NEET MDS Shorts
865520
PhysiologyThe conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D3) in the skin is initiated by the action of UVB light from sunlight, not by any specific hormone.
755122
Dental Materialthe initial release is generally higher, making 0.075 mg during the 1st week
the rate of release is typically highest during the initial few hours and days after placement and then decreases with time
572993
PhysiologyThe vagus nerve, a part of the parasympathetic nervous system, has a negative chronotropic effect on the heart, meaning it decreases the heart rate. It does this by releasing acetylcholine onto the sinoatrial (S1) node, which slows the SA node's pacemaker activity.
965925
RadiologyThe X-ray view which is best for the maxillary sinus is Waters view.
141980
PhysiologyThe decreased CO2 concentration in the airways can cause bronchoconstriction,
which is the constriction of the airways. This is the correct answer among the
options provided. Here is the detailed explanation:
CO2 (carbon dioxide) is an important regulator of bronchial tone. It acts
primarily through the chemoreceptors located in the carotid body and the
medullary centers of the brain, which respond to changes in the partial pressure
of CO2 in the arterial blood (PaCO2). When the concentration of CO2 in the
airways decreases, it leads to a reduction in the PaCO2. This drop in PaCO2 is
detected by the central nervous system, which then responds to maintain
homeostasis.
The body normally adjusts the diameter of the airways to ensure proper gas
exchange and ventilation. When PaCO2 levels decrease, the respiratory center in
the brain perceives this as an increase in pH (alkalosis), which can be
detrimental to the body's overall homeostasis. To counteract this, the
respiratory center initiates a reflex that can lead to bronchoconstriction. This
reflex is known as the Hering-Breuer reflex. The vagus nerve, which innervates
the airway smooth muscles, is activated by the increase in pH, causing the
release of acetylcholine and other bronchoconstrictive substances. This, in
turn, results in the contraction of the smooth muscles surrounding the
bronchioles, leading to a narrowing of the airway diameter.
Therefore, the correct answer is 2. Constriction of airways.
This response is essential in the regulation of respiration and maintaining the
optimal pH balance in the body. It is part of the body's complex system to
ensure that oxygen and carbon dioxide are properly exchanged in the lungs and
that the blood remains at a slightly alkaline pH level. However, in individuals
with certain respiratory conditions such as asthma or chronic obstructive
pulmonary disease (COPD), bronchoconstriction can exacerbate their symptoms and
potentially lead to respiratory distress.
649999
General Medicine
TNF is considered the main effector of injury in alcoholic hepatitis. It is produced by activated macrophages, particularly Kupffer cells, and plays a critical role in the initiation and perpetuation of inflammation and necrosis in the liver.
157831
PhysiologyDefective bile acid absorption primarily leads to fat malabsorption and vitamin deficiencies, including vitamin K, but not directly to hemolytic anemia.
120433
General MicrobiologyPrions are extremely small infectious agents, typically measuring between 4 to 6 nanometers in diameter. Their small size contributes to their ability to evade the immune system and resist conventional sterilization methods.