Booster Cheat Sheets™– Renal System
Booster Prep
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Excretion in Humans
1
•
Kidneys
2
Juxtaglomerular Apparatus
3
Excretes waste, maintains homeostasis of body fluid volume & solute composition, and
regulates blood pressure
•
Macula Densa: Monitors filtrate
pressure in kidney tubules
If low Blood Pressure → adrenal
cortex is signaled to synthesize
aldosterone → more water is
reabsorbed from the kidney back into
the blood → Blood pressure
increases/normalizes
i. Renal Corpuscle
Kidney
Nephron
•
Nephron
Summary
Glomerulus: A capillary network that interacts with Bowman's
capsule
• Afferent arteriole (into glomerulus)
• Efferent arteriole (out of glomerulus)
Bowman’s Capsule: A structure that surrounds glomerulus
• Materials are forced out of blood and into the tubule
• Podocytes: Cells in Bowman's capsule that filter blood
Urine Formation & Flow
ii. Renal Tubule
1.
Proximal Convoluted Tubule (PCT):
• A portion between Bowman's capsule and the loop of Henle
• Substances are reabsorbed from the filtrate back into blood
• Most reabsorption occurs
• Lots of Mitochondria present
2.
3.
4.
Filtration: Large particles (blood cells
& albumin) remain in circulatory
system; only small particles go
through and form the filtrate, which
is pushed into Bowman's capsule
Reabsorption: Glucose is completely
reabsorbed; after passing through
the components of the nephron,
molecules & ions are pulled back
into blood from kidney
Secretion: Substances are removed
and secreted from the blood through
peritubular capillaries into the
nephron
Excretion: Urine physically leaves
the body
Loop of Henle:
• Descending loop: permeable only to water; water leaves the
kidney tubules, which increases the solute concentration in the
tube
• Ascending loop: impermeable to water; NaCl gets removed,
which decreases the solute concentration in the tube
Distal Convoluted Tubule (DCT):
• More reabsorption of glucose, ions, and water
Collecting Duct:
• Collects remaining filtrate
• Hormones can act on it to affect secretion & reabsorption
Hormones
Aldosterone:
• Increases Na+ reabsorption from
the kidney tubules into the
bloodstream → water follows Na+
out of the kidney and back into
the blood → water retention in
blood is increased
Nitrogenous Waste Products
ADH:
• Increases collecting duct permeability to water →
water is reabsorbed out of kidney tubule and back
into the bloodstream → urine becomes more
concentrated while blood pressure increases
• Alcohol & coffee block synthesis of ADH, leading to
more dilute urine flow
•
•
•
Aquatic animals excrete NH3 & NH4
directly into water
Mammals, sharks, amphibians:
convert NH3 → Urea
Birds, insects, reptiles: secrete Uric
Acid
Filtration in Renal
corpuscle
↓
Reabsorption/secretion
in PCT
↓
Descending loop of Henle
concentrates the solutes
↓
Ascending loop
dilutes the filtrate
↓
More reabsorption &
secretion in DCT, leading
into collecting duct
↓
Filtrate descends collecting
duct, becomes more
concentrated
↓
Collecting duct
leads into renal calyces
↓
Renal calyx
empties into renal pelvis
↓
Ureter
↓
Urinary bladder
↓
Urethra
Osmoregulation in Fish
Marine Fish:
• Body cells are hypotonic to environment →
water loss occurs
• Constantly drink water to offset water loss
• Rarely urinate
Freshwater Fish
• Body cells are hypertonic to environment →
water enters
• Rarely drink water
• Constantly urinate to stop body fluid being
diluted