Human Respiratory
Respiration
• Respiration is the act or process of breathing.
• Breathing is an involuntary process that exchanges oxygen and carbon dioxide.
• Two part process: 1) inhalation, 2) exhalation
• Humans inhale oxygen (O2) and exhale carbon dioxide (CO2).
Flow of Gases
O2 is picked up in the lungs through the circulating blood.
CO2 produced by cells is carried through the venous system back to the heart. It is pumped through the lungs and exhaled into the air.
Respiration Rate
Rate of Respiration
- number of breaths per minute.
- One breath = one inhalation and one exhalation.
Respiratory System
Characteristics of Respiration Rate
An increased respiratory rate is called hyperventilation.
A decrease in respiratory rate and depth is called hypoventilation.
Rhythm of Respiration – should be regular.
Quality of Respiration - can be shallow or deep.
How is Respiration Controlled?
- Breathing is an involuntary act controlled by the brain. It can be temporarily controlled consciously such as holding your breath, or purposefully breathing deeper or slower.
- When more oxygen is needed, or an excess of carbon dioxide needs to exhaled, the brain signals the lungs to increase the respiratory rate and/or to increase the volume of air exchange by breathing deeper.
- Tidal Volume [ TV ] - normal volume moved in or out of the lungs during quiet (resting) breathing (500 mL or 0.5 L).
- Inspiratory Reserve Volume [ IRV ] – inhaling deeply to increase lung volume (2900 mL or 2.9 L).
- Expiratory Reserve Volume [ ERV ] - increasing expiration by contracting our thoracic and abdominal muscles (1400 mL or 1.4 L).
- Residual Volume [ RV ] - even when we exhale deeply some air is still in the lungs (1000 mL or 1 L)
- Vital capacity [ VC ] - the total of TV plus IRV plus ERV; it is called vital capacity because it is vital for life, and the more air you can move, the better off you are.
- Total Lung Capacity [ TLC ] – the amount of air in the lungs after a deep inhalation – VC plus RV (about 6000 mL or 6 L)
- Spirometry is a method of assessing lung function by measuring the volume of air and speed flow of air in and out of the lungs.
- This is called a Pulmonary Function Test (PFT) and is the most common lung function test. The measurement of breathing can be crucial in aiding treatment or discovery of various breathing ailments.
- Spirometry is performed with a device known as a spirometer which usually display their results in the form of graphs called spirograms.
- Volumetric Spirometers - records the amount of air exhaled or inhaled within a certain time (volume)
- Flow Spirometers - measure how fast the air flows in or out as the volume of air inhaled or exhaled increases (flow).
