NUR3125 | fluid, electrolytes, acid-base

What are causes of hypokalemia?

-reduced intake of K

-increased entry of K into cells (ex: hyperinsulinism, steroid administration, crushing syndrome)

-increased loss of K (GI and renal losses)

What are clinical manifestations of hypokalemia?

Membrane hyperpolarization that causes a decrease in neuromuscular excitability; skeletal muscle weakness, smooth muscle atony, cardiac dysrhythmias; Prolong PR interval, depression of the ST segment, flattening of the t-wave, prominent U wave

What are the causes and effects of hypophospatemia?

causes:

-intestinal malabsorption

-malnutrition

-respiratory alkalosis

- increased renal excretion associated with hyperparathyroidsm

effects:

-muscle pain and weakness

-mental changes (irritability, confusion, numbness, coma, convulsions)

-possibly respiratory failure

-cardiomyopathies

What are the causes and effects of hypermagnesemia?

causes:

-usually renal insufficency/failure

-excessive intake of Mg-containing antacids

-adrenal insufficency: renal excretion

effects:

-lethary and drowsiness

-hypotension

-muscle weakness

- decreased deep tendon reflexes (DTR)

-bradycardia

What is respiratory acidosis caused by? effects?

causes:

-hypoventilation

-RESPIRATORY DEPRESSION

-AIRWAY OBSTRUCTION (DECREASED ALVEOLAR CAPILLARY DIFFUSION)

-acute and chronic orders of ventilation

- increased PaCO2 production (burns, fever, sepsis, carbohydrate rich diet)

effects:

hypoventilation = hypoxia

What is the name of this abnormal ABG?

pH = 7.33

PaCO2 = 25

HCO3 = 20

metabolic acidosis partially compensated

What are the functions of body fluids?

Transport gases, nutrients, and wastes

Help generate the electrical activity needed to power body functions

Take part in the transformation of food into energy

Maintain the overall function of the body

ENVIORNMENTAL STRESSES AND DISEASE AFFECT THE BALANCE

What type of cellular fluid is 2/3 of total body water?

intracellular fluid

What are the three types of extracellular fluid?

intravascular, interstitial, transcellular

The intracellular compartment has a high concentration of ____?

potassium

The extracellular compartment has a high concentration of _____?

Sodium

osmolarity of extracellular fluid is almost entirely due to ___?

sodium

What are the organs involved in fluid-electrolyte balance?

kidneys, lungs, heart, adrenal glands, parathyroid glands, pituitary gland

What is the adrenal glands role in fluid-electrolyte balance?

secrete aldosterone which causes sodium retention (resulting in water retention) and K secretion → high BP and fluid volume

What is the parathyroid glands role in fluid-electrolyte balance?

regulate calcium and phosphate balance

What hormone does the posterior pituitary gland make?

secretes anti diuretic hormone (ADH)

What is an isotonic solution?

Contains equal concentratinos of solutes on both sides.

cells neither shrink or swell

what is a hypotonic solution?

Solute concentration is less than that inside the cell;

cells gains water (cells swell)

What is a hypertonic solution?

Solute concentration is greater than that inside the cell;

cell loses water (cells shrink)

What forces favor filtration in the capillaries?

capillary hydrostatic pressure (blood pressure)

interstitial oncotic pressure (water-pulling)

What forces favors reabsorption in the capillaries?

plasma (capillary) oncotic pressure (water-pulling)

interstitial hydrostatic pressure

What is edema?

accumulation of fluid within the interstitial spaces

What are some causes of edema?

decreased synthesis and increased loss of plasma proteins + increased sodium and H2O retention → decreased capillary oncotic pressure (decreased keeping water in → more water out)

increased capillary permeability via burns and inflammation → loss of proteins to interstitial space → decreased COP + increased interstitial oncotic (keeping water out) → edema

increased capillary hydrostatic pressure → more movement into tissues → edema

What is the role antidiuretic hormone (ADH)?

secreted when there’s high osmolarity (high Na concentration) or low volume (not enough fluid) = FLUIDS ARE LOW

steps:

high osmolarity (too salty) is detected by osmoreceptors (why eating a lot of salt makes you thirsty duh) → hypothalamus → increased thirst and fluid intake → decrease osmolarity

low plasma volume (low water) is detected by volume receptors → hypothalamus tells pars nervosa of PPG to secrete ADH → renal water retention (kidneys hold water in) → decrease osmolarity and increase plasma volume

what is the role of natriuretic peptide (ANP,BNP)?

