What does the urinary tract function to do?
Transfers and stores urine produced by the kidneys until it is ready for excretion
What are the three parts of the urinary tract?
- the ureters
- the bladder
- the urethra
What are the ureters?
The ureters are two long, thin, muscular tubes connecting the kidneys with the bladder.
They begin as a continuation of the renal pelvis and extend towards the pelvic cavity where they penetrate the posterior wall of the bladder.
What is the ureter made up of histologically?
Three layers:
1. Mucosa (innermost layer lined with transitional epithelium)
2. Muscularis (smooth muscle layer in the middle)
3. Adventitia (outermost layer)
What is the urinary bladder?
- a muscular, expandable, sac-like pelvic organ that functions to temporarily store urine
What is the trigone?
- A smooth triangular area of the urinary bladder
- overlies the base of the internal aspect of the urinary bladder
- enclosed by the two ureteric openings superiorly, and the internal urethral opening inferiorly
- acts as a funnel that directs urine into the urethra
- has a high density of afferent neurons that transmit the urge to void
What is the neck of the urinary bladder?
- the constricted portion that is connected to the urethra inferiorly
- surrounded by an internal urethral sphincter that is made up of smooth muscle and is under involuntary control
Does the interior of the bladder contain rugae?
Yes
Does the trigone of the bladder contain rugae?
No
What is the function of rugae in the interior of the bladder?
To allow the bladder to expand in size to accommodate changes in volume, without any damage to the mucosa.
Where is the bladder located in females?
- in the pelvic cavity posterior to the pubic bone
- posterior to the pubic symphysis
- inferior to the uterus
- anterior to vagina
Where is the bladder located in males?
- in the pelvic cavity posterior to the pubic bone
- posterior to the pubic symphysis
- anterior to rectum
What is the mucosa of the bladder composed of?
Transitional epithelium
What is the muscularis of the bladder made up of?
Three layers of muscle that are collectively called the detrusor muscle.
Detrusor from latin means “to push down” or “to dislodge”
What is the urethra?
A muscular tube connecting the neck of the bladder with the outside word at an opening called the urethral meatus.
Differs in length and position in males and females.
Describe the change in epithelial lining in the urethra.
In both male and females, the epithelial lining of the urethrae starts out as transitional, gradually becoming stratified toward the external opening.
Describe the features of the male urethra.
Divided into three regions named after the structures it passes through.
- prostatic urethra (3-4 cm passing through the prostate gland)
- membranous urethra (2 cm from the prostate to the beginning of the penis. the voluntary urethral sphincter surrounds this area, far from the meatus)
- penile (spongy) urethra (15 cm long through the penis)
Describe the flow of urine (the order of structures)
Produced in kidneys then goes through:
1. glomerulus
2. Bowman’s capsule
3. proximal convoluted tubule
4. loop of Henle
5. distal convoluted tubule
6. collecting duct
7. renal papilla
8. minor calyx
9. major calyx
10. renal pelvis
11. ureter
12. bladder
13. urethra
14. external urethral meatus
What is micturition?
The act of urination
- as the urinary bladder contracts, the external urinary sphincter relaxes to expel urine from the bladder into the urethra, and then outside the body
What is incontinence?
The inability to voluntarily control the expulsion of urine
- leads to patients urinating accidentally
- can be a symptom of many underlying causes, including neurological disorders
A patient is experiencing urinary incontinence. What sphincter might be involved in urinary incontinence and what aspect of the nervous system would innervate that sphincter?
External urethral sphincter, somatic motor
