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ABSN Pathophysiology Summer23 > Chapter 8 Fluids, Electrolytes, Acids and Bases > Flashcards

Chapter 8 Fluids, Electrolytes, Acids and Bases Flashcards

1
Q

Learning Objectives

A
  1. Differentiate the intracellular from the extracellular fluid compartments
  2. Relate the concept of a concentration gradient to the processes of diffusion and osmosis.
  3. Describe the control of cell volume and the effect of tonicity on cell size.
  4. Relate the functions of sodium, chloride, potassium, magnesium, and phosphorus to the manifestations of hypo- and hyper-levels.
  5. Compare the roles of the kidneys and respiratory system in regulation of acid–base balance.
  6. Define metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis.
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2
Q

Body fluid homeostasis

A

dynamic process

disease is caused by an imbalance of this homeostasis

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3
Q

body fluid distribution
- how much of our body is made up of water?
- how much of that is intracellular v extracellular

A

our bodies are made of about 60% water

40% is intracellular (about 28 L or 280mL)

20% is extracellular (interstitial fluid in between the cells > blood plasma > transcellular)

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4
Q

extracellular fluid electrolyte concentration

A

note: extracellular levels can be measured via blood draws

Na+ and Cl- are the most abundant in the EC fluid

Bicarbonate HCO3- is also at a significant level extracellularly

Phosphate and Ca+ are at higher concentrations extracellularly than intracellularly but not at high concentrations

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5
Q

intracellular fluid electrolyte concentration

A

reminder: we have more intracellular water than extracellular (body is 60% water. 40% (of that 60) is intracellular)

K+ is the electrolyte of highest concentration in our cells
(upon injury, K+ will be released into the extracellular fluid)

Mg+ is also at significant levels

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6
Q

Concentration Gradient

A

the difference in concentration over a distance

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7
Q

Diffusion

A

the movement of charged or uncharged (particles) along a concentration gradient from higher to a lower concentration

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8
Q

Osmosis

A

the movement of water across a semipermeable membrane from the side of the membrane with the lesser number of particles to the side with the greater number of particles

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9
Q

Which ion is in the highest concentration in the ICF?

A

K+

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10
Q

Tonicity

A

The effect of osmotic pressure of a solution on cell size

(because of water movement across the cell membrane)

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11
Q

What is a hypertonic solution?

A

a solution where the cell shrinks due to more particles in the fluid.

osmotic pull is higher

ex: dehydration

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12
Q

What is a hypotonic solution?

A

Cells swell because there is a lot of water in the extracellular fluid

“HypO H2O” excess water

(example: water to particle ratio outside the cell 5:1, inside the cell 1:2 –> water wants to balance the ratios… )

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13
Q

How do you balance a hypertonic solution

A

give a hypotonic solution such as a 0.45 NaCl solution (reintroduces water into the cells)

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14
Q

Capillary fluid forces:

Capillary filtration pressure (hydrostatic force)

A

capillaries are where arteries and veins meet

fluids can shift based on capillary pressures

capillary filtration pressure is based on the heart and is the output of blood into the tissue

more output leads to higher tissue hydrostatic pressure (higher BP)

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15
Q

Capillary fluid forces:

Capillary Colloidal Osmotic Pressure (osmotic force)

A

Created by the concentration gradient of albumin

Albumin: a protein that exists only inside the capillaries and cannot be filtered out (due to size)

fluid wants to be pulled back into the capillaries on the venous side in order to balance the solute concentration (set by albumin)

( solute concentration inside the cell&raquo_space;> solute concentration outside the cell … therefore water wants to come in and fix out solute imbalance)

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16
Q

Why does edema occur in malnutrition

A

Edema is swelling caused by too much fluid trapped in the body’s tissues.

