Spinal anesthesia is a widely used technique in the intraoperative setting. It produces characteristic physiological effects on different body systems, which are essential to consider when using this anesthetic method. These effects may be particularly relevant in certain patients depending on their needs, comorbidities and the procedure they will be subjected to. This review highlights the major effects that spinal anesthesia has on the main body systems. In the autonomic nervous system, the effects will depend on the balance and regulation of the sympathetic and parasympathetic systems, secondary to the block level achieved, which can be estimated through temperature discrimination. The sympathetic blockade produced leads to systemic arterial and venous vasodilation, causing a decrease in peripheral vascular resistance, venous return, heart rate and myocardial contractility. Spinal anesthesia also affects the central nervous system in many ways, resulting in a sedative effect. In normal conditions, ventilatory function is not significantly affected, but may become insufficient or unsatisfactory in certain patient groups. Due to blood flow redistribution, thermoregulation may become compromised, decreasing the patient's body temperature according to the degree of the effect. Other organs which may become affected by nervous system regulations are the ones on the gastrointestinal and urinary systems. In addition to this, eventual adrenal blockade could result in lower metabolic and stress responses to stimuli.