Chapter 23. The Urinary System Part 2 (Sections 4-7) Homework Assignment
Complete each statement by using the appropriate word or phrase from the list.
A decrease in ATP synthesis within the cells of the proximal convoluted tubule would result in a significant decrease in tubular reabsorption. A mutation in the proteins that form tight junctions could decrease the ability of the proximal tubular cells to connect to each other. This would result in an increase in the movement of substances out of the tubule via the paracellular route. An osmotic gradient of Na⁺ across the tubule wall drives the transport of water and most other solutes out of the filtrate. The movement of substances out of the filtrate via the transcellular route is dependent on the elaborate microvilli found in proximal tubule cells. Virtually 100% of the glucose is reabsorbed by the time the filtrate reaches the end of the proximal convoluted tubule. Channels called aquaporins aid in the reabsorption of water within the nephron.
Complete each statement by using the appropriate word or phrase from the list.
Glucose in the renal tubules encountering luminal epithelia can be absorbed via the transcellular route by passing through the plasma membrane of the absorptive cell. The process of glucose reabsorption begins in the basolateral membrane, where sodium-potassium ATPase pumps move sodium into the interstitium between the peritubular capillaries and the tubular epithelium. The active movement of sodium out of the cell decreases the concentration of the cytoplasm, creating a diffusional gradient from the lumen to the cytoplasm. Facilitated diffusion of glucose occurs through a sodium and glucose dependent symporter, positioned in the luminal membrane. Glucose then follows through the basal membrane via facilitated diffusion to the tissue interstitium.
Click and drag the appropriate word or phrase on the left to complete the sentences on the right. Then, click and drag the sentences arranging them in order to accurately describe the involuntary micturition reflex.
Production of urine by the kidneys begins to fill the urinary bladder. The fullness of the urinary bladder is detected by stretch receptors. Sensory nerve impulses travel along the pelvic nerve to the sacral spinal cord. Efferent impulses excite the detrusor and relax of the internal urethral sphincter. Voiding of the bladder is delayed by the voluntary control of the external urethral sphincter.
Indicate whether each of the following substances is reabsorbed from the filtrate or secreted into the filtrate.
Secreted: NH4+, H+ Reabsorbed: glucose, water, Mg2+, HCO3-, amino acids, vitamins
Complete each statement by using the appropriate word or phrase from the list.
The cell type in the distal tubule and collecting duct that is responsible for Na⁺ and water reabsorption is the principal cell. The hormone aldosterone acts in this part of the nephron and has a big impact on Na⁺ and K⁺ levels in the filtrate. Overconsumption of alcohol can cause the hypothalamus to sense that the blood is too dilute, resulting in a decrease in the production of antidiuretic hormone. This reduces the reabsorption of water, leading to dehydration. A person who experiences higher than normal levels of phosphate in their blood and higher than normal levels of Ca²⁺ in their urine probably suffers from a deficiency in the production of parathyroid hormone. When the level of the hormone atrial natriuretic peptide increases, a person will experience an increase in Na⁺ excretion in their urine.
Complete each statement by using the appropriate word or phrase from the list. Each label may be used more than once.
The countercurrent multiplier is a phenomenon that occurs in the nephron loop. Countercurrent exchange occurs as both solutes and water move freely in and out of the vasa recta. The increase in osmolarity, as filtrate moves down the descending limb, is due to water moving out of the tubule. The decrease in osmolarity of the filtrate, as it moves up the ascending limb, is due to solutes moving out of the tubule. The osmolarity of the filtrate is virtually the same at the entrance and exit of the vasa recta. The osmolarity of the filtrate is approximately 100 mOsm/L at the end of the ascending limb and around 1,200 mOsm/L at the end of the descending limb. The recycling of urea out of the collecting duct and back into the nephron loop contributes significantly to the medullary osmotic gradient.
Click and drag the appropriate word or phrase on the left to complete the sentences on the right. Then, click and drag the sentences arranging them in order to accurately describe the process of voluntary voiding of the urinary bladder.
The micturition center in the pons receives signals from stretch receptors in the bladder wall. If it is untimely to urinate, impulses from the pons excite spinal interneurons that keep the external urethral sphincter contracted. If it is timely to urinate, efferent signals from the pons to the spinal interneurons excite the detrusor and relax the internal urethral sphincter. Inhibitory signals from the pons cease, and the external urethral sphincter relaxes. Urine is voided.
Complete each statement by using the appropriate word or phrase from the list.
The rate at which substances are removed from the blood by the kidneys is called renal clearance. Assuming a GFR of 125 ml/min, if a drug appears in the urine at a rate of 150 ml/min, then it is secreted by the nephron. A substance that is reabsorbed from the filtrate would appear in the urine at a rate that is less than the GFR. It is possible to measure GFR by injecting the carbohydrate inulin into a patient and measuring the rate at which it appears in the urine. When carrier proteins for glucose become saturated and this sugar begins to appear in the urine, the transport maximum for glucose has been reached.
Read each of the descriptions regarding the composition and properties of urine. Then, click and drag each into the appropriate category to indicate whether it is true or false.
True: urine is more dense than distilled water, the most abundant solute in urine is a nitrogenous waste, urine is approximately 95% water, hematuria may indicate trauma to the kidneys, it is possible for urine to be hypertonic compared to blood plasma, the odor of urine can be influenced by different foods False: normal urine is alkaline, bacterial infections of the urethra may cause a sweet, fruit odor in urine, clear urine indicates dehydration, sodium chloride, potassium chloride, glucose, and uric acid are present in normal urine
Place the correct word into each sentence to describe tubular secretion and reabsorption.
Tubular reabsorption and secretion occurs with varying solutes in the renal tubules. In the PCT, there is secretion of urea, H⁺, creatine, and uric acid. Conversely, there is a noticeable reabsorption of glucose, amino acids, urea, and vitamins in the same region of the tubule. Once in the nephron loop, the descending limb reabsorbs water. Heading up the ascending limb, urea is secreted. In the DCT, K⁺ can be reabsorbed and secreted heading into the collecting duct.