In malnutrition, there are insufficient albumin levels so water does not want to enter back into the capillaries

excess of extracellular fluids and insufficient water reabsorption leads to edema and poor circulation

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17
Q

what role does the lymph play in circulation

A

lymph channels can transport and leftover fluids back into the capillaries

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18
Q

4 causes of Edema Formation

A

edema: the moving out /excess of fluid into the interstitial space

mechanisms that contribute to edema formation:

  1. ^^^ capillary filtration pressure (hydrostatic forces)
    - ex: pregnant women have swelling in their ankle due to the increased pressure from the distended uterus
  2. decreased colloidal osmotic pressure
  3. increased capillary permeability
  4. obstruction to lymph flow
    • impairs recirculation of residual fluids
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19
Q

3 Location Types of Edema

A
  1. Localized
  2. General
    - everywhere
  3. Dependent
    - wherever gravity takes the fluid
    - ie: sacral area (back & butt) in bedridden patients, legs in pregnant

Edema can also be organ specific
- ie: fluid filled lungs, cerebral edema

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20
Q

Pitting v Nonpitting edema

A

pitting: indents
- when you push on it with your finger, the dent stays there

nonpitting: no indents

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21
Q

Methods for assessing edema

A

daily weight- assesses general edema

visual assessment

measurement of affected part

application of finger pressure to assess pitting edema

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22
Q

Loss of bodily fluids

insensible v sensible

A

we can lose bodily fluids via:

kidneys
skin (sweat)
lungs
GI tract (feces)

insensible=unmeasurable
ex: breath

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23
Q

4 pillars of fluid balance (IADE)

A
  1. Intake (thirst, habit, age)
    • we are thirsty when we are low on volume
  2. Absorption (GI tract and kidneys absorb water –funnels–> blood)
    - the different types of fluids you drink impact osmolarity (ie: soda will cause you to retain more water due to the body’s attempt to balance out the sugar. coffee will make you lose water since it’s a diuretic)
  3. Distribution
    • 2/3 of our fluids are intracellular, 1/3 is extracellular
  4. Excretion
    • urine
    • GI tract
    • lungs
    • skin
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24
Q

Hypovolemia vs Hypervolemia

A

hypovolemia= dehydration (low volume of water)

