RESPIRATION –PART II : RESPIRATION –PART II
Parts of the respiratory system : Parts of the respiratory system
Respiratory system : Respiratory system
Structure of lungs : Structure of lungs The human lungs are the organs of respiration in humans. Humans have two lungs, with the left being divided into two lobes and the right into three lobes.
Together, the lungs contain approximately 2400 km (1500 mi) of airways and 300 to 500 million alveoli, having a total surface area of about 70 m2 (8,4 x 8,4 m) in adults — roughly the same area as one side of a tennis court.
If all of the capillaries that surround the alveoli were unwound and laid end to end, they would extend for about 992 km.
Each lung weighs 1.1 kilograms (2.5 pounds), therefore making the entire organ about 2.3 kilograms (5 pounds).
Breathing : Breathing Breathing is the process of drawing air into and expelling air from the LUNGS, also called pulmonary respiration.
Specialized centers in the brainstem regulate the rate and rhythm of respiration to harmonize breathing with HEART RATE and BLOOD PRESSURE.
Inhalation : Inhalation Breathing occurs through the mechanical actions of MUSCLE movement.
The DIAPHRAGM (the large, flat muscle that extends across the floor of the thoracic cavity) and the INTERCOSTAL MUSCLES (the muscles between the ribs) contract to expand the thoracic cavity, pulling air into the lungs (INHALATION).
Inhalation is an active process.
The path of inhaled air : The path of inhaled air Simultaneously the EPIGLOTTIS, a cartilaginous flap at the top of the throat normally closed across the top of the TRACHEA to prevent food and other materials from entering the lungs, opens to allow the air to pass. The air flows through the trachea into the bronchi, bronchioles, and alveoli.
Exhalation : Exhalation When the diaphragm and the intercostal muscles relax the thoracic cavity returns to its resting position, pressuring air out of the lungs (EXHALATION) in reverse sequence. EXHALATION is a passive process.
Exhalation and Inhalation : Exhalation and Inhalation
Who triggers the cycle? : Who triggers the cycle? Breathing patterns help the doctor assess pulmonary function and respiratory effectiveness.
Breathing is an involuntary process under control of the brainstem. The concentration of carbon dioxide in the BLOOD is the primary trigger for initiation of a RESPIRATORY CYCLE (one inhalation and one exhalation), triggering the brainstem to signal the diaphragm and the intercostal muscles to contract.
Breath Sounds - Characteristic noises the flow of air makes as it courses through the TRACHEA and bronchi. : Breath Sounds - Characteristic noises the flow of air makes as it courses through the TRACHEA and bronchi. Normal breath sounds are of nearly equal duration with inhalation and exhalation and are particular to specific locations.
The absence of normal breath sounds indicates that the segment or lobe of the lung is not receiving air, usually as a result of a blockage of a bronchus or lung collapse.
Other breath sounds the doctor can hear through the stethoscope are abnormal and indicate INFECTION or disease.
Among them are wheezes, steady high-pitched whistling noise heard with exhalation that is typical of obstructed airways such as might result with ASTHMA, inhaled foreign objects.
RHONCHI, low-pitched, continuous whistling noises heard with exhalation that suggest airways blocked with mucus
Breath sounds present important diagnostic information that helps the doctor determine the health status of the lungs as well as assess the progress of conditions under treatment.
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summary : summary