Renal System Flashcards

1
Q

What are the functions of the kidney?

A

Filter metabolic products and toxins from the blood and excrete them as urine
Regulate the body fluid status, electrolytes, and acid-base balance
Humoral regulation of blood pressure and flow

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2
Q

What does the cortex of the kidney have?

A

Glomeruli and highly convoluted epithelial structures in the form of tubules

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3
Q

What does the medulla of the kidney have?

A

Parallel arranged tubules and small blood vessels

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4
Q

What is the nephron?

A

The basic structural and functional unit of the kidney

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5
Q

What makes up the renal corpuscle?

A

The glomerulus, Bowman’s space, and Bowman’s capsule

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6
Q

What are filtration slits?

A

Interdigitations connected by the slit diaphragm

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7
Q

Where is the largest portion of the glomerular filtrate retreived?

A

The proximal tubule

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8
Q

What are the main functions of the loop of henle?

A

Assisting in the formation of concentrated or dilute urine, increasing osmolarity of the interstitial space

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9
Q

What is the main function of the distal tubule and collecting duct?

A

Performing fine control of electrolyte and water excretion

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10
Q

What is the juxtaglomerular apparatus?

A

The region where the glomerulus makes contact with the thick ascending limb of the loop of henle

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11
Q

What does sympathetic stimulation of the kidney do?

A

Causes vasoconstriction, sodium reabsorption in the proximal tubules, and renin secretion

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12
Q

What are the three processes of the kidney?

A

Glomerular filtration, tubule reabsorption, and secretion

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13
Q

What is renal clearance?

A

The virtual volume of plasma that would be totally cleared of a solute in a given time

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14
Q

Why isn’t inulin used to determine GFR?

A

It has to be given intravenously and is difficult to measure

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15
Q

What endogenous metabolite is often used to measure GFR?

A

Creatine phosphate

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16
Q

Why is a high glomerular filtration rate essential?

A

To maintain stable and optimal extracellular levels of solutes and water

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17
Q

What are the four elements of a glomerular filtration barrier?

A

Endothelial cells, glycocalyx on the endothelial cells, glomerular basement membrane, and epithelial podocytes

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18
Q

What are the three determinants of the filterability of solutes across the glomerular filtration barrier?

A

Molecular size, electrical charge, and molecule shape

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19
Q

What determines fluid movement across the capillary wall?

A

Capillary hydrostatic pressure difference and colloid osmotic pressure difference

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20
Q

Why does the glomerulus filtration rate exceed other regions of the body?

A

Greater starling forces and higher capillary permeability

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21
Q

Which two forces favour ultrafiltration?

A

Hydrostatic pressure in the glomerular capillary and oncotic pressure in the Bowman’s space

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22
Q

Which two forces oppose ultrafiltration?

A

Hydrostatic pressure in the Bowman’s space and oncotic pressure in the glomeruli

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23
Q

What are the two unique features of the renal microvasculature?

A

Two major sites of resistance (afferent and efferent arterioles) and the two capillary beds in series

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24
Q

Which capillary bed favours filtration and which favours reasorption?

A

The glomeruli favours filtration and the peritubular capillaries favours reabsoption

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25
Q

What is the myogenic response?

A

Afferent arterioles have the ability to respond to changes in vessel circumference by contracting or relaxing

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26
Q

What is tubuloglomerular feedback?

A

Macula densa cells sense increase in GFR which translates into contraction of afferent arterioles and decreases GFR

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27
Q

What kind of transport drives the movement of solutes and water across different sections of the nephron?

A

Transepithelial transport

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28
Q

What is one of the main jobs of epithelial cells?

A

To work against the laws of thermodynamics to impact the movement of substances

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29
Q

What is an important feature of epithelial cells that helps mediate movement of ions?

A

Two membranes with asymmetrical distribution of transporters

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30
Q

What do membrane bound carriers rely on to move solutes?

A

The cumulative thermodynamic gradient of the substances being moved

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31
Q

Where are the three membrane potentials in an epithelial cell?

