Quiz & Worksheet - Organs of the Urinary System | Study.com - Free Printable

Let's go through each question in the worksheet and solve them step by step with explanations.

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Question 1:

In a healthy individual, how much glucose should be in the urine by the time it reaches the urinary bladder?

Options:
a. 10 ng/microliter
b. 100 ng/microliter
c. 100 milligram/microliter
d. 0

✔ Correct Answer: d. 0

Explanation:
In a healthy person, the kidneys filter blood and reabsorb all the glucose from the filtrate back into the bloodstream. This happens primarily in the proximal convoluted tubule of the nephron. The renal threshold for glucose is around 180 mg/dL; below this level, all glucose is reabsorbed. Therefore, normal urine contains no glucose (i.e., glucose concentration is zero). Glucosuria (glucose in urine) occurs only when blood glucose levels exceed the renal threshold, such as in uncontrolled diabetes mellitus.

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Question 2:

In this diagram, which urinary organs are in the retroperitoneal space?

Options:
a. Kidneys
b. Ureters
c. Urinary bladder
d. Urethra

✔ Correct Answer: a. Kidneys

Explanation:
The retroperitoneal space is the area behind the peritoneum (the membrane lining the abdominal cavity). Organs that are retroperitoneal are partially or fully surrounded by the peritoneum on their anterior side but are not suspended within the peritoneal cavity.

- Kidneys → Retroperitoneal (they lie behind the peritoneum)
- Ureters → Also retroperitoneal, but they are often considered part of the urinary tract extending from kidney to bladder.
- Urinary bladder → Intraperitoneal at first, then becomes extraperitoneal as it fills — but generally classified as extraperitoneal (not retroperitoneal).
- Urethra → Not retroperitoneal; it’s located outside the peritoneal cavity.

However, among the choices listed, kidneys are the most clearly and definitively retroperitoneal organs. While ureters also run in the retroperitoneal space, they are not typically classified as “organs” in the same way. But since both kidneys and ureters are retroperitoneal, let’s check what is expected here.

But based on standard anatomy:

> ✔ Best answer: a. Kidneys
> (Kidneys are the primary retroperitoneal organs of the urinary system.)

Some sources may say ureters are also retroperitoneal, but kidneys are the main retroperitoneal organs. If multiple answers were allowed, both a and b might be correct. But since it's single-choice and asking "which urinary organs," the most accurate and commonly accepted answer is the kidneys.

So:
✔ Answer: a. Kidneys

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Question 3:

Which enzyme, produced by the kidneys, is the initiating enzyme that starts a cascade of reactions that produce substances in the body that regulate blood pressure?

Options:
a. Renin
b. Aldosterone
c. Angiotensin I
d. Angiotensin II

✔ Correct Answer: a. Renin

Explanation:
The renin-angiotensin-aldosterone system (RAAS) is a key hormonal system regulating blood pressure and fluid balance.

- Renin is an enzyme secreted by the juxtaglomerular cells in the kidneys (specifically in the afferent arterioles) in response to low blood pressure, low sodium, or sympathetic nervous system activation.
- Renin converts angiotensinogen (from the liver) into angiotensin I.
- Then, ACE (angiotensin-converting enzyme) converts angiotensin I into angiotensin II, a potent vasoconstrictor.
- Angiotensin II increases blood pressure by:
- Constricting blood vessels
- Stimulating aldosterone release (from adrenal glands), which increases sodium and water reabsorption in the kidneys
- Increasing ADH release and thirst

So, renin is the initiating enzyme in this cascade.

> ✘ Aldosterone – hormone, not an enzyme, produced by adrenal cortex
> ✘ Angiotensin I – intermediate product, not an enzyme
> ✘ Angiotensin II – final active peptide, not an enzyme

✔ Answer: a. Renin

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✔ Final Answers:

1. d. 0
2. a. Kidneys
3. a. Renin

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