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Clinical Chemistry > L.6 Renal Physiology & Function > Flashcards

L.6 Renal Physiology & Function Flashcards

1
Q

What is one function of the kidneys?

A

Excretion of waste products

Includes metabolic waste products like urea, creatinine, uric acid, and xenobiotics such as drugs and toxins.

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2
Q

What are the metabolic waste products excreted by the kidneys?

A

Urea, creatinine, uric acid

These are byproducts of metabolism that need to be removed from the body.

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3
Q

Define xenobiotics.

A

Chemical compounds foreign to the body

Includes drugs and toxins that the kidneys help to excrete.

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4
Q

What is one aspect of homeostatic regulation performed by the kidneys?

A

Regulation of water and electrolyte balance

This is crucial for maintaining the body’s internal environment.

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5
Q

What is regulated by the kidneys to maintain acid-base balance?

A

Blood pH levels

The kidneys help to regulate the levels of hydrogen and bicarbonate ions.

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6
Q

What hormone is produced by the kidneys that helps regulate blood pressure?

A

Renin

Renin is part of the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure.

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7
Q

What is the role of erythropoietin produced by the kidneys?

A

Stimulates red blood cell production

Erythropoietin is crucial for maintaining adequate oxygen levels in the blood.

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8
Q

What is activated by the kidneys to help with calcium absorption?

A

Vitamin D

The kidneys convert inactive vitamin D to its active form.

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9
Q

What is the primary function of the glomerulus?

A

Blood filtration

Blood is filtered from the afferent arteriole to the efferent arteriole.

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10
Q

What happens to blood cells and proteins in the glomerulus?

A

They are too large to pass through glomerular capillaries

Only smaller molecules and water pass into the Bowman’s capsule.

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11
Q

What percentage of filtrate is reabsorbed in the proximal tubule?

A

65%

The proximal tubule is key for reabsorption of water, ions, and organic nutrients.

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12
Q

What is reabsorbed in the Loop of Henle?

A

Water and ions

Approximately 15% of the filtrate is reabsorbed here.

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13
Q

What specific ion is reabsorbed in the Loop of Henle?

A

Chloride ions

This process helps in maintaining the osmotic gradient in the kidney.

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14
Q

What percentage of filtrate is reabsorbed in the distal tubule?

A

10%

This segment fine-tunes the reabsorption and secretion of ions.

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15
Q

Which hormone acts in the distal tubule to regulate sodium and potassium balance?

A

Aldosterone

Aldosterone increases sodium reabsorption and potassium secretion.

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16
Q

What percentage of filtrate is reabsorbed in the collecting duct?

A

9%

The collecting duct plays a crucial role in final water reabsorption.

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17
Q

What hormone acts in the collecting duct to regulate water balance?

A

ADH (Antidiuretic Hormone)

ADH promotes the insertion of aquaporin-4 proteins for increased water reabsorption.

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18
Q

Fill in the blank: The primary site of blood filtration in the kidneys is the _______.

A

glomerulus

The glomerulus is essential for the initial step in urine formation.

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19
Q

True or False: The proximal tubule is responsible for the secretion of waste products.

A

True

The proximal tubule reabsorbs nutrients and also secretes waste.

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20
Q

What is the primary function of the kidneys in relation to waste products?

A

To maintain homeostasis by excreting waste products that have no use in the body

Waste products include urea, creatinine, uric acid, ammonia, and bilirubin, along with hormones, drugs, and toxins.

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21
Q

Name five waste products excreted by the kidneys.

A
  • Urea
  • Creatinine
  • Uric acid
  • Ammonia
  • Bilirubin

Other waste products include hormones, drugs, and toxins.

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22
Q

What are the three processes involved in the excretion of waste products?

A
  • Glomerular filtration (ultrafiltration)
  • (Selective) tubular reabsorption
  • (Selective) tubular secretion

The nephron is the functional unit of the kidney responsible for these processes.

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23
Q

What is the filtration rate of the kidneys?

A

≈ 125 ml/min or 180 L/day

Filtration is driven by hydrostatic pressure.

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24
Q

What is the glomerular basement membrane’s charge and its effect on filtration?

A

Negatively charged, repelling negatively charged particles

This charge influences the filtration of solutes based on size and charge.

