Physiology of Micturition

Question 1

What anatomical structures make up the lower urinary tract?

Answer 1

Bladder –> Bladder neck –> Prostate Gland –> Urethra and Urethral Sphincter

Question 2

What are the 4 main functions of the LUT?

Answer 2

1) Store Urine
2) Allow the continuous filling of urine into the bladder, with continual excretion converted into
3) Prevent leakage of urine or fluid
4) Allow for appropriate excretion of urine and voiding of bladder into a controlled and volitional process

Question 3

What state is the detrusor muscle found in during the storage and voiding phase of micturition?

Answer 3

Storage: Relaxed
Voiding: Contracted

Question 4

What type of epithelium lines the LUT?

Answer 4

Urothelium (Pseudostratified - Transitional)

Question 5

What stage is the EUC found in during storage and voiding of micturition?

Answer 5

Storage: Contracted
Voiding: Relaxed

Question 6

What are the physiological steps of micturition?

Answer 6

1) Bladder continuously fills and stretch receptors are stimulated
2) Afferent impulses stimulate the PSNS action of detrusor muscle –> Contracts
3) Urethral sphincters relax, with inhibition of pudendal nerves etc.
4) PAG stimulated