Post on 22-Jul-2020
Review
Urine Forma.on • Urine forma.on depends on three func.ons: – ___________: process by which blood or body fluids pass through a selec.vely permeable membrane
– _____________: transfer of glomerular filtrate from the nephron back into the capillaries
– _____________: movement of some material from the blood back into the distal tubule
Filtra.on • Blood moves through the afferent arteriole into a
capillary bed called the ____________. The efferent arteriole drains from each glomerulus into the ____________ capillaries, which wrap around the nephron. The capillaries carry away material that is ______________.
• Water and dissolved solutes are filtered through the walls of the glomerulus into the _____________ __________
• Materials such as, plasma protein, blood cells, and platelets are too ________ to pass through the walls, therefore they are leG in the efferent arteriole
Reabsorp.on • About _____mL of fluid flows through the kidney every
minute and about _____% of it is filtered in the nephrons. Only ___ mL of urine is formed for every 120 mL of this fluid.
• Selec.ve reabsorp.on occurs un.l the maximum amount of material that can be moved across the nephron is reached (____________ _________) – Excess NaCl is excreted with urine
• Occurs through ____________ and __________ transport – Water, Cl-‐, Na+, glucose, amino acids
1. Proximal convoluted tubule
• Responsible for most of the ______________ of water and solutes from the filtrate. – Na+, Cl-‐, glucose and amino acids are transported out of the filtrate
– Water will follow by diffusion – These molecules are returned to the venous blood leaving the kidney
2. Loop of Henle
• The kidneys produce urine that is _____________ to the blood plasma – Loop of Henle func.ons as a ___________________ _______________, crea.ng a concentra.on gradient in the surrounding medulla
• Thick ascending Loop of Henle is NOT _______________ to water
• Water is forced to stay ___________ the tubule – This means that the medulla fluid has a ____________ concentra.on of Na+ and Cl-‐ than the cells of the tubule
• Descending Loop of Henle: • _____ permeable to water but _______ very permeable to Na+ and Cl-‐ • Because water always wants to move down its concentra.on gradient from high to low concentra.on, it will move out of the tubule by _____________ • This is because the medulla fluid is more concentrated (remember what just happened in the ascending loop)
• Now, the tubule fluid is less concentrated than the blood plasma and solutes that have been leG behind in the medulla have created a __________________ _______________.
3. Distal convoluted tubule
• Distal Convoluted Tubule: – The fluid entering is less concentrated than the surrounding cortex fluid so the tubule will lose ____________ by _____________
4. CollecAng duct
• Now the fluid entering the collec.ng duct is at the ____________concentra.on as blood plasma but NaCl has been moved out of the tubule fluid so urea and other waste products make up the solute content now
• The concentra.on gradient established by the loop of Henle increases, so more and more water is absorbed from the tubule fluid and this leaves a very concentrated _____________ in the collec.ng duct.
Secre.on
• The movement of wastes from the _________ into the __________ by _________ transport
• Substances that are secreted include: – Nitrogen-‐containing waste – Excess H+ ions – Minerals such as K+ ions – Drugs such as ______________
Site DescripAon of Process Substances Transported
1. glomerulus and Bowman’s capsule
2. proximal tubule
3. descending limb of loop of Henle
4. ascending limb of loop of Henle
5. distal tubule
6.Collec.ng duct