Kidneys

Question 1

How do the kidneys function to contribute to homeostasis?

Answer 1

• excretion of metabolic waste products (urea, uric acid, creatinine)
• elimination of foreign substances (toxins)
• regulation of body water (volume and osmolarity)
• mainenance of extracellular fluid volume
• regulation of salts to be retained or excreted (electrolytes)
• control of acid-base balance (maintains serum pH)

Question 2

The kidneys also function as endocrine organs because they:

Answer 2

• Synthesize and secrete erythropoietin (EPO), a growth factor regulating RBC formation in the bone marrow
• -Synthesize and secrete renin, hormone involved in the control of blood pressure and blood volume
• -Hydroxylate a precursor to vitamin D, to produce its active form

Question 3

What are the three physiological processes involved in the formation of urine?

Answer 3

1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion

Question 4

In 24 hours, how much fluid (L) is filtered by the kidneys and how many liters of urine are produced?

Answer 4

Approximately 180L are filtered, but only 1-2 liters of urine are produced.

Question 5

Identify the parts of the kidney:

cortex, medulla

renal sinus, renal pelvis

renal pyramid

renal column

renal papilla

major/minor calyx

Answer 5

Question 6

What are the functional units of the renal parenchyma? and how many of the units per kidney?

Answer 6

uriniferous tubules

about 1.5-2 million per kidney

Question 7

Name the functionally distinct parts of the uriniferous tubules.

Answer 7

1. The nephron
2. Collecting tubules and collecting duct system

Question 8

What is a nephron and what are its two main components?

Answer 8

• a part spherical-part tubular structure, where a filtrate of the blood is first formed and then transported into a twisted ductal system where material is resorbed and secreted.
• Two parts
• 1) the renal corpuscle: beginning of the nephron
• 2) the renal tubular system: represents the various tubular segments (NOT the same ase the collecting duct system (different embryologic derivation))

Question 9

What occurs in the collecting tubules and collecting duct system?

Answer 9

absorption of water and other compounds takes place to produce a hypertonic urine