A

The entire endothelial cell, the basolateral membrane, and the apical membrane

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32
Q

What causes paracellular electrical coupling to occur?

A

Large shunts which allow a lot of current movement through the paracellular space

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33
Q

How does water move through a cell?

A

It moves from regions of low solute to high solute. It can not be actively transported

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34
Q

What is osmolarity?

A

A measure of the solute concentration

This is the number of osmoles per liter

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35
Q

Where does reabsorption in the kidney occur and in what quantities?

A

The proximal tubule (67%)
Loop of Henle (25%)
Convoluted tubule, connecting tubule, initial collecting duct, and cortical collecting tubule (5%)
Medullary collecting ducts (3%)

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36
Q

How is sodium transported across the apical membrane of the proximal tubule?

A

Cotransporters (glucose, amino acids, etc.) and Na-H exchanger

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37
Q

How is sodium transported across the basolateral membrane of the proximal tubule?

A

Na-K pump and Na-HCO3 co-transporter

Backleak through the paracellular pathway

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38
Q

How is sodium transported in the thin limb of the loop of henle?

A

Passively and paracellularly

39
Q

How is sodium transported across the apical membrane of the loop of henle?

A

NaKCl co transporter

40
Q

How is sodium transported across the basolateral membrane of the loop of henle?

A

Na-H antiporter

41
Q

How is sodium transported across the apical membrane of the distal convoluted tubule?

A

Na-Cl co-transporter

42
Q

How is sodium transported across the basolateral membrane of the distal convoluted tubule?

A

Na-K pump

43
Q

How is sodium transported across the apical membrane of the connecting tubule, cortical collecting tubule, and medullary collecting duct?

A

EnaC

44
Q

How is sodium transported across the basolateral membrane of the connecting tubule, cortical collecting tubule, and medullary collecting duct?

A

Na-K pump

45
Q

How does oxygen consumption relate to Na reabsorption?

A

There is a linear relationship because Na transport is dependent on the Na-K pump, which is ATP dependent

46
Q

Where in the proximal tubule is paracellular transport dominant and where is transcellular transport dominant for chloride?

A

Paracellular is dominant in the early proximal tubules and transcellular is dominant in the later proximal tubules

47
Q

How is chloride transported across the apical membrane of the proximal tubule?

A

Cl anion exchangers

48
Q

How is chloride transported across the basolateral membrane of the proximal tubules?

A

Cl channels and K-Cl cotransporter

49
Q

How is chloride transported across the apical membrane of the loop of henle?

A

NaKCl cotransporter

50
Q

How is chloride transported across the basolateral membrane of the loop of henle?

A

Cl channels

51
Q

How is chloride transported across the apical membrane of the distal convoluted tubule?

A

Na-Cl cotransporter

52
Q

How is chloride transported across the basolateral membrane of the distal convoluted tubule?

A

Cl channel

53
Q

How is chloride transported across the apical membrane in B intercalated cells of the cortical collecting duct?

A

Cl-HCO3 exchanger

54
Q

How is chloride transported across the basolateral membrane of B intercalated cells in the cortical collecting duct?

A

Cl channels

55
Q

How is chloride transported across principal cells?

A

Paracellular transport

56
Q

What drives water reabsorption?

A

Small osmotic gradients and high permeability of water to aquaporins

57
Q

How is water reabsorbed in the proximal tubules?

A

High levels of aquaporin allow for transcellular and paracellular water flow

58
Q

What is glomerulotubular balance?

A

The proximal tubules response to alterations in GFR. It reabsorbs a constant fraction of Na

59
Q

How does increased filtration fraction impact the driving force for reabsoprtion?

A

It increases it

60
Q

What is renin?

A

An enzyme produced by JGA that leads to the production of ANG II

61
Q

What does ANG II do?

A

Binds to AT1 receptors and stimulates Na reaborption

62
Q

What does aldosterone do?

A

Stimulates Na reabsorption in later regions of the nephron

63
Q

How does sympathetic innervation of the kidney impact the circulating volume?

