Excretory System Sarah Norton Giselle Lehman Cam Hansel

Urinary System FUNCTION: remove waste and excess water from blood and get it out of the body in the form of urine; counters unwanted shifts in the volume and composition of extracellular fluid (8)

Urine Formation Helps Maintain Homeostasis - excretion regulates the water content (to ensure the correct amount is the body) in the blood by producing hypotonic or hypertonic urine (compared to blood plasma) (3) in summer, water is lost through sweat--> urine is hypertonic (8) no water loss from sweating in winter--> urine is hypotonic (8) - urine formation counters shifts in volume and concentration of solutes and foreign substances (like drugs) (3) - excretion regulates pH of the blood by removing waste (3)

The Kidney STRUCTURE: in the rib cage, next to the spine, have 2 (4) small (about 10 cm), bean-shaped (8) FUNCTION: filters used/unwanted water, minerals, and urea (waste) from blood--returns all but 1% to blood (8) makes that 1% into urine (~1.5 liters a day) (8) blood pressure regulation (by secreting enzyme renin) (9) controls production of erythropoietin, which controls red blood cell production (4) regulates the volume, composition and pH of body fluids (1) regulates calcium absorption via vitamin D (4)

The Nephron - tiny filtering units in the kidney, millions in cortex (8) - purifies and filtrates blood (7) - the whole nephron is made of the Renal Corpuscle (glomerulus + Bowman's capsule) and the Renal Tubule (proximal convoluted tubule+ loop of Henle) (7) -Glomerulus: ball formed of small blood capillaries (glomerular) -Bowman's capsule: nephron starts here, double-walled epithelial cup that holds the glomerulus (7) -proximal convoluted tubule:absorbs and regulates the potassium, calcium, sodium and pH of filtrate and secretes natural acids into filtrate (7) -loop of Henle: U-shaped tube, concentrates salt of the tissue around it (7) -Distal Tubule: adjustment stage, can lead to urine that is highly dillute, concentrated or in between (8) -Collecting Duct: leads to kidney's central cavity then into an ureter (8)

The Nephron

Filtration blood is filtered by osmosis and diffusion in glomerulus (2) driven by heart's contractions blood enters through the glomular capillaries (glomerulus) in the nephron blood pressure filters blood when it forces water and solutes (except proteins) out of the glomerular capillaries. this protein-free solution moves into the proximal tubule filtered fluid in the Bowman's capsule is isotonic (2) [all from source 2 and 8]

Tubular Reabsorption happens in tubules; sodium is pumped out through active transport in loop of Henle and proximal tubule (8) reclamation (reabsorption) of water (80%), glucose, electrolytes, amino acids, sodium, potassium, etc-- restores their concentrations in blood done by capillary network around tubules osmosis and active transport (for glucose, amino acids). then filtrate's water and solutes move into peritubular capillaries. [all from source 2 and 8]

Tubular Secretion as the tubular filtrate drains, toxic substances(not filtered in the glomerulus) are secreted through the blood and tubular wall into the filtrate (in the opposite direction of reabsorption) cells in the tubule wall accept solutes then secrete them into the nephron wall filtered waste products make urine [all from source 2 and 8]

How does this relate to diabetes? - the kidney filters waste from the blood - in diabetes there is an excess of glucose in blood because of a lack of insulin - extra glucose is considered waste gets filtered from blood in kidney - the kidneys make that glucose (waste) into urine and thus it becomes a symptom of diabetes that glucose appears in the urine

References 1. "Anatomy and Physiology."Welcome to Kaskaskia College Faculty Homepages. N.p., n.d. Web. 4 Nov %20Physiology.htm 2."Excretion And Osmoregulation In Man, Functions Of The Kidney Tutorvista.com."Tutorvista.com - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. Tutorvista, Web. 04 Nov osmoregulation/excretion-and-osmoregulation-man.php 3. Franklin Institute,. "Excretory System: Poison Protection."The Human Heart. Unisys, Web. 4 Nov "How Your Kidneys Work." National Kidney Foundation. National Kidney Foundation, Web. 04 Nov Lucile Packard Children's Hospital at Stanford. "Anatomy and Function of the Urinary System." Packard Children's Hospital at Stanford LPCH: Northern California Children's Hospital. N.p., n.d. Web. 4 Nov Nelson, Robert. "Excretory System | Untamed Science."Biodiversity Web and Ecogeek Community | Untamed Science. N.p., n.d. Web. 4 Nov biology/excretory/excretory-system 7. "Nephron." COE - Main. N.p., n.d. Web. 4 Nov Starr, Cecile, and Ralph Taggart. Biology The Unity and Diversity of Life. 9th ed. Pacific Grove, CA: Brooks/Cole, Print. 9. " Your Urinary System and How It Works." National Kidney and Urologic Diseases Information Clearinghouse. Aug Web. 04 Nov