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Kidney Day : Introduction

Kidney Day : Introduction . The Kidney’s Functions. Functions of Kidneys: 1. Produce Urine (as a function of ridding body of Nitrogenous waste and other wastes. 2. Regulate water balance 3. Regulate acid-base of body fluids 4. Calcium Homeostatis ( Calcitriol )

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Kidney Day : Introduction

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  1. Kidney Day : Introduction The Kidney’s Functions

  2. Functions of Kidneys: • 1. Produce Urine (as a function of ridding body of Nitrogenous waste and other wastes. • 2. Regulate water balance • 3. Regulate acid-base of body fluids • 4. Calcium Homeostatis ( Calcitriol) • 5. In times of starvation ( Gluconeogenesis) • 6. Secretes Erythropoieten • 7. Secretes Renin ( Controls Blood pressure) • 8. Detoxify free radicals with use of peroxisomes.

  3. Formation of Urine Figure 15.5

  4. Summary of Tubular Reabsorption and Secretion

  5. Kidney Function: Regulation of Body Fluids, their volume and osmolarity; How is this accomplished? THE COUNTERCURRENT MECHANISM

  6. The Countercurrent Mechanism ? ? ? ? Unit 1 - Objective 7

  7. Glomerulus • the Glomerulus is the site of filtration • the filtration mechanism is sieve-like and consists of fenestrated glomerularcapillaries, podocytes and a basementmembrane that allows free passage of water and solutes smaller than plasma proteins Site of Filtration Unit 1 - Objective 4

  8. Efferent Arteriole Afferent Arteriole Bowman’s Capsule Glomerulus Location of the Glomerulus Proximal Convoluted Tubule

  9. Podocyte with Basement Membrane Glomerulus Bowman’s Capsule Glomerular Filtration Mechanism Fenestrated Capillary

  10. Podocytes- (or visceral epithelial cells) are cells of the visceral epithelium in the kidneys and form a crucial component of the glomerular filtration barrier contributing size selectivity and maintaining a massive filtration surface. Look for these in the kidney section slide ; focus on glomerulus. What are PODOCYTES?

  11. Used in maintaining blood pressure continued: • the macula densa cells monitor the salt content of the blood • if the blood salt content gets too high, the macula densa cells begin to inhibit the granular cells and suppress renin release The Juxtaglomerular (JG) Apparatus Unit 1 - Objective 6

  12. Description • the juxtaglomerular apparatus consists of specialized macula densa cells that develop in the distal convoluted tubule (DCT) and specialized granular juxtaglomerular (JG) cells that develop mainly in the afferent arteriole. See following diagram. The Juxtaglomerular Apparatus Unit 1 - Objective 6

  13. Bowman’s Capsule Efferent Arteriole The Juxtaglomerular Apparatus (JG) DCT PCT MaculaDensa Cells GranularJuxtaglomerular (JG) Cells Afferent Arteriole

  14. - vasomotion - monitor salinity Juxtaglomerular Apparatus

  15. Renin-Angiotensin-Aldosterone

  16. Used in maintaining blood pressure continued: • Angiotensin II also stimulates the release of aldosterone hormone from the adrenal cortex • aldosterone stimulates the DCT to reabsorb salt (NaCl). Continued on next slide. The Juxtaglomerular Apparatus Unit 1 - Objective 6

  17. Used in maintaining blood pressure continued: • salt reabsorption attracts water to the blood by osmosis and raises blood volume, as well as, contributing to the increase in blood pressure. Continued on next slide. The Juxtaglomerular Apparatus Unit 1 - Objective 6

  18. Used in maintaining blood pressure continued: • suppression of renin acts as a negative feedback mechanism to prevent further increases in angiotensin II, Aldosterone and blood pressure The Juxtaglomerular Apparatus Unit 1 - Objective 6

  19. Effects of Angiotensin II

  20. Water intake must equal water output • Sources for water intake • Ingested foods and fluids • Water produced from metabolic processes • Sources for water output • Vaporization out of the lungs • Lost in perspiration • Leaves the body in the feces • Urine production Maintaining Water Balance

  21. Dilute urine is produced if water intake is excessive • Less urine (concentrated) is produced if large amounts of water are lost • Proper concentrations of various electrolytes must be present Maintaining Water Balance

  22. Regulation is primarily by hormones • Antidiuretic hormone (ADH) prevents excessive water loss in urine • Aldosterone regulates sodium ion content of extracellular fluid • Triggered by the rennin-angiotensin mechanism • Cells in the kidneys and hypothalamus are active monitors Regulation of Water and Electrolyte Reabsorption

  23. Maintaining Water and Electrolyte Balance Figure 15.10

  24. Blood pH must remain between 7.35 and 7.45 to maintain homeostasis • Alkalosis – pH above 7.45 • Acidosis – pH below 7.35 • Most ions originate as byproducts of cellular metabolism Maintaining Acid-Base Balance in Blood

  25. Most acid-base balance is maintained by the kidneys • Other acid-base controlling systems • Blood buffers • Respiration Maintaining Acid-Base Balance in Blood

  26. Molecules react to prevent dramatic changes in hydrogen ion (H+) concentrations • Bind to H+ when pH drops • Release H+ when pH rises • Three major chemical buffer systems • Bicarbonate buffer system • Phosphate buffer system • Protein buffer system Blood Buffers

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