Urinary System Flashcards
What are the 6 structures that make up the urinary System?
Two kidneys, two ureters, one urinary bladder, one urethra.
Nitrogenous waste materials from protein breakdown are eliminated from the body primarily as ______.
Urea.
Name one hormone whose release is regulated by the kidney, one hormone that directly affects kidney function, and one hormone produced by the kidney.
The release of antidiuretic hormone is regulated by the kidneys, aldosterone directly affects kidney function, and erythropoietin is produced in the kidneys.
What is the difference between the hilus of the kidney and the renal pelvis?
The hilus is the area on the medial side of each kidney where blood and lymph vessels, nerves, and the ureter enter and leave the kidney. The renal pelvis is inside the hilus and is a urine collection chamber at the beginning of the ureter.
What is meant by the term retroperitoneal?
Retroperitoneal means outside of the abdominal cavity, between the parietal peritoneum and the dorsal abdominal muscles.
List, in order, the parts of the nephron. Indicate if a specific part is found in the cortex or the medulla of the kidney.
1) Renal corpuscle (cortex)
2) Proximal convoluted tubule (PCT) (cortex)
3) Loop of Henle (medulla and cortex)
4) Distal Convoluted Tubule (DCT) (cortex)
What is the difference between glomerular filtrate and tubular filtrate?
Glomerular filtrate is the fluid that leaves the glomerular capillaries and enters the capsular space. It is similar to plasma, but without proteins. It contains waste products that need to be cleared from the body, as well as important substances that the body needs, such as sodium, potassium, calcium, magnesium, glucose, amino acids, chloride, bicarbonate, and water. Glomerular filtrate enters the PCT and is termed tubular filtrate, which travels through the tubular part of the nephron. The important substances are reabsorbed from the tuublar filtrate back into the body along with some urea. The body eliminates some waste products by secreting them into the tubular filtrate. Examples include hydrogen, potassium, ammonia, and some drugs.
What is the function of the brush border on the epithelial cells of the proximal convoluted tubule?
The brush border increases the cellular surface area exposed to the fluid in the tubule by a factor of about 20. This is especially important to the PCT’s reabsorption and secretion functions.
How does the blood in the efferent glomerular arteriole differ from the blood in the afferent glomerular arteriole?
The blood in the efferent glomerular arteriole is more concentrated because some of the fluid has been removed to the nephron for urine production.
What is the difference between tubular reabsorption and tubular secretion?
The glomerular filtrate contains substances found in plasma that the body doesn’t want to lose because it needs them to maintain homeostasis. Tubular reabsorption involves removing these substances from the tubular filtrate. The useful substances are reabsorbed from the tubules into the peritubular capillaries.
Many waste products and foreign substances are not filtered from the blood in sufficient amounts from the glomerular capillaries. The body still needs to get rid of these substances, so it transfers them from the peritubular capillaries into the tubular filtrate in the tubules to be eliminated in urine
How does ADH deficiency affect urine volume? What is the mechanism?
Insufficient ADH will increase urine volume. ADH acts on the DCT to promote water reabsorption into the body. If ADH is absent, water will not be reabsorbed and will be lost in urine.
What is the mechanism by which glucose and amino acids are reabsorbed out of the proximal convoluted tubule and back into the body?
As the glomerular filtrate enters the lumen of the PCT, sodium is actively pumped out of the fluid and back into the bloodstream. Sodium in the tubular filtrate attaches to a carrier protein that carries it into the cytoplasm of the PCT epithelial cell. The transfer of sodium from the tubular lumen into the epithelial cell requires energy. At the same time glucose and amino acids attach to the same protein as sodium and follow the sodium into the epithelial cell by passive transport. Glucose and amino acids passively diffuse out of the tuublar epithelial cell into the interstiital fluid and then into the peritubular capillaries.
Explain the concept of the renal threshold of glucose.
The renal threshold of glucose is the amount of glucose that can be reabsorbed by the proximal convoluted tubules. If the blood glucose level gets too high, the amount of glucose that is filtered through the glomerulus exceeds the amount that can be reabsorbed (the renal threshold) and the excess is lost in urine. Fortunately, the renal threshold exceeds the normal amount of glucose found in blood, so 100% of the glucose filtered through the glomerulus is reabsorbed back into the body, and no glucose is lost in the urine. However, in pathologic conditions such as uncontrolled diabetes mellitus where blood glucose levels can be extreemely high because of insufficient insulin production, the amount of glucose filtered through the glomerulus exceeds the limit that can be reabsorbed by the PCT.
Diabetes insipidus gets its name from what physical characteristic of urine produced by patients with this disease?
The word insipid means tasteless. The disease diabetes insipidus was given its name because clinically it looked similar to diabetes mellitus, but the urine was “tasteless” rather than sweet because it didn’t contain glucose.
Why is it important that the ureters have an inner lining of transitional epithelium?
The transitional epithelium allows the ureters to stretch as urine is passed through them on its way to the urinary bladder.
