Lecture_16r_Renal_Principles - ReadingsThisWeek

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1 Lecture 16: Renal System -- Principles Professor Steven L. Lehman Thank you for filling in for Prof. Brooks who was ill . 2 Readings This Week • Chapter 14, Today Section A • Next Lecture (Renal Control): Chapter 14 B,C,D 3 Outline: Renal Principles 1. Renal functions 2. Structure of Kidneys and Urinary System 3. Basic principles of renal physiology 4 Kidney Functions 1. The principal function of the kidney is to maintain homeostasis of Extracellular Fluid fluid volume ion concentrations acid-base balance 2. Kidneys also excrete metabolic wastes and many non-biological chemicals, and synthesize glucose during prolonged fasting 5 Claude Bernard (1813-1878) invented the homeostasis concept The primary function of the kidneys is to maintain homeostasis of the extracellular fluid (ECF) 6 Recall: ECF volume filtered 13 times/day
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2 7 Mode of operation: filter the blood, then reabsorb almost everything • The kidneys filter about 125 ml/min – 180 L/day – About 11 L during this class • They reabsorb over 90% of the plasma that they filter – 99% of water – 99.5% of Na – 100% of glucose 8 9 Kidneys receive the most blood flow per gram of any tissue Organ Flow • Kidney 420 ml/min per 100g tissue • Heart 87 • Liver 58 • Brain 54 • Muscle 2.7 (resting skeletal) 10 The paired kidneys form a filtrate of the blood that is modified by reabsorption and secretion; urine moves along the ureters to the bladder and out through the urethra. Figure 14-1 The Urinary System 11 Figure 14-4 Kidney Structure The outer layer of the kidney is the renal cortex ; it is the site of glomerular filtration as well as the convoluted tubules. Renal cortex The inner part of the kidney is the renal medulla ; this is the location of the longer loops of Henle, and the drainage of the collecting ducts into the renal pelvis and ureter. Renal medulla 12 Figure 14-4 Each kidney has ~1 million functional units, called nephrons
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3 13 A NEPHRON consists of: Renal Corpuscle Renal Tubule Fig. 14-2a The functional unit of a kidney is the Nephron The Renal Corpuscle is in the cortex; the renal tubule begins at the corpuscle, and descends into the medulla Figure 14-3 The Renal Corpuscle is the apparatus for filtration Blood enters the renal corpuscle via the A fferent Arteriole A Glomerulus: ~50 looped capillaries where blood pressure filters fluid into Bowman’s capsule 80% of the blood that entered exits the renal corpuscle via the E fferent Arteriole Fenestrae in the capillaries and filtration slits between podocytes allow filtration. 15 Proximal Convoluted Tubule reabsorbs water, electrolytes, Glucose, amino acids … The renal tubule is the apparatus for reabsorption Loop of Henle produces a concentration gradient between renal cortex and medulla Collecting Duct regulates water and ions through actions of hormones, Collects filtrate from many loops of Henle Fig. 14-2a 16 Basic Renal Processes 1. Glomerular filtration 2. Tubular reabsorption 3. Tubular secretion 17 Filtration 1. Glomerular Filtration
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Lecture_16r_Renal_Principles - ReadingsThisWeek

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