T3 L11: Lower urinary tract Flashcards
Where does tubular fluid exit the collecting ducts?
At the tip of the renal pyramid (the renal papilla)
What is the site of drug-induced nephrotoxicity?
The renal papilla (renal papillary necrosis)
Which structures fuse to form the renal pelvis?
Major calices
What triggers peristaltic contraction in the kidneys?
The fluid moving into the renal pelvis and causing distention
What are the 2 types of muscle that make up the ereters?
Inner muscle is longitudinal and outer muscle is circular
How many peristaltic waves are generated per minute in the ureters?
1-6 per minute
What type of epithelium makes up the mucosal layer of ureters?
Transitional epithelium
What is the effect of the parasympathetic NS on the number of peristaltic contraction in ureters?
Enhance
What is the effect of the sympathetic NS on the number of peristaltic contraction in ureters?
inhibition
Describe the process of peristalsis in ureters
- longitudinal muscle contracts and circular muscles relaxes
- Longitudinal muscle relaxes so a bolus forms and then circular muscle contracts to push the bolus
Which structures prevent backflow of urine in the bladder?
The ureteral openings
What is the detrusor muscle layer in the bladder?
The outer muscle layer consisting of longitudinal muscle and circular muscle
What is the trigone and what is its function?
A triangular area bound by openings of the ureters and entrance to the urethra. It acts as a funnel to channel urine towards the neck of the bladder
Which NS stimulates the bladder to contract?
The parasympathetic NS
What are the 2 urethral sphincters?
Internal and external
Which urethral sphincter is under involuntary control?
The internal sphincter
Why does incontinence after childbirth occur in women?
Because the female external sphincter is not as well developed
What is mucturation?
Urination
What impact do higher centres have on micturation?
They keep the micturition reflex under inhibition
What impact do cortical centres have on micturition?
They facilitate micturition by initiating the micturating reflex and relaxing the external sphincter. The internal sphincter relaxes at the same time
What happens to contractions when the bladder becomes increasingly full?
Contractions become more frequent, intense, and last longer
Which nerve carries sympathetic involuntary control to the bladder and sphincters and from which vertebral level?
The hypogastric from L2
Which nerve carries parasympathetic involuntary control to the bladder and sphincters and from which vertebral level?
The pelvic nerve from S2 and S3
Which nerve carries somatic voluntary control to the bladder and sphincters and from which vertebral level?
The pudendal nerve from S2 and S3
Which nerves inhibit micturation?
The hypogastric and pudendal nerve
Which nerve facilitates micturation?
The pelvic nerve
What stimulates the pelvic nerve?
Activation of stretch receptors in the bladder wall and internal sphincter
Describe the guarding reflex
Bladder distention stimulates the pelvic nerve which stimulates the hypogastric nerve. Stimulation of the hypogastric nerve causes relaxation and reduced excitability of the detrusor muscle and constriction of the internal sphincter. The external sphincter is held closed by the pudendal nerve
After how many mL are micturition contractions stimulated?
200 mL
Which muscles are involved in micturition?
Lowering of the diaphragm, contraction of abdominal muscles, and opening of the internal sphincter
What is Paraplegia?
The complete severing of nerve input from the cerebral cortex. It means there is no cortical control
What causes an automatic bladder?
Paraplegia
What is meant by an automatic bladder?
The involuntary emptying of the bladder
What causes an unintended bladder?
Partial spinal cord damage with loss of inhibitory descending signals
What is an unintended bladder?
Frequent urination as excitatory impulses from cerebral cortex remain unopposed
What causes an atonic bladder?
Crush injury of the dorsal root causing afferent nerve destruction so micturition reflexes are lost
What is an atonic bladder?
When the bladder fills till it overflows
Why do infants lack the voluntary mechanism to control urination?
Their corticospinal connections are not established
Which diseases can cause loss of micturition control?
Stroke, Alzheimer’s, problems affecting cerebral cortex
What cause cause bladder sphincter muscles to lose tone?
Pregnancy
What diseases can cause urinary retention?
Enlarged prostate gland because it compresses the urethra
What foods can cause heightened urge incontenence?
Spicy food (capsaicin), caffeine/chocolate (xanthine’s), citrus food (citric acid), and carbonated beverages
What does ACh released by the pelvic nerve cause?
Promotes micturition
What di anticholinergic drugs do?
Inhibit bladder contractions and facilitate involuntary contractions of the internal sphincter
Oxybutinin is a type of which drug?
An anticholinergic drug
What are some unwanted effects of anticholinergic drugs?
Dry mouth, blurred vision, palpitations, drowsiness, facial flushing
What is atropine?
- Increases the heart rate and improves the atrioventricular conduction by blocking the parasympathetic influences on the heart
- It dilates vessels
What type of drug is Imipramine?
A tricyclic antidepressant
When is Imipramine used?
Low doses are given to children who wet the bed. It can cause behavioural problems on withdrawal
What type of drug is Desmopressin and what is it used for?
It’s and ADH analogue used for children who wet the bed
What type of drug is Mirabegron and what is it used for?
A selective beta-2 agonist used for overactive bladder syndrome
What is the treatment for acute urinary retention?
Catherisation or surgery
What is the treatment for chronic urinary retention?
Pharmacological intervention or surgery
What does noradrenaline released by the hypogastric nerve do?
Reduces micturition
What type of receptors are found on the prostate and external sphincter?
Alpha-1 receptors
What are alpha-1 receptors stimulated by?
noradrenaline
What do stimulated alpha-1 receptors do to urinary flow?
Increase it
Alfuzosin, Doxazosin, Indoramin, Prazosin, Tamulosin, and Terazosin are types of which drug?
Alpha-1 agonists
What do parasympathomimetics (choline esters) do?
They have agonist action at muscurinic ACh receptors that cause increased contractions of the detrusor muscle
What are parasympathomimetics (choline esters) used for?
To treat urinary retention
What type of drug is Bethanecol?
A parasympathomimetic (choline ester)
What are the unwanted effects of parasympathomimetics (choline esters)?
Nausea, vomiting, intestinal colic, bradychardia, blurred vision, sweating
What do Neostigmine and Pyridostigmine do?
They inhibit the breakdown of ACh and promote bladder emptying (Incontinence)
What are Pinasteride and Dutasteride and what are they used for?
They’re inhibitors of androgen synthesis used to relieve urinary retention caused by prostate hyperplasia
