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Physiology > Nephrology > Flashcards

Nephrology Flashcards

1
Q

How can solute exchange occur?

A

1) Passive exchange

2) Bulk flow

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2
Q

What is passive exchange?

A

Exchange of glucose, O2, and CO2 between interstitial fluid and plasma membranes of cells

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3
Q

What is bulk flow?

A

Movement of water and a number of solutes across the capillary wall via pores

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4
Q

What does bulk flow determine?

A

The distribution of ECF volume between vasculature and IF compartments

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5
Q

What are the main components of the body fluid?

A

ICF and ECF (plasma and IF)

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6
Q

What percent of body fluid does ICF make up?

A

67%

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7
Q

What percent of body fluid does ECF make up?

A

33%

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8
Q

What percent of ECF is made up of plasma?

A

20%

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9
Q

What percent of ECF is made up of IF?

A

80%

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10
Q

What is interstitial fluid?

A

An intermediary between the fluids in capillaries and the fluids within the cells of the tissues

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11
Q

True or false: H2O and all plasma constituents are actively exchanged across the capillary wall

A

False, H2O and all plasma constituents are continuously and freely exchanged passively

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12
Q

True or false: plasma and IF are nearly identical in composition

A

True

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13
Q

What is different between IF and plasma?

A

Plasma contains plasma proteins while IF does not

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14
Q

What happens if a change occurs in plasma and why?

A

A change in IF will also occur because they are constantly mixing

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15
Q

True or false: ICF and ECF are nearly identical in composition

A

False, their compositions differ greatly due to the highly selective plasma membrane

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16
Q

What statement can be made about any control mechanism that operates on plasma?

A

It in effect regulates the entire ECF

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17
Q

True or false: ICF is influenced by changes in the ECF

A

True

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18
Q

To what extent is ICF influenced by changes in ECF?

A

To the extent permitted by the permeability of membrane barriers surrounding the cells

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19
Q

Why must ECF volume be regulated?

A

To maintain blood pressure

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20
Q

Why must ECF solute concentration be regulated?

A

To prevent swelling or shrinking of cells

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21
Q

What are negligible compartments of body fluid?

A

Lymph and transcellular fluids

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22
Q

What are transcellular fluids?

A

Fluid that is secreted by specific cells into a particular body cavity to perform a specialized function

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23
Q

What are 4 examples of transcellular fluids?

A

1) CSF
2) Synovial fluid
3) Serous fluids (peritoneal, pericardial)
4) Digestive juices

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24
Q

True or false: transcellular fluids reflect changes in the body’s fluid balance

A

False, they do not reflect changes in the body’s fluid balance

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25
Q

When would transcellular fluids reflect fluid imbalances?

A

Under pathological conditions

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26
Q

What occurs in glaucoma?

A

Too much intraocular fluid pressure that pushes against the inner neural layer of the retina causing retina and optic nerve damage

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27
Q

How is glaucoma treated?

A

Any means that can decrease fluid pressure

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28
Q

What is dehydration?

A

Fluid loss, either loss of water or loss of water and solutes together

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29
Q

What is hypotonic hydration?

A
  • Cellular overhydration or renal deficiency
  • ECF is diluted causing low solute concentration promoting net osmosis into tissue cells
  • Increased amount of fluid in all compartments
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30
Q

What can hypotonic hydration cause?

A

Nausea, vomiting, muscular cramping, and cerebral edema ultimately leading to death

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31
Q

How is hypotonic hydration treated?

A

Administration of IV hypertonic saline solution

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32
Q

What is edema?

A

An atypical accumulation of fluid in the IF leading to tissue (not cell) swelling

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33
Q

What does edema cause?

A

Increased distance that fluids must diffuse between the blood and cells

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34
Q

What can cause edema?

A
  • Increase in ultrafiltration
  • Decrease in absorption
  • Decrease in lymphatic return
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35
Q

What percentage of most tissues is made up of water?

A

70-80%

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36
Q

What percentage of plasma does water make up?

A

93%

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37
Q

What percentage of fat is made up of water?

A

10%

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38
Q

What percentage of bone is made up of water?

A

22%

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39
Q

How can body composition be estimated?

A

1) Bioelectrical impedance analysis
2) Hydrostatic weighing
3) Magnetic resonance imaging (MRI)
4) Mirror

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40
Q

True or false: once urine is formed by the kidneys it can be altered in composition or volume

A

False, it cannot be altered

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41
Q

What can prostatic hypertrophy cause?

A

Partial or complete occlusion of the urethra

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42
Q

How do kidneys contribute to homeostasis?