A

It decreases it

64
Q

What does arginine vasopressin do?

A

Produces urine with high osmolarity, which means there is more water retention

65
Q

What does atrial natriuretic peptide do?

A

Causes renal vasodilation which increases blood flow and sodium load

66
Q

Where is most of the filtered glucose reabsorbed?

A

The proximal convoluted tubule

67
Q

How is glucose transported across the apical and basolateral membranes?

A

Apical via secondary active transport through the Na-glucose cotransporter
Basolateral via facilitated diffusion

68
Q

What is the difference between SGLT1 and SGLT2?

A

SGLT1 has a high affinity and less activity

SGLT2 has a low affinity and high activity

69
Q

What is the transport maximum of glucose?

A

Around 400mg/min

70
Q

Where is 98% of the amino acids which are filtered reabsorbed?

A

The glomerulus

71
Q

How are amino acids moved across the membranes?

A

Apical via Na or H linked transport

Basolateral via exchangers and facilitated diffusion

72
Q

Where are the majority of oligopeptides reabsorbed?

A

The proximal tubule

73
Q

What prevents the filtration of large amounts of proteins?

A

Glomerular barrier

74
Q

What is considered chronic kidney disease?

A

Decreased kidney function shown by GFR of less than 60ml/min per 1.73m^2 or markers of kidney damage for at least three months duration

75
Q

What is mesoamerican nephropathy?

A

Kidney disease with little evidence of diabetes or hypertension with lack of proteinuria. This suggests that kidney disease is primarily tubulointerstitial

76
Q

What is suggested to be the cause of mesoamerican nephropathy?

A

High amounts of work being done in extreme temperatures with few breaks and little water

77
Q

What is causing the increase in mesoamerican nephropathy?

A

Climate change

78
Q

What is wet bulb globe temperature?

A

A composite index that includes air temperature, solar radiation, wind speed, and humidity

79
Q

How does working in hot conditions decrease blood pressure?

A

Blood volume is lost through sweat and there is redistribution of blood to muscles and skin

80
Q

What impacts the function of macromolecules?

A

Aqueous environments which impact the catalytic rate and affinity

81
Q

What do solutes do to proteins?

A

Interact with them which impacts their stability and function

82
Q

How does fructose impact mesoamerican nephropathy?

A

Fructose is a precursor to uric acid, which is causing major damage to the kidneys.

83
Q

What is high intracellular potassium important for?

A

Maintaining cell volume, regulation of pH, and enzyme function

84
Q

What happens when potassium is first ingested?

A

There is transient movement into cells for storage before it can be excreted by the kidneys. This is important for buffering K

85
Q

How does the distal nephron respond to low dietary potassium?

A

It reabsorbs K

86
Q

How does the distal nephron respond to high or normal dietary potassium?

A

It secretes potassium

87
Q

How does the proximal tubule reabsorb potassium?

A

Paracellularly

88
Q

How does the thick ascending limb move potassium?

A

NKCC mediated transport

89
Q

How do the different cells of the cortical collecting tubule differ in their response to potassium?

A

Principal cells secrete potassium via Na-KATPase and ENaC

a-Intercalated cells reabsorb potassium

90
Q

How does the concentration of urine change in the loop of henle?

A

The descending limb is permeable to water so filtrate concentrates
The ascending limb is impermeable to water so the filtrate dilutes

91
Q

How does the countercurrent multiplier system show positive feedback?

A

The more transport by the ascending limb, the more concentrated the descending limb fluid gets. This facilitates transport by the ascending limb

92
Q

What draws excess water and solutes from the medulla?

A

The vasa recta blood vessels

93
Q

Where do loop diuretics work?

A

On NKCC in the apical membrane of the thick ascending loop of henle, which prevents the generation of the hypertonic medulla

94
Q

How does AVP work?

A

Interacts with receptors to activate the adenylate cyclase pathway, which results in insertion of aquaporin channels into the apical membrane