Chapter 19 Notes - Renal Physiology

Chapter 19 Notes - Renal Physiology - Dark yellow urine is...

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Dark yellow urine is indicative of concentrated urine In contrast, pale urine is indicative of dilute urine - Black urine indicates the presence of hemoglobin metabolites - Urine was commonly tasted to test for diabetes mellitus (since glucose was not reabsorbed, and was excreted in the urine, the urine would taste sweet) Function of the kidneys: Regulation of ECF volume and BP - Decreases in ECF volume result in a decrease in BP, and the body cannot maintain adequate blood flow to the brain and other essential organs Maintenance of ion balance - Sodium, potassium and calcium are closely regulated pH regulation - If the ECF becomes too acidic, kidneys remove hydrogen ions and conserve bicarbonate ions (increasing the pH). Conversely, if the ECF becomes too alkaline, bicarbonate ion is removed and hydrogen ions are conserved. Relevant equation: CO2 + H2O  H + + HCO3 - Excretion of wastes - Waste products are creatinine, urea and uric acid . - Other random waste products are saccharin (artificial sweetener), benzoate, which is in soft drinks . Produces hormones - Erythropoietin – RBC synthesis - Renin – converts angiotensin II to angiotensin I (via the angiotensin converting enzyme ), which ultimately causes the release of aldosterone (which stimulates sodium reabsorption), and consequentially ADH (also known as vasopressin , which stimulates water reabsorption to follow the sodium, ensuring the blood’s dilution after reabsorbing the sodium). Renin is usually secreted by the juxtoglomerular cells to increase BP . Kidneys ureter urinary bladder urethra expulsion At any given time, the kidneys receive about 20-25% of the cardiac output There must be a relatively high blood flow to the kidneys to ensure proper waste removal. Nephron – functional unit - Kidneys contain an outer cortex and inner medulla - Medullar pyramids contain the nephrons . Interesting sidenote: UTI’s (urinary tract infections) are more common in females than in males (Why? women have shorter urethras than males, and they are proximal to the large intestine. If E. Coli from the large intestine gets into the urethra, it can cause painful, burning and frequent urination. UTI’s can be treated with antibiotics) Afferent arteriole – leading to the glomerulus
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Efferent arteriole – leading away from the glomerulus, which eventually become the peritubular capillaries . The peritubular capillaries eventually become the vasa recta , which surround the loop of Henle. The kidneys contain a portal system (what does this mean? blood flows to the kidneys via the renal arteries , and then goes back into circulation via the renal veins) Bowman’s capsule contains the glomerulus Fluid is filtered through the glomerulus, and ends up in the Bowman’s capsule (now known as filtrate) . From here, the filtrate goes to the proximal convoluted tubule ( where most reabsorption of solutes takes place ), then the Loop of Henle ( where more reabsorption occurs ), and the
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Chapter 19 Notes - Renal Physiology - Dark yellow urine is...

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