A

1) Maintain plasma volume
2) Regulate H2O and ion concentrations
3) Acid-base balance
4) Eliminate all metabolic wastes (except CO2)
5) Endocrine

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43
Q

What is also regulated when the kidneys regulate plasma volume?

A

Systemic blood pressure

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44
Q

How do the kidneys regulate ion and H2O concentrations?

A
  • Adjust for wide variations in ingestion of water, salt, and other electrolytes
  • Adjust to adnormal losses through heavy sweating, vomiting, diarrhea, or hemorrhage
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45
Q

What 2 sections is the kidney divided into?

A

1) Renal cortex

2) Renal medulla

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46
Q

What is found in the renal medulla?

A

Renal pyramids

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47
Q

What is a nephron?

A

The basic functional unit of the kidney that forms urine

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48
Q

How many nephrons are found in one kidney?

A

More than 1 million

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49
Q

What does the nephron regulate and how?

A

Water and solutes by filtering the blood under pressure and then reabsorbing necessary fluid and molecules back into the blood while secreting other unneeded molecules

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50
Q

What is the main function of a nephron?

A

Maintain consistency in the ECF composition, which produces urine

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51
Q

What 2 basic components can a nephron be divided into?

A

1) Tubular component

2) Vascular component

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52
Q

What is a nephron composed of?

A

1) Renal corpuscle

2) Renal tubules

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53
Q

Where is the renal corpuscle found?

A

In the renal cortex

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54
Q

What does the renal corpuscle do?

A

Filters blood (first step in urine formation)

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55
Q

What type of fluid does the renal corpuscle filter?

A

Fluid that is almost identical in composition to plasma

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56
Q

What is the renal corpuscle composed of?

A

1) Glomerulus
2) Bowman’s capsule
3) Filtration membrane

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57
Q

What is the glomerulus?

A

A capillary bed

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58
Q

Where is the Bowman’s capsule found?

A

Surrounding the glomerulus

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59
Q

What does the Bowman’s capsule do?

A

Collects filtrate from the glomerulus

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60
Q

What are the 2 layers of the Bowman’s capsule?

A

1) Outer layer

2) Inner layer

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61
Q

What is found in the inner layer of the Bowman’s capsule?

A

Podocytes wrapped around the glomerular capillaries

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62
Q

What does the filtration membrane consist of?

A

1) Glomerular endothelium
2) Basement membranes
3) Podocytes (of Bowman’s capsule)

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63
Q

What type of cells are found in the glomerular endothelium?

A

Simple squamous with pores (fenestrations)

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64
Q

What are podocytes?

A

Projections that “cling” to the glomerulus

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65
Q

What are the 4 parts of a renal tubule?

A

1) Proximal convoluted tubule
2) Loop of Henle
3) Distal convoluted tubule
4) Collecting ducts

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66
Q

Where is the proximal convoluted tubule found?

A

Renal cortex

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67
Q

Where is the Loop of Henle found?

A

Renal medulla

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68
Q

Where is the distal convoluted tubule found?

A

Renal cortex

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69
Q

Where are collecting ducts found?

A

Renal cortex and renal medulla

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70
Q

How many nephrons drain into one collecting duct?

A

About 8

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71
Q

What do collecting ducts do?

A

Drain to the renal pelvis

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72
Q

What are the 2 types of nephrons?

A

1) Cortical (80%)

2) Juxtamedullary (20%)

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73
Q

Describe cortical nephrons

A
  • Renal corpuscle near kidney surface in cortex

- Short loop of Henle in outer medulla

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74
Q

Describe juxtamedullar nephrons

A
  • Renal corpuscle in cortex near medulla

- Long loop of Henle that penetrates deep into medulla

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75
Q

With respect to the renal blood supply, what does the aorta branch into?

A

Renal arteries

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76
Q

With respect to the renal blood supply, what do the renal arteries branch into?

A

Segmental arteries

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77
Q

With respect to the renal blood supply, what do the segmental arteries branch into?

A

Interlobar arteries

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78
Q

With respect to the renal blood supply, what do the interlobar arteries branch into?

A

Arcuate arteries

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79
Q

What is significant about the arcuate arteries?

A

Medulla-cortex junction

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80
Q

With respect to the renal blood supply, what do the arcuate arteries branch into?

A

Cortical radiate arteries

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81
Q

With respect to the renal blood supply, what do the cortical radiate arteries branch into?

A

Afferent arterioles

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82
Q

With respect to the renal blood supply, what do the afferent arterioles feed into?

A

Glomeruli

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83
Q

With respect to the renal blood supply, what exits the glomeruli?

