Lecture 16 Flashcards
Kidneys and Excretion
What is the primary role of kidneys in terrestrial animals?
Kidneys are primarily responsible for maintaining fluid homeostasis by regulating water intake and loss, especially when environmental conditions fluctuate.
What is the primary role of kidneys in terrestrial animals?
Kidneys are primarily responsible for maintaining fluid homeostasis by regulating water intake and loss, especially when environmental conditions fluctuate.
What are the three common features shared by kidneys across animals?
- Tubular structures that discharge solutions to the external environment.
- They produce and excrete solutions derived from blood plasma or extracellular fluid.
- Their function is the regulation of the composition and volume of blood plasma and extracellular fluid by controlled excretion (urine).
What are the two main steps in urine formation?
- Primary urine is first introduced to the kidney tubules at the Bowman’s capsule via ultrafiltration.
- The filtered solution is modified as it passes through the kidney tubules, becoming definitive urine that is excreted.
What are the basic kidney mechanisms for urine formation?
Reabsorption involves the movement of substances back into the blood from the tubules, while secretion involves the transport of substances from the blood into the tubules for excretion.
How do the tubules in amphibians and vertebrates differ in size?
The tubules are microscopic in diameter but can be macroscopic in length, allowing for efficient filtration and modification of urine.
How does the nephron structure change along its length in amphibians?
The epithelium structure and function change along the length of the nephron, allowing for specific processes like reabsorption of water, ions, and glucose in different sections.
What is the function of the proximal convoluted tubule?
The proximal convoluted tubule is where fluid (water), ions, and glucose are reabsorbed into the blood.
What happens in the distal convoluted tubule?
The distal convoluted tubule is involved in ion reabsorption and restricted water reabsorption.
How is water reabsorption regulated in the distal convoluted tubule?
The extent of water reabsorption is determined by the permeability of the membrane, which is regulated by antidiuretic hormone (ADH).
What is diuresis?
Diuresis refers to the increased production of urine, often influenced by hormonal changes.
How does the loop of Henle help mammals produce concentrated urine?
The loop of Henle allows mammals to produce hyperosmotic urine, which has a higher concentration of ions than blood plasma.
How does the length of the loop of Henle impact urine concentration?
Longer loops of Henle enable the production of more concentrated urine, which is crucial for animals living in arid climates to conserve water.
What is countercurrent multiplication in the loop of Henle?
Countercurrent multiplication refers to the process where the descending and ascending limbs of the loop of Henle create a concentration gradient, allowing for increased water reabsorption and more concentrated urine.
