Physiology Test 2 - Renal System

Front 1

What are the (8) major functions of the kidneys?

Back 1

• (Ultra)filtration of the blood
• (Re)absorption – CONSERVATION
• Secretion
o From NON-GLOMERULAR blood into tubule
• Electrolyte & Water Balance
o Moving solutes achieves BOTH
• Excretion
• Acid-base balance – MAJOR
• Hormone production & regulation
o Local & systemic effects
• Regulation of BOTH intrarenal AND systemic arterial pressure

Front 2

What are the distinguishing characteristics of the PTCN?

Back 2

 Mid/upper cortex glomeruli
 Lie in CORTEX around PCT & DCT
 Carry LOTS of blood

Front 3

What are the distinguishing characteristics of the vasa rectae?

Back 3

 ONLY juxtamedullary glomeruli (near the junction)
 Lie in MEDULLA around NL and CD
 Carry A LITTE blood

Front 4

What type of innervation do the kidneys receive?

Back 4

• Autonomic – SYMPATHETIC ONLY
o Splachnic nn  vasoconstriction
• Efferent
o INCREASE systemic blood pressure
• Afferent
o Specialized baroreceptors & chemoreceptors for BP regulation

Front 5

What is the nephron? what is it composed of?

Back 5

the FUNCTIONAL unit of the kidney

glomerulus w/ arterioles + renal tuble + collectiing duct

Front 6

What is the glomerulus and what does it do?

Back 6

tuft of capillaries

INITIATES formation of the filtrate

Front 7

What are the renal tubule segments, in order?

Back 7

urinary capsule, PCT, NL, DCT, CD

Front 8

What is the urinary corpuscle? what is it composed of?

Back 8

the FILTRATION unit

glomerulus + urinary capsule

Front 9

What are the 2 main functions of the PCT?

Back 9

absorption and secretion

Front 10

what are the 3 parts of the nephric loop?

Back 10

descending thin, ascending thin, ascending thick

Front 11

What is the main function of the "unspecialized" portion of the DCT? What is the "specialized" portion called and what is its function?

Back 11

fine tuning & continued dilution

macula densa - regulation of GFR & systemic BP

Front 12

What are the 2 types of cells present in the CD? How do they differ?

Back 12

• Principal cells
o Greater #, simpler form
o Deal with Na & K

• Intercalated cells
o Fewer, more complex
o Deal with H+ and HCO3

Front 13

What are the 4 functions of the CD?

Back 13

conduct fluid
respond to ADH
regulate K
**acid-base balance

Front 14

What is the main function of the JGA?

Back 14

CRUCIAL regulatory mechanism
--affects BP/flow in kidney AND whole body

Front 15

What is the tubular component of the JGA and what does it do?

Back 15

macula densa of DCT

 Tall cells that touch A&E arterioles and the glomerulus
 Senses something about tubular fluid and increases plasma volume/BP

Front 16

What is the arterial component of the JGA and what do they do?

Back 16

juxtaglomerular cells

 Modified SM cells of afferent arteriole
 Contain secretory granules with RENIN

Front 17

What is the extra-arterial component of the JGA and what do they do?

Back 17

mesangial cells

 Contractile cells among glomerular capillaires & A&E arterioles

Front 18

Which renal structures lie in the cortex?

Back 18

renal corpuscles, PCT, DCT and PTCN, JGA

Front 19

Which renal structures lie in the medulla?

Back 19

NL, CD, vasa reta

Front 20

What are the (3) cortical functions?

Back 20

Filter blood, “adjust” filtrate, regulate BP

Front 21

What are the (5) medullary functions?

Back 21

dilute fluid, concentrate salts, determine final urine con’c, acid-base balance, K homeostasis

Front 22

What are the 4 hormones produced BY the kidneys? What do they do?

Back 22

o Renin – BP regulation
 Made & stored in JG cells
 Released with decreased BP
 Transforms AT I to AT II in the lung

o 1,25 dihydroxycholecalciferol – Vit D metabolism
 Net effect = increases plasma Ca

o Erythropoietin – RBC production

o Prostaglandins – vasoactive

Front 23

What are the 4 hormones produced ELSEWHERE but act on the kidneys? What do they do?

Back 23

o Antidiuretic hormone (ADH) – concentrates urine
 Allows water recovery in late distal tubule

o Aldosterone – RAISES systemic BP
 Increases tubular Na & water absorption

o Atrial natriuretic peptide – LOWER systemic BP
 Increases tubulare Na & water excretion

o Parathyroid hormone, calcitonin – Ca metabolism

Front 24

What is the 1st step of renal processing? Where does it take place?