A

Efferent arterioles

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84
Q

What is significant about the efferent arterioles of the glomeruli?

A

They are the only arterioles that drain from capillaries

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85
Q

With respect to the renal blood supply, what do the efferent arterioles branch into?

A

Peritubular capillaries and vasa recta

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86
Q

What are peritubular capillaries?

A

Cortical nephrons in renal cortex

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87
Q

What are vasa recta?

A

Juxtaglomerular nephrons in the renal medulla

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88
Q

With respect to the renal blood supply, what do the peritubular capillaries and vasa recta form when they join?

A

Cortical radiate veins

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89
Q

With respect to the renal blood supply, what do the cortical radiate veins become?

A

Arcuate veins

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90
Q

With respect to the renal blood supply, what do the arcuate veins become?

A

Interlobar veins

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91
Q

With respect to the renal blood supply, what do the interlobar veins become?

A

Renal veins

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92
Q

With respect to the renal blood supply, what do the renal veins become?

A

Inferior vena cava

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93
Q

What is the function of the juxtaglomerular complex?

A

Regulates filtrate formation

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94
Q

What does the ascending limb of the juxtaglomerular complex pass through?

A

The fork formed by the 2 afferent and efferent arterioles

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95
Q

What is special about the juxtaglomerular complex?

A

Is the point of contact between the end of the ascending limb and the afferent and efferent arterioles at the renal corpuscle of the same nephron

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96
Q

What are the 2 portions of the juxtaglomerular complex?

A

1) Tubular portion

2) Vascular portion

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97
Q

What does the tubular portion of the juxtaglomerular complex contain?

A

Macula densa, which are modified (tall and narrow) ascending limb cells

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98
Q

What does the vascular portion of the juxtaglomerular complex contain?

A

Granular juxtaglomerular cells, which are the afferent and efferent arteriolar portion

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99
Q

What is the function of granular juxtaglomerular cells?

A
  • Monitor BP

- Contain renin

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100
Q

At rest, what percent of cardiac output is going to the kidneys?

A

About 20%

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101
Q

What 3 basic processes occur in the nephron to form urine?

A

1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion

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102
Q

Where does glomerular filtration occur?

A

Glomerular capillaries

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103
Q

What percent of plasma in glomerulus is filtered into the Bowman’s capsule?

A

20%

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104
Q

How is plasma in the glomerules filtered into the Bowman’s capsule?

A

Bulk flow (pressure gradient) across the filtration membrane

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105
Q

How much filtrate is collectively formed per minute?

A

125 mL

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106
Q

How many times is the entire plasma volume filtered per day?

A

About 65 times per day

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107
Q

What is filtrate?

A

Plasma minus large proteins

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108
Q

What makes up filtrate?

A

Water, glucose, amino acids, vitamins, ions, urea, and small amounts of small proteins

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109
Q

What is the pH of filtrate?

A

About 7.45

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110
Q

What is albuminuria

A
  • When the filtration membrane allows excessive albumin into the urine
  • Occurs in some renal disease
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111
Q

What are the 4 types of pressure that occur in glomerular filtration?

A

1) Glomerular hydrostatic pressure
2) Plasma-colloid osmotic pressure
3) Capsular hydrostatic pressure
4) Capsular osmotic pressure

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112
Q

What is the normal value of glomerular hydrostatic pressure and does it favour or oppose filtration?

A
  • 55 mmHg

- Favoured

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113
Q

What is the normal value of plasma-colloid osmotic pressure and does it favour or oppose filtration?

A
  • 30 mmHg

- Opposed

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114
Q

What is the normal value of capsular hydrostatic pressure and does it favour or oppose filtration?

A
  • 15 mmHg

- Opposed

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115
Q

What is the normal value of capsular osmotic pressure and does it favour or oppose filtration?

A
  • 0 mmHg

- Favoured

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116
Q

What is value of net filtration pressure?

A

(55 + 0) - (30 + 15) = 10 mmHg

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117
Q

What is the normal glomerular filtration rate?

A

About 180 L/day of filtrate

118
Q

What happens to about 1% of filtered volume?

A

It remains at the end of collecting duct

119
Q

Why must GFR be regulated?

A

To keep GFR from changing when MAP changes

120
Q

How is GFR regulated?

A

1) Autoregulation (intrinsic regulation), which is aimed at preventing spontaneous changes in GFR
2) Extrinsic symp. control, which is aimed at long-term regulation of MAP

121
Q

How do both control mechanisms work to regulate GFR?

A

Adjust glomerular blood flow by regulating the radius and thus the resistance of the afferent arteriole

122
Q

How does autoregulation work to regulate GFR?

