All of the following things occur during meiosis I. Select the statement below that does NOT occur during meiosis I.

A. Net filtration pressure will decrease: The efferent arteriole provides resistance to blood exiting the glomerulus, which maintains high hydrostatic pressure within the glomerular capillaries. If this vessel dilates, blood exits the glomerulus more easily, causing a drop in glomerular hydrostatic pressure. This reduces the overall net force available to drive filtration.

B. Systemic blood pressure will decrease: The vasodilation of a single efferent arteriole, or even all of them within the kidneys, is unlikely to significantly impact systemic arterial blood pressure. Systemic pressure is regulated by total peripheral resistance across all vascular beds. This choice describes a systemic effect resulting from a localized renal vascular change.

C. Urine output will decrease: A decrease in the glomerular filtration rate directly leads to a smaller volume of filtrate entering the renal tubule system. With less fluid being processed, the final volume of urine produced will naturally decline. This is a direct consequence of the reduced filtration pressure caused by efferent vasodilation.

D. Glomerular filtration rate will decrease: The glomerular filtration rate is highly dependent on the hydrostatic pressure gradient across the filtration membrane. By dilating the efferent arteriole, the "back-pressure" on the glomerulus is relieved, leading to a lower filtration rate. This illustrates how the resistance of the efferent vessel regulates renal function.

A. is not reabsorbed by the tubule cells: While some substances like mannitol act as osmotic diuretics because they remain in the tubule lumen, alcohol follows a different physiological pathway. Alcohol is a lipid-soluble molecule that can diffuse across membranes rather than relying on tubular transport inhibition. Its diuretic effect is neuroendocrine in origin rather than purely osmotic.

B. increases the rate of glomerular filtration: Although alcohol can cause minor changes in systemic blood pressure, it does not significantly increase the glomerular filtration rate as its primary mode of action. A slight increase in flow would not account for the profound volume of dilute urine produced. The primary diuretic effect occurs later in the distal segments of the nephron.

C. increases secretion of ADH: Increased secretion of antidiuretic hormone would result in the insertion of aquaporins and the retention of water, leading to concentrated urine. This is the opposite of the clinical effect observed with alcohol consumption. Stimulating ADH would prevent diuresis rather than promote it, leading to fluid volume expansion.

D. inhibits the release of ADH: Ethanol directly suppresses the hypothalamic-hypophyseal tract, reducing the secretion of antidiuretic hormone from the posterior pituitary. Without ADH, the collecting ducts remain impermeable to water, preventing reabsorption and resulting in the excretion of large volumes of dilute urine. This inhibition is the primary cause of alcohol-induced dehydration.