Nephron Functional Anatomy

proximal convoluted tubule

reabsorbs ions, water, and nutrients; removes toxins and adjusts filtrate pH

distal tubule

selectively secretes and absorbs different ion to maintain blood pH and electrolyte balance

collecting duct

reabsorbs solutes and water from filtrate

descending loop of henley

aquaporins allow water to pass from filtrate into interstitial fluid

ascending loop of henly

reabsorbs Na+ and Cl- from filtrate into interstitial fluid

glomerulus

filters small solutes from blood

renal corpuscle

blood pressure forces water and solutes out of glomerular capillaries thru filtration

filtration

process that produces filtrate

filtrate

protein free solution that allows kidneys to filter out waste while retaining essential substances; collected in capsular space from renal corpuscle

renal tubule

tubular passageway that flows surrounding by peritubular capillaries

renal tubule function

receives filtrate and modifies it to create urine; uses proximity to blood vessels to adjust filtrate composition

glomerular capsule (bowman’s capsule)

cup shaped chamber, capillary network (glomerulus)

nephron loop

establishes osmotic gradient for water reabsorption; each limb contains thick and thin segment

collecting system

series of tubes carrying tubular fluid away from nephron

intercalated cells

play role in secreting and reabsorbing hydrogen and bicarbonate ions

principal cells

reabsorb water and secrete potassium

papillary duct

collects fluid from collecting ducts; delivers fluid to minor calyx

renal physiology

urinary system maintains homeostasis by regulating volume and composition of blood; excretes solutes

urea

most abundant organic waste, by product of amino acid breakdown

creatinine

by product of creatine phosphate breakdown in muscles

uric acid

formed during recycling of nitrogenous bases of RNA

steps of urine formation

filtration, reabsorption, and secretion

filtration

blood pressure forces water and solutes across the membranes of the glomerular capillaries into capsular space

reabsorption

transport of water and solutes from tubular fluid across tubular epithelium into peritubular fluid

secretion

transport of solutes from peritubular fluid across tubular epithelium into tubular fluid

renal corpuscle general functions

filtration of blood; generates filtrate

nephron loop general function

reabsorption of 25% of water and 25% of Na and Cl; creation of concentration gradient in renal medulla

collecting system general functions

reabsorption of variable amt of water under ADH stimulation, variable amt of Na reabsorption under aldosterone stimulation

peritubular capillaries general functions

redistribution of water and solutes reabsorbed in renal cortex

vasa recta - general functions

redistribution of water and solutes reabsorbed in renal medulla, and stabilization of concentration gradient of renal medulla

vasa recta - specific functions

return of water and solutes from peritubular fluid to general circualtion