Detailed Answers for Current Testing | Walden University
filtration, filtrate
Filtrate = everything pulled out of the blood into the glomerular (Bowman’s) capsule
• water, ions, glucose, waste
reabsorption
Most of the filtrate (~65%) is reclaimed into blood —keep the good stuff
secretion
The opposite of reabsorption Clears the plasma of unwanted substances that can’t be filtered out at the
glomerulus
osmolarity or osmotic concentration
→ Water in nephron moves by osmosis
→ Osmoreceptors detect changes in blood osmolarity
aldosterone
Produced & released by:
• Adrenal gland
Target cells:
• Kidney (distal convoluted tubule)
Actions:
Inserts more Na+/K+ pumps into cells of DCT and collecting duct:
• Na+ reabsorption (↑ blood Na+)
• H2O reabsorption (↑ blood volume and pressure)
• K+ secretion (↓ blood K+)
• ↓ urine production
Stimuli for release:
• Angiotensin II
• ↓ blood Na+ , ↓ blood volume/pressure, ↑ blood K+
Inhibited by:
• ↑ blood Na+, ↑ blood volume/pressure
• Caffeine
, • ANP
antidiuretic hormone (ADH)
Produced & released by:
• Posterior pituitary
Target cells:
• Kidney (collecting duct and DCT)
Actions:
• Inserts more H2O channels (aquaporins) into cells of DCT and collecting duct, resulting in:
o ↑ H2O reabsorption (↑ blood volume and pressure)
o ↓ urine production
o Vasoconstriction
Stimuli for release:
• ↑ ECF osmolarity (detected by hypothalamus osmoreceptors
• ↓ blood volume/pressure
Inhibited by:
• ↓ ECF osmolarity
• ANP
atrial natriuretic peptide (ANP)
Produced & released by:
• Heart (atrial cells)
Target cells:
• Kidney (glomerular cells; misangeal cells)
Actions:
• H2O secretion (↓ blood volume and pressure)
• ↑ urine production
• Vasodilation
• Inhibits ADH and aldosterone
Stimuli for release:
• Stretch in atria as a result of increased blood volume (detected by baroreceptors; high pressure)
pelvic nerve