Entrance Exams
Govt. Exams
The lens adjusts its shape (accommodation) through ciliary muscle contraction to focus light precisely on the retina for clear vision.
Dystrophin is a structural protein that stabilizes muscle cell membranes; its absence causes Duchenne muscular dystrophy with progressive muscle weakness.
During inspiration, external intercostal muscles contract, increasing thoracic volume, decreasing intrapleural pressure, and allowing air to flow into lungs.
The countercurrent multiplier creates an osmotic gradient allowing the production of concentrated urine by establishing osmolarity differences in the medulla.
The sympathetic nervous system triggers 'fight or flight' responses including increased heart rate and pupil dilation via norepinephrine and epinephrine.
Carbohydrate digestion begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase and brush border enzymes.
During the refractory period, sodium channels enter an inactivated state (unable to reopen immediately) while potassium channels remain open, hyperpolarizing the membrane.
ADH (vasopressin) is released in response to increased blood osmolarity, increases aquaporin-2 channels in collecting ducts, and promotes water reabsorption.
The typical resting membrane potential is -70 mV, maintained by the Na+/K+ ATPase pump and selective membrane permeability.
Deoxygenated blood returns to right atrium, passes to right ventricle, pumped to lungs, oxygenated blood returns to left atrium, then left ventricle, and exits via aorta.