Back 24

"glomerular" filtration

takes places in the RENAL CORPUSCLE

Front 25

Why does the renal corpuscle filter such large volumes? (3 things)

Back 25

continuous waste removal
exacting balance of water/electrolytes & acid-base
exposes entire extracellular fluid frequently for adjustment

Front 26

What are the 4 physical features of the renal corpuscular filtration apparatus?

Back 26

glomerular capillaries
podocytes
actual filtration barrier
capillary filtration coefficient - Kf

Front 27

What are the NON-fluid factors affecting glomerular filtration?

Back 27

structural features

characteristics of solute:
o SIZE – primary factor
o Charge
 BM has a slightly negative charge
o Shape & deformability

Front 28

What are the FLUID factors affecting glomerular filtration?

Back 28

pressures FAVORING filtration
-capillary hydrostatic pressure
-oncotic pressure in the urinary space

pressures OPPOSING filtration
-oncotic pressure in the glomerular capillaries
-hydrostatic pressure in the urinary space

Front 29

True/false. The net fluid pressure FAVORS filtration.

Back 29

true

Front 30

Describe the permeability of the filtration barrier.

Back 30

IMPERMEABLE to cells & large proteins
--except albumin

FREELY permeable to water, small molecules, glucose, AAs, salts

Front 31

what are the 3 things that the GFR depends on?

Back 31

mean pressure favoring filtration
permeability of barrier
surface area of barrier

(or simply the mean pressure favoring filtration X Kf)

Front 32

What would happen to the GFR if you decreased Kf?

Back 32

multiplicatively decrease

Front 33

What would happen to the GFR if you increased glomerular capillary hydrostatic pressure?

Back 33

increase

Front 34

What would happen to the GFR if you increased glomerular capillary oncotic pressure?

Back 34

decrease

Front 35

What would happen to the GFR if you increased urinary capsular hydrostatic pressure?

Back 35

decrease

Front 36

What is renal clearance?

Back 36

the ability of the kidney to remove substances from the plasma OR the kidney's effectiveness in secreting something

basically, just a clinical measurement of GFR

Front 37

What are the 3 conditions that must be met by a substance you wish to use to calculate clearance?

Back 37

it must be freely filtered, not reabsorbed, and not secreted

Front 38

What are the 2 substances that are usually used for clearance measurements?

Back 38

inulin & creatinine

Front 39

Renal tubular reabsorption and secretion are the main mechanisms for maintaining normal body ____, _____, and _____

Back 39

osmolarity, electrolyte balance, pH balance

Front 40

What is considered renal FILTRATE?

Back 40

Filtered plasma from the glomerulus that is in the capsular space
PRIOR TO entrance into tubule

Front 41

What is considered renal tubular FLUID?

Back 41

From the PCT until it leaves the CD
continuously altered!

Front 42

What is considered renal tubular flow? Is it passive or active?

Back 42

flow of fluid thru the tubule

always PASSIVELY driven by glomerular capillary hydrostatic pressure

Front 43

What is considered renal tubular transport? Is it active or passive? Which two "outsides" can substances be transported to?

Back 43

transport of substances across/past tubular cells

can be active OR passive

2 outsides:
lumen of the tubule
basal/capillary side

Front 44

What is renal ABSORPTION?

Back 44

Removal of X from tubular fluid and put into the interstitium and then the blood (PTCN or vasa recta) in order to recover it to the body

Front 45

What is renal SECRETION?

Back 45

Removal of X from the PTCN or vasa recta and putting it into tubular fluid

Front 46

What is renal EXCRETION?

Back 46

removal of X from the body as urine

Front 47

What is considered URINE?

Back 47

FINAL product once fluid is OUT of CD and can NO LONGER BE ALTERED

Front 48

What are the 2 mathematical means of assessing renal TUBULAR function?

Back 48

• Fractional Excretion
o What % of the filtrate was actually excreted

Fractional Reabsorption
o What % of the filtrate was reabsorbed from the tubule & returned to the blood

Front 49

True/False. Movement into/out of capillaries can be either passive or active.

Back 49

False. ALWAYS passive

Front 50

What 3 properties facilitate the entrance of SOLUTES into the PTCN (absorption)?

Back 50

concentration gradient
electrical gradient
solvent drag

Front 51

What 2 properties facilitate the entrance of FLUID into the PTCN (absorption)?