A

1) Myogenic mechanism

2) Juxtaglomerular apparatus

123
Q

Describe the myogenic mechanism of GFR regulation

A
  • Increased MAP = stretch = afferent arteriole smooth muscle contracts = prevents increased BP in glomerular caps = GFR stays normal
  • Vice versa
124
Q

Describe the juxtaglomerular apparatus of GFR regulation

A
  • Changes in GFR = changes in flow of flitrate past macula dense cells that detect changes in salt levels of fluid flowing past them
  • Increased GFR = more fluid is filtered = more salt delivery to macula densa cells = release ATP = extracellular degradation forms adenosine = afferentarteriole v/c = increased GFR to normal
  • Decreased salt delivery to macula densa cells = decreased release of ATP = decreased extracellular adenosine = afferent arteriole v/d = increased GFR to normal
125
Q

True or false: intrinsic/autoregulation overrides extrinsic regulation of GFR

A

False, extrinsic overrides intrinsic regulation of GFR

126
Q

What can extrinsic regulation do to GFR?

A

Can change it on purpose even when MAP is within the autoregulatory range

127
Q

What mediates extrinsic control of GFR?

A

The sympathetic nervous system

128
Q

How does extrinsic control regulate GFR?

A
  • SNS causes arteriole v/c
  • Afferent causes decreased flow into glomerules; efferent causes blood to back up in glomerulus
  • Moderate SNS activation causes both to balance and GFR not to change dramatically
129
Q

What can extreme stress do to GFR?

A

Can decrease it

130
Q

What can cause changes to plasma-colloid osmotic pressure (PCOP)?

A

1) Dehydration causes increased PCOP, which causes decreased GFR
2) Severe burns causes decreased PCOP, which causes increased GFR

131
Q

What can cause a change in capsular hydrostatic pressure (CHP)?

A

Urinary tract obstruction (ex: kidney stones, enlarged prostate) causes increased CHP, which causes decreased GFR

132
Q

What percent of filtrate is reabsorbed?

A

99%

133
Q

Where is filtrate reabsorbed from and where to?

A
  • From tubules

- Into peritubular and vasa recta capillaries

134
Q

True or false: all consituents are at the same concentration in the glomerular filtrate and in the plasma

A

False, plasma proteins are at different concentrations in filtrate and plasma

135
Q

What are the 2 steps of reabsorption?

A

1) Active or passive transport from tubule fluid to renal IF

2) Active or passive transport from IF to blood

136
Q

How many barriers must a reabsorbed substance cross?

A

5

137
Q

When will absorption be considered active?

A

If any one of the steps in transepithelial transport of a substance requires energy

138
Q

What is an example of active reabsorption?

A

An active Na/K pump in the basolateral membrane is essential for Na reabsorption

139
Q

What percent of total energy spent by the kidneys is used for Na transport?

A

80%

140
Q

What substances generally require active reabsorption?

A

Na, other ions, glucose, and amino acids

141
Q

What substance generally require passive reabsorption?

A

Cl, water, and urea

142
Q

What is the primary role of the proximal convoluted tubule in the process of reabsorption?

A

Fluid and electrolyte transport

143
Q

What percent of glucose and amino acids are reabsorbed by sodium?

A

100%

144
Q

How does sodium reabsorb glucose and amino acids?

A

Dependent, secondary active transport

145
Q

What percent of sodium is reabsorbed by active transport?

A

67%

146
Q

What is the final result of the proximal convoluted tubule in the process of reabsorption?

A
  • Large amount of solute is removed and filtrate volume is decreased
  • Filtrate is isotonic to plasma
147
Q

What is the primary role of the loop of Henle in the process of reabsorption?

A

Reabsorbs into vasa recta

148
Q

What is reabsorbed in the descending limb of the loop of Henle?

A

Water only

149
Q

What is reabsorbed in the ascending limb of the loop of Henle?

A

25% NaCl only

150
Q

What is reabsorbed in the distal convoluted tubule and collecting duct and what does this cause?

A
  • 8% Na; causes increased aldosterone and decreased atrial natriuretic peptide (ANP)
  • Facultative reabsorption of water; causes increased ADH
151
Q

What 4 things do nephrons normally absorb?

A
  • 99% of filtered water
  • 99.5% of filtered NaCl
  • 100% of filtered glucose
  • 50% of filtered urea
152
Q

What may be found in filtrate?

A

Trace amounts of amino acids and proteins (depending on diet)

153
Q

What should never be found in filtrate?

A

Glucose or blood

154
Q

Where does tubular secretion occur?

