Case 18 Flashcards
(44 cards)
Explain the innervation of the bladder
The detrusor muscle that lines the bladder has stretch receptors that feed into sensory (afferent) pelvic splanchnic nerve, these neurons go into the S2, S3 and S4 spinal cord and go up into T11-L2. Once at T11-L2 the neurons synapse with the inferior mesenteric ganglion to give off the hypogastric nerve, this nerve releases noradrenaline to two places. The first is to the beta-3 adrenergic receptors on the detrusor muscle which causes relaxation and the second is on the alpha-1adrenergic receptor on the internal urethral sphincter which causes contraction.
There is also a efferent motor parasympathetic pelvic splanchnic nerve that innervates the detrusor muscle and arises from T11-L2, it can release Ach to M3 receptors on the detrusor muscle to make it contract
The pudendal nerve gives us somatic control of the external urethral sphincter and works by releasing Ach on nicotinic-1 receptors which causes it to contract aswell
Some of the impulses from the sensory afferent pelvic nerve from the stretch receptors go upwards all the way to the pons and cortex.
The pons has two centres, the pontine storage centre and the pontine micturition centre. The pontine storage centre (PSC), can stimulate the hypogastric nerve (T11-L2) and also the parasympathetic pelvic nerve (S2-S4) (pelvic splanchnic) and activates them to keep urine in. The pontine micturition centre (PMC) goes to the same nerves as the PSC but does the opposite which leads to urination.
Explain the innervation of the bladder whilst it’s empty
When you urinate the bladder keeps about 10-20ml of urine so that is it’s empty state
When the bladder is empty there is very minimal stretching of the detrusor muscle and the stretch receptors in it and so very little activation of sensory pelvic splanchnic nerve that goes into S2, S3 and S4 and then up to T11-L2. Little activity of the sensory pelvic nerve actually activates the hypogastric nerve once it reaches T11-L2 and synapses with the inferior mesenteric ganglion. Activation of the hypogastric nerve causes noradrenaline to be released to two places, first is the beta-3 adrenergic receptors on the detrusor muscle whuch causes it to relax, second is the alpha 1 adrenergic receptors on the internal urethral sphincter which causes it to contract, both of these actions promote holding in urine.
Whilst the bladder is empty the Pontine Storage Centre (PSC) is constantly active, it sends signals down to T11-L2 and activates the hypogastric nerve further to promote urine retention. It also goes to S2, 3 and 4 and inhibits the MOTOR (efferent) pelvic splanchnic nerve which stop the release of Ach to the M3 receptions of the detrusor muscle, inhibiting its contraction. Finally it also stimulates the pudendal nerve to send Ach to the nicotinic-1 receptors on the external urethral sphincter which causes contraction and further promotes urine retention (we have somatic/voluntary control over this action of the pudendal nerve)
All of these actions promote holding in your urine
Explain the innervation of the bladder whilst it’s full / (you need to urinate)
Once the bladder reaches 200ml you usually start getting the desire to use the bathroom, with the desire increasing as it gets more and more filled.
When the bladder starts getting full the stretch receptors in the detrusor muscle starts firing quickly, this sends signals down the sensory afferent pelvic splanchnic nerve, it enters S1, 2 and 3 but this time completely bypasses the thoracic lumbar area and goes straight to the Pons and cortex, this time it goes and activates the Pontine Micturition Centre (PMC) and the cortex inhibits the Pontine Storage Centre (PSC).
When the PMC gets activated it sends signals down and inhibits the hypogastric nerve at the T11-L2 level, this stops the release of noradrenaline to two places. Firstly it stops noradrenaline release to the alpha-1 adrenergic receptos on the internal urethral sphincter which causes it to relax and let urine through. Secondly it stops noradrenaline to the beta-3 adrenergic receptors of the detrusor muscle and stops the effect of it being relaxed. To contract the detrusor muscle the PMC sends signals down to S1,2 and 3 and activates the motor efferent pelvic splanchnic nerve, which was previously inhibited, this causes Ach to be released to the M3 receptors on the detrusor muscle and cause it to contract. Finally the only thing left in the way is to relax the external urethral sphincter (EUS), to do this the PMC sends signals down to S1,2 and 3 and inhibits the pudendal nerve which prevents Ach from being released to the nicotinic-1 receptors on the EUS which was previously keeping it contracted, the inhibition of the pudendal nerve causes the EUS to relax finally letting the urine bass out of the bladder and hopefully into a toilet bowl.
This response to a full bladder is called the micturition reflex.
What are the 3 most common sites for kidney obstructions
- Ureteropevic (or Pelviureteric) Junction (UPJ)- which is from the renal pelvic to the start of the ureter
- Pelvic brim - which is when the ureter crosses over the iliac vessels as it entered the pelvic cavity
- Ureterovesical junction (UVJ) - which is the point where the ureter enters the bladder
What is the name for the pain experienced from kidney stones
Renal colic pain, which is a severe, sharp pain that comes and goes in waves and is usually felt in the side (flanks), lower back or groin. It can also radiate to the abdomen and testicles in men or labia in women
What happens when you get a urinary tract obstruction
Because you can expel the urine it will start to build up in the bladder. This causes bladder distention, and if the bladder gets too full it can cause retrograde flow of urine, this will cause urine to back up into the ureter and even potentially the kidney leading to an enlarged bladder, ureter and kidney (called hydronephrosis). Sometimes in severe hydronephrosis it can impede the glomerular filtration rate (GFR) and eventually cause a post renal AKI (acute kidney injury). This will lead to an increase in creatinine and BUN (blood urea nitrogen) and decrease in urine output.
