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Explore the intricate processes of kidney reabsorption, secretion, and urine formation, including active and passive transport mechanisms. Learn about filtration rates, excretion, and the micturition reflex in the urinary system. Understand renal physiology in detail.
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Chapter 19, part B The Kidneys
Reabsorption: 10 Active Transport • (Passive diffusion in) • Active Transport • Na+ to ECF • K+ into cell • ATP-ase • Uses energy • Na+ ECF peritubular capillaries • Reabsorption blood
Reabsorption: 10 Active Transport Figure 19-11: Sodium reabsorption in the proximal tubule
Reabsorption: Secondary Active Transport • Na+ linked 20 transport • Symport • Glucose • Ions • Amino acids • Proximal tubule, key site Figure 19-12: Sodium-linked glucose reabsorption in the proximal tubule
Reabsorption: Passive Transport & Trancytosis • Passive Transport of urea • Na+ pumped out • H2O follows • Passive • [urea] • [urea] higher than ECF • passive diffusion to ECF • Trancytosis of proteins
Reabsorption: Passive Transport & Trancytosis Figure 19-13: Passive reabsorption of urea in the proximal tubule
Reabsorption: Receptors can Limit • Transport maximum • Saturation (# of receptors) • Competition • Specificity • Renal Threshold • Example: glucosuria
Reabsorption: Receptors can Limit Figure 19-15: Glucose handling by the nephron
Secretion: From Peritubular Blood vessels & ECF • Active Transport into nephron tubules • Example: K+ & H+ (more on this next unit)
Secretion: From Peritubular Blood vessels & ECF Figure 19-2 : Filtration, reabsorption, secretion, and excretion
Solute Clearance: Rate of removal from the Blood • Information on Kidney Function • GFR • Reabsorption rates • Secretion rates Figure 19-16: Inulin clearance
Excretion: All Filtration Products that are not reabsorbed • Excess ions, H2O, molecules, toxins, "foreign molecules" • "nitrogenous waste": NH4+ and excess urea • Kidney Ureter bladder urethraout of body
Excretion: All Filtration Products that are not reabsorbed Figure 19-5: The filtration fraction
Urination: Micturation reflex • Bladder: • smooth muscles • internal sphincter • external sphincter • Regulation
Urination: Micturation reflex Figure 19-18: The micturition reflex
Summary • Kidney produces urine, ureter bladder urethra • Nephron filters, reabsorbs, secretes and excretes • Arteriole pressure dictates GFR through autoregulation, ANS and hormonal influences • Most filtrate is reabsorbed & returned via peritubular blood vessels; excess & toxic remains are excreted • Urination reflex uses involuntary and voluntary paths