Back 51

high capillary oncotic pressure
low hydrostatic pressure

Front 52

What 2 properties facilitate the exit of SOLUTES from the PTCN (secretion)?

Back 52

concentration gradient
electrical gradient

Front 53

What is PARAcellular transport? Does it require any special proteins?

Back 53

PAST/beside tubular cells

NO carriers or ion channels are required

Front 54

What is TRANScellular transport? Does it require any special proteins?

Back 54

ACROSS the membrane and THROUGH the cell

requires proteins bound in the membrane
-channels for solute or fluid - aquaporins & ion channels
-carriers for SOLUTE ONLY

Front 55

Which direction does tubular reabsorption go (ultimately)? What are its 3 characteristics?

Back 55

from blood back to blood
-from glomerular blood to PTCN or VR

VAST quantities
selective
either passive or active

Front 56

Which direction does tubular secretion go (ultimately)? What are its 3 characteristics?

Back 56

from blood to URINE
**ONLY PTCN blood

not as large volume as reaborption
selective
MOSTLY active

Front 57

What is the tubular maximum (Tmax)?

Back 57

the maximum rate at which a substance can be moved thru a tubular cell

Front 58

What is the maximal secretion capacity as it relates to Tmax? What happens if it is exceeded?

Back 58

from PTCN to tubular fluid

if exceed, BLOOD concentrations increase

Front 59

What is maximal reabsorption capacity as it relates to Tmax? What happens if it is exceeded?

Back 59

from tubular fluid to PTCN

if exceeded, URINE concentrations rise

Front 60

What is the renal threshold value as it applies to Tmax & the maximal reabsorption capacity?

Back 60

the plasma concentration of X at which its reabsorption Tmax is reached & it begins to appear in the urine

Front 61

What are the 3 PASSIVE mechanisms of renal tubular cellular solute/water movement?

Back 61

solvent drag
simple diffusion
facilitated diffusion

Front 62

What are the 3 ACTIVE mechanisms of renal tubular cellular solute movement?

Back 62

primary active transport
Na-K ATPase pump
secondary active transport

Front 63

Which primary active transport mechanism of transport sets the stage for a HUGE amount of Na to enter the cell?

Back 63

Na-K ATPase pump

know this or die!!!

Front 64

Does water move actively, passively, or both? Which ion does it usually "follow"?

Back 64

ALWAYS passive

usually follows sodium

Front 65

Which is the most ACTIVE nephric segment?

Back 65

Proximal Tubule

Front 66

What types of substances are secreted by the PCT?

Back 66

those too big to be filtered or that cant be "filtered enough"
those NOT filtered but that need to be excreted
(ex. end products of normal metabolism & exogenous compounds such as drugs)

Front 67

Does the PCT reabsorb or secrete more (volume-wise)?

Back 67

reabsorb

Front 68

What are the mechanisms of reabsorption utilized by the PCT?

Back 68

Simple & facilitated diffusion, solvent drag, ion channels, primary & secondary active transport

Front 69

Which portion of the NL recovers ALL glucose?

Back 69

PCT

Front 70

What are the 3 segments of the neprhic loop?

Back 70

descending thin, ascending thin, ascending thick

Front 71

What is the main job of the nephric limb?Where is ALL active transport completed within the NL?

Back 71

Resorption of solutes WITHOUT water in order to DILUTE the tubular fluid

ascending thick limb handles all active transport

Front 72

What transport mechanisms are located within the TkNL?

Back 72

Na-K ATPase - primary active
Na-K-2Cl COtransporter - secondary active
Na-H ANTIporter - secondary active
apical ion channels & paracellular paths for Ca
Ca-ATPase

Front 73

What percent of urine is water? What percent is solute? Which is the major solute?

Back 73

95% water, 5% solute
mainly urea

Front 74

What does specific gravity tell you?

Back 74

urine concentration as compared to distilled water

Front 75

True/false. Dilution precedes and is requisite to concentration.

Back 75

True

Front 76

How many passes does renal tubular fluid make thru the cortex? Thru the medulla? What happens on each pass?

