Breathing
Normal Respiration
+
Breathing & Heart Rate
LEARNING OBJECTIVES
•
By the end of today's laboratory you will be able to describe and explain the:
– Normal pattern of breathing
– examine the effects of holding your breath after inhaling and after exhaling.
– Relationship between breathing and heart rate
LUNG ANATOMY
Diaphragmatic positions and changes in lung volume at the ends of inspiration and expiration.
•
•
•
FORCEFUL BREATHING
In forceful breathing, rib movements are obvious, and the volume enclosed by the ribcage
changes to a greater extent.
In addition, other muscles are recruited. The sternomastoid muscles of the neck assist in
raising the sternum in forceful inspiration.
During expiration abdominal muscles raise the pressure in the abdomen and push the
relaxed diaphragm up, providing a powerful expiratory force.
•
•
•
•
•
BREATHING CONTROL
Breathing movements are unusual in that they are under dual control from the central
nervous system.
Breathing movements can be made voluntarily in the same way as arm and leg movements.
However, if no conscious attention is focused on breathing, rhythmic muscle contractions
occur spontaneously.
Spontaneous breathing is controlled by the respiratory center in the medulla of the brain.
The respiratory center ensures that gaseous exchange at the lung matches the requirements
of the body. In times of increased demand, the rate and depth of breathing are increased to
bring more fresh air into the lungs.
The respiratory center has chemoreceptors that are sensitive to the partial pressure of
carbon dioxide (PCO2) and pH of the cerebral spinal fluid. Chemoreceptors sensitive to
oxygen partial pressure (PO2) are located in the aorta and carotid arteries.
Normal Respiration
1. Describe the normal respiratory movements. Note the characteristics of the trace such as the
rate, and the relative durations of inspiration (breathing in) and expiration (breathing out).
•
Rate will vary among students. Usually, inspiratory movements are of longer duration
than expiratory movements.
2. In your own words, explain the effect of holding the breath on the subsequent respiratory
pattern.
•
Breathing is faster and deeper after a breath hold.
3. During which phase of respiration can the breath be held longer ?
•
Breath can usually be held longer after a full inspiration.
4. After holding the breath, is the resulting urge to breathe expiratory or inspiratory?
•
It depends on when in the breathing cycle the breath was held; the urge tends be
inspiratory after exhalation and expiratory after inhalation.
BREATHING AND HEART RATE
•
•
1. In what way does the heart rate change during the breathing cycle?
Heart rate increases during inspiration, remains high during breath holding and
decreases as expiration starts. The extent of this normal “respiratory sinus
arrhythmia” differs greatly from subject to subject.
SET UP
PROCEDURE
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Click Start.
Ask the volunteer to breathe rapidly for a few seconds, and then to breathe slowly.
Examine the Breath Rate channel, there should be obvious changes in rate.
Enter a comment: 'Baseline 1' in the slow breathing region of the data.
Click Add.
Record 2-3 minutes of normal, quiet breathing and observe the trace.
Enter a comment: 'inhale, hold'.
Click Add, and immediately ask the volunteer to take a deep breath and hold it in for as
long as possible.
Enter a comment: 'breathe'.
When the volunteer begins to breathe again, click Add .
Wait until a normal (baseline) breathing pattern resumes; then let the volunteer rest and
breathe normally for another 2-3 minutes.
Enter a comment: 'exhale, hold'.
Click Add, and immediately ask the volunteer to breathe out fully and hold the breath for as
long as possible.
Enter a comment: 'breathe'.
When the volunteer begins breathing click Add.
Continue recording until a normal (baseline) pattern resumes.
Click Stop.
ANALYSIS
•
•
•
•
•
•
In the Breathing channel, place the Marker on the large peak following the comment
'inhale, hold'.
Move the Waveform Cursor to the start of the first breath afterwards, which should be
preceded by the comment 'breathe'.
Click to place the selected data in the Value panel and drag it from the Value panel into the
appropriate cell of the table.
Drag the Marker to the large (negative) peak right after the comment 'exhale, hold'.
Move the Waveform Cursor to the start of the first breath afterwards, which should also be
preceded by the comment 'breathe'.
Click to place the selected data in the Value panel and drag it from the Value panel into the
appropriate cell of the table.
•
Exercise 1: Normal respiration
Exercise 2
In this exercise, you will record and examine the effect of breath-holding on heart rate.
SET UP
•
•
•
•
•
•
•
•
PROCEDURE
Click Start.
Record a baseline heart rate and breathing pattern for two minutes. (Variation in the heart
rate is most evident with slow, deep breathing.)
After recording the baseline signals, enter a comment: 'inhale, hold'.
Click Add, and immediately ask the volunteer to take a deep breath and hold it in for as
long as possible.
While the volunteer is not breathing, enter a comment: 'breathe'.
When the volunteer begins breathing, click Add.
Click Stop.
•
•
ANALYSIS:Heart rate variations within the breathing cycle should be seen best at a timescale
compression of 20:1.
RESULT:Pulse rate will be ___________ after holding breath.
*************************************************************************************