A

From peritubular blood into filtrate

155
Q

What are the main substances that are secreted in tubular secretion?

A
  • Wastes such as urea, uric acid, and some hormones
  • Potassium
  • H+ which helps maintain blood plasma pH
156
Q

What does the countercurrent multiplier mechanism permit?

A

Excretion of urine that is dilute or concentrated (100 - 1200 mOsm/L)

157
Q

What does the countercurrent multiplier mechanism produce?

A

A vertical osmotic gradient (solute concentration increases in ISF as you move deeper into the medulla)

158
Q

What produces the vertical osmotic gradient?

A

Juxtamedullary nephrons

159
Q

What 3 things occur within the loop of Henle with respect to the countercurrent multiplier mechanism?

A

1) Filtrate moves down descending limb and water moves into ISF by osmosis
2) Highly concentrated filtrate enters ascending limb
3) Filtrate leaving ascending limb is lower in osmolarity than plasma

160
Q

How is NaCl pumped out of the ascending limb of the loop of Henle?

A

Against the concentration gradient

161
Q

What is the descending limb of the loop of Henle permeable and impermeable to?

A
  • Permeable to water

- Impermeable to NaCl

162
Q

What is the ascending limb of the loop of Henle permeable and impermeable to?

A
  • Permeable to NaCl

- Impermeable to water

163
Q

What is filtrate in the ascending limb lower in osmolarity than plasma?

A
  • Ascending limb is impermeable to water

- Ascending limb NaCl pump

164
Q

What occurs within the early distal convoluted tubule with respect to the countercurrent multiplier mechanism?

A
  • More salt is removed from filtrate (reabsorbed)

- No water removed, therefore 100 mOsm/L when enters late DCT

165
Q

Concentrated urine means a ______ blood pressure

A

Low

166
Q

What happens in the distal convoluted tubule and collecting duct to make urine concentrated?

A
  • Aldosterone increases Na reabsorption

- ADH increases facultative water reabsorption

167
Q

What is the highest concentration that urine can be?

A

1200 mOsm/L

168
Q

Dilute urine means a ______ blood pressure

A

High

169
Q

What happens in the distal convoluted tubule and collecting duct to make urine dilute?

A

ANP inhibits ADH and aldosterone, making it impermeable to water and NaCl

170
Q

What is the average amount of urine produced per day?

A

1 - 1.5 L

171
Q

What are 2 regulators of urine?

A

1) Hormonal

2) SNS

172
Q

What 4 hormonal controls regulate urine concentration?

A

1) Renin-angiotensin system
2) ADH
3) Aldosterone
4) ANP

173
Q

How does the renin-angiotensin system regulate urine concentration?

A

Granular cells of the juxtaglomerular apparatus secrete renin

174
Q

What causes juxtaglomerular cells to secrete renin?

A
  • Decreased blood pressure or ECF volume
  • Decreased NaCl in filtrate
  • Increased SNS activity
175
Q

Granular cells act as _______

A

Intrarenal baroreceptors

176
Q

How is decreased NaCl in filtrate detected?

A

At the macula densa which trigger the granular cells

177
Q

Granular cells are innervated by the ______ NS

A

Sympathetic

178
Q

What are 4 general causes of increased angiotensin 2?

A

1) Increased NaCl reabsorption and K secretion
2) Increased systemic BP (MAP)
3) Decreased GFR
4) Increased facultative water reabsorption

179
Q

What does ADH cause?

A

Increased facultative reabsorption of water in the DCT and collecting ducts

180
Q

What percent of water reabsorption is obligatory in the proximal convoluted tubule?

A

65%

181
Q

What percent of water reabsorption is obligatory in the distal convoluted tubule and collecting duct?

A

It is variable based on the secretion of ADH

182
Q

What does ADH secretion do to tubule cells?

A

Increases the permeability of tubule cells to water

183
Q

Where does an osmotic gradient exist and why?

A

Outside the tubules from the transport of water by osmosis

184
Q

What 4 things cause ADH to increase?

A

1) Low blood pressure/volume
2) Increased plasma osmolarity
3) Increased angiotensin 2
4) Nicotine or nausea

185
Q

What 5 things cause ADH to decrease?

A

1) High blood pressure/volume
2) Decreased plasma osmolarity
3) Decreased angiotensin 2
4) Increased ANP
5) Alcohol and caffeine

186
Q

When does aldosterone increase?

A

When angiotensin 2 increases and plasma K is high

187
Q

What does aldosterone do with respect to genes?

A

Turn on genes that increase the number of Na/K ATPase in DCT and CD, which causes increased Na reabsorption and K secretion

188
Q

What is caused by Na reabsorption in late DCT and CD?

