Kidneys

Question 1

What substances are grater in concentration in urine than plasma?

Answer 1

K⁺
PO₄^3-

Urea

Creatinine

Question 2

What substances are greater in concentration in blood than urine?

Answer 2

HCO^3-

Glucose

Albumin

Question 3

Volume gain of body fluid is passed as?

Answer 3

Urine

Question 4

What is the kidneys’ response to high blood volume and pressure?

Answer 4

Excrete salts and water

ECF, ICF volume falls
BP drops

Question 5

What part of the brain is responsible for regulation of water balance?

Answer 5

Hypothalamus

Question 6

What are some effects of low water volume in the body?

Answer 6

Decreased blood volume

Decreased BP

High osmolarity

Question 7

Which part of which gland releases vasopressin/ADH?

Answer 7

Posterior pituitary

Question 8

What influences the production of vasopressin more, ECF volume or osmolarity?

Answer 8

Osmolarity

Question 9

Where does reabsorption occur along a kidney tubule?

Answer 9

From the proximal tubule onwards to the collecting duct

Question 10

Where along the nephron does secretion occur?

Answer 10

Proximal tubule

Distal tubule

Collecting duct

Question 11

Where does excretion occur along a nephron?

Answer 11

In the collecting duct

Question 12

What is the equation for the net solute excreted?

Answer 12

E=F-R+S

Question 13

What cells contract to alter filtration rate in glomerular capillaries?

Answer 13

Mesangial cells

Question 14

What processes surround glomerular capillaries to increase filtration rate?

Answer 14

Podocyte foot processes

Question 15

What is the order of filtration out of a glomerular capillary?

Answer 15

Fenestrated capillary, basal lamina, filtration slits

Question 16

What happens to GFR when the afferent arteriole is constricted?

Answer 16

Decreased

Question 17

What is the range of MAP for which autoregulation maintains a constant GFR?

Answer 17

80-180 mm Hg

Question 18

Tubuloglomerular feedback is an autoregulation system of GFR involving the macula densa cells in the distal tubule sensing increased flow and then releasing what to constrict the afferent/efferent arteriole?

Answer 18

A paracrine

Question 19

What are the units of clearance?

Answer 19

mL/min

Question 20

What is the equation for clearance?

Answer 20

Clearance (X)= Excretion rate (X) mg/min / [X] mg/ml

Question 21

What is the main transport process that occurs at the proximal tubule?

Answer 21

Bulk reabsorption

Question 22

Tubular reabsorption occurs in what two ways?

Answer 22

Transepithelial (active transport through cells)

Paracellular (between cells)

Question 23

In tubular reabsorption, Na⁺ is actively transported from the lumen to the ECF through the tubular epithelium. What pathway is this?

Answer 23

Transepithelial

Question 24

Anions cross the tubular epithelium after Na⁺ is actively transported to the ECF and then water follows. What are the last things to be reabsorbed and how?

Answer 24

Permeable solutes

Diffusion through membrane transporters

or through paracellular pathway

Question 25

In reabsorption in the proximal tubule, Na⁺ is transported down its electrochemical gradient from the lumen to the cell by _____ and then into the IS fluid by \_\_\_\_\_\_

Answer 25

ENaC Na⁺ K⁺ ATP-ase

Question 26

Glucose follows the Na⁺ path to reabsorption by what two proteins?

Answer 26

SGLT (lumen to epithelial cell) GLUT (epithelial cell to IS fluid)

Question 27

When K⁺ is pumped into the cell in exchange for Na⁺, how does it re-establish its concentration in the IS fluid?

Answer 27

Moving across a leak channel

Question 28

Renal threshold is the plasma concentration at which _____ occurs and the transport maximum is the transport rate at this point onwards

Answer 28

Saturation

Question 29

What is the normal range of plasma glucose?

Answer 29

100-200mg/100ml plasma

Question 30

When does glucose excretion begin?

Answer 30

When the renal threshold is reached (300mg/100ml plasma glucose)

Question 31

In potassium secretion in the **distal** nephron, K⁺ moves from the peritubular capillary, through the IS fluid and into the cell via _____ and then _____ through leak channels into the lumen

Answer 31

Na⁺ K⁺ ATP-ase diffuses

Question 32

In the **proximal** tubule, hydrogen is secreted into the lumen by exchange with ____ and combines with filtered HCO₃^- to make CO₂ which can diffuse into the cell. Inside the cell, CO₂ combines with water and carbonic anhydrase to form H⁺ and HCO₃^-. HCO₃^- is then reabsorbed along with ____ .

Answer 32

Na⁺ Na⁺

Question 33

In the collecting duct, H⁺ is secreted by moving from the ________ into the cell and then into the lumen while ____ and ____ are reabsorbed into the IS space

Answer 33

IS space K⁺ and HCO₃^-

Question 34

What two factors stimulate Granular cells in the afferent arteriole to produce renin?

Answer 34

Sympathetic activity from decreased blood pressure Paracrines from the macula densa from decreased GFR

Question 35

What is the function of renin?

Answer 35

Converts angiotensinogen (ANG) to ANG1

Question 36

What enzyme converts ANG1 to ANG2?

Answer 36

Angiotensin-converting enzyme (ACE)

Question 37

When there is a drop in BP, what parts of the brain does ANG 2 coordinate with?

Answer 37

Medulla oblongata (increase CV output) Hypothalamus (Increase ADH production and thirst) Adrenal cortex (increase Aldosterone production)

Question 38

What is the ultimate pupose of aldosterone and what cells does it act on??

Answer 38

Increase Na⁺ reabsorption and thus blood volume K⁺ secretion Principal cells in distal nephron

Question 39

Natriuretic peptides are released in response to _____ blood volume

Answer 39

incerased

Question 40

Nautriuretic peptides has the opposite effect of aldosterone in that it decreases ____ reabsorption and thus increases ____ excretion and decreases blood pressure.

Answer 40

Na⁺ Water (Also tells hypothalamus to produce less ADH and adrenal cortex to produce less aldosterone)

Question 41

Although aldosterone serves to increase Na⁺ reabsorption and thus water reabsorption, why is its release inhibited during severe dehydration?

Answer 41

Osmolarity is already extremely high Osmolarity must be kept in narrow range Do not want more Na⁺ uptake

Question 42

What is the sympathetic response to dehydration?

Answer 42

Constriction of afferent arteriole Lowers GFR and maintains blood volume

Question 43

In the descending loop of Henle, what is reabosrbed?

Answer 43

Water

Question 44

In the ascending loop of Henle, what is reabsorbed?

Answer 44

Ions

Question 45

For the countercurrent multiplier, what is the osmolarity gradient established by the ion pumps in the ascending loop of Henle?

Answer 45

200 mOsm

Question 46

Filtrate in the descending loop of Henle will equilibrate with the IS fluid by ____ moving out passively.

Answer 46

Water (IS fluid osmolarity does not change from this)

Question 47

What factors maintains the high osmolarity in the medulla interstitium of the kidney?

Answer 47

Urea (makes up almost 50% of solutes in medulla) Vasa recta/peritubular capillaries takes up water as well

Question 48

What is the first step in insertion of Aquaporin-2 channels into the apical membrane of the collecting duct from exocytosis of storage vesicles?

Answer 48

Vasopressin binds to surface receptor