24.1.9 nephrons

nephron

structural and functional unit of urine formation in the kidney

glomerulus

• like a knot of capillary vessels clumped up in one section

• afferent arterioles drain here

filtration

occurs when fluid and solutes are forced from blood into the space in the surrounding Bowman’s capsule

effeerent arterioles

drains blood from the glomerulus

proximal convoluted tubule (PCT)

• located entirely within the cortex

  • simple cuboidal epithelium with microvilli

descending tubule (DT)

• descends into medulla

• alternates between thick and thin segments

• simple squamous epithelium

loop of henle (LH)

• connects ascending and descending tubes

• in the medulla

ascending tube (AT)

alternates between thick and thin segments

• thick

• simple cuboidal epithelium

distal convoluted tubule (DCT)

• simple cuboidal epithelium without microvilli

• in cortex

peritubular capillaries

wrap around the proximal convoluted tubule

vasa recta

wraps around the loop of henle

juxtaglomerular apparatus

• another “check and balance point”

  • occurs when a portion of the DCT comes into contact with the afferent arteriole

macula densa cells

• in renal tubule

• monitor concentrations of Cl^- and Na⁺ in filtrate

granular/juxtaglomerular cells

respond to changes in blood pressure in afferent arteriole