Kaplan Prep - Renal System (Kidneys) - problem set 4

Question 1

Describe the two factors that contribute to how urine concentration and volume are altered.

Answer 1

It is accomplished by:

1. the countercurrent flow of filtrate through the loop of Henle and
2. the flow of blood through the limbs of its adjacent vasa recta blood vessels.

Question 2

Why is it necessary that urine concentration and volume be altered?

Answer 2

In order to maintain a relatively constant total solute concentration of body fluids.

Question 3

What is another way of saying μOsm

Answer 3

mosm

Question 4

How do you say mosm as a word?

Answer 4

milliosmole

Question 5

Describe the solute concentration of the renal filtrate at the beginning of the loop of Henle of juxtamedullary nephrons

Answer 5

The solute concentration of the filtrate is 300 mosm at the beginning of the descending limb

Question 6

Describe the solute concentration of the renal filtrate at the hairpin turn of the loop of Henle of juxtamedullary nephrons

Answer 6

The solute concentration of the filtrate is 1200 mosm at the hairpin turn

Question 7

Describe the solute concentration of the renal filtrate at the end of the loop of Henle of juxtamedullary nephrons

Answer 7

The solute concentration of the filtrate is 100 mosm at the top of the ascending limb where it becomes the distal convoluted tubule

Question 8

What is the resulting amount of concentration difference in the gradient from the cortex to the inner medulla?

Answer 8

about 900 millliosmoles

Question 9

What structure maintains the concentration gradient present in the renal medulla?

Answer 9

The vasa recta

Question 10

Describe how the vasa recta maintain the concentration gradient present in the renal medulla.

Answer 10

They contain hairpin loops and carry blood at a very slow rate.

The slow rate of blood enables them to passively interact with the surrounding interstitial fluid.

That is what maintains the gradient which has been established in the medullary interstitial space.

Question 11

Does ADH aid or inhibit urine output?

Answer 11

It inhibits urine output

Question 12

HOW does Antidiuretic hormone (ADH) inhibit urine output?

Answer 12

Antidiuretic hormone (ADH) inhibits urine output by increasing the number of channels in cells of the collecting ducts so that water passes easily into the surrounding interstitial space.

Question 13

What happens when ADH is not being released?

Answer 13

When ADH is not being released, even more dilute urine is excreted

Question 14

When ADH is released and the filtrate passes through the collecting ducts, the water rapidly leaves the filtrate through the channels opened by the hormone. This causes the osmolarity of the filtrate to become equal to that of the interstitial fluid, which could be as high as ______ mosm

Answer 14

1200 mosm

Question 15

Under what conditions and for what purpose is ADH released?

Answer 15

ADH is released in response to dehydration conditions (such as excessive water loss through sweating or diarrhea, or reduced blood volume or blood pressure or hemorrhage)

Question 16

When ADH is released, the body can retain up to ____% of the water in the filtrate

Answer 16

99%

Question 17

Describe the action of a diuretic

Answer 17

Diuretics cause a greater flow of urine and therefore increase urinary output.

Question 18

List the four mechanisms by which diuretics operate and a specific example of each of the four types.

Answer 18

1. Some like glucose cause osmotic reabsorption of water into the tubules.
2. Most diuretic drugs decrease Na+ ion reabsorption and therefore water reabsorption into the renal tubule filtrate.
3. Caffeine causes the renal tubules to increase in diameter which increases the flow of urine through the tubules.
4. Alcohol inhibits the release of ADH. All of these effects cause a greater flow of urine.

Question 19

What is the usual color of urine?

Answer 19

Urine is usually pale to deep yellow in color

Question 20

What causes the usual color of urine?

Answer 20

the presence of urochrome.

Question 21

Why does urine develop a stinging odor upon standing?

Answer 21

Urine develops a stinging odor upon standing because of bacterial breakdown of the urea to form ammonia.

Question 22

What is the normal pH range of urine?

Answer 22

The normal range of urine pH is 4.5 to 8.0

Question 23

How is the normal pH range of urine affected by a diet high in dairy or a diet high in protein?

Answer 23

A diet high in dairy causes a higher pH and a diet high in protein causes a lower pH.

Question 24

How is the normal density of urine affected by whether it is dilute or concentrated?

Answer 24

The density of urine will be higher if it is concentrated or lower if it is dilute.

Question 25

What are the two most abundant substances in urine?

Answer 25

The two most abundant substances in urine are water and urea

Question 26

What are the approximate concentrations in urine of water and urea?

Answer 26

water (~95%) and urea (~2%).

Question 27

Describe the structures within and arrangement of the ureter which prevents urine from flowing backward toward the kidney.