List some types of stones
- Calcium oxalate (75% of kidney stones)
- Calcium phosphate
- Struvite (common in chronic UTI)
- Uric acid stones
- Cystine stones
What investigation can you do to detect kidney stones
- Urinalysis
- Xray
- Ultrasound
How can X-rays and Ultrasounds show kidney stones and other diseases
- Stones composed of calcium or structure are typically visible on plain X-rays, other types of stones like uric acid and cystine stones can be spotted using contrast
- For ultrasounds stones can appear as echogenic (bright) structures with a posterior acoustic shadowing (which is a dark area behind the stone due to sound wave reflection)
- Ultrasounds can also identify hydronephrosis as the kidney appears to be dilated on ultrasounds
- Ultrasounds can also be used to identify bladder distension aswell
What is Intravenous Urogram/Pyelogram
It is when a radiopaque contrast due (iodine-based) is injected intravenously, the dye gets diluted by the kidneys and excreted into the urine which highlights urinary tract structures and can be used to check for obstructions, stones or tumors.
CT Urography is also similar but uses a CT scan and is more sensitive than IVU for detecting small stones, tumors or subtle obstructions.
Why are females more likely to get UTIs than men
Women are more prone to UTIs because they have a shorter urethra which is about 4cm compared to a male’s urethra which is on average 20cm.
A shorter urethra means that bacteria have to travel a shorter distance to reach the bladder making women more prone to UTIs.
Where is the prostate gland located and what is its function
The prostate gland id a walnut-sized gland located behind the base of the penis, in front of the rectum and below the bladder, it surrounds the urethra.
It’s primary function is to produce seminal fluid, which is the fluid in the semen that protects, supports and helps transport sperm
What are the risk factors for prostate cancer (and what is the biggest one)
Biggest risk factor is Age
then u have:
Race
Family history
Ethnicity
Genetics
Diet, Exercise and Obesity
How common is prostate cancer in the UK
1 in 8 men in the UK are diagnosed with prostate cancer
Symptoms of Prostate cancer
- Local (Lower urinary tract symptoms [LUTS]):
Obstructive
Irritative - Metastatic:
Pain etc (can spread to bone) - Systemic:
Fatigue, weight loss
How to diagnose prostate cancer
- First u take a history
Then: - Digital rectal exam (DRE)
- Prostate-specific antigen (PSA) blood test (usually you want to do PSA test first then DRE cause moving the prostate can lead to PSA to be released)
- Multi-parametric MRI scan (more detailed MRI)
- Biopsy
What can increase and decrease PSA
Increase:
- Benign prostatic hypertrophy
- Age
- Prostatitis
- Ejaculation
- DRE
Decrease:
- Drugs such as Finasteride/Dutasteride
- Obesity
- Herbal preparations
What is the main Biopsy done to check for prostate cancer and what are the side effects
the biopsy done is called a Transperineal template prostate biopsy and it involves first giving a local or general anaesthetic then take tissue samples from the prostate gland through the perineum (the skin between the scrotum and the anus)
Side effects include:
- Bleeding
- Infection
- Urinary obstruction (because of prostate swelling after puncturing)
You can also do a transrectal ultrasound biopsy which goes through the rectum (transperineal = through perineal)
(transrectal = through rectum)
Why are prostate biopsies done
To know:
- Type of tumor (vast majority is a adenocarcinoma [A cancer that affects glandular tissue and is cancerous])
- Grade of tumor
- Percentage of tumor found
- T stage of cancer
what is the scoring used for prostate tumor grading
- Gleason Score
- Grading system used to define aggressiveness
- Score is out of 5 and 3-5 is considered cancerous
- Gleason score consists of two X/5 scores added together so the least aggressive cancer of the prostate is (3+3=6) and the most aggressive is (5+5=10)
- Based on the gleason score a grade group is given.
Grade group 1 = 3+3 = 6
Grade group 2 = 3+4 = 7
Grade group 3 = 4+3 = 7
Grade group 4 = 4+4 = 8
Grade group 5 = 5+5 = 10
Explain what T1 and their respective a, b and c mean
This is the TNM Staging system: T refers to the tumor
T can go from 1-4 and have a, b and c
T1: Tumor is not palpable or visible on imaging
T1a: Tumor is ≤5% of tissue removed during surgery for benign conditions (like TURP).
T1b: Tumor is >5% of tissue removed during surgery for benign conditions (like TURP).
T1c: Tumor identified via needle biopsy, typically due to elevated PSA.
Explain what T2 and their respective a, b and c mean
T2: Tumor is confined within the prostate
T2a: Tumor involves ≤half of one lobe of the prostate.
T2b: Tumor involves >half of one lobe but not both lobes.
T2c: Tumor involves both lobes of the prostate.
Explain what T3 and their respective a and b means
T3: Tumor extends beyond the prostate
T3a: Tumor extends through the prostate capsule (extracapsular extension) but does not invade nearby structures.
T3b: Tumor invades the seminal vesicles
Explain what T4 means
T4: Tumor invades nearby structures
The tumor has spread to adjacent tissues beyond the seminal vesicles, such as:
- Bladder neck
- Rectum
- Pelvic wall
- External sphincter
