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Study Day

Anatomy & Physiology of the Urinary System

Gillian Nottidge

Continence Nurse Specialist

Skills for Health CCO1

• Urine production• Normal micturition• The nervous system

including autonomic dysreflexia

• The bowel and it’s links to voiding problems

• The endocrine system• The pelvic floor• The prostate gland, the

urethra and sphincters• Voiding dysfunction• Reflexes

Definition of Urinary Incontinence

The complaint of any

involuntary leakage of urineAbrams 2002

Physical Requirements for Continence

• A bladder

• A sphincter mechanism

• A pelvic floor

• A nervous system

Urine production

Urine production

• Glomerulus receives blood via afferent arteriole

• Fluids and waste material forced out and collected in Bowman’s capsule

• Blood leaves glomerulus via efferent arteriole

• Urine drained into bladder via ureters – peristalsis

• 1-2 mls per minute

(Guyton et al 2006)

Effect of endocrine system

• Vasopressin released by hypothalamus– concentrates urine

• Diabetes Mellitus – polyuria may be presenting symptom

• Diabetes Insipidus – loss of production of vasopressin

• Renin-angiotensin system

What does the Bladder do?

The normal bladder has two phases:

A storage phase An emptying phase

Average bladder capacity:

Approximately 500mls First desire to void at

300mls

The Bladder

Is a hollow muscular sac made up of 4 layers

An outer layer (Visceral peritoneum) covers bladder and other abdominal organs

A muscular layer (Detrusor muscle) 3 layers of muscle

A submucous layer (With nerve & blood supply) An inner layer (Epithelium)

Anatomy of the bladder (female)

Under voluntary control

Divided into 2 segments

The base – Trigone

The body - Detrusor

Ureter

Internal sphincter

UrethraExternal Sphincter(Pelvic floor muscle)

Trigone

Detrusor Muscle

Female Urethra

• 3-5cm long• Consists of smooth

muscle• Lining of squamous

epithelium– easily damaged

• External sphincter striated muscle - control Credit to Alexander Tsiaras - Science photo library

Endoscope image of the human urethra

Anatomy of the urinary tract - man

Cross section of male anatomy Including:

Bladder Prostate Urethra

Male urethra

18 -22cm long• Inside has spiral groove –

wider urinary stream• Prostatic• Bulbourethra• Membranous• Spongy• Sexual function

Effect of bowel on the bladder

Pelvic floor muscles

• Supports the pelvic organs• Contraction causes

urethral compression – helps maintain continence during abdominal pressure

• Collectively called “Levator Ani”

• Striated muscle slow and fast

• muscle fibres

(under Voluntary control)

Normal micturition1. Filling and Storage Stage

Detrusor relaxed

Bladder neck closed

External sphincter contracted

2. Voiding Phase

Bladder neck opens

External sphincter& pelvic floor relaxed

Urine expelled

DetrusorContracts

Detrusor relaxes

Emptying the bladder

• Micturition centre co-ordinates the change from storage to voiding

• Sensory impulses initiate the desire to void• Co-ordinated relaxation of the urethral

sphincter and detrusor contraction allows the bladder to empty

• This action can be suppressed

Neuronal control of the bladder

Cerebral Function

• So, what might go wrong and why?

• Who might be at risk?

• How might they feel about it?

Autonomic Dysreflexia

• It develops after spinal cord injury/ lesion at or above T6

• Exaggerated response of nervous system to localised trigger below level of spinal cord injury

• This causes an sudden extreme rise in blood pressure

• It can occur without warning and is a medical emergency

Autonomic Dysreflexia

• Normally a harmful stimulus causes the autonomic nervous system to respond resulting in a rise in blood pressure.

• If T6 lesion or above present, stimulus below the injury causes BP to rise, but autonomic nervous system does not act to lower it below the lesion.

• Therefore BP continues to rise until stimulus is removed

• Autonomic nervous system attempts to lower BP above lesion: this causes the symptoms that aid the diagnosis of AD

Signs and symptoms

• Stuffy nose / nasal obstruction• Severe pounding headache, usually frontal• Raised BP (by 20mm/hg) / bradycardia • Cutis anserina (goose bumps) above and possibly

below level of SCI and shivering• Flushing above level of lesion due to vasodilation • Reduced urine output• Blurring vision – spots before eyes• Increased spasms

Voiding Dysfunction

• Voiding dysfunction and urinary incontinence are conditions in which the bladder is not able to store urine properly (incontinence) or conditions in which the bladder is not able to empty properly (voiding dysfunction).

(US Department of Urology 2009)

Reflex Voiding Dysfunction

• Detrusor areflexia Detrusor areflexia

• Detrusor-sphincter dyssynergia

• Detrusor failure / hyporeflexia

• Detrusor hyperreflexiaDetrusor hyperreflexia

• Neurogenic bladder

• Spinal cord injuries/MS

Risk Factors

• Age• Gender• Obesity• Smoking• Exercises• Previous surgery• Childbirth

Skills for Health CCO1

• Urine production• Normal micturition• The nervous system

including autonomic dysreflexia

• The bowel and it’s links to voiding problems

• The endocrine system• The pelvic floor• The prostate gland, the

urethra and sphincters• Voiding dysfunction• Reflexes

Thank You for listening.

Any Questions?Gillian.nottidge@BDCT.nhs.uk

01274 322210