A

Water follows and Cl follows

189
Q

What is the net result of aldosterone on regulation of urine concentration?

A

Greater passive inward flux of Na into the tubular cells from the lumen and increased active pumping of Na out of the cells into the plasma (Increased Na reabsorption with Cl following)

190
Q

What happens to nephrons in the absence of aldosterone?

A

Nephrons can rapidly remove excess Na from the body

191
Q

How much Na can be lost with complete absence of aldosterone?

A

20 grams per day

192
Q

How much Na can be lost with maximum secretion of aldosterone?

A

0 grams because all filtered Na will be reabsorbed

193
Q

What 2 mechanisms can cause aldosterone secretion?

A

1) Increased plasma K

2) Decreased Na, ECF volume, or arterial pressure

194
Q

What causes ANP to be secreted?

A
  • Increased blood pressure
  • Hypervolemia (too much fluid in the blood),
  • Exercise
195
Q

What does ANP cause?

A
  • Inhibition of Na reabsorption, thus increasing Na excretion
  • Inhibition of renin, angiotensin 2 and aldosterone
  • Increased GFR by v/d of afferent arteriole
  • Decreased CO by inhibiting symp nervous activity to heart and blood vessels
196
Q

What can exacerbate a failing heart and why?

A
  • Increased salt and water reabsorption

- Failing heart means CO is reduced and MAP is low, which means angiotensin 2 is increased

197
Q

What do diuretics do?

A

Inhibit tubular reabsorption of Na, increasing water loss and reducing excess EFC

198
Q

What else besides diuretics can inhibit salt and fluid reabsorption?

A
  • ACE inhibitors

- Aldosterone receptor blockers

199
Q

What does increased sympathetic NS impulse cause with respect to regulation of urine concentration?

A

Afferent and efferent arterioles constrict

200
Q

What does decreased sympathetic NS impulse cause with respect to regulation of urine concentration?

A

Afferent and efferent arterioles relax

201
Q

What happens when MAP increases with respect to regulation of urine concentration?

A

Flow to kidney increases causing v/c in spite of decreased SNS, renin, and angiotensin 2 and increased ANP, meaning GFR returns to resting

202
Q

What does a lack of ADH and aldosterone mean for urine?

A

It will be dilute, so blood volume will decrease and MAP will decrease

203
Q

What happens if there is a large decrease in blood pressure or volume?

A

V/c signals get stronger than intrinsic mechanisms, so GFR decreases

204
Q

What are the normal constituents of urine?

A
  • Water
  • Nitrogenous wastes
  • Regulated substances (ex: ions)
205
Q

What type of nitrogenous wastes are found in urine?

A
  • Urea
  • Uric acid
  • Creatinine
206
Q

How is urea produced?

A

From amino acid metabolism

207
Q

What percent of urea is reabsorbed?

A

About 50%

208
Q

How is uric acid produced?

A

From nucleic acid breakdown

209
Q

What percent of uric acid is reabsorbed?

A

About 10%

210
Q

What is gout?

A

When uric acid accumulates between joints because it is poorly water soluble

211
Q

What are kidney stones made of?

A

Crystallized uric acid

212
Q

How is creatinine produced?

A

From breakdown of creatine in skeletal muscle

213
Q

What percent of creatinine is reabsorbed?

A

None because production and excretion is constant

214
Q

What are creatinine levels used to estimate?

A

GFR, which can indicate kidney disease before symptoms occur

215
Q

What is the normal pH range of urine?

A

4.5 - 8

216
Q

What are 3 abnormal constituents of urine?

A

1) Proteins

2) Glucose

217
Q

What is another name for proteinuria?

A

Albuminuria

218
Q

What causes albuminuria?

A

Increased permeability of glomerules due to heavy metals or glomerulonephritis

219
Q

What is glycosuria?

A

When glucose is present in urine

220
Q

What are 5 causes of renal failure?

A

1) Infectious organisms
2) Toxic agents
3) Inappropriate immune responses
4) Obstruction of urine flow
5) Insufficient renal blood supply

221
Q

What is urinary incontinence?

A

Inability to prevent discharge of urine

222
Q

What is renal plasma clearance?

A

The volume of plasma cleared of a substance in one minute

223
Q

What is renal plasma clearance used for?

A

To estimate the time a substance remains in blood

224
Q

What substance can be used to estimate GFR and why?

A
  • Inulin

- Is filtered but not reabsorbed, secreted, or metabolized, therefore the amount in urine = amount filtered

225
Q

What does it mean if plasma clearance is less than GFR of a substance and what are 2 examples of this?

