Week 8: Fluids, Electrolytes, and Acid-Base Balance Flashcards
(56 cards)
1
Q
Balance
A
reflection of overall body function (homeostasis)
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
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
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)
5
Q
Electrolytes: Electricity?
A
- electrolytes develop an electrical charge when dissolved in water
- non-electrolytes do not conduct electricity
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
7
Q
Body Fluid Compartments
A
- Intracellular
- Extracellular
8
Q
Body Fluid Compartments: Intracellular
A
- within the cells
- essential for cell function and metabolism
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
10
Q
Extracellular: Interstitial Fluid
A
between body cells
11
Q
Extracellular: Intravascular Fluid
A
plasma within the body – transports blood cells
12
Q
Extracellular: Transcellular Fluid
A
special fluid such as peritoneal, synovial, pleural, CSF
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)
14
Q
Major Electrolytes in Intracellular Fluid?
A
- potassium
- magnesium
- phosphate
15
Q
Major Electrolytes in the Extracellular Fluid?
A
- sodium
- chloride
- bicarbonate
Transcellular fluid –> (gastric + intestinal secretions) – contain electrolytes
16
Q
Non-electrolyte Present in ECF?
A
albumin (mostly intravascular)
17
Q
Electrolyte Imbalances
A
-when electrolytes move into a compartment not normally occupied
-lost in excessive amounts from body:
>perspiration
>wounds
>injury
>illness
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
19
Q
Passive Transport
A
requires no energy
- Osmosis
- Diffusion
- Filtration
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
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
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
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
Colloids
larger molecules that do not dissolve readily (proteins-- blood products/ transfusions)
26
Osmolality
- 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
Greatest Determinant of Serum Osmolality
sodium
28
Greatest Determinant of Intracellular Osmolality
potassium
29
What Contributes to both Intracellular and Extracellular Osmolality?
- glucose
| - urea
30
Isotonic Fluid
-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
Hypotonic Solution
- lower osmolality (solutes) than blood
- moves by osmosis (passive) from vascular system into cells
- cells swell
- 0.45% NaCl and 0.33 NcCl
32
Hypertonic Solution
- 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
Osmotic Pressure
- power of a solution to draw water (more molecules in solution)
- osmotic pressure from plasma proteins maintains fluid in vascular space
34
Fluid Intake
-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
Fluid Output
-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
Hormonal Regulation
- antidiuretic hormone (ADH)
- renin-angiotensin system
- aldosterone
- kidneys are principle regulator of fluid + electrolyte balance
- entire process occurs when fluid volume is low
37
Principle Regulator of Fluid + Electrolyte Balance?
kidneys
38
ADH is Released From?
pituitary gland
39
Hormonal Regulation: ADH
- pressure sensors in the vascular system stimulate or inhibit release
- (kidneys will retain or excrete more fluid)
40
Hormonal Regulation: Renin-angiotensin System
(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
Hormonal Regulation: Aldosterone
- 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
How Does the Body Regulate Electrolytes?
- 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
Major Electrolytes
- Sodium (Na+)
- Potassium (K+)
- Calcium
- Magnesium
- Chloride
- Phosphate
- Bicarbonate
44
Sodium (Na+)
(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
Potassium (K+)
(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
Calcium
- 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
Magnesium
- 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
Chloride
- 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
Phosphate
(phosphorus)
- major electrolyte in ICF
- catalyst for many intracellular activities
- promotes muscle + nerve action
- bound with calcium in teeth + bone; inverse relationship
50
Bicarbonate
- major buffer in body
- maintains acid-base balance
- regulated by kidneys
- lost through diarrhea, diuretics, renal insufficiency
51
Acid
- compounds that contains hydrogen (H+) ions
| - stronger the acid is, the lower the pH
52
Base
compound that accepts hydrogen ions
53
How is Acid-Base Balance Regulated?
```
>Buffer Systems
>Respiratory Mechanisms
> Renal Mechanisms
-measured by arterial blood gases (ABGs)
-serum pH between 6.9 and 7.8
```
54
Acid- Base Balance Regulated: Buffer Systems
prevent a wide swing in pH
55
Acid-Base Balance Regulated: Respiratory Mechanisms
remove carbon dioxide through rapid, deep breathing
56
Acid-Base Balance Regulated: Renal Mechanisms
kidneys regulate the concentration of plasma bicarbonate (buffer)
