This document summarizes the physiology of the urinary bladder and micturition reflex. It begins with the anatomical components of the bladder, including the body, trigone, internal sphincter, and external sphincter. It then describes the nerve supply to the bladder, including sympathetic, parasympathetic, and somatic nerves. The micturition reflex is a spinal reflex facilitated by higher brain centers that is initiated when urine fills the bladder and stretches its receptors, causing inhibition of the external urethral sphincter and allowing urination. Precise control of micturition involves a balance between inhibitory centers in the midbrain and cortex and facilitatory centers in the pons. Applied aspects discuss conditions like

1. Department of Physiology
UTKARSH SINGH
ROLL NO.17146

2. 1. INTRODUCTION
2. PHYSIOLOGICAL ANATOMY OF THE BLADDER
3. NERVE SUPPLY TO URINARY BLADDER AND SPHINCTER
4. MICTURITION REFLEX
5. APPLIED PHYSIOLOGY

3. REFLEX
It is an involuntary and nearly instantaneous
movement in response to a stimulus
MICTURITION
It is the process by which the urinary
bladder empties when it gets filled.

4. Urinary bladder is a smooth muscle
chamber. It is composed of the following:-
1) THE BODY
2) TRIGONE

5. 3) INTERNAL SPHINCTER
4) EXTERNAL SPHINCTER

6. • SYMPATHETIC NERVE
SUPPLY
• PARASYMPATHETIC
NERVE SUPPLY
• SOMATIC NERVE
SUPPLY

7. MICTURITION-a fundamentally spinal reflex
facilitated and inhibited by higher brain centres.
To understand micturition reflex first we have to
understand cystometrogram
CYSTOMETROGRAM-it represents pressure
changes in urinary bladder in relation to volume of urine
collected in it.

8. Once urine enters urethra the stretch receptors in the urethra are
stimulated and send afferent impulses to spinal cord via pelvic nerve
Fibres.
Now the impulse generated from spinal centres inhibit pudendal
nerve. So the external sphincter releases and micturition occurs.
Once a micturition reflex begins it is self regenerative that is the initial
contraction of bladder further activates the receptors to cause still further
increase in sensory impulse from the bladder and urethra.
This cycle continues repeatedly until the force of contraction of bladder
reaches the maximum and the urine is excreted out completely.

9. INHIBITORY
CENTRES FOR
MICTURITION
FACILITATORY
CENTRE FOR
MICTURITION
• Centres in midbrain & cortex
• Inhibit micturition
• Centres in pons
• Facilitate micturition

10. 1. ATONIC BLADDER
i. Caused by destruction of sensory nerve fibres.
ii. Detrusor muscle loses the tone.
iii. Bladder completely filled with urine and urine overflows.
iv. It is called overflow dribbling or overflow incontinence.
2. AUTOMATIC BLADDER
i. Characterised by hyperactive micturition reflex.
ii. Even small quantity of urine present in bladder produces micturition reflex.
3. UNINHIBITED NEUROGENIC BLADDER
i. Characterised by frequent and uncontrolled micturition.
ii. It is due to lack of inhibitory signals from brain.
4. NOCTURNAL MICTURITION
i. It is common and normal in infants and children.
ii. It is because of incomplete myelination of motor nerve fibres.

11. 1) GUYTON AND HALL
2) A.K JAIN
3) GANONG’S REVIEW OF MEDICAL PHYSIOLOGY

12. THANK YOU