When the radius of the efferent arteriole was decreased, the pressure and the filtration rate both increased. 7. When the radius of the efferent arteriole was increased, the pressure and the filtration rate both decreased. Activity 2: 1. When you increase the blood pressure, the glomerular capillary pressure and the glomerular filtration rate will also increase. 2. As the pressure increased, the urine volume increased proportionally. 3. Increased blood pressure can be a result of increased blood volume. For this reason, an increase in urine volume would stabilize blood volume.
4. If you close the one way valve, pressure will increase in the Bowman’s capsule and filtration rate will decrease. 5. With increased pressure and the valve closed, the filtration rate decreased but the glomerular pressure stayed the same. Urine output was zero. Activity 3: 1. Both increasing the afferent arteriole radius and decreasing the efferent arteriole resulted in an increase in glomerular filtration rate. 2. When both arteriole radii changes were implemented, glomerular filtration rate and pressure rose above baseline values.
3. Increasing the afferent radius or decreasing the efferent radius would compensate for lowered blood pressure. 4. Increasing the afferent radius had a greater effect than decreasing the efferent radius because there was a greater increase in glomerular pressure. 5. Intrinsic & extrinsic mechanisms result in changes to the afferent & efferent arterioles to maintain glomerular filtration rate. Activity 4: 1. When the solute concentration gradient in the interstitial space was increased, the urine volume decreased.
2. When the solute concentration gradient in the interstitial space was increased, the concentration of the urine increased. 3. The urine volume will increase in the absence of ADH in the collecting duct. 4. Most of the tubular filtrate is reabsorbed to prevent fluid loss and maintain homeostasis. 5. Yes, the reabsorption of solutes affects water reabsorption because water will follow the solutes by osmosis. Activity 5: 1. As glucose carriers were added, the glucose concentration in the bladder increased. 2.
Glucose is first reabsorbed by secondary active transport at the apical membrane of PCT cells and then via facilitated diffusion along the basolateral membrane. 3. When the number of glucose carriers becomes great enough, all of the glucose is reabsorbed. 4. The absence of insulin or decreased sensitivity to the hormone, leads to excess glucose in the blood so the carriers reach their maximum transport levels. Activity 6: 1. When aldosterone was added, the urine volume slightly decreased. Aldosterone results in increased sodium and water reabsorption and increased potassium secretion.
2. When ADH was added, the urine volume dramatically decreased. The addition of ADH resulted in the potassium being more concentrated because the volume of urine decreased. 3. Aldosterone release (from adrenal cortex) is stimulated by decreased blood pressure and the need to reabsorb sodium. 4. The addition of BOTH aldosterone and ADH caused urine volume to decrease. 5. Aldosterone release (from the posterior pituitary gland) is stimulated by decreased blood pressure and the need to reabsorb water into the blood to increase blood pressure.
ADH favors the formation of concentrated urine – ADH causes an increase of water permeability in DCTs & collecting ducts. 6. ADH has the greater effect on urine volume. ADH is responsible for fluid retention. Aldosterone is primarily increasing sodium uptake and potassium secretion. 7. No, the urine concentration will NOT vary in the absence of ADH. 8. In order to reabsorb sodium without affecting urine volume, you would need to increase the amount of aldosterone and decrease ADH.