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Question 1

Define micturition

Answer 1

Wanting to pass urine

Question 2

Describe the urinary bladder

Answer 2

Is a smooth muscle organIS derived from the hindgutBelongs to “midline structures”

Question 3

What components make up the urinary bladder?

Answer 3

Body TrigoneNeck

Question 4

Describe the body of the bladder

Answer 4

Is temporary store of urineIs supplied by the autonomic nervous system so not under voluntary controlIs operated by reflex pathways in the spinal cord

Question 5

Describe the trigone

Answer 5

Angles of a triangle made between the ureteric orifices and the internal urethral orifice.

Question 6

Describe the neck of the bladder

Answer 6

Connects the bladder tot he urethra

Question 7

What are the main muscles that make up the bladder?

Answer 7

Detrusor urinaeInternal urethral sphincterExternal urethral sphincter

Question 8

Describe the detrusor urinae

Answer 8

Smooth muscle fibres arranged in layers of differing direction. Allow bladder to stretch in any direction and still have strength. Lined with transitional epitheliumFound in true/lesser pelvis of the adult

Question 9

Describe the nerve supply to the detrusor urinae muscle.

Answer 9

Is from the spinal cordIs bilateral

Question 10

Why are disorders of the nerve supply varied for the bladder?

Answer 10

Have different nerve supplies to different areas, so can have many combinations of nerve disorders

Question 11

What are the differences between the internal and external urethral sphincter?

Answer 11

IS is an physiological sphincter – ES is an anatomical sphincterIS is smooth muscle – ES is skeletal muscle IS is involuntary – ES is voluntary

Question 12

Give the characteristics of the internal urethral sphincter

Answer 12

Is a continuation of the detrusor muscleSmooth musclePhysiological sphincter – no muscle thickening, sphincter action is due to its structure

Question 13

Give the characteristics of the external urethral sphincter

Answer 13

Derived from pelvic floor musclesSkeletal muscles, under voluntary controlConstricts in order to hold in urineMuscle is thickened in order to facilitate action

Question 14

What is the parasympathetic innervation of the detrusor muscle?

Answer 14

Pelvic nerve (S2-S4)ACh at M3 receptorsCauses contraction

Question 15

What is the sympathetic innervation of the detrusor muscle?

Answer 15

Hypogastric nerve (T10-L2)NA at beta3 receptorsCauses relaxation

Question 16

What is the sympathetic innervation of the internal urethral sphincter?

Answer 16

Hypogastric nerve (T10-L2)NA at alpha1 receptorsCauses contraction

Question 17

What is the somatic innervation for the external urethral sphincter?

Answer 17

Pudendal nerve (S2-S4)Has spinal motor outflow from Onof’s nucleus (ventral horn of the cord)ACh at nicotinic receptorCauses contraction

Question 18

What is the continence phase of the urinary bladder controlled by?What does damage to this structure cause?

Answer 18

Neuronal apparatus called the continence neurones .Damage leads to a failure to store urine which reduced the filling capacity, therefore increasing the frequency of passing urine is greater.

Question 19

Define incontinence

Answer 19

The failure to store urine

Question 20

Describe the normal voiding reflex

Answer 20

–Afferent signals pass to brain micturition centres, to spinal micturition centres and then to parasympathetic neurones. – Increased stimulation of the pelvic nerve causes the detrusor muscle to contract, increasing intravesicular pressure, causing the internal urethral sphincter to relax. – Cerebral cortex makes a conscious decision to urinate, which reduces the somatic stimulations to the external urethral sphincter causing it to relax– The combination of contraction of the detrusor muscle and relaxation of the external urethral sphincter causes voiding to occur.

Question 21

Describe the storage of urine in the urinary bladder

Answer 21

Walls of bladder distend when filling with urine due to rugae. Intravesicular pressure hardly changes. Afferent nerves in bladder wall (stretch receptors) signal to void the bladder. Signal to brain micturition centres, which signal to the spinal cord and then the sympathetic neurones which causes the detrusor muscle to relax and the external urethral sphincter to contract, constricting the urethra. This reduced the intravesicular pressure and constricts the urethra.

Question 22

What are the four functions of the nervous system in relations to the lower urinary tract?

Answer 22

– provide sensations of bladder filling and pain– allow bladder to relax and accommodate urine– initiate and maintain voiding so bladder empties completely– to provide an integrated regulation of the smooth muscle and skeletal muscle sphincters of the ureters.

Question 23

What types of muscle fibres make up the detrusor muscle?

Answer 23

Longitudinal fibres for the inner and outer layers with circular muscle in the middle layer

Question 24

What neurones exclusively mediate continence?

Answer 24

Sympathetic neurones

Question 25

What is the name for the centre on the brain that controls the storage of urine?

Answer 25

Pontine storage centre

Question 26

What occurs when the bladder wall is stretched?

Answer 26

There is an increase in frequency of action potentials from the urinary bladder to the sacral regions and then onto the ascending spinal pathways to the pons and cerebrum.

Question 27

What functional parts of the bladder do sympathetic efferents innervate?

Answer 27

DetrusorInternal urethral sphincterTrigone

Question 28

What functional parts of the bladder do parasympathetic efferent fibres innervate?

Answer 28

DetrusorInternal urethral sphincterTrigone