hypervolemia= too much fluid

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25
What is the mechanism of thirst? mention ADH
Thirst is triggered from the hypothalamus in response to osmolarity changes Antidiuretic Hormone (ADH): hormone formed in the posterior pituitary gland - reabsorbs more water in kidneys - retains more water in overall extracellular water volume - stops our feelings of thirst
26
clinical signs of low/lost fluids dehydration/hypovolemia
vital signs: increased Heart rate decreased Blood pressure Venous volume/filling - could even cause collapsed veins decreased Capillary refill rate (delayed redness return on skin)
27
Psychogenic polydipsia
compulsive water drinking - large amounts of water intake and urine excretion
28
how does cigarette smoking affect thirst?
smoking releases antidiuretic hormone (ADH) this leads to fluid retention in kidneys and decreases sense of thirst
29
how do psychiatric medications affect thirst?
antipsychotic medications increase ADH levels - increased ADH levels - renal fluid retention - decreased sense of thirst
30
how does drinking large amounts of water impact blood tonicity?
your blood becomes hypotonic the increase of water leads to the excess of water wanting to enter RBCss
31
Diabetes Insipidus
deficiency of or decreased response to ADH patients unable to concentrate urine during periods of water restriction and excrete large volumes of dilute urine decreased concentrated blood volume caused by damage / defect to posterior pituitary (central or neurogenic diabetes) or kidneys (nephrogenic diabetes)
32
SIADH (syndrome of inappropriate ADH)
failure of the negative feedback system that inhibits of ADH - this increases ADH release leads to very little outputs of concentrated urine blood becomes very dilute because body is attempting to save water
33
Causes of Isotonic fluid volume excess (hypovolemia)
1. inadequate sodium and water elimination - kidney failure, heart failure, liver failure, medications 2. excessive sodium and water intake in relation to output - dietary intake - isotonic IV fluid replacement (saline 0.9mm)
34
Baroreceptors
receptors for sodium that sense changes in blood pressure (sensing fullness of circulation, how much blood volume there is) located in the atria of the heart, the pulmonary blood vessels, and kidneys sends signals to the kidneys via SNS stimulation to alter amount of urine production, aka GFR (globular filtration rate)
35
how do the kidneys regulate sodium?
1. baroreceptors sense BP change 2. SNS is stimulated which tells the kidneys to alter urine production (GFR) and Na reabsorption rate (pulling Na+ back into the blood volume) (low BP= release aldosterone and retain Na+ and water) (high BP eliminate Na+ and water) 3. if the BP is low, activation of the RAAS (renin-angiotensin-aldosterone system) leads to production of aldosterone which increases Na+ (sodium) and water reabsorption 4. if the BP is high (heart stretching), ANP (atrial natriuretic peptide) hormone is released to increase sodium and water excretion **Na+ follows water***
36
Sodium (Na+) imbalance (Range, Hypo, Hyper)
blood plasma value: 135-145 meQ/L -or- mmol/L Hyponatremia (below 135): - headache - lethargy/confusion - orthostatic tension - tachycardia - seizures could be caused by: hypotonic IVs, diuretics Hypernatremia (above 145) - seizures - thirst, dry mucous membranes - fever - restless, irritable - high BP - edema - decreased urine output
37
Potassium K+ (Range, Hypo, Hyper)
Blood plasma value: 3.5-5.0 meQ/L -or- mmol/L (remember there is a lot of Calcium inside the cell... only 2% outside the cell) Hypokalemia (below 3.5): -Weak irregular heart rhythm & pulse -Muscle weakness -Leg cramps* -Lethargy - greater risk for cardiac arrest -Nausea/Vomiting (N/V) Causes include Vomiting/Gastric sx. Diarrhea, Diuretics, High glucose Treatment: supplements Hyperkalemia (above 5.0): -Weak, slow, irregular heart rhythm & pulse --> cardiac arrest -Muscle weakness -N/V/Diarrhea Causes include renal failure, acid/base imbalance, cell injury (trauma), ^^ intake Treatment: - calcium antagonizes potassium's effect on heart excitability - sodium bicarbonate can cause K+ to move into the ICF (into the cell) - insulin decreases ECF K+ concentration (K+ moves into the cell) - increasing renal excretion (dialysis)
38
what are the major bodily divalent cations and what is their pathway in the body ?
Calcium, Phosphorus, and magnesium ingested in the diet absorbed from the intestine filtered, reabsorbed, and eliminated by kidney
39
3 forms of extracellular (ECF) Calcium (Ca2+)
1. protein bound (40% of ECF calcium is bound to albumin 2. Complexed: 10% is chelated with citrate, phosphate, and sulfate 3. Ionized: 50% of ECF calcium is present in the ionized form *normal range is 4.6-5.3 mg/dL
40
how is calcium regulated (2)?
