kidney

• What are the main regions of the nephron?

  Bowman’s capsule, glomerulus, PCT, Loop of Henle, DCT, collecting duct
• What is the function of the glomerulus?

  Ultrafiltration of small molecules into Bowman’s capsule
• What adaptations of the glomerulus aid ultrafiltration?

  Afferent arteriole wider, fenestrated capillaries, basement membrane, podocytes
• What occurs in the PCT?

  Selective reabsorption of glucose, amino acids, Na⁺, Cl⁻, and water
• How is the PCT adapted for reabsorption?

  Microvilli, many mitochondria, tight junctions
• What is the function of the Loop of Henle?

  Establishes a counter current multiplier system for water reabsorption
• What happens in the descending and ascending limbs of the Loop of Henle?

  Descending limb: permeable to water; ascending limb: Na⁺ and Cl⁻ transported out
• What happens in the DCT?

  Fine-tunes ion concentration and contributes to pH regulation
• How does the collecting duct regulate water balance?

  ADH increases permeability, leading to more water reabsorption
• Why should glucose not be present in urine?

  It is completely reabsorbed in the PCT
• What causes glucose to appear in urine?

  Diabetes mellitus—blood glucose exceeds reabsorption threshold
• How can glucose concentration in urine be measured?

  Benedict’s test, biosensors, calibration curve
• What is the method for Benedict’s test?

  Add reagent to urine and heat; observe color change
• What does a color change in Benedict’s test indicate?

  Presence of glucose in urine
• What detects blood water potential changes?

  Osmoreceptors in the hypothalamus
• What hormone regulates water reabsorption?

  ADH (antidiuretic hormone)
• Where is ADH released from?

  Posterior pituitary gland
• How does ADH increase water reabsorption?

  Binds to receptors, triggers aquaporin insertion
• What happens when blood water potential is low?

  More ADH released, more aquaporins inserted, more water reabsorbed
• What happens when blood water potential is high?

  Less ADH released, fewer aquaporins, less water reabsorbed
• What type of feedback loop regulates ADH?

  Negative feedback
• Define ultrafiltration.

  High-pressure filtration of small molecules into Bowman’s capsule
• Define selective reabsorption.

  Active transport of useful molecules from nephron to blood
• Define osmoregulation.

  Control of water balance in the body via hormones
• What is the counter current multiplier system?

  A mechanism in the Loop of Henle maintaining high solute concentration
• What is glycosuria?

  Presence of glucose in urine, often due to diabetes
• What is the structure of the nephron?

  The nephron is the functional unit of the kidney
• What occurs in Bowman’s capsule and glomerulus?

  Ultrafiltration occurs due to high pressure
• What is the role of the proximal convoluted tubule?

  Selective reabsorption of glucose, amino acids, water, and ions
• What happens in the descending limb of the Loop of Henle?

  Water moves out by osmosis
• What happens in the ascending limb of the Loop of Henle?

  Na⁺ and Cl⁻ actively transported out
• What is the function of the distal convoluted tubule?

  Fine-tunes ion and water balance
• What is the role of the collecting duct?

  Final water reabsorption site
• What happens during secretion in the DCT?

  K⁺ and H⁺ are secreted into urine
• What is the process of excretion?

  Remaining fluid moves to collecting duct, renal pelvis, ureter, bladder
• How is blood water potential maintained?

  Regulated by ADH to prevent dehydration or overhydration
• How does ADH affect the collecting duct?

  Increases permeability, allowing more water reabsorption
• What is the negative feedback system for ADH?

  Low water potential increases ADH release; high water potential decreases it
• What happens during dehydration regarding ADH?

  More ADH is released, increasing water reabsorption
• What happens during overhydration regarding ADH?

  Less ADH is released, decreasing water reabsorption