Answer 27

Ureters descend to the base of the bladder and contain sphincters where the ureter enters the bladder to prevent urine from flowing backward toward the kidney.

Question 28

Name the three layers that make up the wall of the ureter

Answer 28

inner lining
middle layer
outer layer

Question 29

What is the inner lining of the wall of the ureter made of?

Answer 29

the inner lining is made of transitional epithelium

Question 30

What is the middle layer of the wall of the ureter made of?

Answer 30

the middle layer is made of two sheets of muscle, one longitudinal and the other circular

Question 31

What is the outer layer of the wall of the ureter made of?

Answer 31

the outer layer is made of fibrous connective tissue

Question 32

Which layer within the wall of the ureter works to push urine through the ureter and how does it do it?

Answer 32

Contraction of the middle muscle layer causes it to contract and push the urine through the ureter.

Question 33

Give three words that describe the urinary bladder pouch

Answer 33

The urinary bladder is a:
hollow,
muscular,
elastic pouch

Question 34

What is the urinary bladder’s function?

Answer 34

it receives and stores urine

Question 35

Describe the location of the urinary bladder in males

Answer 35

In males, the base of the bladder lies in front of the rectum and just behind the pubic symphysis.

Question 36

Describe the location of the urinary bladder in males

Answer 36

In males, the base of the bladder lies in front of the rectum and just behind the pubic symphysis.

Question 37

What is the trigone?

Answer 37

The trigone is the smooth, triangular center region of the bladder the corners of which are occupied by the opening of the urethra and the ureters.

Question 38

Is the bladder a static size or is it very elastic?

Answer 38

It is very elastic

Question 39

What happens to the shape of the bladder when it is empty?

Answer 39

It collapses into its basic pyramidal shape when empty

Question 40

What happens to the shape of the bladder when as it is filled with urine?

Answer 40

As it is filled by urine, the bladder swells and becomes pear-shaped

Question 41

As it is filled by urine, does the bladder lower into the abdominal cavity or rise in the abdominal cavity?

Answer 41

It rises in the abdominal cavity.

Question 42

Describe the action of the muscular wall of the bladder in receiving and storing urine and whether or not the pressure rises.

Answer 42

The muscular wall stretches and thins allowing the bladder to store larger amounts of urine without a significant rise in internal pressure.

Question 43

Approximately how much urine does a moderately full bladder hold?

Answer 43

Approximately 500 ml

Question 44

If necessary, how much urine can the bladder store/hold?

Answer 44

1000 ml

Question 45

What does the urethra do and are it’s walls thin or thick?

Answer 45

The urethra is a thin-walled muscular tube that carries urine from the urinary bladder out of the body.

Question 46

What are the names of the two sphincters around the urethra that are near the bladder?

Answer 46

internal urethral sphincter

external urethral sphincter

Question 47

Is the internal urethral sphincter under voluntary or involuntary control and where is it located?

Answer 47

The involuntary-controlled internal urethral sphincter is located near the bladder.

Question 48

What does the internal urethral sphincter do?

Answer 48

It keeps the urethra closed to prevent urine from leaving the bladder.

Question 49

What type of muscle is the external urethral sphincter composed of?

Answer 49

skeletal muscle

Question 50

Where is it (at what point) does the external urethral sphincter surround the urethra?

Answer 50

The voluntary-controlled external urethral sphincter, composed of skeletal muscle, surrounds the urethra as it passes through the pelvic floor.

Question 51

Describe the difference in structure and function of the female and male urethra.

Answer 51

The female urethra is shorter and only used to carry urine while the male urethra is about 5 times longer and carries both urine and semen from the body.

Question 52

Define micturition

Answer 52

Micturition is urination or the act of emptying the bladder.

Question 53

How many ml of urine accumulation kicks off the urge to urinate start?

Answer 53

When about 200 ml of urine has accumulated and causes distension of the bladder walls.

Question 54

When 200 ml of urine has accumulated, what does the distension of the bladder walls trigger?

Answer 54

This causes:

1. the detrusor muscle (in the bladder wall) to contract

and

2. the internal sphincter to relax, forcing stored uring through the internal sphincter into the upper part of the urethra.

Question 55

Why is it easy for a person to resist this initial urge to urinate?

Answer 55

Because the external urethral sphincter is voluntarily controlled.

Question 56

What happens as the bladder continues to fill?

Answer 56

As the bladder continues to fill, the desire to urinate becomes stronger and harder to ignore and eventually, the bladder fills to the point where the urge to urinate becomes such that it can no longer be ignored.

Question 57

What happens if the amount of urine reaches 100% of the urinary bladder’s capacity?

Answer 57

If the amount of urine reaches 100% of the urinary bladder’s capacity, the voluntary sphincter becomes involuntary, and micturition occurs involuntarily.