1. Vitamin D: increases GI absorption to sustain normal plasma levels of calcium and phosphate - calcitriol increases calcium absorption from the intestines 2. Calcitonin: (from parathyroid gland of the neck) acts on the kidney (tells kidney to keep Ca) and bone (draws C out of the bones) to remove calcium from the extracellular circulation.
41
Calcium Imbalanca (range, hypo, hyper)
normal blood plasma levels: 8.5-10 mg/dL Hypocalcemia: - Tachy or brady, Hypotension - ^^ neuro-muscular excitability (seizures, tetany... due to too little Ca in the gap) -Nerve cells less sensitive to stimuli (numbness in toes, fingers, face)*** - Bone fractures Causes may include: Dietary deficiency, ETOH, Impaired mobilization from bone, Kidney loss, decreased Vit D Renal failure, decreased Mg++, ^^^Phos Hypercalcemia: -Bradycardia, HTN (^^ BP) - decreased N-M response: decreased DTR (deep tendon reflex), weakness -GI: anorexia, N/V, abd. pain, ileus Causes may include: Increase dietary intake Hyperparathyroidism or Cancer are most common Antacid overuse, decreased Phos^ increase in vitamin D (helps retain calcium)
42
Chvostek and Trousseau's signs of hypocalcemia
Chvostek’s: brief contraction of upper lip, nose, or side of face when tapping facial nerve by the ear Trousseau’s: carpopedal spasm after BP cuff has been inflated 20 mmHg above systolic for 1 to 4 minutes
43
which 3 electrolytes have the biggest impact on the heart
1. potassium K+ 2. Calcium Ca2+ 3. Magnesium Mg2+
44
Phosphorus role/function
Functions: Bone formation Cellular metabolism N-M regulation Hematologic function (WBCs, RBCs, platelets) Acid/base buffer in kidneys Regulated by PTH (parathyroid hormone) is like the inverse to Ca2+
45
Phosphorus imbalance
normal range: 2.5-4.5 mg/dL (decilitre) Hypophosphatemia- Symptoms: * Same as ^^Ca++ (weak, numbness, N/V/ileus) Causes: decreased intestinal absorption (pancreatitis, Vit D deficit) Acid base imbalance resp alkalosis Hyperglycemia --> insulin --> Phos into cells Symptoms: Same as decreased Ca++ (cramps, tetany, hypotension) Causes: Renal failure (^ Ca and lower phos -- kidney reabsorption) Acid base imbalance resp acidosis Laxative overuse
46
Role of Magnesium
Essential to all reactions that require ATP: Cellular energy metabolism Metabolism of carbohydrates and protein synthesis Helps Na and K cross cell membranes (involved in Na/K pump) Maintains Ca levels by stimulating PTH secretion (parathyroid hormone) Regulates cardiac and skeletal muscle contractions, rhythm Ingested in the diet, Absorbed from the intestine, Excreted by the kidneys
47
Magnesium Imbalance
Normal plasma levels: 1.8-3.0 meQ/L
48
What is the normal range for arterial blood pH
7.35-7.45
49
what 2 extracellular substances work together to regulate pH
carbonic acid ( H2CO3) and bicarbonate (HCO3-)
50
what is an acid?
a substance that releases H+ ions (electron donors) CO2
51
what is a base
a substance that accepts H+ ions (electron acceptor) HCO3 bicarbonate
52
Arterial Blood Gas Normal Values pH, pCO2, HCO3
pH: 7.35-7.45 pCO2 35-45 (partial pressure CO2... how much is dissolved into the blood) - lowers pH if added - regulated by the lungs (respiratory) HCO3 Bicarbonate 22-26 - adds base and raises pH - kidney regulated (metabolic)
53
Buffering
a normal body mechanism that occurs rapidly in response to acid-base disturbances in order to prevent changes in H+ concentration
54
What 2 systems work to regulate pH in acid-base balance? which system works fastest?
The respiratory and renal systems Respiratory works fastest
55
ROME (Acid Base Balance disorders mnemonic)
Respiratory Opposite (alkalosis: ph ^ pCO2 decreases acidosis: pH decrease pCO2 ^) Metabolic Equal (alkalosis: ^^ both pH and HCO3 acidosis: both pH and HCO3 decrease)
56
Respiratory Acidosis
ph under 7.35 respiratory CO2 >> 45 we are retaining CO2 (hypoventilation) body would try to self regulate by raising bicarb (increasing the level of a base) in the blood to fix pH
57
Respiratory Alkalosis
pH above 7.45 CO2 is below 35 hyperventilation (blowing off lots of CO2) body would try to self regulate by getting rid of HCO3 (bicarb)
58
Metabolic Acidosis
ph << 7.35 Metabolic bicarbonate (HCO3) << 22 (kidney is excreting. lower levels of base allow for more acidic pH) body starts hyperventilating to get rid of the acid (CO2) anion gap is a method of fixing metabolic acidosis
59
Metabolic Alkalosis
ph > 7.45 HCO3 > 26 body starts hypoventilation (retaining CO2) to bring more acid
60
Respiratory Control Mechanisms
Works within minutes to control pH; maximal in 12-24 hours Only about 50-75% effective in returning pH to normal Excess CO2 & H+ in the blood act directly on respiratory centers in the brain CO2 readily crosses blood-brain barrier reacting w/ H2O to form H2CO3 Carbonic acid, H2CO3, splits into H+ & HCO3- & the H+ stimulates an increase or decrease in respirations

ABSN Pathophysiology Summer23 (9 decks)

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