Week 8: Fluids, Electrolytes, and Acid-Base Balance Flashcards

1
Q

Balance

A

reflection of overall body function (homeostasis)

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2
Q

Acid Base Balance

A
  • disruption of the balance pH (acid/base) has profound effect on overall health
  • outside of the “normal” pH range can lead to death
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3
Q

Body Fluids

A
  • transport gases (CO2 and O2) –> dissolved and transported throughout the body
  • make up 60% of body weight
  • water content affected by age, sex, and fat cells
  • infants = high water content
  • decreases with age
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4
Q

Water

A

-primary body fluid
-content varies with age, sex, adipose tissue (fat cells)
-contains dissolved gases (CO2, O2)
-contains solutes (solid substances)
>electrolytes (sodium, potassium)
>non-electrolytes (glucose, urea)

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5
Q

Electrolytes: Electricity?

A
  • electrolytes develop an electrical charge when dissolved in water
  • non-electrolytes do not conduct electricity
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6
Q

Important Function of Bodily Fluids

A
  • maintain blood volume
  • regulate body temperature
  • transport material to and from cells
  • serve as a medium for cellular metabolism
  • assist with digesting food
  • serve as medium for excreting waste
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7
Q

Body Fluid Compartments

A
  • Intracellular

- Extracellular

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8
Q

Body Fluid Compartments: Intracellular

A
  • within the cells

- essential for cell function and metabolism

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9
Q

Body Fluid Compartments: Extracellular

A

-Interstitial
-Intravascular
-Transcellular
>outside the cells
>carries water, electrolytes, nutrients, and oxygen to the cells and removes waste products of cellular metabolism

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10
Q

Extracellular: Interstitial Fluid

A

between body cells

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11
Q

Extracellular: Intravascular Fluid

A

plasma within the body – transports blood cells

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12
Q

Extracellular: Transcellular Fluid

A

special fluid such as peritoneal, synovial, pleural, CSF

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13
Q

Third Spacing

A

-occurs when fluid is “trapped” in a third space
-not within cells or intravascular spaces (blood vessels)
-occurs in illness, trauma, or disease
>pleural effusion (pleural space)
>ascites (peritoneal cavity)
>vesicles (blisters)

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14
Q

Major Electrolytes in Intracellular Fluid?

A
  • potassium
  • magnesium
  • phosphate
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15
Q

Major Electrolytes in the Extracellular Fluid?

A
  • sodium
  • chloride
  • bicarbonate

Transcellular fluid –> (gastric + intestinal secretions) – contain electrolytes

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16
Q

Non-electrolyte Present in ECF?

A

albumin (mostly intravascular)

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17
Q

Electrolyte Imbalances

A

-when electrolytes move into a compartment not normally occupied
-lost in excessive amounts from body:
>perspiration
>wounds
>injury
>illness

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18
Q

How Do Fluids and Electrolytes Move in the Body?

A

-passive or active mechanisms across the selectively permeable membranes that separate the ICF and ECF

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19
Q

Passive Transport

A

requires no energy

  • Osmosis
  • Diffusion
  • Filtration
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20
Q

Active Transport

A
  • requires energy (ATP) to move against a concentration gradient
  • occur when molecules (particles such as electrolytes) move across cell membranes from area of low concentration to area of high concentration
  • Adenosine triphosphate (ATP) helps in active transport movement
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21
Q

Osmosis

A
  • passive transport
  • water moves from less concentration to higher concentration to dilute the higher concentration of solutes
  • think of it as if the solute particles are pulling the water over
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22
Q

Diffusion

A
  • passive transport
  • molecules from higher to lower concentration
  • solute (particles) move through a cell membrane
  • movement occurs until concentration is equal on both sides of the membrane
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23
Q

Filtration

A
  • passive transport
  • movement of both water and smaller particles from area of high pressure to one of low pressure
  • hydro-static pressure takes place in blood stream (closed system), allows for normal circulation
24
Q

Crystalloids

A

solutes that readily dissolve (electrolytes– intravenous solution)

25
Q

Colloids

A

larger molecules that do not dissolve readily (proteins– blood products/ transfusions)

26
Q

Osmolality

A
  • number of particles of solute per kilogram of water (Osmols)
  • concentration of solutes providing pressure in body fluid
  • expressed is milliosmols per kilogram (mOsm/kg)
  • serum osmolality = 275-295 mOsm/kg
27
Q

Greatest Determinant of Serum Osmolality

A

sodium

28
Q

Greatest Determinant of Intracellular Osmolality

A

potassium

29
Q

What Contributes to both Intracellular and Extracellular Osmolality?

