Respiratory Physiology
Functional residual capacity (FRC)
2,400 mL, is the amount of air remaining in the lungs after a normal expiration (FRC = RV + ERV).
Inspiratory capacity
3,600 mL, is the maximum amount of air that can be inspired (IC = TV + IRV).
Respiration
Breathing is an active process The primary muscles of respiration include the external intercostal muscles (located between the ribs) and the diaphragm (a sheet of muscle located between the thoracic & abdominal cavities).
37 degrees Saturated with water vapor
Conducting zone Warms and humidifies inspired air
Mucus secreted to trap particles Mucus/particles moved by cilia to be expectorated.
Conducting zone filter and clean
Contraction of external intercostal muscles > elevation of ribs & sternum > increased front- to-back dimension of thoracic cavity > lowers air pressure in lungs > air moves into lungs
Contraction of External intercostal muscle
Contraction of diaphragm > diaphragm moves downward > increases vertical dimension of thoracic cavity > lowers air pressure in lungs > air moves into lungs:
Contraction of diaphragm
Bradypnea
Decrease respiratory rate
Spirogram
Graphical recording of changes in the lung volume under different Stages of breathing
Conducting zone
Includes all the structures that air passes through before reaching the respiratory zone. Mouth, nose, pharynx, glottis, larynx, trachea, bronchi.
Spirometry
It is a process of recording volume movements of air into and out of the lungs.
Respiration
It is the process by which the body takes in oxygen and utilizes and removes CO2 from the tissues into the expired air It comprises of Ventilation by the lungs inspiration and expiration Gas exchange across alveolar membrane Diffusion in the alveoli, Fick's law Transport of gases by blood (haemoglobin) Uptake of O2 and release of CO2 by tissues Diffusion at the cellular level
nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)
Pathway
pulmonary ventilation external respiration transport of the gases through the body by blood internal respiration cellular respiration
Process of respiration can be divided into 5 stages
Respiratory zone
Region of gas exchange between air and blood Respiratory bronchioles Alveolar ducts, Alveolar Sacs and Alveoli
Dead space air/volume
Volume of breathed air that never reaches gas exchange areas but simply fill respiratory passage. its value is 150 ml.
Tachypnea
increased respiratory rate
Spirometer
is an apparatus for measuring the volume of air inspired and expired by the lungs. It is a precision differential pressure transducer for the measurements of respiratory flow rates
Pleural friction rub
low-pitched, grating, or creaking sounds that occur when inflamed pleural surfaces rub together during respiration. To determine whether the sound is a pleural friction rub or a pericardial friction rub, ask the patient to hold his breath briefly. If the rubbing sound continues, its a pericardial friction rub because the inflamed pericardial layers continue rubbing together with each heart beat - a pleural rub stops when breathing stops.
Stridor
refers to a high-pitched harsh sound heard during inspiration.. Stridor is caused by obstruction of the upper airway, is a sign of respiratory distress and thus requires immediate attention.
Expiration/exhalation
relaxation of external intercostal muscles & diaphragm > return of diaphragm, ribs, & sternum to resting position > restores thoracic cavity to preinspiratory volume > increases pressure in lungs > air is exhaled
Wheezes
sounds that are heard continuously during inspiration or expiration, or during both inspiration and expiration. They are caused by air moving through airways narrowed by constriction or swelling of airway or partial airway obstruction. Wheezes that are relatively high pitched and have a shrill or squeaking quality may be referred to as sibilant rhonchi Wheezes that are lower-pitched sounds with a snoring or moaning quality may be referred to as sonorous rhonchi.
Abnormal breath sounds
the absence of sound and/or the presence of "normal" sounds in areas where they are normally not heard. The term "adventitious" breath sounds refers to extra or additional sounds that are heard over normal breath sounds. Detection of adventitious sounds is an important part of the respiratory examination, often leading to diagnosis of cardiac and pulmonary conditions.
Respiratory Physiology
the branch of human physiology focusing upon respiration. Primary function is to obtain oxygen for use by body's cells & eliminate carbon dioxide that cells produce Includes respiratory airways leading into (& out of) lungs plus the lungs themselves
25-40 breaths per minute
Average resting respiratory rates by age are: 6 months:
18-25 breaths per minute
Average resting respiratory rates by age are: 6 years:
12-20 breaths per minute
Average resting respiratory rates by age are: adults:
30-60 breaths per minute
Average resting respiratory rates by age are: birth to 6 weeks:
15-20 breaths per minute
Average resting respiratory rates by age are: 10 years:
20-30 breaths per minute
Average resting respiratory rates by age are: 3 years:
Normal findings in auscultation
Loud, high-pitched bronchial breath sounds over the sternum Medium pitched bronchovesicular sounds over the mainstream bronchi, between the scapulae, and below the clavicles Soft, breezy, low-pitched vesicular breath sounds over most of the peripheral lung fields.
Breath sounds
Normal breath sounds are classified as tracheal, bronchial, bronchovesicular, and vesicular sounds. The patterns of normal breath sounds are created by the effect of body structures on air moving through airways.
Eupnea
Normal respiratory rate
Tidal volume
The amount of air which enters the lungs during normal inhalation at rest. The average tidal volume is 500ml. The same amount leaves the lungs during exhalation.
Inspiratory reserve volume
The amount of extra air inhaled (above tidal volume) during a deep breath. This can be as high as 3000ml.
Inspiration/inhalation
The external intercostals plus the diaphragm contract to bring about inspiration
Normal respiratory cycle
The inspiratory phase is shorter with faster airflow. The majority of breath sounds, both normal and adventitious, are in the range of 16 to 200 Hz. This is at the lower end of the spectrum of normal hearing (16 to 16,000 Hz).
Residual volume
about 1,200 mL The amount of air left in the lungs following a maximal exhalation. There is always some air remaining to prevent the lungs from collapsing.
Expiratory reserve volume
about 1,200 mL, The amount of extra air exhaled (above tidal volume) during a forceful breath out.
Vital capacity
about 4,800 mL, is the total amount of air that can be expired after fully inhaling (VC = TV + IRV + ERV = approximately 80 percent TLC). The value varies according to age and body size.
Total lung capacity
about 6,000 mL, is the maximum amount of air that can fill the lungs (TLC = TV + IRV + ERV + RV).
Respiratory rate
also known as ventilation rate, respiration rate, breathing rate, pulmonary ventilation rate, breathing frequency, and respiratory frequency the number of breaths a person takes during one minute. It is usually measured at rest, while sitting. Average respiratory rate reported in a healthy adult at rest is usually given as 12-20 breaths per minute
Respiratory volumes
amount of air inhaled, exhaled and stored within the lungs at any given time
Crackles (rales)
caused by fluid in the small airways or atelectasis. are referred to as discontinuous sounds; they are intermittent, nonmusical and brief. may be heard on inspiration or expiration. The popping sounds produced are created when air is forced through respiratory passages that are narrowed by fluid, mucus, or pus. are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli. that don't clear after a cough may indicate pulmonary edema or fluid in the alveoli due to heart failure or adult respiratory distress syndrome (ARDS).
