The Structure and Function of a Nephron

A physiology mini lecture presented by: Kaylee Knowles Lydia Morrison

The Kidney!!6 General Functions!

1. Extracellular fluid volumeand blood pressure regulation.

2. Osmolarity regulation

3. Ion balance

4. pH homeostasis

5. Excretion

6. Hormone production

Anatomy of the Kidney:

THE NEPHRON

The functional unit of the kidney.

1 million nephrons in a kidney – and that never changes!

80% - cortical nephrons & 20% juxtamedullary

Filtration:

-Takes place in the renal corpuscle

-Substances flow out of the glomerular capillaries into the surrounding Bowman’s capsule

-Substances must cross three filtration barriers: -glomerular capillary endothelium -basal lamina -epithelium of Bowman’s capsule

-What drives filtration? -Hydrostatic pressure! 10 mm Hg of it!

-GFR (glomerular filtration rate) -average kidney is ~125 ml/min that’s: 180 L/day which calculates to: 60 times the kidney filters the entire blood plasma volume. so: Your little kidneys filter your entire blood plasma volume 2.5 time in an hour!!!

Go kidneys go!

Proximal tubule transport particles out of the lumen into the interstitial fluid (70% of filtrate reabsorbed)

Active or Passive Total: over 99% of

filtrate is reabsorbed

Molecules move from ECF to the nephron lumen

Active Membrane transport

protein Na+/K+ transport•Decrease secretion by competition

•Penicillin

More solute reabsorbed than reabsorbed water descending limb of

the loop of Henle: into the renal medulla

ascending limb of the loop of Henle: returns to the renal cortex

Juxtaglomerular apparatus (JGA): BP

2 cells types: principal cells: ADH and Aldosterone

receptors intercalated cells: maintain blood pH

Bowman’s capsule proximal convoluted tubule Loop of Henle distal convoluted tubule collecting duct papillary duct minor calyx major calyx renal pelvis ureter

Goodpasture (Pulmonary renal syndrome;) Autoimmune disease attacking collagen Treatment: removing blood plasma to get

rid of anti-GBM antibodies and replace it with fluid, protein, or donated plasma

Nephrogenic diabetes insipidus Acquired Tubules do not respond to ADH Treatment: anti-diuretic

Used once 85-90% of kidney function is lost Removes excess Na+, waste, and water from the body Maintains K+, Na+, and bicarbonate levels Aids in the control of blood pressure

Hemodialysis: intervenous Peritoneal: put dialysate in the peritoneal cavity

via a catheter via a machine

Charytan, D. M. (2006, November 16). Goodpasture syndrome. Medline Plus Medical Encyclopedia. Retrieved February 24, 2009, from http://www.nlm.nih.gov/medlineplus/ency/article/000142.htm

National Kidney Foundation. (2009). A to Z Health Guide: Dialysis. Retrieved February 25, 2009, from http://www.kidney.org/atoz/atozItem.cfm?id=39

Patel, P. (2008, April 14). Diabetes insipidus - nephrogenic. Medline Plus Medical Encyclopedia. Retrieved February 24, 2009, from http://www.nlm.nih.gov/medlineplus/ency/article/000511.htm

Silverthorn, D. U., Ober, W. C., Garrison, C. W., Silverthorn, A. C., & Johnson, B. R. (2007). The Kidneys. In D. Espinoza, I. Nunes, & W. Earl (Eds.), Human Physiology: An Integrated Approach (pp. 614-635). San Fransisco: Pearson Education as Benjamin Cummings.

Tortora, G. J. (2005). The Uninary System. In B. Roesch, & K. Trost (Eds.), Principles of Human Anatomy (pp. 810-). Hoboken, NJ: John Wiley & Sons.