Bio 449Lecture 26 – Renal Physiology IINov. 10, 2010 Nephrons (cont’d) Urine formation Glomerular filtration Proximal tubule Loop of Henle & initial distal tubule End distal tubule & collecting duct Mechanisms of reabsorption and secretion Counter-current multipliers Summary of nephron function Terms to Know Bowman's capsule Proximal tubule Loop of Henle Descending limb Thin ascending limb Thick ascending limb Distal tubule Collecting duct Glomerular filtration Glomerular filtration rate (GFR) Tubular lumen Apical or luminal membrane Basolateral membrane Counter-current multiplier Readings Lectures 25-27: Chapters 19 & 20

Nephrons

Secretion and reabsorption

Urine Formation

Overview of nephron function Fig Collecting duct Distal tubule Afferent arteriole Loop of Henle Efferent arteriole Glomerulus Peritubular capillaries Proximal tubule Bowman’s capsule To renal vein To bladder and external environment KEY = Filtration: blood to lumen = Reabsorption: lumen to blood = Secretion: blood to lumen = Excretion: lumen to external environment

Glomerular filtration

Renal corpuscle Fig Bowman’s capsule Podocyte Glomerular capillary Lumen of Bowman’s capsule Proximal tubule Efferent arteriole Afferent arteriole Thick ascending limb of loop of Henle

Podocytes Fig. 19-5

Renal corpuscle Fig Lumen of Bowman’s capsule Podocyte foot processes Glomerular capillary Podocyte Mesangial cell Capillary endothelium

Renal corpuscle Fig Filtration slit Basal lamina Filtered material Foot process of podocyte Lumen of Bowman’s capsule Capillary lumen Pores in endothelium

Proximal tubule

Loop of Henle & initial distal tubule

End distal tubule & collecting duct

Mechanisms of reabsorption and secretion

Counter-current multipliers

Summary of nephron function Fig Collecting duct Distal tubule Afferent arteriole Loop of Henle Efferent arteriole Glomerulus Peritubular capillaries Proximal tubule Bowman’s capsule To renal vein To bladder and external environment KEY = Filtration: blood to lumen = Reabsorption: lumen to blood = Secretion: blood to lumen = Excretion: lumen to external environment

Summary of nephron function