Renal Physiology Functions of the kidneys Homeostasis Fluid

Renal Physiology • Functions of the kidneys – Homeostasis • Fluid balance (blood pressure) • Electrolyte balance (blood pressure, membrane excitability) • Acid-base balance (in concert with lungs) • Structures of the kidney • Three fundamental renal mechanisms – Filtration – Reabsorption – Secretion

Kidneys are source of 3 hormones: Renin, EPO, and Vit D. Kidneys are targets of 3 hormones: ADH, Aldosterone, ANH Topics discussed: cortex, medulla, kidney stones, micturition (detrussor, internal and external urethra sphincters and innervation), incidence of bladder infections by gender

Renal artery = 1 way in. 2 ways out of kidney (renal vein or ureter) Distinction between urine and tubular fluid.

The nephron

Board diagram of a nephron and its blood supply Afferent arteriole Glomerular capillary Efferent arteriole Peritubular capillary and vasa recti Bowman’s capsule & Bowman’s space Proximal tubule Ascending and descending limbs of the Loop of Henle Distal tubule (and juxtaglomerular apparatus) Collecting ducts And where these parts are in relation to cortex and medulla Ultrafiltrate that appears in Bowman’s capsule = blood – formed elements - proteins

Renal corpuscle CO 24 Renal corpuscle Renal tubules

Special terms • Filtration: movement of fluid from blood into the lumen of the nephron • Reabsorption: the movement of specific compounds from the lumen back into the blood (peritubular capillaries) • Secretion: the transport of specific compounds from blood into the lumen • Excretion: elimination from the body in urine