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Med 310B > Renal > Flashcards

Renal Flashcards

1
Q

what is the urinary system composed of?

A

paired kidneys
ureters
bladder
urethra

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2
Q

where is urine produced?

A

the kidneys

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3
Q

where does urine drain through?

A

ureters into urinary bladder

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4
Q

where is urine stroed?

A

bladder

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5
Q

what is urine elimainted through?

A

urethra

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6
Q

what are the major blood vessels connceting the urinary system with the rest of the body?

A

abdominal/thoracic aorta

inferior veina cava

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7
Q

kidneys need ____ blood in _______ time

A

max blood
min time

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8
Q

where are the kidneys loacted in the body?

A

T12 to L3
retro-peritoneally (outside the cavity)

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9
Q

what is the approximate size of the kidney?

A

12 cm tall
6 cm wide
3 cm thick

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10
Q

why is the location of the kidney’s strategic?

A

the kidney’s are located centrally near major vessels, tissues, arteries etc…

its close proximation to the heart allows for max blood in min time

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11
Q

kidneys clean the body of _________ and ___________

A

metabolic waste and foreign substances

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12
Q

kidneys regulate _______and __________

A

fluid volume and blood pressure

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13
Q

although kidneys mostly deal with urine, they help to regulate ___ and ____of ECF and blood

A

osmolarity
essential ion concentration

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14
Q

why are the kidneys important to endocrine functions?

A

they produce erythropoietin which stimulates RBC production

and produce renin which activates angiotensin and aldosterone

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15
Q

what are nephrons and where are they located in the kidney?

A

nephrons are microscopic tubular structures

they are located in both the cortex and medulla

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16
Q

what represents the outer region of the kidney?

A

cortex

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17
Q

what represents the inner region of the kidney?

A

medulla

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18
Q

what does the medulla form?

A

pyramids or lobes which are prolonged by large cavities connected with the renal pelvis

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19
Q

what is the renal pelvis?

A

the central receptacle collecting the urine

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20
Q

where is urine made?

A

the nephrons

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21
Q

where is urine collected?

A

pelvis

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22
Q

as you go from the head of the nephron tubule to the end, name the parts;

A

bowman’s capsule
proximal tubule
descending loop of henle
ascending loop of henle
distal tubule
renal pelvis

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23
Q

what does the bowman’s capsule contain?

A

a set of micro vessels called the glomerulus

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24
Q

the bowmans capsule AND the glomerulus form ______

A

the renal corpuscle

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25
Q

when the renal tubule folds back on itself so that the distal tubule contacts the renal corpuscle, it is called _________

A

juxtaglomerular apparatus

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26
Q

blood enters the nephrons via ______

A

afferent arteriole

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27
Q

describe the path of blood after entering the afferent arteriole;

A

glomerular capillaries
efferent arteriole
peritubular capillaries

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28
Q

renal micro circulation is a ______-

A

portal circulation

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29
Q

why is renal microcirculation a portal?

A

interconnecting
capillary mixing
facilitates a large change in blood compositiion

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30
Q

what are the 2 types of nephrons?

A

cortical and juxtamedullary

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31
Q

what is the location of a cortical nephron?

A

most of the loop of henle is in the cortx or outer layer

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32
Q

what is the location of the juxtamedullary nephron?

A

most of the loop of henle is loacted in the medulla or the inner portion

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33
Q

cortical nephrons make up the larger portion of nephrons they have _____ loops and make ______ of filtrate

A

short loops
90%

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34
Q

juxtamedullary nephrons are larger and contain the ________ capillaries and a _________ loop

A

vasa recta
long loop

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35
Q

what is the vasa recta?

A

a long, narrow capillary set that follows down the loop of henle

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36
Q

what is the path of blood flow into a kidney?

A

reneal artery
segmental artery
interlobar artery
arcuate artery
cortical radiate artery
arterioles (nephron)

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37
Q

which artery interacts directly with the glomerulus?

A

cortical radiate artery

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38
Q

are the arteries within the medulla of the kidney?

A

no they are within the spaces around the medulla

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39
Q

renal microcirculation is located _________

A

in the nephron

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40
Q

describe the path of blood out of the kidney;

A

vasa recta and peritubular capillaries (naphron)
cortical radiate vein
arcuate vein
ionterlobar vein
renal vein

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41
Q

what are the 3 different processes involved in the renal blood treatment and urine formation?