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25
How much of the cardiac output do the kidneys receive?
≈ 25% ## Footnote This allows for the filtration of blood at a rate of 120 mL per minute.
26
What percentage of the filtrate produced by the kidneys is reabsorbed?
99% ## Footnote 170-180L of filtrate is produced daily, but only 1-2L of urine is excreted.
27
List the substances reabsorbed in the proximal tubule.
* Proteins * Glucose * Amino acids * Bicarbonate * Water * Ions ## Footnote The proximal tubule plays a key role in the reabsorption process.
28
What substances are reabsorbed in the loop of Henle?
* Water * Ions ## Footnote The loop of Henle is crucial for concentrating urine.
29
What ions are mainly fine-tuned during secretion in the kidneys?
* K+ ions * H+ ions * Na+ ## Footnote This process helps regulate blood composition.
30
How is urine pH regulated in the kidneys?
By secreting H+ and NH4+ ions ## Footnote Urine pH can range from 4.5 to 8.0, typically around 6.0.
31
Fill in the blank: The nephron is the _______ unit of the kidney responsible for filtration, reabsorption, and secretion.
[functional]
32
True or False: The kidneys filter blood cells and proteins during glomerular filtration.
False ## Footnote Almost all solutes are filtered, except for blood cells and proteins.
33
What is the typical volume of blood filtered every 40 minutes by the kidneys?
Total blood volume ## Footnote This is based on the rate of 120mL of blood filtered every minute.
34
What mechanisms are involved in the secretion of substances in the kidneys?
* Diffusion * Active transport ## Footnote Diffusion moves solutes from high to low concentration, while active transport moves solutes against a gradient using ATP.
35
How does the kidney correct imbalance in pH?
By removing excess H+ or HCO3- ions and restoring HCO3- ions to the blood ## Footnote Kidney cells produce a constant supply of H+ and HCO3- ions due to their own cell metabolism.
36
What are the two critical systems for control of water and sodium balance?
* Renin-angiotensin-aldosterone system (RAAS) * Antidiuretic hormone (ADH/vasopressin)
37
Where is the juxtaglomerular apparatus (JGA) located?
At the afferent arteriole and distal tubule
38
What does the juxtaglomerular apparatus (JGA) monitor?
Blood pressure and blood volume via the macula densa cells and granular cells
39
What does the juxtaglomerular apparatus (JGA) release in response to low blood pressure?
Renin
40
Define osmolality.
Measurement of moles of solute per kilogram of solvent (mOsm/kg)
41
What does osmotic pressure depend on?
Number of particles; size is not important
42
Why is the importance of kg of solvent emphasized in osmolality?
Because osmolality is dominated by small molecules like Na+, K+, Cl-, HCO3-
43
What is the osmolar gap?
Difference between measured and calculated osmolality
44
What is the formula for calculated osmolality?
2[Na+] + [glucose] + [urea] + 2[K+]
45
What monitors blood osmolality?
Osmoreceptors in the hypothalamus ## Footnote These receptors play a crucial role in detecting changes in blood osmolality.
46
What hormone is released by the pituitary gland in response to high blood osmolality?
ADH (Antidiuretic Hormone) ## Footnote ADH helps regulate water balance in the body.
47
What proteins are inserted into the collecting duct by ADH?
Aquaporin-4 proteins ## Footnote These proteins facilitate water reabsorption.
48
What effect does an increase in ADH have on urine volume?
Decreases urine volume ## Footnote Higher levels of ADH lead to greater water reabsorption, resulting in less urine output.
49
What is the effect of a decrease in ADH on urine volume?
Increases urine volume ## Footnote Lower ADH levels lead to less water reabsorption, resulting in more urine output.
50
What is one of the endocrine functions of the kidney?
Secretion of Renin ## Footnote Renin plays a key role in regulating blood pressure.
51
What hormone stimulates red blood cell production?
Erythropoietin ## Footnote This hormone is produced by the kidneys in response to low oxygen levels.
52
What is the active form of vitamin D produced in the kidneys?
1,25-dihydroxyvitamin D (calcitriol) ## Footnote Calcitriol is essential for calcium and phosphate metabolism.
53
What regulates sodium and potassium balance in the kidney?
Aldosterone ## Footnote Aldosterone is secreted from the adrenal cortex in response to renin.
54
What triggers the release of renin from the kidneys?
A drop in blood pressure at the afferent arteriole ## Footnote This drop signals the kidneys to release renin to help increase blood pressure.
55
What system is involved in increasing blood pressure through renin?
Renin-angiotensin-aldosterone system (RAAS) ## Footnote RAAS leads to vasoconstriction and volume expansion.
56
What are the effects of aldosterone in the distal tubule?
Induces reabsorption of sodium and water ## Footnote This process contributes to increased blood volume and pressure.
