Chapter 46: Urinary Elimination Flashcards
Urinary elimination depends on the function of what organs?
kidneys, ureters, bladder and urethra
What nerves must be present for urinary elimination to occur?
efferent (motor) and afferent (sensory) nerves from the bladder to the spinal cord and brain
When the urinary system fails to function, eventually
all organ systems are affected
Approximately ________ of the cardiac output circulates through the kidneys each minute.
20-25%
Nephron
functional unit of the kidney that forms urine
glomerulus
filters approximately 125 ml of filtrate per minute
Not all of the filtrate is excreted as urine:
approximately 99% is resorbed into the plasma leaving 1% excreted as urine
Normal urine output in an adult per day
1000-2000 ml/day
an output of less than 30 m/hr indicates what?
possible circulatory, blood volume or renal alterations
The kidneys are responsible for maintaining a normal RBC by producing
erythropoietin
Erythropoietin
functions within the bone marrow to stimulate RBC production, maturation and prolongs the life of mature RBC’s
Patient with chronic kidney conditions cannot produce
sufficient quantities of erythropoietin therefore are prone to anemia
Aldosterone is secreted from
the adrenal cortex
Aldosterone causes
retention of water -> increases blood volume -> increases arterial blood pressure -> increases renal blood flow
Why are patients with chronic renal failure prone to developing renal bone disease?
they do not make a sufficient amount of active vitamin D
Renal bone disease results in
demineralization of bone caused by impaired calcium absorption
ureters
tubular structures that enter the urinary bladder from the kidneys
ureters enter the bladder from the
posterior wall
What causes urine to enter the bladder in spurts?
peristaltic waves
A kidney stone (renal calculus) within the ureter results in
strong peristaltic waves that attempt to move the stone into the bladder resulting in renal colic (causes intense flank pain)
The urinary bladder
hollow, distensible, muscular organ that stores and secretes urine.
The urinary bladder lies where?
in the pelvic cavity behind the pubic symphysis
Urethra
exits the bladder and passes out of the body
The urethra is lined with
mucous membranes
Glands of the urethra
secrete mucus into the urethral canal
In a woman, the urethra is how long?
1.5-2” long
In men, the urethra is approximately how long?
8” long
Most people feel the need to void from
400-600 ml/urine
As the bladder stretches,
sensory impulses are sent to the micturition center in the sacral spinal cord.
What makes urination a voluntary process?
the fact that impulses can be ignored or acted upon
Damage to the spinal cord above the sacral region causes
reflex incontinence.
however, the micturition reflex pathway may remain in tact.
reflex incontinence
loss of voluntary control to urinate.
Overflow incontinence
occurs when the bladder is overly full and the pressure in the bladder exceeds the sphincter pressure.
involuntary loss of urine results
Causes of overflow incontinence include:
head injury, spinal cord injury, diabetes and trauma to the urinary system
Factors influencing urination
- urinary retention
- urinary tract infections
- catheter associated urinary tract infections
- urinary incontinence
- urinary diversions
Urinary incontinence
T. 46-1 p 1104-5’
involuntary leakage of urine that is sufficient to be a problem
Urinary Retention can be caused by
post void residual
BPH
Types of UTI’s
bacteriuria
pyelonephritis
dysuria
cystitis
Urinary diversions include
ureterostomy
nephrostomy
Diabetes Mellitus and neuromuscular diseases cause
changes in nerve functions
Diabetes mellitus and neuromuscular diseases causes changes in nerve functions that can lead to
reduced bladder tone
reduced sensation of bladder fullness
inability to inhibit bladder contractions
End Stage Renal disease
irreversible damage to the kidney tissue marked by fluid and electrolyte imbalances, accumulation of wastes in the blood and systemic symptoms of N/V, headache, coma and convulsions
Urinary retention
accumulation of urine due to the inability of the bladder to empty
With severe retention, the bladder can hold as much as
2000-3000 ml of urine
When assessing for bladder distention in a patient with urinary retention, it may be
extremely painful