(F) L4: Renal Function (Part 1: Introduction)

Question 1

• Paired bean-shaped organs located retroperitoneally on either side of the spinal column below the ribcage
• Is 4-5 inches in length, 2-3 inches in width, and 3 inches thick
• Is divided into a cortex and medulla with an outer renal capsule layer

Answer 1

Kidneys

Question 2

Recall the 3 main urine waste products (no choices, recall NPNs in CC):
1. From protein metabolism (ammonia first, then this)
2. From muscle metabolism (a marker for GFR)
3. From purine metabolism

Answer 2

1. Urea
2. Creatinine
3. Uric Acid

Question 3

If NPNs are (elevated/decreased) in blood, one possibility is because of kidney disease

Answer 3

Elevated

Question 4

• Aka vasopressin
• Purpose: For water absorption

Answer 4

Antidiuretic Hormone (ADH)

Question 5

Antidiuretic Hormone (ADH)

Hypothalamus vs. Posterior Pituitary Gland
1. Which endocrine gland synthesizes ADH?
2. Which endocrine gland released/secretes ADH?

Answer 5

1. Synthesis - Hypothalamus
2. Release/Secretion - Posterior Pituitary

Recall in Anaphy/Histo that the pituitary merely STORES hormones produced by the hypothalamus until they are needed

Question 6

Antidiuretic Hormone (ADH)

The posterior pituitary releases ADH whenever blood volume is (increased/decreased) while blood osmolality is (increased/decreased)

Answer 6

Blood volume: Decreased
Blood osmolality: Increased

Question 7

Antidiuretic Hormone (ADH)

ADH promotes water reabsorption which makes what part of the kidney more permeable to water?

Answer 7

Distal Convoluted Tubules (DCT)

Question 8

Antidiuretic Hormone (ADH)

A deficiency of ADH causes what disease?

Answer 8

Diabetes Insipidus (increased frequency of urination)

Question 9

These 3 electrolytes may be secreted or absorbed depending on the hormones present (e.g. aldosterone)

Note: Where sodium goes, water follows

Answer 9

1. Sodium (Na+)
2. Potassium (K+)
3. Chlorine (Cl-)

Question 10

Aside from sodium, potassium, and chlorine, what are the other 3 electrolytes in the blood?

Answer 10

1. Phosphate
2. Calcium
3. Magnesium

Question 11

What 2 organs are responsible for the maintenance of the acid-base balance?

Answer 11

1. Kidneys
2. Lungs

Question 12

The kidneys maintain the acid-base balance by reabsorbing (blank) and excreting (blank)

Answer 12

1. Reabsorption of bicarbonate
2. Excretion of acids (hydrogen ions)

Question 13

Endocrine Functions

• Is released when BP and/or sodium is low
• There is a vasoconstriction and regulation of osmolarity
• Part of the RAAS and produced by the juxtaglomerular apparatus
• This decreases blood volume

Answer 13

Renin

Question 14

Endocrine Functions

• Is secreted to stimulate the production of RBCs
• There is a chance of acquiring anemia secondary to chronic kidney disease because of the affected production of this hormone
• Can cause hypoxia and anemia

Answer 14

Erythropoietin (EPO)

Question 15

Endocrine Functions

• Aka Calcitriol (active vitamin D)
• Increased blood calcium levels

Answer 15

1,25-dihydroxy vitamin D3

Question 16

Endocrine Functions

• A vasodilator
• Increases permeability, renal blood flow, sodium and H2O secretion and release of renin

Answer 16

Prostaglandins

Question 17

• The basic functional unit of the kidney
• Around 1 to 1.5 million of these per kidney
• Has a glomerulus, renal tubules, and collecting ducts

Answer 17

Nephron

Question 18

What is the number 1 requirement in order to filter metabolic waste products for urine formation?

Answer 18

Renal blood flow

Question 19

Familiarize with the general renal blood flow

Answer 19

1. Renal artery
2. Afferent arteriole
3. Glomerulus
4. Efferent arteriole
5. Peritubular capillaries
6. Vasa recta
7. Renal vein

RAGE-PVR

Question 20

Give the corresponding values for urine formation:
1. Cardiac output in percent?
2. Renal blood flow in mL/min.?
3. Renal plasma flow in mL/min.?
4. Renal filtrate in mL?

