Breathing Mechanism and Respiratory System

Spirometry is the process of recording the changes in the volume and movement of air in and out of the lungs and the instrument used for this purpose is called spirometer or respirometer.

The diaphragm is a characteristic feature of all mammals, used for respiration. Other options like pinna, 7 cervical vertebrae, or scrotal sacs have exceptions among mammals.

Statement (2) is correct because the chest expands, lowering intrapleural and intrapulmonary pressure, which causes air to enter. Statement (4) is correct since a healthy human typically breathes 12 to 16 times per minute. Statements (1) and (3) incorrectly reverse cause and effect.

• The respiratory tract carries air from the mouth and nose to the lungs.
• In the lungs, the gases oxygen and carbon dioxide are exchanged between the alveoli and the capillaries. 
• Exhaled air contains less oxygen and more carbon dioxide, Hence, The air we breathe out contains more carbon dioxide.

• The diaphragm is a thin skeletal muscle that sits at the base of the chest and separates the abdomen from the chest.
•  It contracts and flattens when you inhale. 
• This creates a vacuum effect that pulls air into the lungs.
•  When you exhale, the diaphragm relaxes and the air is pushed out of lungs. Hence, diaphragm forms the floor of the chest cavity.

• Respiration includes two processes: inhalation and exhalation.
• Inhalation (also known as inspiration) occurs when air or other gases enter the lungs.
•  And exhalation is the process by which the body expels carbon dioxide. Hence, Taking in of carbon dioxide is inhalation is a wrong statement.

Component                        Inspired air         Expired air
  $CO _2$                                    0.04%                   4%
Because carbon dioxide is released at the alveolar surface during the gaseous exchange between blood and alveoli.

Component              Inspired air            Expired air
Nitrogen                      79%                     79.6%

Inspired air contains more oxygen whereas, the expired air contains more of carbon dioxide content as well as water vapours. Air enters with oxygen is diffused with carbon dioxide leading to the exchange of gases.

The act of breathing air into the body the help of lungs is called inhalation. By this process, fresh air enters into the lungs that contain large amount of oxygen.

The act of breathing out air from the lungs is called as Exhalation. By this process, the foul air i.e, (containing ${ CO } _{ 2 }$) is expelled out of the lungs.

The diaphragm is a dome-shaped, muscular and membranous structure that separates the chest and abdominal cavities in mammals. It is the principal muscle of respiration that maintain the volume of air in the chest cavity during breathing.

Humans have lungs to carry out respiration. Lungs are ingrowths of the body wall and correct to the outside by a series of tubes and small openings.

During inspiration, the diaphragm moves down. The contraction of muscle fibers of the diaphragm causes it to become flat and lowered down thereby increasing the volume of the thoracic cavity in anteroposterior axis, in rabbit or lengthwise in man.

Increased CO2 levels in the blood (hypercapnia) are detected by chemoreceptors, which signal the respiratory center to increase the rate and depth of breathing to expel excess CO2.

CO2 is transported in the blood primarily as bicarbonate ions, but also as carbaminohaemoglobin (bound to hemoglobin) and dissolved in plasma. Option D covers the main transport mechanisms.

The pneumotaxic and apneustic centers are located in the pons and are responsible for controlling the rhythm and pattern of breathing.

At rest, metabolic requirements are at their lowest, which is reflected in lower pulse rates, lower breathing rates, and reduced O2 intake and CO2 output.

Frogs and earthworms are classic examples of organisms that utilize cutaneous respiration, meaning they breathe through their moist skin. While frogs also have lungs, their skin is a primary respiratory surface, and earthworms rely entirely on cutaneous respiration.

The rate of breathing in humans is primarily regulated by the concentration of carbon dioxide in the blood. Chemoreceptors detect changes in CO2 levels and pH, signaling the brain to adjust the ventilation rate to maintain homeostasis.

At high altitudes, the partial pressure of oxygen is lower. To compensate for the reduced oxygen availability, the body increases the production of red blood cells and alters hemoglobin affinity to facilitate better oxygen delivery to tissues.

Tachypnea is the medical term for rapid, shallow breathing. Hypercapnea refers to high levels of CO2 in the blood, orthopnea is difficulty breathing while lying down, and eupnea is normal, quiet breathing.

Physiological studies have historically observed that abdominal breathing is more common in women, while thoracic (chest) breathing is more common in men. This is a general anatomical and physiological trend.

The intrapleural pressure is normally negative relative to atmospheric pressure to keep the lungs inflated. This pressure is typically about 4 mm Hg lower than the atmospheric pressure between breaths.

At high altitudes, the partial pressure of oxygen is lower. The body compensates for this hypoxia by increasing the production of red blood cells (erythropoiesis) to increase the oxygen-carrying capacity of the blood.

Exhalation is a passive process because of the elastic properties of the lungs. During forced exhalation, internal intercostal muscles which lower the rib cage and decrease thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract. 

Carbon dioxide is a waste product of the body. It is majorly exhaled out by the body so that it will reduce the competition to gets bind to the haemoglobin with oxygen. It is saturated with water vapours.