PBL 8 Flashcards
What is the uretorenal reflex?
Prevents excessive flow of urine into the pelvis of a kidney when the ureter is blocked
Pain nerve fibres supplying the ureters detect blockage and cause a sympathetic reflex back to the kidney to constrict renal arterioles, decreasing the renal output from the kidney
What is the vesicoureteral reflex?
This is where some urine in the bladder is propelled backwards into the ureters
This can lead to enlargement of the ureters
What is the voiding reflex?
This is where once you have started to expel urine from the bladder, sensory signals are sent to the sacral plexus
This further stimulates signals through the pelvic splanchnic nerve to cause contraction of the detrusor muscle until the bladder is empty
How much urine remains in the bladder after micturition?
Less than 10mL
How can higher centre control prevent micturition?
Firing signals through the voluntary pudendal nerve
This causes continual tonic contraction of the external sphincter until a continent time presents
What is the parasympathetic control of micturition?
Pelvic splanchnic nerve arises from S2-S4
Synpases on M3 receptor on bladder and releases ACh
This causes contraction of the detrusor muscle
What is the sympathetic control of micturition?
Hypogastric nerve arises from T10-L2
Synapses on B3 receptor on bladder and releases noradrenaline - this causes inhibition and relaxation of detrusor
Synapses on alpha 1 receptor on internal sphincter - causes contraction of sphincter
How does the bladder know when it is empty or full?
The amount of sensory signals coming from the bladder detects the stretch in the bladder wall - the more signals coming, the fuller the bladder is
Which part of the brain is responsible for controlling micturition?
Pons
What are the 4 types of urinary incontinence?
Urge incontinence
Stress incontinence
Overflow incontinence
Functional incontinence
What happens in urge incontinence?
You have an overactive bladder, which results in the sudden urge to urinate
Due to an uninhibited detrusor muscle which contracts randomly
What happens in stress incontinence?
Increased abdominal pressure overwhelms the sphincter muscles allowing urine to leak out
E.g, sneezing, coughing, laughing, during pregnancy
What happens in overflow incontinence?
Problem with emptying the bladder due to:
- blockage (e.g, BPH)
- ineffective detrusor muscle
- ineffective signalling
What is the function of the prostate?
Release alkaline fluid in semen to help neutralise acidity of the vagina
Contains smooth muscles that help to expel semen during ejaculation
What are the 4 zones of the prostate and where are they?
Central zone - surrounds the ejaculatory ducts
Transitional zone - centrally surrounds the urethra
Peripheral zone - posteriorly (largest zone)
Fibromuscular stroma - anteriorly
Which part of the prostate is most likely to undergo BPH?
Transitional zone
Which part of the prostate is most likely to undergo prostate carcinoma?
Peripheral zone
What is the function of prostate specific antigen (PSA)?
Protease which breaks down the high molecular weight of seminal coagulum into smaller polypeptides
What cells produce PSA?
Prostatic epithelial cells
How does testosterone regulate prostatic growth?
Converted into dihydrotestosterone (DHT) in prostatic stromal cells by 5alpha-reductase type 2
DHT binds to nuclear androgen hormone receptors in both stromal and epithelial cells that regulate gene expression of growth factors
How much more potent is DHT than testosterone?
1000x more potent
What important growth factors does DHT cause expression of?
Fibroblast growth family (FGF)
What does LUTS stand for?
Lower urinary tract symptoms
What are the storage symptoms associated with BPH?
Frequently passing urine
Feeling the bladder is full (urgency)
Waking up in the night to pass urine (nocturia)
Urge incontinence
What are the voiding symptoms associated with BPH?
Hesitancy (waiting for stream to start) Weak stream Stream starts and stops Dribbling at the end of urination Sensation of incomplete bladder emptying
What are the different findings you would find on a DRE for BPH and prostatic cancer?
BPH - prostate enlarged but smooth
Cancer - nodules present on prostate
Why does PSA level increase in BPH?
Epithelial cells are dividing as the prostate enlarges
More epithelial cells are secreting PSA
Why must you wait to take PSA levels until some time after ejaculation?
Ejaculation can raise PSA by 20%
What is the pathogenesis of BPH?
As you age, you pee more, each causing trauma to the urethra resulting in inflammatory response
This causes the release of more testosterone
Testosterone is converted into DHT
DHT signals growth factors signalling
This causes an enlargement in the transitional zone
What are the two main types of treatment for BPH?
Alpha1 adrenergic receptor antagonists
Anti-androgen (5-alpha reductase inhibitors)
How are alpha 1-adrenergic receptor antagonists used to treat BPH?
Inhibit the binding of noradrenaline to alpha 1 Receptors in the internal urethral sphincter
This causes relaxation of the sphincter
Relaxation around the bladder neck
This reduces urethral occlusion
What is a major side effect of using alpha 1 -adrenergic receptor antagonists and why?
Postural hypotension
Arterioles have alpha receptors, so blocking these can lead to relaxation of arterioles
Give some examples of alpha-1adrenergic receptor antagonists?
Tamsulosin
Alfuzonsin
Doxazosin
How are 5alpha reductase inhibitors used to treat BPH?
Block conversion of testosterone to DHT
This slows the growth of stromal and epithelial prostate cells
Drug also promotes apoptosis
Give some examples of 5alpha reductase inhibitors?
Finasteride
Dutasteride
What is transurethral resection of the prostate (TURP)?
Surgical procedure used to treat BPH
Resectoscope is inserted into the urethra and to the prostate
Electric current is used to heat the loop of the wire
The loop is then used to remove part/all of the prostate
After, saline solution is pumped into the bladder to flush away the pieces of prostate removed
What is holmium laser enucleation of the prostate (HOLEP)?
Surgical procedure used to treat BPH
Alternative to TURP
Uses laser to separate excess tissue from the prostate
What kind of tumour is a prostatic cancer?
Adenocarcinoma
How are prostate cancers grouped into risk categories?
Low risk: Gleason score 6, PSA <10ng/ml
Intermediate risk: Gleason score 7, PSA 10-20ng/ml
High risk: Gleason score 8-10, PSA > 20ng/ml
What is the Gleason score?
The grading system to determine the aggressiveness of prostate cancer
Where does prostatic cancer metastases to?
Liver
Lungs
What is brachytherapy?
Treatment for prostatic care
Implant radioactive seeds into prostate
These deliver high dose of radiation to prostate gland and cancer
What is hydronephrosis?
Dilation of the renal pelvis and calyces due to excessive fluid
