Introduction to the Kidney

Question 1

List 4 functions of the kidneys.

Answer 1

1. Excretion of metabolic waste and toxins
2. Regulation of body fluid volume
3. Regulation of body fluid composition
4. Endocrine functions

Question 2

What are the key processes of the kidneys?

Answer 2

• Filtration
• Reabsorption
• Secretion

Question 3

What are the 5 types of tissue in the human body?

Answer 3

1. Blood
2. Nervous tissue
3. Muscle tissue
4. Epithelial tissue
5. Connective tissue

Question 4

What are the components of the uriniferous tubules of the kidney?

Answer 4

Nephron + Collecting duct.

Question 5

What is a nephron?

Answer 5

The functional unit of the kidney.

Question 6

How many nephrons are there per kidney?

Answer 6

1 million.

Question 7

In the kidney are there more nephrons or collecting ducts? How do you know this?

Answer 7

More nephrons, because multiple nephrons drain into the same collecting duct.

Question 8

Which terms are used to describe the locations of nephrons? What is this dependent on? What percentage of nephrons belong to each group?

Answer 8

• Cortical (80%)
• Juxtamedullary (20%)

Dependent on the position of the renal corpuscle.

Question 9

What are the 4 components of a nephron?

Answer 9

1. Renal corpuscle
2. Proximal convoluted tubule
3. Loop of Henle
4. Distal convoluted tubule

Question 10

What are the components of the renal corpuscle?

Answer 10

Glomerulus + Bowman’s capsule.

Question 11

Describe the arterial supply to the kidney starting from the renal artery.

Answer 11

Renal artery - Segmental arteries - Interlobar arteries - Arcuate arteries - Interlobular arteries.

Question 12

Describe the location of the Arcuate arteries.

Answer 12

Run along the corticomedullary junction.

Question 13

What do the interlobular arteries give off and to what?

Answer 13

Give off afferent arterioles to the renal corpuscles.

Question 14

Describe the two capillary beds of the nephrons in terms of their pressure, location, and function.

Answer 14

• High pressure glomerular capillaries - filtration.

- Low pressure peritubular capillaries - reabsorption / secretion.

Question 15

What is the function of the outer parietal layer of Bowman’s capsule and what is the epithelium?

Answer 15

Containment - simple squamous.

Question 16

What is the function of the inner visceral layer of Bowman’s capsule and what is the epithelium?

Answer 16

Filtration - modified simple squamous (Podocytes).

Question 17

Which cells are found between the glomerular capillary loops and what is their function?

Answer 17

Mesangial cells - provide support.

Question 18

What makes up the filtration barrier of the glomerulus?

Answer 18

1. Glomerular capillary endothelium (fenestrated)
2. Basement membrane (negative charge)
3. Epithelial cells (podocytes)(interdigitating foot processes & filtration slits)

Question 19

The glomerular filtration barrier limits the passage of substances based on their what?

Answer 19

Size, charge, and shape.

Question 20

In nephrons, where does the majority of water, sodium, chloride, amino acids, and glucose reabsorption take place?

Answer 20

Proximal convoluted tubule

Question 21

What is the epithelium of the Proximal convoluted tubule?

Answer 21

Simple cuboidal with microvilli.

Question 22

What parts can the Loop of Henle be divided into?

Answer 22

1. Thin descending limb
2. Thin ascending limb
3. Thick ascending limb

Question 23

Describe the thin descending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.

Answer 23

• Permeable to water
• No active reabsorption or secretion of solutes
• Simple squamous

Question 24

Describe the thin ascending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.

Answer 24

• Impermeable to water
• Essentially no active reabsorption or secretion of solutes
• Simple squamous

Question 25

Describe the thick ascending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.

Answer 25

- Impermeable to water - Active reabsorption of sodium and other solutes - Simple cuboidal

Question 26

What is the net effect of the Loop of Henle? What is this important in?

Answer 26

To generate a hyperosmolar interstitium in the medulla, which is important in the concentration of urine.

Question 27

What is the epithelium of the distal convoluted tubule?

Answer 27

Simple cuboidal

Question 28

What forms the juxtaglomerular apparatus?

Answer 28

The early part of the distal convoluted tubule passing back to the vascular pole of its own renal corpuscle.

Question 29

Is there active reabsorption and secretion in the distal convoluted tubule?

Answer 29

Yes

Question 30

What is the water permeability of the distal convoluted tubule dependent on?

Answer 30

The precise part of the distal tubule and the presence of antidiuretic hormone (ADH).

Question 31

What are the three components of the Juxtaglomerular Apparatus?

Answer 31

1. Macula dense cells 2. Extraglomerular mesangial cells (Lacis cells) 3. Granular or juxtaglomerular cells in the afferent arteriole

Question 32

Describe the water permeability of the collecting duct.

Answer 32

It is under hormonal control by antidiuretic hormone (ADH).

Question 33

Which arteries give off afferent arterioles to the renal corpuscles?

Answer 33

Interlobular arteries

Question 34

What are the main components of extracellular fluid?

Answer 34

1. Interstitial fluid | 2. Plasma

Question 35

The plasma and interstitial fluid have similar compositions apart from what?

Answer 35

Apart from proteins - which remain in the plasma.

Question 36

What is the main cation and anion in ECF?

Answer 36

- Sodium is the main cation. | - Chloride is the main anion.

Question 37

What is the main cation and anion in ICF?

Answer 37

- Potassium is the main cation | - Phosphate is the main anion

Question 38

What is the approximate osmolarity of bodily fluids?

Answer 38

280-300 mOsm/L.