Mootra Vega Dharana — Physiology & Pathology of Urine Suppression

🧠 PART 1: NORMAL PHYSIOLOGY OF URINATION (Micturation)

How the Bladder Fills — Storage Phase

• Kidneys produce ~1.5–2 L of urine per day
• An empty bladder has ~0 cm H₂O pressure
• At 30–50 mL: pressure rises to 5–10 cm H₂O
• At 200–300 mL: pressure stays relatively flat (bladder wall is compliant)
• Beyond 300–400 mL: pressure rises sharply

The Micturition Reflex — How Urge Begins

The dashed spikes are micturition contractions — each spike is your body saying "time to urinate!" — Guyton & Hall

Bladder fills beyond ~200–300 mL
        ↓
Stretch receptors in bladder wall + posterior urethra activated
        ↓
Afferent signals travel via PELVIC NERVES → Sacral spinal cord (S2–S4)
        ↓
Parasympathetic efferent signals return → Detrusor muscle CONTRACTS
        ↓
Self-regenerating cycle: contraction → more stretch → more contraction
        ↓
Signal sent to PONS (pontine micturition center) + cerebral cortex
        ↓
"Urge to urinate" perceived consciously

Role of Higher Brain Centers

In simple words: Your spinal cord says "bladder is full, let it go." Your brain says "not yet, wait." This is exactly Vega Dharana — the voluntary cortical inhibition of a natural reflex.

Voluntary Urination — How it Actually Happens

1. You voluntarily contract abdominal muscles → raises bladder pressure
2. Urine enters the bladder neck and posterior urethra → stretches walls
3. This fires stretch receptors → triggers full micturition reflex
4. Simultaneously, cortex inhibits the external sphincter → urine flows out
5. Bladder normally empties completely — only 5–10 mL residual urine remains

⚠️ PART 2: PATHOPHYSIOLOGY OF URINE SUPPRESSION (Mootra Vega Dharana)

What happens when you voluntarily suppress the urge?

• The pontine micturition center receives constant inhibitory signals from the cortex
• External sphincter remains contracted (voluntary tonic contraction)
• The micturition reflex fires but gets overridden and fatigued
• The bladder continues to fill → intravesical pressure increases sharply

Habitual urine suppression
        ↓
Bladder overdistension (>400–500 mL)
        ↓
Intravesical pressure rises dramatically
        ↓
Retrograde pressure transmitted BACKWARDS:
Bladder → Ureter → Renal Pelvis → Kidney
        ↓
HYDRONEPHROSIS (dilation of renal pelvis and calyces)
        ↓
Compression of renal parenchyma → Reduced GFR
        ↓
Obstructive nephropathy → Irreversible kidney damage if prolonged

"Any obstruction of urinary flow at any point may cause retention of urine and increased retrograde hydrostatic pressure, leading to kidney damage and interference with waste and water excretion." — Brenner & Rector's The Kidney

Functional Problems (also mentioned in your notes)

The Two Types of Problems (Your Notes: Point 1 & 2)

• Bladder wall overdistension → loss of smooth muscle elasticity
• Chronic back-pressure → hydronephrosis → cortical atrophy of kidney
• Ureteric reflux — urine flows backward into ureters

• Loss of bladder wall compliance (becomes stiff)
• Detrusor overactivity or underactivity
• Altered albumin clearance (proteinuria from glomerular damage)
• Loss of blood proteins in urine (mentioned in your notes: "dysuria, headache, pain in bladder & sides, increased albumin clearance and loss of blood proteins")

🔄 Summary Flow Chart

Normal Urge → Cortical Inhibition → Vega Dharana (Suppression)
                                              ↓
                              Bladder overdistends chronically
                        ┌──────────────┴───────────────┐
                  STRUCTURAL                       FUNCTIONAL
           (Hydronephrosis,                  (Reduced GFR, impaired
           ureteric dilation,              concentration, azotemia,
           renal cortical atrophy)         electrolyte disturbances)
                        └──────────────┬───────────────┘
                                       ↓
                           Irreversible kidney damage
                           if not treated promptly

🔑 Key Points to Remember for Exams