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HOMEOSTASIS
HOMEOSTASIS
A set of self-regulation phenomena, leading to the maintenance of relative consistency in the composition and properties of the internal environment of an organism.
Oxygen is taken and used. Carbon dioxide is produced and removed
MECHANICS OF PULMONARY RESPIRATION
MECHANICS OF PULMONARY RESPIRATION
The Pulmonary Respiration is a process in which the respiratory gases are regularly exchanged between the atmosphere and the lungs.
The rhythmic act of breathing involves inward and outward flow of air that is brought about by changing the size of the thoracic cavity and ultimately, resulting in creating a pressure gradient between lungs and the atmosphere. This is done by two ways-
The downward and upward movement of the diaphragm, which lengthens and shortens the chest cavity.
The elevation and depression of the ribs which increase or decrease the diameter of the chest cavity.
All this occurs during inspiration and expiration.
I
INSPIRATION (INHALATION):
Inspiration is brought about by the construction of inspiratory muscles of two types, phrenic and external intercostal muscles.
Phrenic Muscles: These muscles extend from the diaphragm to the ribs and vertebral column. When these contract, the diaphragm is flattened which increases the thoracic cavity anteroposteriorly. It is a principal inspiratory muscle and is responsible for about 75% of the tidal volume.
External Intercostal Muscles: They are 11 pairs of muscles present between the 12 pairs of ribs in slanting forward and downward direction. At rest, the ribs slant downwardly. As the external intercostal muscles contract the ribs move in an upward and outward direction. It elevates the rib cage which also expands in anteroposterior direction by about 20%. At this time the internal intercostal and abdominal muscle relax. Relaxation of abdominal muscles creates space for accommodating the abdominal viscera.
EXPIRATION (EXHALATION):
Expiration is the process by which foul air from the lungs is released into the atmosphere. Ordinarily, the expiration is brought about by the relaxation of inspiratory muscles due to which the ribs move backward downward and inward. Simultaneously, diaphragm also moves upward and again becomes dome-shaped. These changes reduce the thoracic cavity from all sides which increasing the internal pressure. Thus the lungs contract and the air present inside is forced out.
Inspiration and expiration alternate with each other. One inspiration followed by one expiration collectively constitutes one respiration.
Internal Intercostal Muscles: These are also 11 pairs of muscles present between the ribs. The contraction of these muscles pulls the ribs backwards, upward and inward, as the thoracic cavity decreases dorsoventrally and laterally.
Abdominal Muscles: These extend from the ribs to the abdominal visceral organs. When these muscles contract, the abdominal visceral organs are pulled upward towards the diaphragm. So the diaphragm becomes more convex and the thoracic cavity decreases anteroposteriorly.
GAS EXCHANGE:
GAS EXCHANGE:
Gas will move along a gradient from an area of higher
partial pressure to lower partial pressure.
RESPIRATORY SYSTEM TERMS
RESPIRATORY SYSTEM TERMS
Pulmonary ventilation: It consists of the entry of oxygen into the body of a living being and the exit of carbon dioxide from it
Total lung capacity (TLC): Amount of air in the lungs after maximum inhalation
Vital capacity (VC): Maximum amount of air that a person can expel from the lungs after maximum inhalation
Tidal volume (TV): Amount of air inhaled with each normal breath
Expiratory reserve volume (ERV): Amount of extra air that can be exhaled after a normal exhalation
Inspiratory reserve volume (IRV): Amount of air in the lungs after normal breathing
Residual volume (RV): Amount of air that remains in the lungs after exhaling completely
VO2Max
VO2Max
VO2max: is the maximum amount of oxygen that the body can absorb, transport and consume in a given time. Also called Aerobic Capacity, it is the most effective way to measure the aerobic capacity of an individual. The higher the VO2 max, the higher your cardiovascular capacity is.
Formula: Maximum cardiac output * Maximum arterio-venous oxygen difference
Poor 30-35
Regular 35-40
Good 40-45
Very good 45-50
Excellent 50-55
Exceptional +55
In this graph we can see how we can distinguish between the levels of VO2max of a person. The media of VO2max is of 40-50 ml/kg/min
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