57
What does calcitriol do in the intestines?
Increases calcium and phosphate absorption ## Footnote This action is crucial for maintaining bone health and metabolism.
58
What does calcitriol do in bones?
Increases calcium and phosphate resorption ## Footnote This process mobilizes calcium into the bloodstream.
59
What is the composition of urine?
95% water & 5% waste products, including: * urea * creatinine * uric acid * ammonia * urobilinogen * calcium * potassium * sulfate * phosphate * sodium * chloride * a few RBCs and WBCs ## Footnote None
60
What volume of urine indicates polyuria?
>2500ml/day ## Footnote None
61
What volume of urine indicates oliguria?
<400ml/day ## Footnote None
62
What volume of urine indicates anuria?
<100ml/day (no urine pass) ## Footnote None
63
What are the two potential causes of polyuria?
* excess water excretion * excess solute excretion causing osmotic diuresis ## Footnote None
64
What are the major components measured in biochemical kidney function tests?
* serum creatinine * urea * uric acid ## Footnote The major route of excretion for these analytes is urine.
65
What type of tests are included in biochemical kidney function tests?
* clearance tests * urine & plasma osmolality * renal acidification tests * serum and urine protein (and albumin) * serum and urine electrophoresis ## Footnote These tests assess renal handling of protein and tubular function.
66
What is one clinical application of kidney function tests?
Establish the presence of renal disease ## Footnote None
67
What is another clinical application of kidney function tests?
Monitor the progression of renal disease ## Footnote None
68
How can kidney function tests help in defining renal disease?
Define the type of renal disease ## Footnote None
69
What aspect of renal disease can kidney function tests assess?
Assess the severity of renal disease (staging) ## Footnote None
70
What can kidney function tests assess regarding renal dysfunction?
Assess the severity of renal dysfunction ## Footnote None
71
What is a clinical use of kidney function tests in relation to drug therapy?
Monitoring and adjusting drug therapy (nephrotoxic drugs) ## Footnote None
72
What can kidney function tests monitor in relation to treatment?
Monitoring response to therapy ## Footnote None
73
What is creatinine?
A biochemical marker produced by muscle metabolism (creatine breakdown) ## Footnote Creatinine is a byproduct of creatine, a compound that stores energy in muscle cells.
74
How is creatinine production influenced?
Depends on muscle mass, diet, age, and activity level ## Footnote These factors can cause variability in creatinine levels.
75
Why is creatinine clearance used?
To monitor renal disease progression ## Footnote It helps assess kidney function over time.
76
Is creatinine a sensitive marker of renal function?
No, creatinine is not a sensitive marker of renal function ## Footnote Its levels can vary due to multiple factors.
77
What is the most reliable marker for kidney damage?
Serum creatinine ## Footnote It provides a more consistent measure of kidney function.
78
What does BUN stand for?
Blood urea nitrogen ## Footnote It is a specific type of urea measured in the blood.
79
What is the role of urea in the body?
Major nitrogenous waste product of protein metabolism ## Footnote Urea is produced in the liver from ammonia and excreted by the kidneys.
80
What conditions can increased BUN indicate?
* Kidney disease or failure * Blockage of the urinary tract by kidney stones * Congestive heart failure * Dehydration * Gastrointestinal bleeding * Sepsis ## Footnote Elevated BUN levels can signal various health issues.
81
Is urea a specific marker of renal function on its own?
No, urea is not a specific marker of renal function ## Footnote It requires context from other tests for accurate interpretation.
82
What is creatine used for in muscle cells?
To store energy ## Footnote Creatine plays a crucial role in energy metabolism in muscles.
83
How is urea filtered and reabsorbed in the kidneys?
Filtered by glomeruli and partially reabsorbed by the tubules ## Footnote This process is essential for maintaining nitrogen balance in the body.
84
3 functions of the kidney
1. Excretion of waste products 2. Homeostatic regulation of ECF volume and composition 3. Endocrine functions
85
Excretion of waste products includes
Metabolic waste products (urea, creatinine, uric acids) Xenobiotics (drugs and toxins).
86
Homeostatic regulation of ECF volume and composition includes
Regulation of water and electrolytic balance Regulation of acid-base balance Regulation of blood pressure and blood volume.
87
Endocrine functions of the kidney
Renin production Erythropoietin production Activation of vitamin D
87
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Clinical Chemistry (16 decks)

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