Urinary System

Question 1

Which organs are part of the urinary system?

Answer 1

• kidneys
• ureters
• urinary bladder
• urethra

Question 2

Describe the shape and location of the kidneys.

Answer 2

• small fist-sized organs located within the abdominal cavity on either side of the midline between the levels of ~T12-L3

Question 3

Why are the kidneys surrounded by connective and adipose tissue?

Answer 3

• to protect and anchor them in place

Question 4

What percentage of cardiac output do the kidneys receive?

Answer 4

• normally receive 20-25% of the resting cardiac output

Question 5

What are the names of the areas of the kidney?

Answer 5

• renal cortex (outside)
• renal medulla (inside - renal pyramids)
• renal hilum

Question 6

What is the renal hilum and entry or exit point for?

Answer 6

• ureter
• renal blood vessels
• nerves and lymphatic vessels

Question 7

How many nephrons extend through the renal cortex and renal pyramids of each kidney?

Answer 7

• 1,000,000

Question 8

What is a nephron?

Answer 8

• the functional units of the kidney

Question 9

Describe the composition of a nephron.

Answer 9

• each nephron is composed of a renal corpuscle and renal tubule

Question 10

What does the renal corpuscle do?

Answer 10

• glomerulus (capillary network) that is surrounded by a glomerular (Bowman’s) capsule
• filters the blood in the glomerulus and deposits the filtered fluid (“filtrate”) into the renal tubule

Question 11

Describe the function of the renal tubule.

Answer 11

• divided into a proximal convoluted tubule, loop of Henle, and distal convoluted tubule
• each section (as well as the adjoining collecting duct) adjusts the concentration and composition of the filtrate
• the end product is called urine

Question 12

What are afferent arterioles?

Answer 12

• each gives rise to a glomerulus that enters a nephron’s glomerular capsule

Question 13

What are efferent arterioles?

Answer 13

• exit the glomerular capsule and branch into peritubular capillaries that surround the tubular portion of the nephron

Question 14

Describe glomerular filtration.

Answer 14

• the movement of water and solutes from the glomerular capillary into the glomerular capsule
• the amount of filtrate that is formed (“glomerular filtration rate”) is regulated by neural
  and hormonal mechanisms as well as by the kidney itself (“renal autoregulation”)

Question 15

Describe tubular reabsorption.

Answer 15

• the movement of water and solutes from the tubule back into the peritubular capillaries
• most tubular reabsorption occurs in the proximal convoluted tubule, which reabsorbs all of the filtered nutrients (e.g., glucose, amino acids) and most of the filtered water and ions

Question 16

Describe tubular secretion.

Answer 16

• the movement of certain substances (e.g., H+, wastes, drugs) from the peritubular
  capillaries into the tubule and collecting duct
• most tubular secretion occurs in the proximal convoluted tubule

Question 17

What are some hormones that regulate tubular

reabsorption and secretion?

Answer 17

• Antidiuretic Hormone
• Parathyroid Hormone
• Aldosterone

Question 18

What does the Antidiuretic Hormone do?

Answer 18

• increases H20 reabsorption

Question 19

What does the Parathyroid Hormone do?

Answer 19

• increases Ca++ reabsorption

Question 20

What does Aldosterone do?

Answer 20

• increases Na+/H20 reabsorption (🡩BP)

- increases H+ secretion (acid-base balance)

Question 21

What are diuretics?

Answer 21

• substances that lead to decreased reabsorption of H2O and therefore increased urine production

Question 22

From the collecting ducts, urine drains into a series of progressively larger ducts. What are they called?

Answer 22

• papillary duct
• minor calyx
• major calyx

Question 23

How long are ureters?

Answer 23

• 25-30 cm long

Question 24

What is the function of the ureters?

Answer 24

• transport urine from the kidneys to the urinary bladder

- transport urine from the kidneys to the urinary bladder

Question 25

Where is the urinary bladder located?

Answer 25

• in the pelvic cavity between the pubic symphysis (anteriorly) and rectum/vagina (posteriorly)

Question 26

Why is the bladder wall is highly folded?

Answer 26

• smooth muscles

- allows the bladder to expand

Question 27

How many openings are there in the bladder wall?

Answer 27

• uretral openings (2 posterior) – ureters

- internal urethral orifice (anterior) – urethra

Question 28

Describe the internal urethral sphincter.

Answer 28

• smooth muscle sphincter around the internal urethral orifice (involuntary)

Question 29

Describe the external urethral sphincter.

Answer 29

- skeletal muscle sphincter within the muscles of
the perineum (voluntary)

Question 30

What is the urethra?

Answer 30

• small tube leading from the internal urethral orifice to the external environment (external urethral orifice)

Question 31

What are the functions of the urinary system?

Answer 31

• eliminates wastes (urine)
• regulates blood ionic composition
• regulates blood volume and blood pressure
• regulates the acid-base balance of the body
• secretes erythropoietin (EPO), which stimulates the production of RBCs in
  red bone marrow
• produces the active form of vitamin D