Govt Exams
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.
Acetylcholine is the primary neurotransmitter at the neuromuscular junction, binding to nicotinic receptors on muscle fiber membranes to trigger muscle contraction.
Tidal volume, the volume of air inspired or expired during normal quiet breathing, is approximately 500 mL in adults.
The loop of Henle, particularly the descending and ascending limbs, creates a countercurrent multiplier system that establishes an osmotic gradient necessary for concentrated urine formation.