A
  • glucose

- urea

30
Q

Isotonic Fluid

A

-when a fluid has the same osmolality (number of particles) as blood
>0.9% NaCl, LR (sodium chloride + lactated ringers electrolyte solutions)
-isotonic intravenous fluids often given when blood volume is low
>fluid will remain in the vascular space because it has the same concentration as blood — NO OSMOSIS

31
Q

Hypotonic Solution

A
  • lower osmolality (solutes) than blood
  • moves by osmosis (passive) from vascular system into cells
  • cells swell
  • 0.45% NaCl and 0.33 NcCl
32
Q

Hypertonic Solution

A
  • higher osmolality (solutes) than blood
  • water moves by osmosis (passive) from cells into the extracellular fluid (vascular system)
  • cells shrink
  • D10W, D5W w/ 0.9% NaCl, D5W w/ 0.45 Nacl
33
Q

Osmotic Pressure

A
  • power of a solution to draw water (more molecules in solution)
  • osmotic pressure from plasma proteins maintains fluid in vascular space
34
Q

Fluid Intake

A

-primarily through drinking fluids
-IOM recommends: 2700 ml/day women, 3500/day men
-regulated by thirst
>change in plasma osmolality (solute to fluid ratio)
>less solutes in blood (fluid overload)
>more solutes in blood (fluid loss)
-hypothalamus (thirst center)

35
Q

Fluid Output

A

-fluid loss is constant + needs to be replenished
-intake = output
-Sensible loss: measurable
>urine (min 30 mL/hour)
>diarrhea
>feces
-Insensible loss: non-measurable
>skin; perspiration, wound drainage, burns
>lungs: exhalation

36
Q

Hormonal Regulation

A
  • antidiuretic hormone (ADH)
  • renin-angiotensin system
  • aldosterone
  • kidneys are principle regulator of fluid + electrolyte balance
  • entire process occurs when fluid volume is low
37
Q

Principle Regulator of Fluid + Electrolyte Balance?

A

kidneys

38
Q

ADH is Released From?

A

pituitary gland

39
Q

Hormonal Regulation: ADH

A
  • pressure sensors in the vascular system stimulate or inhibit release
  • (kidneys will retain or excrete more fluid)
40
Q

Hormonal Regulation: Renin-angiotensin System

A

(only when needed)

  • Renin (enzyme) is released in kidneys when fluid volume is decreased–> leads to release of angiotensin and angiotensin II (hormones)
  • angiotensin II retains sodium and water in kidneys and directs release of aldosterone (hormone)
41
Q

Hormonal Regulation: Aldosterone

A
  • stimulates distal tubules of kidneys to reabsorb sodium + excrete potassium
  • sodium reabsorption results in passive reabsorption of water
  • increase plasma volume and kidney perfusion
42
Q

How Does the Body Regulate Electrolytes?

A
  • balance loss + intake
  • loss must be replaced by dietary potassium or supplements
  • normal serum electrolyte levels depend on dietary intake as well as body regulatory mechanisms
43
Q

Major Electrolytes

A
  • Sodium (Na+)
  • Potassium (K+)
  • Calcium
  • Magnesium
  • Chloride
  • Phosphate
  • Bicarbonate
44
Q

Sodium (Na+)

A

(135-145 mEq/L)

  • regulates fluid volume
  • major electrolyte in ECF
  • moves by active transport
  • interacts with calcium to maintain muscle contraction
  • stimulates conduction of nerve impulses
  • kidney excretes + reabsorbs– maintain ECF volume
  • excessive intake can affect BP (high)
  • regulated by aldosterone + ADH levels
  • low sodium–> excess water intake
45
Q

Potassium (K+)

A

(3. 5- 5 mEq/L)
- key in cellular metabolism
- major electrolyte in ICF
- transmits electrical impulses in multiple body systems
- regulates conduction of cardiac rhythm
- deficiency associated with high BP; risk of stroke
- kidneys retain or excretes; assists with acid-base balance
- regulated by aldosterone
- lost though vomiting, diarrhea, many diuretics

46
Q

Calcium

A
  • most abundant electrolyte in the body
  • catalyst for many cellular activities
  • important in bone + teeth health, neuromuscular function, cardiac function
  • regulates muscle contraction
  • essential in blood clotting
  • insufficiency–> osteoporosis
  • formation of clots
  • absorption needs vitamin D
  • increased calcium = decreased phosphorus (vice versa)
47
Q

Magnesium

A
  • second most abundant electrolyte in ICF
  • many cellular functions
  • involved in protein + CHO metabolism
  • needed for protein + DNA synthesis
  • loss–> triggered by diuretics, poorly controlled diabetes mellitus, excess alcohol intake
  • involved in electrical activity in nerve + muscle membranes Including the heart)
48
Q

Chloride

A
  • major electrolyte in ECF
  • bound to other ions like Na+ to maintain fluid balance
  • essential for production of HCl for gastric secretions
  • functions as buffer in oxygen carbon dioxide exchange in RBGs
  • assists with acid-base balance
49
Q

Phosphate

A

(phosphorus)

  • major electrolyte in ICF
  • catalyst for many intracellular activities
  • promotes muscle + nerve action
  • bound with calcium in teeth + bone; inverse relationship
50
Q

Bicarbonate

A
  • major buffer in body
  • maintains acid-base balance
  • regulated by kidneys
  • lost through diarrhea, diuretics, renal insufficiency
51
Q

Acid

A
  • compounds that contains hydrogen (H+) ions

- stronger the acid is, the lower the pH

52
Q

Base

A

compound that accepts hydrogen ions

53
Q

How is Acid-Base Balance Regulated?

A
>Buffer Systems
>Respiratory Mechanisms
> Renal Mechanisms 
-measured by arterial blood gases (ABGs)
-serum pH between 6.9 and 7.8
54
Q

Acid- Base Balance Regulated: Buffer Systems

A

prevent a wide swing in pH

55
Q

Acid-Base Balance Regulated: Respiratory Mechanisms

A

remove carbon dioxide through rapid, deep breathing

56
Q

Acid-Base Balance Regulated: Renal Mechanisms

A

kidneys regulate the concentration of plasma bicarbonate (buffer)