A

filtration
reabsorption
secretion

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42
Q

where does filtration occur?

A

renal corpuscle

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43
Q

where does reabsorption and secretion occur?

A

peritubular capillaries

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44
Q

what results in the formation of urine?

A

from the adjustment of bloof composition and volume by the nephron

urine is produced by the progressive transformation of the initial blood filtrate through the renal tubule

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45
Q

what are the 3 processes involved in urine formation?

A

glomerular filtration
tubular reabsorption
tubular secretion

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46
Q

what is glomerular filtration?

A

nondiscriminant filtration of a protein-free plasma from the glomerulus into the bowmans capsule

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47
Q

what is tubular reabsorption?

A

selective movement of the filtered substances from the tubular lumen into the peritubular capillaries

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48
Q

what is tubular secretion?

A

selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen

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49
Q

what percentage of plasma that enters the glomerulus is filtered?

A

20%

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50
Q

what percentage of plasma that enters the glomerulus is not filtered and leaves through the effernet arteriole?

A

80%

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51
Q

where does blood filtration occur?

A

renal corpuscle aka the filter

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52
Q

the internal wall of the renal corpuscle is made of 2 cell types of different origins, what are they?

A

cells from vessels
cells from the primitive tubule

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53
Q

what is the layer of cells in contacy with the glomerulus called?

A

visceral

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54
Q

what is the layer of cells not in contact with the glomerulus on the renal corpuscle called?

A

parietal

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55
Q

the cells from the primitive tube differentiate into __________

A

podocytes

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56
Q

what do podocytes form?

A

a layer that surrounds the glomerular capillaries

they form the visceral layer of the bowman’s capsule

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57
Q

what are pedicels?

A

extensions from podocytes

they form filtration slits

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58
Q

what are the components that form the glomerular filtration barrier?

A

the visceral layer and capillary wall

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59
Q

what is filtered into the bowman’s capsule? (aka ultrafiltrate of plasma)

A

water
small solutes (Na, Cl, HCO3, glucose, amino acids)

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60
Q

what is not filtered into the bowman’s capsule and gets left in the blood stream?

A

large particles such as proteins (albumins, antibodies, hormones, enzymes)

blood cells

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61
Q

what is the numeric value of the normal filtration fraction?

A

0.2

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62
Q

what measures the intensity of filtration?

A

glomerular filtration rate

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63
Q

what is the glomerular filtration rate?

A

the rate at whcih ultrafiltrate of plasma moves from the glomerulaar capillaries into the bowmans capsule

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64
Q

what is GFR under normal conditions?

A

125ml/min

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65
Q

what determines the GFR?

A

filtration coefficient (properties of the filtration barrier, surface area, permeability)

net filtration pressure (starling forces)

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66
Q

what are starling forces?

A

forces that determine the net movement of fluid across membranes of capillaries

fluid movememnt across the wall of a capillary results from the balance between hydrostatic pressure gradient and osmotic pressure gradient

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67
Q

what are the hydrostatic forces?

A

intra-capillaary pressure
external pressure

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68
Q

what are the osmotic forces?

A

intra capillary osmotic pressure
external osmotic pressure

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69
Q

what does the net hydrostatic force/pressure result from?

A

blood pressure in the glomerulus
(capillary pressure = 55)

pressure of fluid in the bowmans capsule
(external pressure = 15)

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70
Q

how do you calculate net hydrostatic pressure?

A

net = P(cap) + P(ext)

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71
Q

what does net hydrostatic pressure actually mean?

A

it pushes the fluid from glomerular capillary into the bowman’s capsule

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71
Q

what does net osmotic pressure result from?

A

osmotic pressure in the bowman’s capsule
(=0)

osmotic pressure in the glomerular capillaries
(=30)

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72
Q

how do you calculate net osmotic pressure?

A

Pos = P(bow) + P(glo cap)

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73
Q

what does net osmotic pressure actually do?

A

pulls back the fluid from the bowman’s capsule into the glomerular capillary

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74
Q

in the renal corpuscle, hydrostatic pressure is __________

A

opposed by osmotic pressure
greater than osmotic pressure

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74
Q

how do you calculate net glomerular filtration pressure?

