Renal Function

Question 1

What is the structure of the kidney from superficial to deep?

Answer 1

cortex–>medulla–>renal pelvis

Question 2

What collects in the renal pelvis?

Answer 2

urine that is not futher modified once it reaches the renal pelvis

Question 3

What is a nephron?

Answer 3

a “mini-kidney”

functional unit of the kidney

Question 4

What 2 surfaces make up the epithelial cells?

Answer 4

the luminal surface, closest to the lumen,
sometimes called the apical surface!
- the basolateral surface, closest to capillaries in
interstitium!

Question 5

What is the private blood supply of the nephron?

Answer 5

the afferent arteriole that forms tufts of capillaries called the glomerulus in Bowman’s capsule

Question 6

How much of plasma filters out into Bowmans capsule?

Answer 6

about 20%

Question 7

How does the remaining 80% exit the nephron?

Answer 7

by the efferent arteriole that can break into a capillary network surrounding the tubule called the peritubular capillary network

Question 8

Where are the glomeruli found?

Answer 8

in the cortex of the kidney

Question 9

Where do the collecting ducts run to empty?

Answer 9

they run through the medulla and empty into the renal pelvis

Question 10

3 processes that the kidney performs to maintain homeostatis

Answer 10

filtration
reabsorption
secretion

Question 11

What is tubular secretion?

Answer 11

this is an active process involving ATP by which the kidneys add solute to tubular fluid from the
peritubular capillary network
drugs and toxins are removed from the blood this way

Question 12

What is tubular reabsorption?

Answer 12

this is the movement of water and solute from
tubular fluid back into peritubular capillaries!
• this is the major process of modification of
tubular fluid
dependent on active transport
uses energy to drive Na+/K+ ATPase

Question 13

difference between systemic and renal capillaries

Answer 13

systemic capillaries filter 3-4 liters per day as
compared to renal capillaries at 180 liters per day!
renal capillaries also have a large hydrostatic pressure that remains high along the capillary

Question 14

describe glomerular capillaries

Answer 14

they are leaky
everything that is in the capillary except cells and proteins can get out of
capillary into Bowman’s space

Question 15

What happens to GFR if plasma creatinine is increasing?

Answer 15

GFR must be decreasing

Question 16

What happens if the sodium/potassium pump is shut down?

Answer 16

the kidneys ability to reabsorb solute will also be shut down

Question 17

When can glucose appear in the urine?

Answer 17

if the transport maximum is reached ( when concentration is 250 mg/dl)

Question 18

What solutes are secreted?

Answer 18

H+
K+
drugs
toxins

Question 19

What cells initiate absorption or secretion?

Answer 19

kidney tubular cells

Question 20

How much does the proximal nephron reabsorb?

Answer 20

67% of all filtered solutes and water except glucose, AA and bicarbonate

Question 21

How is the loop of henle(LOH) different from bowmans space?

Answer 21

its fluid lacks glucose and AA

Question 22

what is preferential solute reabsorption?

Answer 22

more solute than water is being reabsorbed

This is a property of the loop of Henle

Question 23

What is the homeostatic segment of the nephron?

Answer 23

the distal nephron

Question 24

Ascending limb of the LOH

Answer 24

impermeable to water

Question 25

Descending limb of LOH

Answer 25

permeable to both salt and water

Question 26

State of anti-diuresis (water conservation)

Answer 26

large gradient
285 mOsm in cortex to 1200
mOsm in medulla

Question 27

state of diuresis (excess water consumption)

Answer 27

small gradient

285 to 425 Osm

Question 28

role of ADH (vasopressin) in water conservation

Answer 28

antidiuretic hormone (ADH) or vasopressin is the hormone
that homeostatically regulates distal nephron water
reabsorption

Question 29

how is osmolarity monitored?

Answer 29

osmolarity is the monitored variable via osmo-receptors in the
hypothalamus

Question 30

role of aldosterone

Answer 30

aldosterone is the hormone that controls distal nephron

sodium reabsorption

Question 31

renin-angiotension- aldosterone pathway

Answer 31

increased activate or renal sympathetic nerves!
- decreased arterial pressure!
- decreased GFR, which causes decreased flow to macula
densa and a subsequent decrease in NaCl concentration in
the macula densa !
- renin is an enzyme that converts angiotensinogen to
angiotensin I!
- angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II!
- angiotensin II stimulates aldosterone secretion by the adrenals!
- aldosterone increases sodium reabsorption from the distal nephron!
- water follows passively, resulting in an increase in volume

Question 32

How does the renal system function to regulate extracellular fluid volume?

Answer 32

by controlling the amount of ingested NaCl that is retained rather than excreted