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Pulmonary Ventilation
Introduction The major function of the respiratory system is to receive oxygen and provide it to the tissues of the body and remove the carbon dioxide, that is formed in the body due to metabolism, into the environment. Respiration, as a whole, comprises of the following distinct processes: 1. Pulmonary ventilation: movement of air in…
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Fetal and Neonatal Circulation
Fetal blood circulation is different from that of adults. The lungs, which are responsible for the gaseous exchange in blood (retaining oxygen and washing out carbon dioxide) become active only after birth. So, till the time we spend in our mothers’ wombs, it is the placenta, which carries out the vital task of oxygenating and…
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Short-term regulation of blood pressure
Blood pressure needs to be maintained in a narrow, healthy range for the body to function well. Regulation of blood pressure can be short-term or long-term. Short-term regulation occurs over the span of seconds to minutes and is mediated through the reflex activity of various receptors; long-term regulation occurs over the span of days to…
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Proteasomes
Introduction Proteins are an immensely vital component of cellular structures. Hence, the way they are regulated – their synthesis, degradation and modification – is very crucial to appropriate bodily function. Degradation of proteins is carried out in lysosomes but also in proteasomes, which are intracellular multi-protein complexes. Structure Proteasomes consist of a middle barrel shaped…
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Atrial fibrillation
It is a condition in which the atria beat at an abnormally high rate. The cause is the same as that for ventricular fibrillation – chaotic impulses, but in the atria, not ventricles. As the atria and ventricles are separated, except at the AV bundle, fibrillation can occur separately in them. An enlarged atria, which…
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Endothelium
Endothelium is the inner lining of blood vessels, lymph vessels and the heart. Derived from mesoderm, it comprises of a single layer of simple squamous cells. The endothelium makes a semi-permeable interface or barrier. Structure Endothelial cells are held together by tight junctions but can also have intercellular clefts between them. They embed many proteins,…
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Ventricular Fibrillation
Ventricular fibrillation is when the ventricles beat at an abnormally high rate. It occurs due to chaotic impulses in the ventricles. While some portions of the ventricles are being stimulated and contracted, other portions are unstimulated and relaxed. Thus, overall ventricular function is impaired, and the the heart cannot pump blood effectively. This ineffective pumping…
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Paroxysmal Tachycardia
Due to rhythmical discharge of impulses that can originate in any part of the heart and spread throughout the heart, the heart rate can become rapid in paroxysms – paroxysmal tachycardia – which can last for a few seconds, few minutes, few hours or much longer. There are two types of paroxysmal tachycardia:- Paroxysmal atrial…