Category: Physiology

Contrary to a simple classification, the effect of cholinergic drugs on blood vessels is not uniform and can be paradoxical, depending on the state of the vascular endothelium. The intricate interplay between acetylcholine, endothelial health, and different receptor subtypes determines whether cholinergic drugs cause vasoconstriction or vasodilation.

The heart has five fundamental properties that govern its function, first described in 1897. This guide breaks down what is inotropic vs chronotropic vs dromotropic vs bathmotropic by exploring how medications and the nervous system precisely modulate the heart's rate, contractility, electrical conduction, and excitability.

Over 70% of filtered sodium is reabsorbed in the proximal convoluted tubule alone. To counteract this process and increase urination, what is the main mechanism of action of diuretics? These drugs function primarily by inhibiting sodium reabsorption at various points along the kidney's nephron.

After taking aspirin, the drug's rapid hydrolysis into its active metabolite, salicylic acid, is only the beginning of its journey out of the body. Understanding how is aspirin eliminated from the body involves a complex interplay between metabolism in the liver and excretion by the kidneys.

Approximately 80% of the body's natural output from the adrenal medulla is epinephrine, making it a critical hormone for survival. This potent chemical, more commonly known as adrenaline, is the body's own version of the medication, giving us insight into exactly what is a natural epinephrine.

Approximately 90% of ingested alcohol is metabolized by the liver, with the remaining 10% eliminated through breath, urine, and sweat. Understanding what metabolises alcohol faster is crucial, as the rate is determined by a complex interplay of genetic and biological factors that cannot be rushed.

Lidocaine, an amide-type local anesthetic synthesized in 1943, is widely used for pain relief, but its systemic effects extend to several vital organs. When absorbed into the bloodstream, a question arises: "What organ does lidocaine affect?" The answer is that its influence extends well beyond the site of application, particularly affecting the brain, heart, and liver.

The chemoreceptor trigger zone (CTZ) is a specialized area in the brain that detects emetogenic (vomiting-inducing) substances in the blood and cerebrospinal fluid [1.2.1, 1.3.1]. But from a pharmacological standpoint, what does CTZ do and how is it targeted by medications?

Discovered in 1914, acetylcholine (ACh) was the very first neurotransmitter to be identified [1.5.3]. Understanding **what is the mechanism of action of acetylcholine?** is fundamental to grasping how our nervous system controls everything from muscle movement to memory [1.5.3, 1.5.5].

In a study on healthy young men, a 12-week regimen combining L-carnitine with high-dose carbohydrates increased muscle carnitine content by a significant 20%. This finding demonstrates the physiological principles governing **what increases carnitine uptake into the muscle** and is key for anyone looking to maximize metabolic performance.