Explain how the structure of the nephron and its associated blood vessels enable the kidney to carry out its functions. (11)

Excretion of nitrogenous waste is a function of the kidney with the use of processes like ultrafiltration, reabsorption and osmoregulation Ultrafiltration occurs in the glomerulus which filters the blood entering the renal artery so that only the smaller molecules get filtered in not the larger molecules such as protein and blood cells = bec of basement membrane the glomerulus has a high hydrostatic pressure within due to the wide afferent which the blood enters through and the narrow efferent whereby blood leaves. This forces the fluid into the capsule bec of the p gradient Next in the proximal convulating tube useful materials such as ions, glucose and water is reabsorbed which has adaptations such as microvilli to aid it in reabsorbing The water is reabsorbed in the descending limb of the loop of henle as it is permeable to water which creates a salt gradient in the medulla the urine is passed out through the collecting duct to the ureter which stores the urine in the bladder the water permeability varies depending on the ADH levels which depend on the person's hydration levels