A

GFP = [net hydro] - [net osmo]

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75
Q

what does net pressure cause?

A

movement of fluid from blood to filtrate (glomerulus to bowman’s capsule)

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76
Q

because GFR depends on blood pressure, does GFR rise when the arterial blood pressure increases?

A

yes when the blood pressure is outside normal range

no when it is inside normal range

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77
Q

what does autoregulation do?

A

maintains a nearly constant GFR when the mean arterial blood pressure is between 80 and 180

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78
Q

what are the mechanisms of autoregulation?

A

reducing BP in glomeruli which result in reduced GFR

1: myogenic response of afferent arterioles
2: tubulo-glomerular feedback

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79
Q

what are the regulation by hormones and autonomic neurons?

A

1: change in the resistance of the arterioles
2: alteration of the filtration coefficient

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80
Q

what is the myogenic response?

A

inherent property of smooth muscle that surroind all blood vessels EXCEPT capillaries and mesenteric artery

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81
Q

increased stretch of the blood vessel walls causes _________

A

contraction if smooth muscle
constriction of vessel

this decreases flow and pressure

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82
Q

the myogenuc responses always tends to _________ excessive BP in the glomerulus

A

limit

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83
Q

what is the tubulo-glomerular feedback?

A

a local control pathway in which the flow rate of filtrate inside the renal tubule influences the GFR

any increase in GFR enhances the flow of filtrate

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84
Q

increased flow in the renal tubule is detected by?

A

macula densa cells

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85
Q

what do macula densa cells do?

A

secrete a vaso constrictive substance reducing the blood flow to afferent arteriole and glomerulus

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86
Q

describe the tubulo-glomerular feedback steps;

A

1&2: in response to increased GFR due to elevated BP, urine flow increases through the renal tubule

3: the resulting larger amount of NaCl in the distal tube is sensed by the cells of the macula densa

4: increase of production of a vasoconstrictor (adenosine)

5: constriction of afferent arterole

6: decrease of intraglomerular BP (hydrostatic pressure) and reduction of GFR

87
Q

what is hormonal control/barostatic control of renin secretion?

A

the granular cells behave like baroreceptors and respond to drops in BP by secreting renin

88
Q

what does renin do?

A

activates the synthesis of angiotensin 2 which contributes to increase in the total peripheral resistance (TPR) and restores normal BP and GFR

89
Q

if GFR increases, what works to lower it?

A

macula densa cells

myogenic response

90
Q

if GFR decreases, what works to increase it?

A

granular cells

91
Q

what percentage of the fluid that enters the renal tubule, how much is reabsorbed?

A

about 19%

92
Q

reabsorption takes place in all regions of the renal tubule EXCEPT?

A

the renal corpuscle

93
Q

what does reabsorption do?

A

moves fluids and solutes from the renal tubule to the peritubular capillary

94
Q

what seperates the renal tubule and capillaries?

A

the ISF

95
Q

what are the 2 steps in the reabsorption process?

A

1: from renal tubule to ISF

2: from ISF to peritubular capillary

96
Q

the epithelial cells of the proximal tubule are designed to _________

A

facillitate exchanges

97
Q

what are the epithelial cells on the large surface areas designed for exchange?

A

microvili on apical membrane

infoldings of basal membrane

98
Q

what are the epithelial cells on the polarized epithelium designed for excahnge?

A

apical and basal membranes have different transporters and permeabilities

99
Q

describe the general mechanism of reabsorption steps;

A

1: sodium is reabsorbed by active transport. ISF becomes more positive

2: electrochemical gradient drives anion reabsorption. attractive of negative charges in the ISF

3: water moves by osmosis, following solute reabsorption. ISF becomes more concentrated. H2O moves to ISF

4: concentrations of other solutes increase as fluid volume in lumen decreases. permeable solutes afre reabsorbed by diffusion

100
Q

what is the first element absorbed in the proximal tubule?

A

sodium

101
Q

what is active transport?

A

uses energy to move substances againts their concentration gradients

102
Q

what is secondary active transport?

A

uses energy of sodium transport

103
Q

what is passive diffusion?

A

substances moves down their concentration gradients

104
Q

what is endocytosis?

