Juxtaglomerular apparatus

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Created by
Maitri Parikh

Cards (11)

  • juxtaglomerular apparatus is specialized organ situated near the glomerulus
  • juxtaglomerular apparatus is formed by :
    1. macula densa
    2. extraglomerular mesangial cell
    3. juxtaglomerular cells
  • Macula densa :
    end portion of thick ascending segment before opens into DCT.
    situated between afferent and efferent arterioles.
    formed by tightly packed cuboidal epithelial cells.
    plays important role in tubuloglomerular feedback.
    also secretes thromboxane A2
  • Primary function of juxtaglomerular apparatus is the secretion of hormones
  • Juxtaglomerular apparatus secretes 2 hormones :
    1. Renin
    2. Prostaglandin
  • Stimulants of Renin secretion:
    1. Fall in arterial blood pressure
    2. Reduction in ECF volume
    3. Increased sympathetic activity
    4. Decreased load of sodium and chloride in macula densa
  • Actions of Angiotensin II
    1. Increases arterial blood pressure by directly acting on blood vessels and causing vasoconstriction
    2. Increases blood pressure indirectly by increasing release of noradrenaline from post-ganglionic sympathetic fibers
  • Angiotensin II's actions on adrenal cortex
    1. Stimulates zona glomerulosa to secrete aldosterone
    2. Aldosterone acts on renal tubules and increases sodium retention, which elevates blood pressure
  • Angiotensin II's actions on kidney
    1. Regulates glomerular filtration rate by constricting efferent arteriole and contracting glomerular mesangial cells
    2. Increases sodium reabsorption from renal tubules, more predominant on proximal tubules
  • Angiotensin II's actions on brain
    1. Inhibits baroreceptor reflex, thereby indirectly increasing blood pressure
    2. Increases water intake by stimulating thirst center
    3. Increases secretion of corticotropin-releasing hormone (CRH) from hypothalamus, which increases secretion of adrenocorticotropic hormone (ACTH) from pituitary
    4. Increases secretion of antidiuretic hormone (ADH) from hypothalamus
  • Extraglomerular mesangial cells of juxtaglomerular apparatus secrete Prostaglandins