BIOL&253Ch26NotesFall11

BIOL&253Ch26NotesFall11 - Ch. 26 The Urinary System...

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1 Ch. 26 – The Urinary System •T h e general functions of the major organs of the urinary system are indicated at right Fig. 26-1, p. 966 Specific functions of the urinary system •1 . Excretion = the removal of organic metabolic waste products from body fluids •2 . Elimination = the discharge of these waste products to the external environment •3 . Regulation of blood plasma volume and solute concentration , by… Regulating blood volume and pressure , by… • Adjusting the volume of water in the urine • Releasing erythropoietin (EPO) • Releasing renin Regulating plasma concentrations of Na + , K + , Cl - , Ca 2+ , etc. Helping to regulate blood pH , by… • Excreting or conserving H + and HCO 3 - Conserving valuable nutrients Assisting the liver in detoxifying poisons and deaminating amino acids
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2 Fig. 26-3, p. 968 FYI (for lecture) – renal gross anatomy is covered in lab Fig. 26-2, p. 967 FYI (for lecture) – renal gross anatomy is covered in lab
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3 Fig. 26-4, p. 968 FYI (for lecture) – renal gross anatomy is covered in lab Fig. 26-5, p. 970 FYI (for lecture) – renal gross anatomy is covered in lab
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4 Fig. 26-6, p. 971 Nephrons •C a 2+ reabsorbtion is variable due to PTH and calcitriol •N a + reabsorption is variable due to aldosterone •H 2 O reabsorption is variable due to ADH = the microscopic functional units of the kidneys Each consist of a renal corpuscle and a renal tubule Function : form urine via filtration of the blood, reabsorption of water and some solutes, and secretion of other solutes There are over 1 million nephrons per kidney! Fig. 26-7, p. 973 Cortical nephrons Make up ~ 85% of all nephrons; their renal corpuscles are located in the outer cortex The efferent arteriole sends blood to peritubular capillaries that surround the entire renal tubule Have short nephron loops (loops of Henle) that are mainly in the cortex and superficial region of the medulla
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5 Juxtamedullary nephrons Make up ~ 15% of all nephrons; their renal corpuscles are located deep in the cortex The efferent arteriole sends blood to both peritubular capillaries and the vasa recta Have long nephron loops which penetrate deep into the medulla and are surrounded by the vasa recta – The ascending and descending limbs of the nephron loop have different permeability characteristics, allowing the production of concentrated urine (more on this later) Fig. 26-7, p. 973 Fig. 26-8, p. 974 The renal corpuscle = the glomerular (Bowman) capsule + the glomerulus – The glomerular capsule is made up of an outer parietal layer of simple squamous cells called the capsular epithelium and an inner visceral layer of simple squamous cells that cover the glomerulus called the visceral epithelium (the individual cells of the visceral epithelium are called podocytes ), with the capsular space in between – The glomerulus is a bed of fenestrated capillaries
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6 Fig. 26-8b, p. 974 The glomerular filtration membrane • Consists of 3 layers : – 1. The glomerular capillary endothelium is fenestrated (i.e.,
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BIOL&253Ch26NotesFall11 - Ch. 26 The Urinary System...

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