Govt. Exams
Entrance Exams
Myasthenia gravis is an autoimmune disorder where antibodies attack acetylcholine receptors at the neuromuscular junction, reducing muscle contraction capability.
Renin, secreted by juxtaglomerular cells, cleaves angiotensinogen to form angiotensin I, which is then converted to angiotensin II by ACE.
During absolute refractory period, inactivated sodium channels cannot open regardless of stimulus strength, making another action potential impossible.
Low oxygen at high altitude stimulates EPO release, which increases RBC production, restoring oxygen levels and decreasing EPO secretion—a classic negative feedback loop.
Both PTH and calcitonin regulate calcium-phosphate balance. PTH increases blood calcium while calcitonin decreases it through opposing mechanisms.
The T wave represents ventricular repolarization. The QRS complex represents ventricular depolarization, while P wave represents atrial depolarization.
Myelin sheath, formed by oligodendrocytes in CNS and Schwann cells in PNS, increases conduction velocity by enabling saltatory conduction.
Contraction of external intercostal muscles elevates the ribs and sternum, increasing thoracic cavity volume, which decreases intrapulmonary pressure and causes air to flow in.
Thyroid hormone deficiency decreases metabolic rate and oxygen consumption. Increased oxygen consumption would not occur; rather, it would decrease significantly.
S3 occurs during rapid ventricular filling phase (early diastole) when blood rapidly enters the ventricle. It's normal in young individuals but may indicate heart failure in older patients.
