Topic 83 - Mineralocorticoids

Question 1

Words to include

Answer 1

• Adrenal cortex
• Zona glomerulosa / zona arcuata
• Zona fasciculata
• Zona reticularis
• Fat
• Cholesterol
• Phospholipids
• Ascorbic acid
• ACTH
• Atropic
• Aldosterone
• Aldolase enzyme
• Electrolyte and water metabolism
• Kidney
  
  • Distal convoluted tubule
• Reabsorption
  
  • Na⁺ ions
  • Tubular sodium reabsorption
    
    • Proximal tubule (PST)
    • Connecting tubule (CNT)
    • Collecting tubule system (CCT)
• Secretion
  
  • K⁺ ions
  • Aldosterone synthesis
  • CNT
  • CCT
• Lumen
• Blood
• Na⁺/K⁺ ATPase pump
• Overdose
  
  • Isoosmotic hypervolemia
  • Reabsorption
    
    • Na⁺
    • H₂O
  • Renal escape
  • Blood pressure
  • K⁺ depletion
    
    • Muscular weakness
    • Paralysis
    • Aciduria (Alkalosis)
• Deficiency
  
  • Acidosis
  • K⁺ retention
  • H⁺ retention
  • IC hypervolemia
  • Na⁺ loss
  • Water loss
  • Isoosmotic EC hypovolemia
  • Hyposmotic EC hypovolemia
  • Oligemia
  • Hemoconcentration
  • O₂ uptake
  • Cardiac failure
  • Blood volume (↓)
  • Blood pressure (↓)
  • Renal blood flow (↓)
  • Azotemia
  • Death
• Regulation
  
  • Plasma K⁺ concentration
  • Renin-Angiotensin system (RAS)
  • Juxtaglomerular apparatus
  • Na⁺ deficiency
  • Angiotensin II
  • Aldosterone
  • Synthesized
  • Volume regulation
  • ACTH
    
    • Tolerant effect
    • Permissive effect

Question 2

Topics to include in the essay

Answer 2

1. Layers of the adrenal cortex
   
   • Aldosterone
   • Produced in zona glomerulosa
2. Effects of mineralocorticoids
   
   • Tubular sodium reabsorption
   • Potassium secretion in the distal tubules
   • Overdose of mineralocorticoids
   • Deficiency of mineralocorticoids
3. Regulation of mineralocorticoids

Question 3

Where are the mineralocorticoids produced? And why?

Answer 3

• In zona glomerulosa of the adrenal cortex
  
  • ​This is because aldosterone enzyme can only be found here

Question 4

Effects of mineralocorticoids

Answer 4

• Mineralocorticoids regulate electrolyte and water metabolism by acting on the distal convoluted tubule of the kidney
  
  • The main effect is the reabsorption of sodium ions and secretion of potassium ions
• Tubular sodium reabsorption:
  
  • In proximal tubule also without the hormone
  • In connecting tubule, collecting duct system Na- reabsorption only in the presence of aldosterone
• Potassium secretion in distal tubules:
  
  • Plasma potassium levels increase
    
    • Causing aldosterone synthesis increases
  • Aldosterone dependent in connecting tubule and collecting duct system
• CNT = connecting tubule
• CCT = collecting duct system
• PST = proximal tubule

Question 5

Effects of mineralocorticoids

Overdose of mineralocorticoids

Answer 5

• Isosmotic hyervolemia
  
  • Due to reabsorption of Na⁺ and H₂O
• Renal escape can occur
  
  • Increased urinary secretion due to rising blood pressure

​

• Lack of of K⁺ leading to:
  
  • Muscular weakness
  • Paralysis
  • Aciduria (alkalosis)

Question 6

Effects of mineralocorticoids

Deficiency of mineralocorticoids

Answer 6

• K⁺ and H⁺ retention
• Acidosis
• IC hypervolemia
• Na⁺ and water loss
• Isoosmotic EC hypovolemia
• Hyposmotic EC hypovolemia
• Blood volume ↓
• Blood pressure ↓
• Renal blood flow ↓
• Azotermia
• Death

Question 7

Regulation of mineralocorticoids

Answer 7

• Elevation of K⁺ concentration
  
  • Most important regulator
  • Rapid reactive ability
• Renin-Angiotensin system (RAS)
  
  • Will be activated when the juxtaglomerular apparatus detects Na⁺ deficiency
  • First angiotensin II, then aldosterone will be synthesized
• Na⁺ content of the body
  
  • Decrease of Na⁺ content will activate the synthesis of mineralocorticoids
  • Important in volume regulation
• ACTH
  
  • Permissive effect
  • ACTH deficiency → zona glomerulosa becomes thinner, but aldosterone synhtesis is not terminated