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A&P Fall 24' > AP 24 Nov Lecture 33 > Flashcards

AP 24 Nov Lecture 33 Flashcards

1
Q

What are water conservation states?

A

Characteristics of a system aimed at conserving water within the nephron

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2
Q

What is the osmolarity of tubular fluid in the proximal tubule?

A

About 300 mOsm/L

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3
Q

Why is the osmolarity in the proximal tubule the same as plasma osmolarity?

A

Because it reabsorbs electrolytes and glucose, allowing water to follow

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4
Q

What happens to tubular fluid as it moves deeper into the kidney?

A

It becomes more concentrated due to water reabsorption

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5
Q

What is the maximum osmolarity that can be achieved in the kidney?

A

1200 mOsm/L

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6
Q

What is the permeability of the thin ascending limb of the loop of Henle?

A

Not very permeable to water

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7
Q

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

A

Lots of solutes, including 25% of all filtered solutes

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8
Q

What is the osmolarity of tubular fluid in the thick ascending limb?

A

Diluted to about 100 mOsm/L

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9
Q

What role do principal and intercalated cells play in water conservation?

A

They can be permeable to water in the presence of ADH

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10
Q

What happens to osmolarity in the collecting ducts if water channels are present?

A

Osmolarity increases, reflecting the concentration of renal interstitial fluid

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11
Q

What is the osmolarity of urine during water conservation mode?

A

Can reach up to 1200 mOsm/L

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12
Q

What occurs during a water excess state?

A

Interstitial osmolarity decreases to about 600 mOsm/L

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13
Q

What is the effect of ADH on water reabsorption?

A

Increases water reabsorption in the collecting duct

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14
Q

What happens to osmolarity in the proximal tubule during water excess?

A

Remains the same as what was filtered

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15
Q

What occurs in the diluting segment of the nephron?

A

Fluid is diluted regardless of ADH presence

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16
Q

What happens to creatinine concentration in the nephron?

A

Increases due to water reabsorption without reabsorption of creatinine

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17
Q

What is the role of the NKCC/NCCK pump?

A

Reabsorbs sodium, potassium, and chloride ions

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18
Q

What is the characteristic of PAH in the nephron?

A

Easily filtered and heavily secreted

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19
Q

What is the effect of diuretic therapy on fluid excretion?

A

Causes an increase in fluid excretion from the body

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20
Q

What happens to sodium and water excretion with diuretic use?

A

Both sodium and water excretion increase

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21
Q

Fill in the blank: The osmolarity in the thick ascending limb dilutes tubular fluid to _______.

A

100 mOsm/L

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22
Q

True or False: The second half of the loop of Henle is permeable to water.

A

False

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23
Q

What is the relationship between salt intake and water intake?

A

High salt intake usually correlates with high water intake

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24
Q

What is diuresis?

A

Loss of fluid and electrolytes

Diuresis refers to the increased production of urine, which results in the loss of fluid and electrolytes from the body.

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25
Q

What components make up extracellular fluid (ECF)?

A

Plasma portion (1/5) and interstitial portion (4/5)

The extracellular fluid is divided into two components: the plasma portion, which constitutes one-fifth of the ECF, and the interstitial portion, which makes up the remaining four-fifths.

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26
Q

What happens to urine output when a person is initially exposed to diuretic drugs?

A

Urine output goes way up

When a patient first takes diuretic medication, there is typically a significant increase in urine output as the body begins to excrete excess fluid.

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27
Q

True or False: The primary effect of diuretics is to maintain fluid balance over the long term.

A

True

Diuretics primarily help maintain fluid balance by promoting the excretion of excess fluid, which can help manage conditions like hypertension.

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28
Q

What is the relationship between vascular resistance and blood pressure?

A

Increased vascular resistance leads to increased blood pressure

Blood pressure is determined by the resistance in the vascular system; higher resistance results in higher blood pressure.

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29
Q

What role does Angiotensin II play in sodium and fluid balance?

A

Regulates sodium reabsorption and blood pressure

Angiotensin II is crucial in managing sodium reabsorption in the kidneys, influencing blood pressure by affecting fluid balance.

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30
Q

Fill in the blank: If angiotensin II levels are high, we would expect arterial blood pressure to ______ if salt intake is increased.

A

Rise

High levels of angiotensin II lead to increased sodium retention, which can raise blood pressure when salt intake is increased.

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31
Q

What happens if there is a blockade of the angiotensin system?

A

Difficult to maintain normal blood pressure

Blocking the angiotensin system can lead to low blood pressure due to inadequate sodium reabsorption and fluid retention.

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32
Q

How does a high sodium diet affect angiotensin II levels?

A

It suppresses angiotensin II levels

A diet high in sodium can lead the body to decrease angiotensin II levels to help manage excess salt intake.

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33
Q

What is the effect of renal artery stenosis on glomerular filtration rate (GFR)?

