Heart The heart increases in size during aging as a result of concentric ventricular hypertrophy. This occurs in response to the increase in left ventricular afterload. This increase in afterload…

Antidepressants are logically classified based on their chemical structures and their acute neuropharmacologic effects (Table 43-2). The precise mechanism by which antidepressants work is unknown, but they appear to act…

Structure–Activity Relationships All corticosteroids are constructed on the same primary molecular framework, designated as the steroid nucleus (see Fig. 40-1). Changes in molecular structure may result in altered biologic responses…

The central focus of treating acid–base disturbances is the understanding of the biochemistry of the hydrogen ion. Hydrogen ion concentrations in the various body fluid compartments are precisely regulated in…

Drug Resistance Resistance to chemotherapeutic drugs often occurs and has many causes.3 Some chemotherapy agents lead to induction of drug-metabolizing enzymes in the liver, other tissues, or tumor cells, accelerating…

The effects of cardiac antiarrhythmic drugs on the action potential and effective refractory period of the cardiac action potential determine the clinical effect of these drugs. Drugs that primarily block…

It is generally believed that twitch depression results from block of postsynaptic nicotinic acetylcholine receptors, whereas tetanic or TOF fade results from block of presynaptic nicotinic acetylcholine receptors.10,11 Blockade of…

Body fluids can be divided into intracellular and extracellular fluid, depending on their location relative to the cell membrane (see Fig. 1-1).1 Approximately two-thirds of the total body fluid in…

Severely injured patients, burn patients, and those with sepsis often are hypermetabolic, so directed nutritional support within 24 to 48 hours of admission may be beneficial. For example, energy requirements…