A
  • The substance is reabsorbed from filtrate

- Ex: urea and glucose

226
Q

What does it mean if plasma clearance is greater than GFR of a substance and what are 2 examples of this?

A
  • Substance is secreted into filtrate

- Ex: penicillin and H+

227
Q

What does acid-base balance refer to?

A

Precise regulation of free H+ concentration in body fluids

228
Q

What are acids?

A

A group of H+ containing substances that dissociate in solution to release free H+ and anions

229
Q

What are bases?

A

A group of substances that combine with free H+ and remove it from solution

230
Q

Where does most H+ in the body come from?

A

Metabolic activities

231
Q

What is acidosis?

A

When the body pH is between 6.8 - 7.35

232
Q

What is alkalosis?

A

When the body pH is between 7.45 - 8

233
Q

What are 3 sources of H+ in the body?

A

1) Carbonic acid formation
2) Inorganic acids produced during breakdown of nutrients
3) Organic acids resulting from intermediary metabolism

234
Q

How is carbonic acid formed?

A

CO2 + H2O

235
Q

What is an example of an inorganic acid that is produced during breakdown of nutrients?

A

Sulphuric and phosphoric acids are produced when sulphur and phosphorus from dietary proteins are broken down

236
Q

What are 3 examples of organic acids resulting from intermediary metabolism?

A

1) Fatty acids
2) Amino acids
3) Lactic acid

237
Q

What are 3 consequences of H+ fluctuations in the body?

A

1) Changes in excitability of nerve and muscle cells
2) Marked influence on enzyme activity
3) Influence on K+ levels in body

238
Q

What does acidosis cause to the CNS?

A

Depression of CNS

239
Q

What does alkalosis cause to the PNS?

A

Overexcitability to PNS and later to the CNS

240
Q

Why do H+ fluctuations have an influence on enzyme activity?

A

Enzymes have a narrow range of temperature and pH where their activity can be maximal, and H+ is a factor in the enzyme staying within these ranges

241
Q

Why do H+ fluctuations have an influence on K+ levels in the body?

A
  • When reabsorbing Na from filtrate, tubular cells secrete either K+ or H+ in exchange
  • An increased rate of one decreases the rate of the other
242
Q

What are the 3 lines of defense against changes in H+ concentration?

A

1) Chemical buffer systems
2) Respiratory mechanism of pH control
3) Renal mechanism of pH control

243
Q

How do chemical buffer system prevent changes in H+ concentration?

A
  • Minimize changes in pH by binding with or yielding free H+

- Act within fractions of a second

244
Q

True or false: chemical buffer systems eliminate H+ from the body

A

False, they are removed from solution by being incorporated within one member of the buffer pair

245
Q

What is the first line of defense for acid-base balance?

A

Chemical buffer systems

246
Q

What are the 4 buffer systems of the body?

A

1) Carbonic acid/bicarbonate
2) Protein buffer system
3) Hemoglobin buffer system
4) Phosphate buffer system

247
Q

How do carbonic acid and bicarbonate work as a buffer system?

A

Carbonic acid and bicarbonate are abundant in the ECF with the kidneys regulating bicarbonate and CO2 in the lungs (generating carbonic acid)

248
Q

What is unique about the carbonic acid/bicarbonate buffer system?

A

Is the primary ECF buffer for noncarbonic acids

249
Q

What is the most plentiful buffer system in the body?

A

Protein buffer system

250
Q

What is the primary ICF buffer?

A

Protein buffer system

251
Q

True or false: protein buffer systems contain body acidic and basic groups

A

True

252
Q

What is unique about the hemoglobin buffer system?

A

Primary buffer against carbonic acid changes

253
Q

What is unique about the phosphate buffer system?

A

Can switch Na for H+

254
Q

The phosphate buffer system has a low concentration in ______

A

ECF

255
Q

What is the most important urinary buffer and why?

A
  • Phosphate buffer system
  • There is normally excess phosphate in diet, so it remains in tubular fluid to be excreted and buffers urine as it is being formed by removing H+
256
Q

True or false: there are no buffer systems present in tubular fluid

A

True

257
Q

True or false: little to none bicarbonate and CO2 are reabsorbed

A

False, most or all of the filtered bicarbonate and CO2 are reabsorbed

258
Q

Why must H+ be removed from the body if buffer systems exist?

A

Because each buffer system has a limited capacity to soak up H+

259
Q

What would happen if H+ was never removed from the body?

A

All the body-fluid buffers would already be bound with H+ and there would be no further buffering ability

260
Q

What is the second line of defense in acid-base balance?