Back 76

• 1st Cortical pass
o FORMS filtrate
o Makes 1st MASS adjustments
o Reduces volume

• 1st medullary pass
o DILUTES fluid
 Takes salts out while KEEPING FLUID IN
 LEAVES salt in the medulla

• 2nd cortical pass
o Continues dilution
o RECOVERS salt to blood

• 2nd medullary pass
o Determines final urine concentration
 Lets dilute fluid past
 Recovers water to make urine more concentrated

Front 77

Beta 2 receptor:

Back 77

Gs: vasodilation, bronchodilation, increase heart rate, increase contractility, increase insulin release
, decr uterine tone
Qiss (kiss) and qiq (kick) till you're siq (sick) of sqs (sex)

Front 78

What are the (general) roles of the various tubular regions in urine osmoregulation?

Back 78

urinary corpuscle - NOTHING
PCT - delivers isosmotic fluid to medulla
NL - dilutes fluid & raises medullary osmolarity
DCT - further dilutes fluid
CD - uses vertical osmotic gradient in the presence or absence of ADH to adjust final urine concentration

Front 79

What are the 6 anatomical features that are essential to establish & maintain high medullary osmolarity?

Back 79

• Hairpin turn of NL
• Immediate proximity of des & asc limbs
• Opposite direction of flow in des & asc limbs
• Parallel arrangement of vasa recta to each other & NLs
• Proximity of the CD to vasa recta
• Minimal “thickness” of interstitium

Front 80

True/False. The most used osmotically active particles are Na, Cl, and bicarbonate.

Back 80

FALSE! Na, Cl, and UREA

Front 81

True/False. All movement of urea is passive.

Back 81

True

Front 82

Is the Ascending thick NL permeable to salt, water, or both?

Back 82

salt only

Front 83

Is the Ascending thin NL permeable to salt, water, or both?

Back 83

salt only

Front 84

Is the Descending thin NL permeable to salt, water, or both?

Back 84

water only

Front 85

Is the vasa recta permeable to salt? Urea? Water?

Back 85

yes, ALL of them

Front 86

What is considered the countercurrent MULTIPLIER of the kidney?

Back 86

the nephric loop as a whole

Front 87

How is the high vertical medullary osmolarity gradient initiated and maintained?

Back 87

initiation - Ascending THICK NL pumps Na into UPPER medulla

Desc thin (permeable to water only) will release water into the concentrated medulla

Asc thin (permeable to salt) has a higher salt conc inside than outside, so it will release salt into the deep medulla

once you get back to the asc thick, it can continue to actively pump Na out and repeat

Front 88

Which portion of the nephric loop is urea IMpermeable?

Back 88

from the ascending NL to the beginning of (outer) CD

Front 89

Which portion of the nephric loop contains carriers for the facilitated diffusion of urea?

Back 89

the late (inner) CD

Front 90

Once urea is placed into the inner medulla by facilitated diffusion, where does it go?

Back 90

it goes into the permeable descending thin NL and continues the cycle

Front 91

What are the 3 goals of the vasa recta?

Back 91

o Bring blood to the living medullary cells
o Remove the water that was put in the medulla by the desc TnNL & CD
o Allow the above WITHOUT washing out the medullary salts

Front 92

What is considered the countercurrent EXCHANGERS of the kidney?

Back 92

vasa recta

Front 93

Does the vasa recta experience a net recovery from or loss of water to the medulla? Why?

Back 93

net RECOVERY because the VR have
-low hydrostatic pressure
-high oncotic pressure

Front 94

What 2 properties allow the DCT to continue the dilution of tubular fluid?

Back 94

it's IMpermeable to water
the ACTIVE transport of Na out

Front 95

What does the CD have to do in order to excrete dilute urine?

Back 95

nothing, it's already been diluted

Front 96

What does the CD have to do in order to excrete concentrated urine?

Back 96

use ADH

ADH acts on INNER medullary CD
-makes it more permeable to urea
-more urea moves out, raising medullary osmolarity even higher

ADH acts on the late DCT and the entire CD
-makes them WATER permeable
-inner medulla has a high osmolarity, so water easily moves OUT

Front 97

What is the normal blood pH?

Back 97

7.4

know this or die!!

Front 98

Is there a net addition of acid or alkaloids to the body due to daily bodily processes?

Back 98

acid

Front 99

What are the 4 ways that kidneys regulate body pH?

Back 99

• Secrete then excrete acid
• Recover filtered bicarb
• Make NEW bicarb
• Excrete bicarb (during alkalosis)

Front 100

True/false. Carbonic anhydrase can drive the carbonic acid equation in either direction.

Back 100

true

Front 101

Are extrarenal buffers a temporary or sustainable way to maintain bodily pH?

Back 101

rapid but temporary

Front 102

Briefly explain how the lungs help with bodily pH maintenance.

