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PHGY 216 Mod 4 > Section 1 > Flashcards

Section 1 Flashcards

1
Q

What are some of the many homeostatic functions of the kidneys?

A
  • regulating electrolytes
  • acid-base control
  • blood volume control
  • regulation of blood pressure
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2
Q

What are the two major compartments of the body fluid, and how much is each out of the total?

A
  • Intracellular fluid (2/3)
  • Extracellular fluid (1/3) ; composed majorly of plasma and interstitial fluid
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3
Q

Describe the composition of extracellular fluid

A
  • the fluid surrounding the cells
  • includes plasma, interstitial fluid, lymph, and transcellular fluid
  • the amount of lymph and transcellular fluid is negligible (small)
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4
Q

Define transcellular fluid

A
  • the fluid contained within epithelial-lined spaces in the body
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5
Q

Why are there barriers separating the body-fluid compartments?

A

As to limit the movement of water and solutes between the various compartments to differing degrees

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6
Q

What separates the plasma and the interstitial fluid?

A

Blood vessel walls serve as barriers between the plasma and the interstitial fluid.

However, water and everything else in the plasma except proteins can freely exchange with the interstitial fluid.

Therefore the compositions of plasma and interstitial fluid are essentially identical, except for plasma proteins.

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7
Q

What serves as the barrier between intracellular fluid (ICF) and extracellular fluid (ECF)?

A

The plasma membrane surrounding each cell

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8
Q

Do proteins in the intracellular fluid exchange with the extracellular fluid?

A

No

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9
Q

What causes the unequal distribution of ions across the plasma membrane?

A

The plasma membrane prevents the passive movement of ions between the intracellular and extracellular fluid, resulting in an unequal distribution of ions such as K+ and Na+.

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10
Q

T or F: ALL exchanges of water and other constituents between the ICF and the external world are dependent upon the ECF.

A

True,

Even though cells tightly regulate their own ICF, it can be said that the overall control of fluid balance is dependent upon regulating the ECF.

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11
Q

What are the two factors regulated to maintain fluid balance in the body?

A

The two factors regulated are ECF volume and ECF osmolarity.

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12
Q

Why is ECF volume closely regulated?

A

ECF volume is closely regulated to maintain blood pressure, with the maintenance of salt balance being important for long-term regulation.

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13
Q

Why is ECF osmolarity closely regulated?

A

ECF osmolarity is closely regulated to prevent the swelling or shrinkage of cells.

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14
Q

How does ECF directly influence blood pressure?

A

Increase in ECF volume will increase plasma volume (which increases arterial bp)

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15
Q

What are the short-term control measures to regulate blood pressure until ECF is returned to normal values?

A
  • Baroreceptor reflex
  • Fluid shifts
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16
Q

What are baroreceptors and where are they located?

A

Baroreceptors are mechanoreceptors located in the carotid artery and the aortic arch, which detect changes in arterial blood pressure.

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17
Q

How does the Baroreceptor Reflex regulate blood pressure?

A

it adjusts blood pressure by modulating cardiac output and total peripheral resistance in response to changes in arterial blood pressure

e.g. when pressure falls too low, CO and TPR will increase to raise bp (and vice versa)

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18
Q

What is total peripheral resistance? (TPR)

A

the resistance to blood flow due to the constriction of blood vessels

higher TPR leads to increased bp

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19
Q

What are the long-term control factors for regulating blood pressure?

A

The long-term control factors include fluid input/output regulation by the kidneys and the thirst mechanism.

e.g. a decrease in plasma volume can temporarily be compensated for by a shift of the fluids out of the interstitial compartment to the plasma.
vice versa with fluid shifting to interstitial compartment

20
Q

What accounts for more than 90% of the solutes in the extracellular fluid (ECF)?

A

Sodium, along with associated anions, mainly chloride, account for more than 90% of the ECF’s solutes.

21
Q

How is extracellular fluid (ECF) volume controlled?

A

ECF volume is controlled by regulating salt levels because water follows salt through osmosis

22
Q

How is salt balance maintained in the body?

A

Salt balance is maintained through salt input = salt output.

23
Q

What is the main determinant of salt input regulation?

A

Salt input regulation is mainly dependent on dietary salt intake.

24
Q

How much salt is necessary to replace what is lost through feces and sweat on a daily basis for normal activity levels?

