Physiology 3120 Lecture 47: Phys 3120 Lecture 47
2 May 2018
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Human Physiology Lecture 47
Ventilation Lung Volumes Dead space
- Spirometry: a method to measure lung volumes
- Right Old one used in 70s + 90s
o Visual representation
o Upside down bell that is suspended in a liquid (water)
o Air or oxygen in the bell is connected to a person such that they can inhale and exhale
o When a person exhales, bell moves up. When a person inhales, the bell moves down
o If the connected bell is connected to a pen that is calibrated to the volumes inside, and moves
up and down
▪ Inhale – pen moves up
▪ Exhale – pen moves down
▪ You can tell the volumes
- Left Modern: use a computer and you inhale/exhale through a filter that detects the long volumes
o Digitized version
- Spirometer consists of upside down bell filled with air hanging in a liquid
- Subject breathes the air from the bell and the movement of the bell (up with exhalation, down with
inhalation) is recorded with a pen on a moving chart
- Using the spirometer, a number of lung volumes can be determined
Tidal Volume
- = the volume of air inhaled with each breath
- Tidal volume will go up when you start exercising
Minute Volume or Pulmonary Ventilation
- Is the volume of air inhaled per minute
o How many times per minute (frequency) the person breathes
- Calculation: Tidal Volume X Frequency of Respiration
- Example:
o Tidal Volume = 500 ml
o Frequency = 12 breaths/min
o Minute Volume = 6000 ml/min
Vital Capacity:
- is the volume of air that can be forcibly exhaled after a maximal inspiration
- Taking a breathe in as deep as they can and exhale as much as you can
o Volume when you breathe in goes up to the maximal inspiration
- Inspiratory Reserve Volume (IRV): is the volume of air that can be forcibly inhaled following a
normal inspiration
o Inhale more air than your tidal volume
o Taking a breath in, and then try to inhale MORE
- Expiratory Reserve Volume (ERV): is the volume of air that can be forcibly exhaled following a
normal exhalation
o After a passive expiration, you can exhale more air
Maximal Voluntary Ventilation (MVV):
- Volume of air that can be moved into and out of the lung in one min by voluntary effort
- Also called Maximal Breathing Capacity
- Average person: Normal MVV is in the range of 125 to 170 liters per min
Residual Volume (RV):
- is the volume of air remaining in the lungs after a maximal expiration
- After you have maximal expiration (exhale as much as you can), there is still air inside of your lungs
o YOU CAN NOT EXHALE ALL THE AIR INSIDE YOUR LUNG
o Cut hole in the diaphragm – the lung collapses further, it is the residual volume that is
maintained
- RV = FRC - ERV
Document Summary
When a person inhales, the bell moves down. If the connected bell is connected to a pen that is calibrated to the volumes inside, and moves up and down. Inhale pen moves up: exhale pen moves down, you can tell the volumes. Left modern: use a computer and you inhale/exhale through a filter that detects the long volumes: digitized version. Spirometer consists of upside down bell filled with air hanging in a liquid. Subject breathes the air from the bell and the movement of the bell (up with exhalation, down with inhalation) is recorded with a pen on a moving chart. Using the spirometer, a number of lung volumes can be determined. = the volume of air inhaled with each breath. Tidal volume will go up when you start exercising. Is the volume of air inhaled per minute: how many times per minute (frequency) the person breathes.
