Urinary System 2

Question 1

Filtration membrane:
Prevents blood cells and large proteins from passing

Answer 1

Fenestrated endothelium

Question 2

Filtration membrane: Blocks large, negatively charged ions

Answer 2

Basement membrane

Question 3

Filtration membrane: allow water, glucose, ions and small molecules to pass

Answer 3

Filtration slits

Question 4

Determines the direction and amount of filtrate produced

Answer 4

Net Filtration Pressure

Question 5

Normal NFP amount

Answer 5

10mmHg

Question 6

Formula for NFP

Answer 6

NFP = GBHP - (CHP + BCOP)

normal:
10 = 55 - (15 +30)

Question 7

Percentage of renal plasma flow that becomes filtrate

Answer 7

Filtration fraction - typically 16-20%

Question 8

The amount of filtrate formed per minute in all renal corpuscles, normally 105-120 mL/min.

Answer 8

Glomerular Filtration Rate (GFR)

Question 9

Importance of Maintaining GFR: Too high or too low

Answer 9

Too high: Needed substances may not be reabsorbed and are lost in urine.
Too low: Wastes are not adequately removed from blood.

Question 10

3 Modes for Regulation of GFR

Answer 10

1. Renal autoregulation
2. Neural regulation
3. Hormonal regulation

Question 11

Adjusts blood flow locally via the myogenic mechanism and tubuloglomerular feedback.

Answer 11

Renal autoregulation

Question 12

Sympathetic nervous system adjusts GFR, especially in emergencies.

Answer 12

Neural regulation

Question 13

Involves Angiotensin II and Atrial Natriuretic Peptide (ANP).

Answer 13

Hormonal regulation

Question 14

Movement of solutes and water from renal tubules back into the blood (peritubular capillaries or vasa recta).

Answer 14

Reabsorption

Question 15

Transfer of substances (wastes, toxins, excess ions) from blood into the tubules for excretion

Answer 15

Secretion

Question 16

Reabsorption dominates:
100% of glucose and amino acids.
65% of water, sodium, potassium.
85-90% of bicarbonate (HCO₃⁻).

Answer 16

Proximal Convoluted Tubule (PCT):

Question 17

Reabsorbs 15% of water (permeable to water, but not solutes).

Answer 17

Nephron Loop Descending limb

Question 18

Reabsorbs Na⁺, K⁺, Cl⁻ through active transport.

Answer 18

Nephron Loop Ascending limb

Question 19

Reabsorbs Ca²⁺ (regulated by PTH).
Reabsorbs small amounts of water, Na⁺, and Cl⁻.

Answer 19

Early DCT

Question 20

Final adjustments depend on body needs:
Principal cells: Reabsorb Na⁺ and water (regulated by aldosterone and ADH).
Intercalated cells: Regulate pH by secreting H⁺ or reabsorbing bicarbonate (HCO₃⁻).
Secrete urea and K⁺.

Answer 20

Late DCT and Collecting Duct

Question 21

Increases water reabsorption by stimulating aquaporins in collecting ducts.

Answer 21

Antidiuretic Hormone (ADH)

Question 22

Increases Na⁺ reabsorption and K⁺ secretion.

Answer 22

Aldosterone

Question 23

Increases Ca²⁺ reabsorption in the early DCT.

Answer 23

Parathyroid Hormone (PTH):

Question 24

Inhibits Na⁺ reabsorption, leading to more water and Na⁺ excretion.

Answer 24

Atrial Natriuretic Peptide (ANP)

Question 25

Two Types of Water Reabsorption

• Occurs in the DCT and collecting tubule.
• Allows precise control of water reabsorption by ADH.
• Adjusts urine volume by reabsorbing a portion (or all) of the remaining 15% of filtrate volume.

Answer 25

Facultative Water Reabsorption

Question 26

• Normal volume: Approximately 1200 mL/day.
• Normal osmotic concentration: 600 - 1500 mOsm/L.
• Values differ from person to person and from day to day as the kidneys alter their function to maintain homeostasis.

Answer 26

Normal Urine

Question 27

Dilute urine is produced in the absence of

Answer 27

ADH

Question 28

Concentrated urine is produced in the presence of

Answer 28

ADH.

Question 29

A mechanism in the nephron loop of juxtamedullary nephrons that allows the kidneys to produce concentrated urine.

Answer 29

Countercurrent Multiplication System:

Question 30

secrete renin when:

There is intrarenal artery hypotension (low blood flow through kidneys).

Answer 30

Juxtaglomerular cells

Question 31

activates angiotensinogen (from liver) into angiotensin I (AGI).

Answer 31

Renin

Question 32

converts angiotensin I (AGI) into angiotensin II (AGII).

Answer 32

ACE

Question 33

Vasoconstrictor that decreases GFR by constricting afferent arterioles.

Answer 33

Angiotensin II:

Question 34

Acts on principal cells to increase reabsorption of Na+, Cl-, and H₂O, thereby increasing blood volume and pressure.

Answer 34

Aldosterone:

Question 35

released by the posterior pituitary

Answer 35

Antidiuretic Hormone (ADH)

Question 36

secreted by atrial cells in the heart when blood in the atria stretch the walls

Answer 36

Atrial Natriuretic Peptide (ANP):

Question 37

secreted by the parathyroid glands when blood Ca²⁺ levels are low.

Answer 37

Parathyroid Hormone (PTH):

Question 38

secreted by the parafollicular cells (C cells) of the thyroid gland when blood Ca²⁺ levels are high.

Answer 38

Calcitonin