The Kidneys and Homeostasis

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The Kidneys and Homeostasis by Mind Map: The Kidneys and Homeostasis

1. Blood Pressure Control

2. ↓ Blood Pressure

3. Renin in Kidney released

4. Angiotensin I

5. ACE (Angiotensin Converting Enzyme

6. Angiotensin II

7. Angiotensin II acts directly to the blood vessels, causing Vasoconstriction

8. Secretion of Aldosterone is stimulated which stimulates reabsorption of Sodium and water

9. ↑ Blood Pressure

10. Body Fluid Volume and Osmolality

10.1. ADH (Antidiuretic Hormone)

10.1.1. 1. Change in Plasma Osmolality

10.1.2. 2. HYPOTHALAMUS → detects small changes in the plasma osmolality

10.1.3. 3. POSTERIOR PITUITARY → secrete ADH. ↑ Plasma Osmolality = ↑ secretion of ADH ↓ Plasma Osmolality = ↓ secretion of ADH


10.2.1. Via RAAS system, Aldosterone stimulates In kidneys, more sodium and water return to blood and more potassium eliminated in urine ↑ Blood Volume

10.3. Atrial Natriuretic Hormone

10.3.1. Inhibition of aldosterone by the adrenal cortex

10.3.2. Reduction of renin release by the Kidney

10.3.3. Reduction of ADH release from the Posterior Pituitary

10.3.4. Vasodilation

10.3.5. Natriuresis and Diuresis

10.3.6. Results in the excretion of sodium and water through the kidneys reducing the extracellular fluid back to normal

11. Acid - Base Balance

11.1. H20 + CO2→ H2CO3 → HCO3 + H

11.1.1. 1. The filtered Bicarbonate ion undergoes a reaction sequence to produce water and carbon dioxide

11.1.2. 2. The water and carbon dioxide molecules diffuse into the proximal tubule cell and undergo the same reaction sequence in reverse to reform the bicarbonate ion. The resulting hydrogen ion is secreted back into the lumen

11.1.3. 3. The bicarbonate ion diffuses into the blood.

12. FALL IN PLASMA pH = ↑ Hydrogen ions

13. Drive the bicarbonate sequence to the LEFT to produce CO2 and water

14. ↑ Plasma pH

15. RISE IN PLASMA pH = ↓ Hydrogen Ions

16. The kidney reduces the amount of hydrogen ion secretion → results in a reduction in the plasma bicarbonate level.

17. The plasma bicarbonate concentration corrected by a reduction in ventilation rate by the lungs → build up of CO2, which drives the reaction sequence to the RIGHT to generate more bicarbonate ions

18. ↓ Plasma pH

19. Electrolyte Balance

19.1. SODIUM

19.1.1. ↓ Sodium levels ALDOSTERONE via RAAS system increases sodium and water retention.


19.2.1. ↑ Potassium Levels Stimulates ALDOSTERONE secretion ↑ secretion of potassium into the urine

19.2.2. ↓ Aldosterone Reverse occurs and less potassium is secreted into the urine


19.3.1. 1. ↓ Calcium is detected by cells of the parathyroid glands

19.3.2. 2. Parathyroid glands ↑ release of parathyroid hormone (PTH) which circulated in the blood

19.3.3. 3. PTH binds to receptors on the distal tubules and on bone

19.3.4. 4. Kidney → ↑ Calcium reabsorption and ↓ phosphate reabsorption Activation of vitamin D → ↑ intestinal absorption of calcium Bone → increased bone resorption

19.3.5. 5. The resulting increase in calcium reduces the stimulation of the parathyroid glands


19.4.1. ↓ Magnesium levels ↑ Efficiency of magnesium reabsorption in the kidneys from filtrate ↑ magnesium reabsorption = ↓ magnesium loss in the urine

19.4.2. ↑ Magnesium levels Kidneys exceed capacity to reabsorb Magnesium from filtrate ↑ Magnesium remain in the filtrate and are eliminated in the urine

20. Maintenance of Normal Red Blood Cell Count

21. Erythropoietin production in the kidney is stimulated by hypoxia and inhibited when hypoxia is corrected. Erythropoietin is a glycoprotein that promotes the proliferation and differentiation of erythrocyte precursors on the bone marrow making them essential in the maintenance of a normal red cell count