Tag: phases in respiration

Breathing is an act of ventilating a respiratory surface with air. Breathing is usually accomplished through muscular movements that can be divided into inspiration (intake of air ) and expiration (outflow of air). The composition of inhaled air is 20.94 % oxygen, 0.04 % carbon dioxide, 79.02 % nitrogen and trace gases. The composition of exhaled air is 16.49 % oxygen, 4.49 % carbon dioxide, 79.02 % nitrogen and other trace gases. The nitrogen is an inert gas, during breathing, there is no change in nitrogen percentage in inhaled as compared to exhaled air.

During inhalation, diaphragm contraction occurs which induces the lower ribs to move upward and forward, which also increases thoracic volume. The ribs move outward because the central tendon of the diaphragm (at the crown of the dome) pushes down onto the liver and stomach, which act like a fulcrum. Oxygen enters into the alveoli. Alveoli, is the site for gaseous exchange and they increase the surface area for facilitating the process. 
Carbon monoxide has 210 times greater affinity for haemoglobin than oxygen. Thus, the correct answer is option D.

Breathing is the process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, by bringing in oxygen & expelling out carbon dioxide.

Inspiratory reserve volume (IRV) + tidal volume (TV) + expiratory reserve volume (ERV) represents vital capacity (VC). Now, inspiratory capacity is the total volume of air that can be inhaled after a normal expiration. It includes tidal volume and inspiratory reserve volume i.e., IC = TV + IRV. Thus, option (a) is correct which says that vital capacity/.e., IRV + TV + ERV = IC + ERV.

Diaphragmatic or abdominal breathing is the normal pattern of breathing at rest: the abdomen protrudes as the diaphragm is lowered. It is done by contracting the diaphragm, a muscle located horizontally between the chest cavity and stomach cavity. Air enters the lungs and the belly expands during this type of breathing.This deep breathing is marked by expansion of the abdomen rather than the chest when breathing.

The normal respiration rate in an adult rabbit is 30 - 60/minute, but some breathe faster than this if they are hot or stressed.

In fermentation, the carbohydrate gets broken down, but instead of making pyruvate, the final product is a different molecule depending on the type of fermentation. Fermentation is most often triggered by a lack of sufficient amounts of oxygen to continue running the aerobic respiration chain. Humans undergo lactic acid fermentation. Instead of pyruvate, lactic acid is created instead. Other organisms can undergo alcoholic fermentation where the end product is neither pyruvate nor lactic acid. The organism makes ethyl alcohol as an end product. 

The respiratory surface needs moisture for maximum efficiency. Oxygen from the air dissolves in the water on the surface momentarily and this allows the oxygen more time to cross the alveolar membrane. If the surface dries out, gas exchange will happen at a very reduced rate since fast-moving gaseous oxygen molecules do not efficiently cross the alveolar membrane. The reduced gas exchange is mostly likely not enough to support blood oxygenation for vital functions. 

Diffusion is insufficient to meet the oxygen requirement of multicellular organisms like human because all the cells are not direct contact in environment and diffusion is a slow process. Diffusion is too slow to cover the distance between the gas exchange surface and the sites where the oxygen is required. That is why we need a gas transport system - the bloodstream. It would be difficult to allow passive diffusion to transfer oxygen because there would need to be gradients across each and every cell. In the end, it would be too slow and impractical for any multicellular organism to use.