Urinary System

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  1. Give 6 functions of the Urinary system (kidneys!)(question 1)
    • 1. Excretion (unwanted substances)
    • 2. maintenance of water & electrolytes¬†
    • 3. pH regulation of body fluids
    • 4. Production of hormones
    • 5. Regulation of RBC's production
    • 6. Regulation of blood glucose levels
    • 7. Regulation of blood pressure volume & osmolarity
  2. What are the 5 hormones that affect kidney reabsorption of sodium (Na), chloride (Cl) calcium (Ca) & water as well as the secretion of Potassium (K)
    • 1. Angiotensin II
    • 2. Aldosterone
    • 3. Antidiuretic hormone
    • 4. Atrial natriuretic peptide
    • 5. Parathyroid hormone
  3. Explain the Renin-Angiotensin-Aldosterone System (RAAS) (question 2)
    1. Low blood pressure - Kidney cells secrete Renin (angiotensinogenase)

    2. Renin converts Angiotensinogen from the liver into Angiotensin I

    3. Angiotensin converting enzyme (ACE) secreted by the lungs & kidneys (proximal convoluted tubules) converts Angiotensin I into Angiotensin II - The active form of the hormone

    • 4. Angiotensin II (a blood protein):
    • Triggers vasoconstriction
    • Triggers pituitary gland to release ADH (vasopressin)
    • Stimulates adrenal cortex to produce Aldosterone.

    • 5. Aldosterone:
    • Causes the kidneys to retain sodium (Na) and excrete Potassium (K)

    This causes water retention, increasing blood volume and blood pressure.

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  4. How does Atrial Natriuretic Peptide (ANP) work to decrease blood volume/pressure? (question2)
    ANP is released from the heart when there is a large increase in blood volume/pressure.

    • 1. It inhibits reabsorption of sodium (Na+) & water in the renal tubules
    • 2. It suppresses anti-diuretic hormone & aldosterone.

    This results in an increased excretion of sodium (Na) in the urine and increased urine output which decreases blood volume & pressure
  5. Explain how antidiuretic hormone (ADH) works. (question 2)
    • Reduced water concentration in the blood & lowered blood volume (e.g haemorrhage) causes increased osmotic pressure of the blood.
    • Osmoreceptors in the hypothalamus stimulate posterior pituitary to secrete ADH
    • ADH increases the permeability of the distal convoluted tubules, thus increasing water re-absorption in the kidneys, thereby aiding in rebalancing the osmotic pressure.
    • ADH secretion is regulated by a negative feedback mechanism.

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  6. How does Parathyroid Hormone (PTH) work on the kidneys?
    LOW blood calcium stimulates the parathyroid glands to release parathyroid hormone:

    PTH stimulates the kidneys tubules to reabsorb more calcium and inhibits phosphate reabsorption.
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Urinary System
2015-06-26 11:38:55

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