A

transport by membrane vesicles of some large molecuels remaining in the filtrate

105
Q

describe the active transport in the kidneys;

A

sodium reabsorption

sodium in the cell is low

1: Na is pumped out the baasolateral side of the cell by the NaK ATPase
2: Na enters the cell through membrane proteins, moving down its concentration gradient

106
Q

what is the secondary active transport in the kidney?

A

glucose reabsorption

High glucose in the cell

1: Na moving down its gradient using the SGLT protein pulls glucose into the cell against its gradient
2: glucose diffuses out of the basolateral side using the GLUT protein
3: Na is puymped out by NaK ATPase

107
Q

what is transport maxiumum?

A

rate of transport that occurs when all carriers are occupied

108
Q

what happens when the concentration of a substance in the filtrate exceeds the transport maximum?

A

some remains in the filtrate and appears in the urine

109
Q

what is the renal threshold?

A

the plasma concentration at which the substance appears in the urine

110
Q

the resistence increases as the size of the vessel ________

A

decreases

111
Q

high resistence vesseuls = ________ output pressure

A

lower

112
Q

_____ blood pressure in peritubular capillaries facilitates the reabsorption

A

low

113
Q

what is the direction of secretion?

A

from peritubular capillaries to renal tubule

114
Q

where does secretion occur?

A

in the proximal and distal convolute tubules and collecting duct

115
Q

most secretion is perfromed by ____ transport

A

active

116
Q

what is clearance?

A

disapperance rate of substance in the body due to excretion or metabolism

117
Q

what is renal clearance used for?

A

evaluating the renal function via

GFR and RBF

118
Q

what does clearance compare?

A

filtration rate with excretion rate

if X is filtered but not reabsored/secreted
C = GFR

if X is filtered and secreted
C = RPF
C > GFR

if X is filtered and reabsorbed
C < GFR

if X is reabsorbed
C = 0

119
Q

how do you calculated renal clearance?

A

C = urine * rate of production / plasma

120
Q

what is para-aminohippurate?

A

freely filtered from glomerular blood and secreted from peritubular blood

NONE in renal venous blood

C = RPF

121
Q

how do you switch from RPF to RBF?

A

using hematocrit

divide the value by the hematocrit AS A DECIMAL

122
Q

what is inulin?

A

used by researchers

not filtered
not secreted

C = GFR

123
Q

creatinine is ______ absorbed and _______ secreted

A

not, not

124
Q

what are body fluids?

A

refers to the water in the body and all substances dissolved in it

125
Q

water determines the body fluid _____

A

volume

126
Q

solutes determine the ________ and _________ of the body fluid

A

composition and osmolarity

127
Q

what are the functions of water in the body?

A

tempterature regulation
cushioning
lubrication
reactant
solvent
transportation

128
Q

what percentage of total body weight is fluid?

A

60%

129
Q

where are fluids absorbed in the body?

A

into the plasma in intestine

130
Q

where does fluids circulate in the body?

A

within plasma and around cells

131
Q

where is fluids removed from the body?

A

kidneys through urine

132
Q

what are the 2 compartments body fluids are distributed into?

A

ICF and ECF

133
Q

the ECF contains

A

ISF and plasma

134
Q

what percentage of the total weight of body fluids is ICF?

A

40%

135
Q

what percentage of total weight of body fluids is ISF?

A

15%

136
Q

what percentage of total weight of body fluids is plasma?

A

5%

137
Q

what are electrolytes?

A

charged particles that are dissolved in fluids

138
Q

what are the major positive electrolytes?

A

Na
K
Ca
Mg

139
Q

what are the major negative electrolytes?

A

Cl
HCO3
HPO4
H2PO4
SO4
proteins
organic acids

140
Q

in each compartment, positive and negative charges must balance _________

A

electro-neutrality

141
Q

what type of membrane seperates the ECF and ISF?

A

semi permeable membrane

142
Q

plasma and ISF have _____ osmolatiry

A

the same

143
Q

what are membranes responsible for?

A

controling the fluxes of ions in and out of cells

144
Q

membrane active transports maintain?

A

the difference of some iion concentrations between ICf and ECF

145
Q

is the ECF is hyperosmolar, what happens to the cells?

A

cells would shrink because water is rushing into the ECF

146
Q

if the ECf is hypoosmolar, what happens to the cells?