A

Respiratory system

261
Q

How does the respiratory system work to balance acids and bases?

A

Removes CO2, therefore also removing H+

262
Q

What will the respiratory system do when H+ is too high?

A

Hyperventilate

263
Q

What will the respiratory system do when H+ is too low?

A

Hypoventilate

264
Q

What is the third line of defense in acid-base balance?

A

Renal system

265
Q

How does the renal system work to balance acids and bases?

A

Eliminates H+ from metabolically produced acids by secreting H+ into tubule

266
Q

How does the majority of H+ enter urine?

A

Via tubular secretion

267
Q

What parts of the nephron secrete H+?

A

Proximal convoluted tubule, distal convoluted tubule, and collecting tubules

268
Q

When does the respiratory system begin to work with respect to acid-base balance?

A

Minutes

269
Q

When does the renal system begin to work with respect to acid-base balance?

A

Hours to days

270
Q

What can H+ energy-dependent carriers in tubular cells do?

A

Can secrete H+ against a concentration gradient until the tubular fluid is 800 times as acidic as the plasma

271
Q

What is needed for H+ secretion to continue?

A

It must be buffered in the tubular fluid

272
Q

What happens to make bicarbonate be considered “reabsorbed”?

A

One filtered bicarbonate disappears from the tubular fluid (through combination with H+), and one bicarbonate appears in the plasma (through combination of OH and CO2)

273
Q

What occurs once all filtered bicarbonate has combined with secreted H+?

A
  • Further secreted H+ is excreted in the urine, primarily in association with urinary buffers
  • This is coupled with the appearance of new bicarbonate in plasma, which represent a new gain as opposed to a replacement of filtered bicarbonate
274
Q

What happens once phosphate ions have soaked up H+?

A

The tubular cells secrete ammonia

275
Q

What happens once ammonia is in the tubule?

A

It binds with H+ to form ammonium

276
Q

True or false: ammonium is not very permeable so it remains in tubular fluid

A

True

277
Q

What synthesizes ammonia?

A

The amino acid glutamate within tubular cells

278
Q

What can cause acid-base inbalances?

A

Respiratory dysfunction of metabolic disturbances

279
Q

What are the 4 general categories of acid-base imbalances?

A

1) Respiratory acidosis
2) Respiratory alkalosis
3) Metabolic acidosis
4) Metabolic alkalosis

280
Q

What is respiratory acidosis?

A

Abnormal CO2 retention arising from hypoventilation

281
Q

What are 4 possible causes of respiratory acidosis?

A

1) Lung disease
2) Depression of respiratory centre by drugs or disease
3) Nerve/muscle disorders that reduce respiratory muscle activity
4) Holding breath

282
Q

What are 2 compensations to counteract respiratory acidosis?

A

1) Chemical buffers immediately take up additional H+

2) Kidneys

283
Q

What is respiratory alkalosis?

A

Excessive loss of CO2 from body as a result of hyperventilation

284
Q

What are 4 possible causes of respiratory alkalosis?

A

1) Fever
2) Anxiety
3) Aspirin poisoing (hyperstimulation of the respiratory centre)
4) Physiologic mechanisms at high altitude

285
Q

What are 2 compensations to counteract respiratory alkalosis?

A

1) Chemical buffer systems liberate H+

2) Kidneys conserve H+ and excrete more bicarbonate

286
Q

What is metabolic acidosis?

A
  • Fall in bicarbonate concentration

- Includes all types of acidosis other than those caused by excess CO2 in body fluids

287
Q

What are 4 possible causes of metabolic acidosis?

A

1) Severe diarrhea
2) Diabetes (ketoacidosis from fatty acid breakdown)
3) Strenuous exercise
4) Uremic acidosis (renal failure)

288
Q

What are 3 compensations to counteract metabolic acidosis?

A

1) Buffers take up extra H+
2) Lungs blow off additional H+ generating CO2
3) Kidneys excrete more H+ and conserve more bicarbonate

289
Q

What is metabolic alkalosis?

A
  • Elevation in bicarbonate concentration

- Reduction in plasma pH caused by relative deficiency of noncarbonic acid

290
Q

What are 2 possible causes of metabolic alkalosis?

A

1) Vomiting – loss of acidic gastric juices

2) Ingestion of alkaline drugs – extra is absorbed in the digestive system into blood plasma

291
Q

What are 3 compensations to counteract metabolic alkalosis?

A

1) Chemical buffer systems immediately liberate H+
2) Ventilation is reduced
3) Kidneys conserve H+ and excrete excess bicarbonate in the urine

Physiology (7 decks)

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