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RT 170
URINARY SYSTEM
The circulatory, respiratory, digestive, and urinary systems are all responsible for maintaining the
metabolism of the body. Both the urinary system and the skin share the common function of assisting in
the maintenance of the water balance of the body.
The urinary system consists of those organs which produce urine and eliminate it from the body. The
urinary system filters the blood and extracts from it the waste products carried in the circulatory system.
The function of the kidneys is to excrete urine, a life-preserving function because homeostasis depends
upon it. Additionally, the kidneys influence blood pressure.
Pathology may occur in the kidney in either of two locations.
1. Structural breakdown in the glomerulus and capsule.
2. Physiologic failure of the cells of the tubules.
The urinary system includes:
2 kidneys (R/L)
2 ureters (R/L)
1 urinary bladder
1 urethra
Functions of the kidneys:
1. remove waste products from the blood
2. maintain fluid and electrolyte balance
3. secrete substances that affect blood pressure and other important kidney functions
Gross Anatomy: size, shape, and localization of the kidneys:
Size - approximately 4½ “ long, 2-3” wide, and 1” thick; usually the left kidney is slightly larger
than the right
Shape - shaped like a bean
Location - retroperitoneal in contact with the posterior wall of abdominal cavity
- approx T12 – L3, depending upon body type
- lie on either side of the spine in the same coronal plane
Kidney
How the kidneys excrete urine:
Approximately 1000-1400 ml of blood are delivered to each kidney each minute.
1. glomerular filtration - rate of glomerular filtration is from 125-130 ml of filtrate each minute.
2. tubular reabsorption - reabsorption of substances needed by the body
(97%-99% water and part of the solutes filtrate back into the blood).
3. tubular secretion
Anatomy of the kidney
Renal capsule - continuous outer membrane which is continuous with outer coating of the ureter.
Hilum - longitudinal slit on medial border
Renal sinus - expanded portion of hilum within the kidney
Renal medulla - composed mainly of the collecting tubules (renal pyramids)
Nephron - is composed of a renal corpuscle and a renal tubule
Calyces - cup-shaped stems arising at the sides of the papilla of each renal pyramid. Minor to
major which goes on to form renal pelvis, then becomes ureter.
Ureters - convey urine from the renal pelves to the bladder by peristaltic contractions.
Approx 10-12” (25-30 cm) long
Enter the bladder on the posterolateral surface.
Function - along with the pelves and calyces, collect urine as it forms and drain it into the bladder.
Urinary bladder - musculomembranous sac to hold urine.
Adult bladder can hold approx 500 ml fluid. The volume of urine production has been estimated to
be from 1000-1800 ml / 24 hours.
Functions - reservoir for urine, and expels urine from the body.
Pg 2, Urinary System
Urethra - musculomembranous tube with a sphincter type of muscle at the neck of the bladder.
Prostate - part of the male reproductive system; secretes a milky fluid
M, Vol II: See pg 201 - Summary of Anatomy
M, Vol II: See pg 202 - Summary of Pathology
Adrenal (suprarenal) Glands
Closely associated with the urinary system are the 2 adrenal glands (endocrine glands).
Secrete:
1. epinephrine secreted by the medulla
2. cortical hormones secreted by the cortex
Imaging: CT or selective catheterization.
Imaging the Urinary System
Imaging Methods -
x-ray (excretory technique); tomography; CT; Angiography
Procedures
All urinary system procedures require a scout film.
Urography (IVU) / Pylography (IVP)
Intravenous Urogram / Intravenous Pyelogram
Visualization of the kidneys requires contrast medium -
organic - nonionic
ionic - iodinated
Injection methods: bolus or infusion
Antegrade filling - allows the contrast medium to enter the kidneys in the normal direction of
flow.
Compression
Common Diagnoses: obstruction; stenosis; urinary retention
Retrograde Pyelogram - This is a therapeutic procedure, so diagnosis is determined prior to
performing the procedure.
- Retrograde filling - contrast is introduced against the normal flow
- Cystoscopy is required
- Procedure usually performed in operating room
Cystogram
- Cystogram or VCUG
- Retrograde filling - contrast is introduced against the normal flow
- Male / female
Common Diagnoses: reflux; urinary retention; obstruction; stenosis
Urethrogram
- Retrograde filling - contrast is introduced against the normal flow
- Male / female
Common Diagnoses: obstruction; stenosis
Procedure Sequencing
It is VERY important to sequence the procedures correctly when performing more than of these procedures
in the same day on a patient.
In order, the sequence is: 1. Urethrogram
2. Cystogram / VCUG
3. IVU