A

cells would swell because water us rushing into them from the ECF

147
Q

controlling water is the most effiecient and easy way to compensate for changes in _________

A

ECF

148
Q

the average adult body contains ________ L of water

A

40

149
Q

water is maintained in a steady state called ______

A

water homeostasis

150
Q

what type of feedback mechanisms maintain water homeostasis?

A

negative

151
Q

what is water homeostasis?

A

a balace between water intake and output

152
Q

what is hypervolemia?

A

too much water and solute taken in at the same time

volume increases BUT osmolarity remains the same

153
Q

what is hypovolemia?

A

water and solute are lost at the same time, usually a loss of plasma volume

Volume decreases BUT osmolarity remains the same

154
Q

what is overhydration?

A

too much water is taken in WITHOUT solute

volume increases and osmolarity decreases

155
Q

what is dehydration?

A

when water is lost but not solute

volume decreases and osmolarity increases

156
Q

what is the name of the model for which represents the kidney’s ability to regulate water loss?

A

the mug model

157
Q

what is diuresis?

A

loss of water in urine

158
Q

how is diuresis measure?

A

from the concentration or osmolarity of urine

159
Q

if the body needs water elimination, the kidneys will produce _____- urine and diuresis is _____

A

diluted
large

160
Q

is the body needs water conservation, the kidneys will produce _____ urine and diuresis is __________

A

concentrated
low

161
Q

ISF of the cortex is _____ to plasma and renal filtrate

A

isosomtic

162
Q

ISF of the medulla is ______ to the plasma and renal filtrate

A

hyperosmotic

163
Q

what part of the renal tubule is impermeable to water?

A

loop of henle

164
Q

because the loop of henle is impermeable to water, is it also impermeable to solutes?

A

no

165
Q

describe what happens in the descending limb of the loop of henle for osmolarity;

A

increasing concentration of the medulla progressively remove water from the filtrate

osmolarity increases

166
Q

describe what happens in the ascending limb of the loop of henle for osmolarity?

A

the salts are progressively extruded from the filtrate with no water loss

osmolarity decreases and the filtrate becomes hypoosmotic

167
Q

what is meant by renal concurrent?

A

the blood in the vasa recta and filtrate circulate in opposite directions in the loop of henle

168
Q

describe what happens in the blood in the loop of henle?

A

the concentration of the blood entering the Vasa Recta progressively increases as the osmolarity in themedulla increases ( the blood loses water and captures solutes from the ascccending limb)

all the water is then reabsorbed in the hyperosmotic blood which is progressively diluted along the descending limb

169
Q

which part of the loop of henle does water reabsorption operate?

A

descending

170
Q

where is water loss partially controlled?

A

distal part of the renal tubule and in teh collecting duct

171
Q

where is anti diuretic hormone secreted?

A

hypothalamus

172
Q

where is anti diuretic hormone released from?

A

posterior pituitary

173
Q

what controls anti diuretic hormone secretion?

A

hypothalamic osmoreceptors

174
Q

describe the hormonal control of water loss;

A

1: normal - low water permeability in collecting duct. there is low ADH, diluted urine, high diuresis

2: increased water permeability in the collecting duct. there is hugh ADH with concentrated urine and low diuresis

175
Q

describe the feedback loop of ADH:

A

1: vasopressin binds to membrane receptor

2: receptor activates cAMP second messenger system

3: cell inserts AQP2 water pores into apical membrane

4: water is absorbed by osmosis into the blood

176
Q

what initiates the ADH secretion?

A

increased osmolarity of ECF
decreased blood volume]decreased arterial blood pressure

177
Q

how does ECF stimulate ADH?

A

when ECf osmolarity rises, water shifts out of the intracellular compartment and the cells shrink

the shrinking hypothalamic osmoreceptors signal for ADH release

178
Q

veins and atria contain ______ receptors which detect changes in wall ______

A

stretch

179
Q

decreased stretch (low blood volume ) signals for ______

A

ADH secretion

180
Q

walls of largge arteries (aorta and carotid) contain _________

A

baroreceptors

181
Q

what are baroreceptors?

A

neurons that monitor BP

182
Q

decrease in BP signals _______

A

ADH secretion

183
Q

gain and loss of ___ affects the ECF volume via control of ADH secretion

A

Na

184
Q

what is natriuresis?

