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Biology - Renal System and Excretory Pathway - MCAT Practice Questions
What segment of the nephron immediately follows the proximal convoluted tubule (PCT) in the urine excretory pathway? Descending limb of the Loop of Henle
In the urine excretory pathway, the filtrate moves from the distal convoluted tubule (DCT) directly into which structure? Collecting duct
What is the functional unit of the kidney? Nephron
The kidney is unique for having two capillary beds in series. These are the glomerular capillaries and which other set of capillaries that surround the nephron tubules? Peritubular capillaries
What structure is the network of capillaries located at the beginning of each nephron where initial filtration occurs? Glomerulus
To regulate blood pH, the kidney adjusts the levels of reabsorbed bicarbonate (HCO₃⁻) and the levels of excreted: H⁺
Aldosterone is synthesized in the adrenal cortex in response to Angiotensin II or high concentrations of which ion? K⁺
Aldosterone increases Na⁺ reabsorption in the collecting duct and which other nephron segment, thereby increasing H₂O reabsorption and raising blood pressure? Distal convoluted tubule (DCT)
ADH (Antidiuretic Hormone) increases the permeability of the collecting duct to H₂O. What is the net effect of this action on water reabsorption? Increases H₂O reabsorption
Urine passes from the kidneys, through which structures, before entering the bladder? Ureters
What is the name of the muscular lining of the bladder that relaxes to store urine and contracts during urination, and is under parasympathetic control? Detrusor muscle
Which urethral sphincter is made of smooth muscle and is under involuntary (parasympathetic) control? Internal urethral sphincter
Which urethral sphincter is made of skeletal muscle and is under voluntary control? External urethral sphincter
The proximal convoluted tubule (PCT) is the site of bulk reabsorption for which of the following? Glucose, amino acids, soluble vitamins, salt, and H₂O
The PCT is the primary site of secretion for H⁺, K⁺, NH₃, and urea. Which compound is the PCT primarily involved in reabsorbing? Na⁺
The descending limb of the Loop of Henle (DLoH) is permeable to: Only water but not salt
The ascending limb of the Loop of Henle (ALoH) is permeable to: Only salt but not water
The opposite flow of filtrate in the Loop of Henle and blood in the vasa recta creates a countercurrent multiplier system that allows for maximal reabsorption of which substance? Water
The diluting segment of the nephron is found in the outer medulla because salt is actively reabsorbed in this site, leaving a dilute filtrate. Which structure is the diluting segment? Ascending limb of the Loop of Henle (ALoH)
The collecting duct has variable permeability to H₂O and is responsive to which two hormones? ADH and Aldosterone