Characteristics of Urine & Micturition Flashcards
How much blood is filtered through the kidneys in 24hrs, and how much of this is collected for urine? (2)
150-180L per 24hrs
1.5-1.8L per 24hrs
Differentiate between filtrate and urine. (2)
- Filtrate - contains everything that blood plasma has (except protein), but by the time it reaches the collecting ducts, most of the H2O has been lost and so it contains mostly nutrients and specific ions
- Urine - contains nitrogenous wastes and unneeded substances
What colour range is urine normally and what is the colour due to?
- Freshly voided urine = clear and pale to deep yellow in colour
- Colour is due to urochrome → a pigment that results from the body’s destruction of hemoglobin
How does the urine colour change with an increase of solutes?
Deeper yellow
What other, healthy way may urine change in colour other than the level of solutes?
Eating certain foods (beets = red)
Why does urine change in odour when left to stand and what kind of odour does it take on? (2)
- Action of bacteria on urine solutes
2. Ammonia odour
List 3 things that change the smell of urine. (3)
- Drugs
- Vegetables (esp asparagus)
- Diseases (diabetic urine → sweet)
What pH is urine usually?
pH 6
What do you call foods that make urine more acidic?
Acid-ash foods
What kind of diets would make urine more alkaline?
Vegetarian diets
What sickness may also make urine more alkaline?
Urinary tract infections (UTI)
Does urine weight more or less than diluted water and why? (2)
- Urine weighs more than diluted water
2. Urine = water + solutes
What is specific gravity (SG)?
A form of measurement used to describe how much heavier or lighter something is compared to distilled water
What is the SG of distilled water?
SG of distilled water = 1.0
What is the range in SG for urine?
Urine SG ranges from 1.001-1.035
Define: micturition (voiding)
Emptying of the bladder
Name the 2 sphincters that control the flow of urine from the bladder. (2)
- Internal urethral sphincter (most superior)
2. External urethral sphincter (most inferior)
At what point does the stretching of the bladder wall activate the stretch receptors?
After the bladder has collected about 200mL of urine
How do nerve impulses travel to the bladder for contractions? (3)
- Impulses are transmitted to the sacral region of the spinal cord
- Impulses go back to the bladder via the pelvic splanchnic nerves
- This causes the bladder to go into reflex contractions
What happens as the reflex contractions grow stronger? (2)
- Stored urine is forced past the internal urethral sphincter into the upper part of the urethra
- This gives the urge to void
When does micturition reflex occur?
After 200-300mL of urine has been collected by the bladder
When does incontinence occur?
When one is unable to voluntarily control the external sphincter
What population is incontinence naturally common in and why? (2)
- Usual in children 2yrs old or younger
2. They have yet to gain control of their voluntary sphincter
What is urine retention?
The opposite of incontinence; the bladder is unable to expel urine
Who is urine retention common in and why? (2)
- Patients who had been administered general anesthesia
2. It takes longer for the smooth muscles to regain their activities
Define: hyperplasia
Hyperplasia: enlargement of the prostate gland which surrounds the neck of the bladder
Why is urinary retention relatively common in older men?
Hyperplasia means that the prostate gland is enlarged, and this often results in the bladder being pressured by the increased size of the prostate