A

Decreases GFR

Renal artery stenosis leads to lower blood pressure in the affected kidney, resulting in decreased glomerular filtration rate.

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34
Q

True or False: Both kidneys are affected by angiotensin II when one kidney has stenosis.

A

True

Angiotensin II will act on both kidneys, leading to conservation of water and increased blood pressure in response to perceived low blood pressure.

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35
Q

What dietary habit can lead to a low angiotensin II level?

A

Consuming a diet high in processed and salty foods

A diet consisting mainly of salty processed foods can lead to low levels of angiotensin II, as the body adapts to excess sodium intake.

36
Q

What is the effect of high renin output from the kidney?

A

Leads to high blood pressure

High renin output can cause significant hypertension, although the presence of a healthy kidney can mitigate it.

37
Q

How does the kidney on the right respond to high renin output from the left kidney?

A

It cannot reduce its renin output enough to compensate

This results in elevated blood pressure, especially if renal artery stenosis is present.

38
Q

What happens to glomerular capillary pressure over time due to high blood pressure?

A

It can lead to damage of the capillary beds

Prolonged high pressure can result in permanent damage, affecting kidney function.

39
Q

What is a potential treatment for renal artery stenosis?

A

Stenting the renal artery

This procedure aims to relieve the stenosis and improve blood flow.

40
Q

What class of medication is recommended to limit crosstalk between kidneys in hypertension?

A

ACE inhibitors

ACE inhibitors reduce the effects of angiotensin II, which is involved in kidney communication affecting blood pressure.

41
Q

What is diuresis?

A

Increased excretion of fluid and electrolytes

This process is often a response to high sodium intake and helps regulate blood pressure.

42
Q

What occurs when there is a high salt diet?

A

Increased sodium concentration in blood and filtrate

This leads to renin release repression, helping to excrete excess salt.

43
Q

True or False: High blood pressure leads to decreased filtration rates at the glomerular capillaries.

A

False

High blood pressure typically increases filtration rates initially.

44
Q

What is the relationship between sodium intake and renin release?

A

Excess sodium represses renin release

This helps the body to eliminate excess sodium and maintain balance.

45
Q

What is essential hypertension?

A

Chronic high blood pressure not significantly affected by salt intake

Patients with essential hypertension often do not see major changes in blood pressure with varying sodium and fluid intake.

46
Q

What characterizes salt-sensitive hypertension?

A

Blood pressure is directly dependent on salt intake

Conditions like renal vascular hypertension exhibit this sensitivity.

47
Q

What is an unexpected finding in salt-sensitive hypertension among African Americans?

A

It is often a low renin form of hypertension

This contrasts with the expected high renin activity in cases of salt sensitivity.

48
Q

Fill in the blank: Excess sodium delivered to the macula densa leads to _______ release.

A

renin

49
Q

What happens to blood volume with increased sodium intake?

A

It increases

Higher blood volume can contribute to increased blood pressure.

50
Q

What role do taste buds play in sodium perception?

A

They become more excitable with increased sodium concentration

This enhances the ability to taste flavors.

51
Q

What is the typical response of the kidney to low blood pressure?

A

Increases renin release

This mechanism helps conserve blood volume and maintain pressure.

52
Q

What role do genes play in blood pressure?

A

Genes play a huge role in determining blood pressure levels

While diet can influence blood pressure, genetics is usually the primary factor.

53
Q

What is the function of osmotic diuretics like mannitol?

A

Osmotic diuretics like mannitol get filtered but not heavily reabsorbed, leading to decreased water reabsorption

Mannitol and excess blood glucose act as osmotic diuretics by remaining in the tubule.

54
Q

How do angiotensin receptor blockers (ARBs) affect sodium reabsorption?

A

ARBs affect sodium reabsorption by reducing the interaction with angiotensin II at AT-1 receptors

This leads to decreased sodium reabsorption in the proximal tubules.

55
Q

What is the normal blood concentration of creatinine?

A

Normal blood concentration of creatinine is about 1 mg/dL

This value is used as a reference in assessing kidney function.

56
Q

What is creatinine clearance and how is it estimated?

A

Creatinine clearance is estimated by measuring blood creatinine levels, typically used as a marker for clearance

Inulin can provide a more accurate estimate of GFR.

57
Q

What is the equation for creatinine excretion?

A

Creatinine excretion = amount filtered + amount secreted

Neither amount is reabsorbed; thus, excretion equals the sum of filtration and secretion.

58
Q

What happens to creatinine clearance after unilateral nephrectomy?

A

Creatinine clearance is likely cut in half after unilateral nephrectomy

This is due to the loss of half the nephrons.

59
Q

What occurs to blood creatinine concentration after nephron loss?

A

Blood creatinine concentration rises as nephron loss decreases filtration

This occurs until plasma concentration increases enough to restore balance between production and excretion.

60
Q

What must happen for creatinine production and excretion to return to balance after nephron loss?

A

Creatinine concentration in the blood must rise to match the reduced excretion rate

This adjustment allows for the same amount of creatinine to be filtered despite decreased fluid volume.

