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Excretionof urine for dental

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Physiology of micturition
Physiology of micturition
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Excretionof urine for dental

  1. 1. Micturition Dr Kiran Kumar C MBBS.,MD.,FAGE.,C DIAB Assistant Professor
  2. 2. • Once urine has been formed by the kidneys, • Smooth–muscle walled ureters to the urinary bladder. • Urine does not flow through the ureters by gravitational pull alone. • Peristaltic (forward-pushing) contractions of the smooth muscle within the ureteral wall propel the urine forward from the kidneys to the bladder.
  3. 3. • The ureters penetrate the wall of the bladder obliquely, before they open into the bladder cavity. • Prevents backflow of urine from the bladder to the kidneys when pressure builds up in the bladder. • As the bladder fills, the ureteral ends within its wall are compressed closed. • Urine can still enter, however, because ureteral contractions generate enough pressure to overcome the resistance and push urine through the occluded ends.
  4. 4. Sphincter • Internal sphincter : - Sphincter vesicae, - Smooth muscle - Involuntary • External sphincter : - Skeletal muscle - Voluntary
  5. 5. Innervation • MOTOR • Parasympathetic : - Sacral detrusor nucleus - Intermediolateral grey horn of spinal cord S2-S4 - Pelvic splanchnic nerve - Excitatory to detrusor muscle - Inhibitory to sphincter vesicae
  6. 6. • Sympathetic : - Intermediolateral grey horn T10- L2 segments of spinal cord - Bladder, bladder neck and urethra - Inhibitory to detrusor - Excitatory to sphincter vesicae
  7. 7. • Somatic motor supply - Sacral pudental nucleus - Nucleus of ONUF - S2,3,4 - Supply to external sphincter
  8. 8. • SENSORY - BLADDER WALL: T10-T12 through pelvic splanchnic nerve & hypogastric nerve - URETHRA: pudental nerve - Stretch receptor in the detrusor - Imminent voiding : periurethral striated muscle - Pontine and Suprapontine micturition centre - Pain fibres: anterolateral column of spinal cord
  9. 9. Micturition • Definition: - Is a process by which urinary bladder empties when it become filled • It involves two steps 1. Filling of bladder until the tension in the bladder increases above the threshold level 2. Micturition reflex which empties the bladder
  10. 10. • FILLING OF URINARY BLADDER • Transport of urine into urinary bladder through ureters • As urine collects in the renal pelvis, • The pressure in the pelvis increases and initiates a peristaltic contraction along the ureter • To force urine towards the bladder. • Capacity of the bladder • Physiological capacity of the bladder varies with age, • 20–50 mL at birth, • 200 mL at 1 year, • 600 mL in young adult males.
  11. 11. CYSTOMETRY • This refers to the process of studying the relationship between the intravesical volume and pressure, • The cystometrogram refers to a graphical record of this relationship • Normal cystometrogram have 3 phases 1. Phase 1 2. Phase 2 3. Phase3
  12. 12. EMPTYING OF BLADDER • Normal voiding is a spinal reflex • Modulated by CNS( brain and spinal cord) • Coordinates the function of bladder and urethra • Urethra and bladder is controlled by 1. Brain 2. Brain stem 3. Spinal cord
  13. 13. Emptying of bladder 1. The sacral micturition centre - Spinal centre for micturition - Sacral pudental nucleus: relaxation of external sphincter - Sacral detrusor nucleus : contraction of detrusor muscle
  14. 14. 2. Pontine micturition center - Aka BARRINGTON CENTRE - Reticulospinal tract - Exert control over sacral micturition centre 3. Cerebral cortex - Detrusor area is located in the medial frontal lobe - Excite detrusor nucleus 4. Basal Ganglia: - Inhibits sacral detrusor nucleus
  15. 15. REFLEX CONTROL VOLUNTARY CONTROL Bladder fills Cerebral cortex Stretch receptor Parasympathetic Motor neuron to external sphincter Bladder Detrusor contraction External urethral sphincter closed Opening of internal sphincter Urination No urination External urethral sphincter opens when motor neuron is inhibited
  16. 16. Applied
  17. 17. • Atonic neurogenic urinary bladder - Destruction of sensory nerve fibres from bladder to spinal cord - Absence of awareness of bladder filling and desire to urinate - Over distention of bladder - Overflow incontinence - Degeneration and traumatic injury of the spinal cord - Aka RETENTION AND OVERFLOW INCONTINENCE, PARALYTIC BLADDER
  18. 18. • AUTOMATIC URINARY BLADDER - Complete destruction of spinal cord above sacral segments - Complete loss of micturition reflex, bladder sensation - Also called as reflex neurogenic bladder
  19. 19. • AUTONOMUS URINARY BLADDER - Lesion in the sacral portion of the spinal cord - Interruption of the reflex arc - Loss of normal reflex - Inability to initiate urination normally - Stress incontinence

Notas do Editor

  • Gross anatomy
    External features: The urinary bladder, a hollow muscular viscus, is a temporary reservoir for urine.
    The main body of empty bladder is pyramidal having an apex and a base.
    The lowest part of the bladder is called neck, which continues as urethra.
    Interior of the bladder. In an empty bladder, the greater part of the mucosa shows irregular folds
    The interior of the base (posterior surface) of the bladder presents a triangular area, the trigone where the mucosa is smooth due to its firm attachment.
    Internal urethral orifice is located at the apex (inferior
    angle) of the trigone. The ureters open into the bladder at
    superior angles of the trigone (Fig. 6.7-1). The ureters pierce
    the bladder wall obliquely, and this provides a valve-like
    action, which prevents a reverse flow of urine towards the
    kidneys as the bladder fills.
  • The wall of the urinary bladder consists of three layers: an
    outer serous layer, a thick coat of smooth muscle, and the
    inner mucous membrane.
    Mucous membrane is lined by the transitional epithelium.
    Its characteristic features are:
    It stretches when the bladder distends,
    It forms a complete barrier to the passage of fluid and
    electrolytes. Therefore, urine stored in the bladder
    remains unchanged in chemical composition. Muscular layer is formed by smooth muscle fibres, which
    constitute the detrusor muscle. Contraction of this muscle
    coat is responsible for emptying of the bladder.
  • Sphincters of the urethra
    1. Internal sphincter. The circular smooth muscle fibres in
    the area of the neck of bladder are thickened to form the
    internal sphincter (sphincter vesicae). The natural tone of
    the internal sphincter prevents emptying of the bladder
    until the pressure in the body of bladder rises above a
    threshold level.
    2. External sphincter. Beyond the bladder neck, it is encircled
    by a ring of voluntary (skeletal type) muscle known as
    external sphincter of the bladder. The external sphincter
    provides voluntary control over micturition.

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