Nephron
Renal corpuscle
Tubular section
Renal corpuscle : only in cortex
Tuft of capillaries called glomerulus
surrounded by cup-shaped, hollow glomerular (Bowman's) capsule
Visceral layer of capsule has podocytes
Unusual branching epithelial cells
Foot processes with slit processes between them
Scanning EM of podocytes clinging to capillaries (left) and membrane diagram (right)
The capillaries pores (fenestrations) restrict the largest elements such as blood cells The diaphragm hold back all but the smallest proteins while letting through small molecules such as water, ions, glucose, amino acids, and urea
Nephron
Renal corpuscle
Tubular section (processes the filtrate)
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Proximal convoluted tubule
Confined to renal cortex
Cuboidal epithelial cells with long microvili (Fuzzy appearance in pics)
Resorption of water, ions and solutes
Loop of Henle
Descending limp
Thin segment
Thick ascen ding limb
Distal convoluted tubule
Confined to the renal cortex
Simple cuboidal epithelium
Selective secretion and resorption of ions
Classes of nephrons
Cortical nephrons
Juxtamedullary nephrons
Collecting Duct
Each receives urine from several nephrons
Run straight through cortex into the deep medulla
Collecting Ducts
At papilla of pyramid ducts join to form larger papillary ducts
Empty into minor calices
Role : conserve body fluids
The collecting ducts
The most important role is to con serve body fluides
When the body must conserve water, the posterior pituitary gland secretes ADH (antidiuretic hormone)
ADH increases the permeability of the collecting tubules and distal tubules to water so more is reabsorbed
This decreases the total volume of urine
Alcohol inhibits the release of ADH, so less water is reabsorbed producing copious amounts of dilute urine (can cause dehydration)
Vesseles
Afferent and efferent arterioles associated with glomerular capillaries
Peritubular capillaries arise from efferent arterioles
The vasa recta
The vasa recta is a portion of the peritubular capillary system which enters the medulla where the solute concentration in the in terslitium is high it acts with the loop of henle to concentrate the urine by a complex mechanism of counter current exchange using urea if the vasa recta did not exist the high concentration of solutes in the medullary interstitium would be washed out
Histology
counter current exchange