61
Q

True or False: ACE inhibitors are less effective in individuals with low renin levels.

A

True

ACE inhibitors may still be useful in these cases despite lower efficacy.

62
Q

Fill in the blank: The filtration rate of creatinine is typically _____ mg/min.

A

1.25 mg/min

This is based on normal filtration rates in healthy individuals.

63
Q

What is the expected plasma creatinine concentration after losing half the nephrons?

A

Plasma creatinine concentration is expected to double

This doubling occurs as the body adjusts to the decreased ability to excrete creatinine.

64
Q

What is the primary means by which creatinine is removed from the body?

A

Filtration is the primary means of creatinine removal

There is minimal reabsorption of creatinine in the kidney.

65
Q

What happens to nephrons as blood pressure increases?

A

Nephrons are likely to disappear faster

Higher blood pressure subjects nephrons to more stress, leading to their loss over time.

66
Q

What is the relationship between nephron loss and creatinine concentration in the blood?

A

As nephrons are lost, creatinine concentration rises due to an imbalance between excretion and production

Reduced nephron count leads to decreased filtration and increased creatinine levels.

67
Q

What is physiological hypertrophy in the context of nephrectomy?

A

The remaining kidney increases its workload and size after the removal of one kidney

This adaptation helps maintain a relatively normal GFR.

68
Q

How much can the remaining kidney increase its GFR after unilateral nephrectomy?

A

By about 50%

This increase helps compensate for the loss of the other kidney.

69
Q

True or False: The systemic blood pressure changes significantly after a unilateral nephrectomy.

A

False

The pressure within the kidney remains relatively stable despite nephrectomy.

70
Q

What happens to nephron workload when 75% of nephrons are lost?

A

The remaining nephrons experience increased stress and workload

This can lead to a shorter life expectancy for the remaining nephrons.

71
Q

What are the consequences of high workload on remaining nephrons?

A

It can lead to progressive nephron loss and renal failure

Increased workload accelerates damage and dysfunction over time.

72
Q

What dietary restrictions are recommended for individuals with reduced nephron function?

A

Sodium and potassium restriction, and moderation of protein intake

These restrictions help reduce the workload on remaining nephrons.

73
Q

What role do kidneys play in acid-base balance?

A

They are responsible for excreting acids and can regulate bicarbonate levels

Impaired kidney function can lead to metabolic acidosis.

74
Q

What is the normal blood osmolarity level in mOsm/L?

A

About 300 mOsm/L

This is the standard osmolarity before any corrections are made.

75
Q

What effect does isotonic saline have on extracellular fluid?

A

It expands the extracellular fluid compartment without causing water shifts

Isotonic saline has the same osmolarity as body fluids.

76
Q

What is the effect of hypotonic saline on osmolarity?

A

It lowers the overall osmolarity in all compartments

Hypotonic saline introduces more water than salts, leading to dilution.

77
Q

Fill in the blank: The total body water is divided into _______ and _______ fluid compartments.

A

intracellular; extracellular

Approximately two-thirds of body water is intracellular, while one-third is extracellular.

78
Q

What happens to the volume of extracellular fluid when hypotonic saline is administered?

A

It increases, and some water may shift into the intracellular compartment

This occurs because the osmolarity of the extracellular fluid is decreased.

79
Q

What happens to osmolarity when a greater proportion of water than salts is added to a system?

A

Osmolarity of the system decreases

This occurs because the addition of more water dilutes the concentration of solutes.

80
Q

What is the expected effect on intracellular fluid when hypotonic saline is administered?

A

Water moves into the intracellular fluid compartment

This movement occurs to balance osmolarity between compartments.

81
Q

What is the osmolarity of cells before the addition of hypotonic saline?

A

300 mOsm/L

This value represents normal osmolarity for human cells.

82
Q

What is the effect of administering .45% saline on osmolarity?

A

Reduces overall osmolarity and expands both intra and extracellular fluid compartments

.45% saline is considered hypotonic.

83
Q

What happens when hypertonic saline (3% saline) is added to a system?

A

Overall osmolarity of the system is elevated

This occurs because more salts are added than water.

84
Q

What is the primary consequence of adding hypertonic saline to the extracellular fluid?

A

It pulls pre-existing water from inside the cells

This movement occurs to balance osmolarity between the extracellular fluid and intracellular fluid.

85
Q

Fill in the blank: The solution .45% saline is considered _______.

A

hypotonic

Hypotonic solutions have a lower concentration of solutes compared to the intracellular environment.

86
Q

Fill in the blank: The osmolarity of extracellular fluid after adding hypotonic saline is expected to be _______.

A

250 mOsm/L

This reflects a dilution effect from the added water.

87
Q

True or False: Water will move across the cell wall until osmolarity is balanced on both sides.

A

True

This is a fundamental principle of osmotic balance in cells.

A&P Fall 24' (12 decks)

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