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Excretory System. Hormonal Controls Dysfunction. Water Balance. Urine output depends on water input and water use An increase in water intake will increase water output Exercise, or a decrease in water will cause a decrease in water output Water balance is dependent on two systems:
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Excretory System • Hormonal Controls • Dysfunction
Water Balance • Urine output depends on water input and water use • An increase in water intake will increase water output • Exercise, or a decrease in water will cause a decrease in water output • Water balance is dependent on two systems: (1) Nervous system (2) Endocrine system
Regulating ADH • ADH (antidiuretic hormone) helps regulate the osmotic pressure of body fluids by acting on the kidneys to increase water reabsorption • When ADH is released, a more concentrated urine is produced, therefore conserving body water • ADH is produced when your brain receives a signal that tells it water is low
Osmoreceptors • Osmotic pressure can: (1) Increase when you decrease water intake or increase water loss (2) Decrease when water intake increases • Osmoreceptors are specialized nerve cells located in your brain that detect changes water pressure. • When water levels drop in your blood, water moves out of your cells in your brain into the blood stream, causing the cells to shrink • When the cells shrink, ADH is released • This causes the kidneys to reabsorb more water, thus producing a more concentrated urine
Aldosterone • Works to increase water intake INDIRECTLY • Causes sodium retention and therefore water follows • Released in response to decreased blood volume (large loss of body fluid – diarrhea or hemmorhage)
Kidney Disease or Problems • Diabetes Mellitus • Inadequate secretion of insulin from pancreas (type I) or resistance to insulin by body cells (type II) • Blood glucose levels rise • Excess glucose remains in nephron and is excreted in urine • Water remains in nephron – large volumes of urine • Always thirsty • Diabetes Insipidus • Defect in ADH • Large volumes of very dilute urine
Kidney Disease or Problems • Kidney Stones • Precipitation of mineral solutes from the blood (most commonly too much calcium is absorbed from food) • Causes: • Dehydration • Urinary tract infection (blockage of urine output)
Nephritis • Inflammation of the nephron • Damage to blood vessels of glomerulus • Proteins/RBC in nephron • High osmotic pressure in nephron – water in • Increased urine output (containing RBC and proteins)
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Dialysis • Hemodialysis • Machine connects to vein • Dialysis tubes with varying concentration gradients • Removal of wastes/addition of important solutes and hormones • Peritoneal Dialysis • Dialysis fluid pumped into peritoneal cavity (abdomen) • Waste diffuses into cavity (fluid replaced several times daily)
Urinalysis • What is it? • What information can be obtained from a urinalysis?