When does an ovum finish meiosis?

A. Tubuloglomerular feedback involves the macula densa sensing changes in sodium chloride concentration and adjusting the glomerular filtration rate (GFR) via the juxtaglomerular apparatus.

B. Renal autoregulation includes mechanisms like the myogenic mechanism and tubuloglomerular feedback that maintain stable GFR despite blood pressure changes. This option is too broad and not specific to the mechanism described.

C. The myogenic mechanism refers to the smooth muscle's tendency to contract when stretched, helping to stabilize GFR by adjusting the diameter of the afferent arterioles. This is the correct answer.

D. Sympathetic control influences renal blood flow and GFR through hormonal and nervous system regulation, but it is not the specific mechanism described in the question.

A. Diuretics increase urine output by inhibiting the reabsorption of water and sodium in the kidneys, which leads to increased water loss. This action is opposite to water conservation, making this the correct answer.

B. The counter current exchange system in the kidneys helps conserve water by maintaining a high osmolarity in the medulla, which facilitates the reabsorption of water in the collecting ducts. This system contributes to water conservation.

C. The collecting duct plays a crucial role in water reabsorption. Antidiuretic hormone (ADH) increases the permeability of the collecting duct to water, allowing more water to be reabsorbed back into the bloodstream, contributing to water conservation.

D. The counter current multiplier is a mechanism in the loop of Henle that creates a concentration gradient in the kidney medulla, which is essential for water reabsorption in the collecting ducts. It contributes to water conservation.