A

excretion of sodium in urine

185
Q

what is pressure natriuresis?

A

increases renal Na excretion when arterial blood pressure increases

186
Q

what is the hypothesis of pressure natriuresis?

A

when BP increases, the hydrostatic pressure within peritubular capillaries increases

this reduces net starling force for reabsorption from renal ISF to capillaries

with reduced peritubular capillary reabsorption, more water and salt stay in the renal tubule and sodium elimination in the urine increases

187
Q

Na excretion and BP goes hand in hand. true or false

A

true

188
Q

what is the feedback loop for Na and BP known as?

A

renal body-fluid feedback mechanism

189
Q

if BP is too low, what happens to salt?

A

the renal elimination of salt and water decreases.

The ECF volume expands until BP is restored

190
Q

if BP is too high, what happens to salt?

A

the renal excretion of salt and water leads to reduction of ECF volume until BP is restored

191
Q

further reabsorption can take place in the distal tubule and collecting duct when the hormone __ is present

A

aldosterone

192
Q

what percentage of filtered Na is dependent on aldosterone?

A

8%

193
Q

increasing aldosterone, _______ Na reabsorption

A

increases

194
Q

what tubules express aldosterone receptors?

A

distal and collecting tubule

195
Q

describe the mechanism of control for aldosterone on Na reabsorption;

A

1: aldosterone combines with a cytoplasmic receptor

2: hormone-receptor complex initiates transcription in the nucleus

3: new protein channels and pumps are made

4: aldosterone-induced proteins modify existing proteins

5 result is increased Na reabsorption

196
Q

where is atrial natriuretic peptide secreted?

A

atrial monocytes

197
Q

ANP synthesis and release depends on ______

A

cardiac filling pressures

198
Q

increased blood volume _______ ANP synthesis

A

activated

199
Q

what does ANP do to salt?

A

limits the normal Na reabsorption by the nephrons and inhibits the aldosterone effect

200
Q

where is renin released from?

A

juxtaglomerulaar cells around afferent arterioles

201
Q

when is angiotensin 2 produced?

A

when the kidneys release renin

202
Q

describe the feedback mechanism for angiotensin 2:

A

liver makes angiotensinogen

kidney makes renin

renin and angiotensinogen make angiotensin 2

angiotensin 2 activates thrist, vasopressin, vasoconstriction

this in turn causes H2O reabsorption and fluid intake to conserve H2O

203
Q

how does a drop in BP mediate the secretion of renin and activate the RAAS?

A

1: direct effect of BP on graqnular cells (decreased vasoconstriction)

2: due to decreased GFR, macula densa stimulates granular cells

3: increase sympathetic activity stimukates granular cells

204
Q

what is the RAAS?

A

renin-angiotensin-aldosterone

205
Q

what are the activators of the RAAS?

A

mecula densa: low GFR, low salt intake

renal BP: low BP, Low ECF volume

increased sympathetic activity

206
Q

what are the mediators of RAAS?

A

renin

angiotensin 2

aldosterone

207
Q

what are the actions of RAAS?

A

descreased salt and water excretion

increased ADH

increased sympathtic activity

thirst

208
Q

describe the cardiopulmonary sympathetic reflec steps:

A

renal sympathetic activity activates;
renin
sodium reabsorption
vasoconstriction

which cause renal salt and water retention

this increases plasma volume which decreases cardio-pulmonary volume/stretch

209
Q

ANP is produced in the atria in respomse to?

A

increased BP or increased plasma volume

210
Q

what does ANP inhibit?

A

Na reabsorption
RAAS
smooth muscle of afferent arterioles
sympathetic nervous system

211
Q

ANP inhibiting the RAAS and Na reabsorption causes?

A

an increases in natriuresis and diuresis

and a decrease in ECF osmolarity/volume

212
Q

ANP inhibiting smooth muscle of afferent arterioles causes?

A

vasodilation

increased GFR

increased Na and H2O filtered

213
Q

ANP inhibiting the sympathetic nervous system causes?

A

decreased cardiac output

decreased TPR

decreased BP

214
Q

which situations would required increased ECF?

A

salt loading
transfusion
heart failure

215
Q

which situations would required decreased ECF?

A

dehydration
hemorrhage

216
Q
A

Med 310B (6 decks)

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