Back 102

 Increases respiratory rate to remove CO2
• Shifts equation to the left
 Turns H+ into H2O
 NO H+ IS ACTUALLY EXCRETED

Front 103

True/false. The kidneys have a delayed, but sustainable response to bodily pH maintenance.

Back 103

true

Front 104

What are the 2 portions of the kidney that are the main contributors to bodily pH maintenance? Which one deals with the highest volume? Which has the greatest effect on pH?

Back 104

PCT - high volume
CD - greater pH effect

Front 105

True/false. Rate of renal acid se/excretion must be greater than or equal to bodily acid production in order to prevent acidosis or alkalosis.

Back 105

FALSE. they must be EXACTLY EQUAL

Front 106

What are the 2 critically important buffers in renal tubular fluid? Where are they the most important?

Back 106

HCO3- - important EARLY in tubule
PO4 - important LATE in nephron

Front 107

What are the 3 renal H transport systems? Where are they mainly found?

Back 107

Na-H antiporter - in PCT
H-ATPase - in CD
H-K ATPase - in CD

Front 108

Which portion of the renal tubule makes NH4+ (ammonium ion)? How?

Back 108

PCT makes it by metabolizing gluatmine

Front 109

What are the 3 (HUGE) net effects of ammoniagenesis in the PCT?

Back 109

 Generate a new bicarb
 Keeps NH4+ and NH3 in the medulla, away from DCT
 Excrete BOTH an ammonia AND a hydrogen

Front 110

Once the NH4+ from the PCT makes it to the TkAL, what are its 3 fates? What are the benefits of each fate?

Back 110

recycling between limbs of nephric loop
-increases medullary osmolarity
-keeps NH3 out of cortext & systemic blood (via PTCN)

NH3 enters CD, is protonated, held in lumen, and excreted
-excretes an ammonia AND an H+

small amt enters vasa recta & goes to liver
-converted to less toxic urea

Front 111

The rate of ______ in the CD is the final determinant of urine pH.

Back 111

acid secretion

Front 112

True/False. The pH of fluid arriving at the CD is basic because it's diluted.

Back 112

FALSE. it's neutral

Front 113

What do type A intercalated cells of the CD do? How?

Back 113

secrete acid & recover bicarb

H+ pumps in apical membrane to send H+ into tubular lumen

HCO3-Cl exchanger in basal membrane to send bicarb to blood & away from tubular fluid

Front 114

What do type B intercalated cells of the CD do? How?

Back 114

secrete bicarb & recover acid

H+ pumps in basal membrane to send H+ into blood and away from tubular lumen

HCO3-Cl exchanger in apical membrane to send bicarb into tubular lumen

Front 115

What is the system that the kidney uses to regulate systemic blood flow?

Back 115

The Renin-Angiotensin-Aldosterone System (RAAS)

Front 116

In the RAAS, what do the different parts of the JGA sense?

Back 116

macula densa - senses decreased Na/Cl conc
granular cells - sense decreased AA pressure

Front 117

What is the effect of aldosterone on the kidney? (as it relates to the systemic control RAAS system)

Back 117

increases Na & water reabsorption which increases systemic blood volume & therefore pressure

Front 118

what is the effect of vasopressin/ADH release on the kidney? (as it relates to the systemic control RAAS system)

Back 118

increases urea concentration of medulla which increases water recovery & thus increases blood volume

Front 119

What are the 2 general mechanisms by which the kidney locally regulates blood flow/GFR?

Back 119

mainly autoregulation

sympathetic nervous system can override local control when necessary

Front 120

What are the 4 mechanisms of controlling diameter of the afferent/efferent arterioles?

Back 120

sympathetic override of local signals
--causes contraction of AAs to shunt blood away from kidneys

endothelial cell paracrine hormones

myogenic reflex

tubuloglomerular feedback

Front 121

Briefly explain how the myogenic reflex regulates GFR when there is increased or decreased afferent arteriolar pressure

Back 121

• Increased AA pressure stretches it, resulting in AA constriction
o Constriction decreases diameter so less blood flows thru
o EA must relax to compensate for the increased pressure


decreased pressure causes the opposite reaction

Front 122

In the case of tubuloglomerular feedback, increased flow/conc of the tubular fluid would imply what? Should the kidneys increase or decrease GFR? How?

Back 122

implies dehydration or that the fluid is moving too quickly

you need to DECREASE the GFR
-constrict AA
-contract mesangial cells (decreasing the Kf)