for sometime after the experiment

  4. Determine the venous pressure roughly before and during the experiment

  5. Explain the above results

  6. Physiological significance of this experiment
• Apnea is produced after forced or continuous breathing
• Cyanosis of lips or skin occurs when apnea is continued
• Breathing with a paper bag

  Allows for longer and easier deep breathing, and prevents apnea