A. 600-700
B. 21-25
C. 1,200
D. 130

Answer 20

1. Cardiac: 21-25%
2. Blood flow: 1,200 mL/min.
3. Plasma flow: 600-700 mL/min.
4. Renal filtrate: 130 mL/min.

Question 21

Give the 3 major steps of urine formation

Answer 21

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

Question 22

Filtration

This acts as a non-selective sieve/filter

Answer 22

Glomerulus

Question 23

Filtration

• Aka basal lamina
• Substances with a MW of < 70k (or 66k) can pass through this
• Cells and large molecules are not able to pass here

Answer 23

Glomerular Basement Membrane

Question 24

Filtration

Passage through the GBM, possible or not?
1. Water, Glucose, Amino Acids, Low MW proteins, and Waste products (creatinine and urea)
2. Cells, plasma proteins, and conjugated proteins (lipoproteins and bilirubin)
3. Albumin

Answer 24

1. Possible
2. Not possible
3. Not possible

Question 25

# Filtration Albumin cannot pass through the GBM despite its MW being only 69k because the glomerulus has what?

Answer 25

Shield of negativity (will only pass through if the glomerulus is damaged) | Note: Albumin is (-) charged; like signs repel

Question 26

# Reabsorption - This receives the glomerular filtrate - The major site of reabsorption of important substances

Answer 26

Proximal Convoluted Tubule (PCT)

Question 27

# Reabsorption (important substances) - Reabsorbed by BOTH PCT and DCT - Aldosterone is responsible for regulating this substance

Answer 27

Sodium (Na+)

Question 28

# Reabsorption (important substances) - Reabsorbed by the PCT, DCT, and Collecting Ducts - This gets reabsorbed because of ADH/vasopressin (effective towards the collecting duct)

Answer 28

Water

Question 29

# Reabsorption (important substances) - Has a threshold of 180 mg/dL - Once it surpasses the threshold, it will now be present in the urine

Answer 29

Glucose

Question 30

# Reabsorption (important substances) Is not commonly used anymore for Clearance Tests because of the tendency of tubules to reabsorb it

Answer 30

Urea

Question 31

# Reabsorption Reabsorbed by BOTH PCT and DCT A. Water B. Sodium C. Both D. Neither

Answer 31

C. Both

Question 32

# Reabsorption Reabsorbed by the collecting duct only A. Water B. Sodium C. Both D. Neither

Answer 32

A. Water

Question 33

# Reabsorption This portion regulates the osmolarity of the interstitial fluid from the renal medulla

Answer 33

Loop of Henle

Question 34

# Reabsorption (Loop of Henle: Countercurrent Multiplier System) - Impermeable to water - Sodium (Na+) and Chloride (Cl-) are reabsorbed

Answer 34

Ascending

Question 35

# Reabsorption (Loop of Henle: Countercurrent Multiplier System) Highly reabsorbs water (passive movement)

Answer 35

Descending

Question 36

# Secretion - The major site of secretion - Able to eliminate waste products such as creatinine and urea - Regulates sodium and potassium and releases vasopressin

Answer 36

Distal Convoluted Tubule (DCT)

Question 37

# Secretion What are the 3 secreted hydrogen ions for acid-base balance?

Answer 37

1. Ammonium ions 2. Dihydrogen phosphate 3. Weak organic acids | Specimen: Urine

Question 38

# Secretion The final site of urine concentration and/or dilution

Answer 38

Collecting Ducts

Question 39

# Secretion Aldosterone, RAAS, and ADH act on what 2 parts of the kidney?

Answer 39

1. Distal convoluted tubule (DCT) 2. Collecting duct

Question 40

Familiarize yourself with the pathway of urine formation

Answer 40

1. Kidneys 2. Renal pelvis 3. Ureter 4. Urinary bladder 5. Urethra 6. Excretion

Question 41

Glomerular Filtration (can be filtered) A. Cells B. Large Molecules C. Both D. Neither

Answer 41

D. Neither (these CANNOT be filtered)

Question 42

Tubular Reabsorption A. Distal Convoluted Tubule B. Loop of Henle C. Both D. Neither

Answer 42

B. Loop of Henle (the DCT is for tubular secretion, PCT is for reabsorption)

Question 43

Tubular Reabsorption A. Countercurrent Multiplier System B. Amino acids and Vitamins C. Both D. Neither

Answer 43

C. Both

Question 44

Loop of Henle: Countercurrent Multiplier System (Ascending) A. Permeable to water B. Potassium is reabsorbed C. Both D. Neither

Answer 44

D. Neither (is IMPERMEABLE to water and it is SODIUM and CHLORINE that get reabsorbed)

Question 45

Loop of Henle: Countercurrent Multiplier System (Descending) A. Passive reabsorption of water B. Active reabsorption of water C. Both D. Neither

Answer 45

A. Passive only

Question 46

Tubular Secretion A. Distal Convoluted Tubule B. Waste product recycling C. Both D. Neither

Answer 46

A. DCT only (waste products are to be eliminated, not recirculated back to the system)