Bladder Flashcards
What is the two main roles of the bladder
Temporary storage of urine
Assists in the expulsion of urine
How does the bladder act as a temporary storage of urine
Hollow organ with distensible walls
Folded internal lining - rugae - allows to accommodate 400-600mL of urine in healthy adults
How does the bladder assist in expulsion of urine
Musculature of the bladder contracts during micturition
Describe the trigone
Triangular area which marks the orifices
Why does the trigone different from the rest of the internal bladder with smooth walls
Has a different embryological origin
What is the specialised smooth muscle of the bladder
Detrusor muscle
How does the detrusor muscle maintain structural integrity when stretched
Fibres are orientated in multiple directions
What innervation does the bladder receive
Parasympathetic and sympathetic
What are the muscular sphincter located in the urethra
Internal urethral sphincter
External urethral sphincter
Describe the internal urethral sphincter in males
Consists of circular smooth muscle fibres
Under autonomic control
Describe the internal urethral sphincter in females
Functional sphincter
Formed by bladder neck and proximal urethra
Describe the external urethral sphincter
Skeletal muscle
Voluntary control
What is the arterial supply of the bladder
Internal iliac vessels
Superior vesical branch of the internal iliac artery
Obturator and inferior gluteal arteries may contribute small branches
In males what is the arterial supply of the bladder supplemented by
Inferior vesical artery
In females what is the arterial supply of the bladder supplemented by
Vaginal arteries
What is the venous drainage of the bladder
Vesical venous plexus
Drains into the internal iliac veins
What innervation does the bladder receive
Autonomic
Somatic
Describe the sympathetic innervation of the bladder
Hypogastric nerve (T12-L2)
Causes relaxation of the detrusor muscle - promotes urine retention
Describe the parasympathetic innervation of the bladder
Pelvic nerve (S2-4)
Increased signals cause contraction of the detrusor muscle
Stimulates micturition
Describe the somatic innervation of the bladder
Pudendal nerve (S2-4)
Innervated external urethral sphincter - provides voluntary control over micturition
What is the role of sensory (afferent) nerves in the bladder
Found in bladder wall
Signal the need to urinate when bladder becomes full
What is the bladder stretch reflex
Primitive spinal reflex
Micturition is stimulated in response to stretch of the bladder wall
Describe the reflex arc
Bladder fills with urine. Stretched. Sensory nerves detect. Transmit information to spinal cord
Spinal cord relay signals to the parasympathetic efferent
Pelvic nerve acts to contract the detrusor muscle - stimulates micronutrition