A

About 0.5g/day of salt is necessary to replace what is lost through feces and sweat for normal activity levels.

25
Q

How is excess salt eliminated from the body?

A

Excess salt is eliminated through pathways including feces, sweat, and primarily through the kidneys.

26
Q

Which organ has the greatest role in salt elimination?

A

The kidneys have the greatest role in salt elimination from the body.

27
Q

What are the three major causes of hypotonicity of the extracellular fluid (ECF)?

A
  • renal failure
  • rapid water ingestion
  • over secretion of vasopressin.
28
Q

How does renal failure contribute to hypotonicity of the ECF?

A

Individuals with renal failure cannot produce concentrated urine, leading to an excess of free water in the body.

29
Q

What can cause rapid water ingestion in healthy individuals?

A

Rapid water ingestion can occur in healthy individuals if they drink volumes of water in excess of what the kidneys can handle in a timely manner.

30
Q

How does over secretion of vasopressin contribute to hypotonicity of the ECF?

A

Vasopressin promotes water retention, which can lead to an excess of free water in the body, causing hypotonicity of the ECF.

31
Q

Why is it important to regulate the osmolarity of the extracellular fluid?

A

Regulating the osmolarity of the extracellular fluid is important to prevent undesirable shifts of water into or out of cells, which can lead to harmful consequences.

32
Q

What are three causes of hypertonicity?

A
  • Insufficient water intake, or not drinking enough
  • Diabetes insipidus, which involves a deficiency in vasopressin
  • Excessive water loss due to heavy sweating during extreme exercise, prolonged bouts of vomiting, or diarrhea
33
Q

What are the cellular consequences of hypertonicity

A

a decrease of normal cell function as the ICF is decreased.

The brain is particularly sensitive and shrinking of neurons can cause confusion, delirium, and even coma or death

34
Q

What are the effects on the volume and concentration of solutes in the extracellular fluid (ECF) when an isotonic solution is administered intravenously?

A

The volume of the ECF increases, but the concentration of solutes remains unchanged.

The ECF remains isotonic, maintaining osmotic equilibrium with the intracellular fluid (ICF), resulting in no net fluid shift between the compartments.

35
Q

How would isotonic fluid loss, such as hemorrhage, impact cells?

A

Isotonic fluid loss affects only the extracellular fluid compartment, maintaining osmotic equilibrium between the ECF and ICF.

Thus, there would be no net fluid shifts between compartments, and cells would maintain their normal size and shape despite the loss of isotonic fluid.

36
Q

What monitors the osmolarity of the fluid surrounding the vasopressin-secreting cells and the thirst center in the hypothalamus?

A

Hypothalamic osmoreceptors, located near the vasopressin-secreting cells and thirst center, constantly monitor the osmolarity of the fluid surrounding them.

37
Q

How do vasopressin secretion and thirst respond to increases in osmolarity?

A

As osmolarity increases, both vasopressin secretion and thirst are stimulated to promote water retention and intake, respectively, until hypertonicity is relieved.

38
Q

What is the role of vasopressin in response to increased osmolarity?

A

Vasopressin acts on the kidneys to increase water reabsorption, helping to retain water in the body.

39
Q

How does the body respond to hypotonic fluid surrounding the osmoreceptors?

A

If the fluid around the osmoreceptors is hypotonic, vasopressin secretion and thirst are not stimulated, promoting water loss.

40
Q

What triggers activation of left atrial volume receptors? And what do they do?

A

Large losses of extracellular fluid (ECF) volume and blood pressure greater than 7% activate left atrial volume receptors.

Left atrial volume receptors stimulate hypothalamic pathways to promote vasopressin release and thirst, helping to restore ECF volume and blood pressure.

41
Q

Is the following a short term or long term control of ECF volume?

Baroreceptor reflex

A

Short-term

42
Q

Is the following a short term or long term control of ECF volume?

The kidneys’ control of urine output

A

Long-term

43
Q

Is the following a short term or long term control of ECF volume?

Fluid shifts in/out of the interstitial compartment

A

Short-term

44
Q

Is the following a short term or long term control of ECF volume?

The body’s control of the thirst mechanism

A

Long-term

45
Q

Is the following a short term or long term control of ECF volume?

A change in cardiac output and total peripheral resistance

A

Short-term

PHGY 216 Mod 4 (7 decks)

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