fluids high in heart → fluids low in heart

secreted when there’s high volume of the heart (lots of fluid in heart, usually during heart failure) → atrial stretching → triggers ANP release → increases GFR (kidneys excrete more water) + decrease sodium reabsorption (more sodium excreted in urine)

What is the role of renin angiotensin aldosterone system (RAAS)?

low BP and low volume → high BP and high volume

low blood pressure and volume sensed by juxtaglomerular cells of kidney → secretes renin → angiotensinogen → angiotensin I → ACE enzyme released from lungs → angiotensin II →

adrenal gland releases aldosterone → reabsorption of sodium and H2O → excretion of potassium→ increase in volume and BP

vasoconstriction of systemic arterioles → increase BP

What is normal osmolarity levels?

275-295

What is hypertonic alterations?

-related to Na gain or water loss

- results in hypernatremia

-intracellular dehydration

what is hypotonic alterations?

-decreased osmolality

-results in hyponatremia

-water moves into the cell via osmosis

What is isotonic alterations?

- total body water changer with proportional electrolyte and water change (no change in concentration)

-isotonic fluid loss

-isotonic fluid excess

What is hypertonic dehydration?

greater loss of water than electrolytes

What is hypotonic dehydration?

greater loss of electrolytes than water

What is isotonic over hydration?

-known as hypervolemia

-results from excessive fluid in the Extracellular compartment

-fluid does not shift between compartments

-causes circulatory overload and interstitial edema

What is hypertonic over hydration?

-caused as a result of excess Na intake

-fluid is drawn from the intracellular fluid compartment

What is hypotonic over hydration?

-known as water intoxication

-fluid moves into the intracellular space and all body fluid compartment expands

What is the normal level of sodium?

135-145 mEq/L

_____ is the primary determinant of plasma osmolality

sodium

What is sodium essential for?

nerve impulse transmission, muscle contraction, and the movement of glucose and amino acids

What is hyponatremia?

- Na level less than 135

- Na deficit cause plasma hypoosmolaltiy and cellular swelling

-most common electrolyte disorder

What are causes + manifestations of hyponatremia?

Na loss or low intake, diuretics, GI losses, excessive water intake, diaphoresis

NERVOUS SYSTEM: lethargy, headache, confusion, apprehension, seizures, coma- early signs: muscle cramps, weakness, and fatigue-if leads to loss of extracellular fluid and hypovolemia: hypotension, tachycardia, decreased urine output

What is hypernatremia? What are some clinical manifestations?

-sodium level greater than 145

- mostly related to large amount of water loss

- thirst (early symtptom)

- DECREASED URINE OUTPUT

-INCREASED URINE OSMOLALITY

-INCREASED SERUM OSMOLALITY

- dry skin and mouth

-seizures

-tachycardia

What is the normal level of potassium?

3.5-5.0 mEq/L

What is the electrolyte potassium essential for?

transmission and conduction of nerve impluses, normal cardiac rhythms, and skeletal and smooth muscle contractions

How is potassium regulated?

regulated by renal mechanisms (aldosterone) and transcellular buffer systems

T/F: changes in pH affect potassium balance.

true

Epinephrine, albuterol, and insulin move potassium _____ the cell.

into

repeated muscle contractions move potassium _____ the cell.

out of

What are causes of hyperkalemia?

increased intake,

shift of K+ from ICF into ECF (acidosis)

decreased renal excretion (potassium sparing diuretics, renal failure, Addison’s disease)

cell trauma

What are manifestations of hyperkalemia?

mild: membrane cell depolarization - initially increased neuromuscular

irritability; restlessness, intestinal cramping, and diarrhea; severe attacks: EKG: Peaked narrow T waves, Widening QRS, Ventricular; fibrillation and cardiac arrest; decreases the resting membrane potential; muscle weakness, loss of muscle tone, and paralysis

What is the role of the hormone aldosterone?

reabsorb Na+ and secrete K+ at the kidney

Ca and PO4 are controlled by _____, _____, and _______

parathyroid hormone (PTH)

vitamin D

calcitonin

What is the main function of parathyroid hormone?

to maintain Ca concentration of the ECF

What happens with the PTH when Ca level is HIGH?

PTH inhibited and Ca gets stored in the bones

What happens with the PTH when Ca level is LOW?

PTH secretion is increased and Ca is mobilized from the bone.

What is hypoparathyroidism?

A condition caused by hyposecretion of the PTH by the parathyroid glands

What is the causes of hypocalcemia?

inhibition of Ca absorption from the GI tract (low vitamin D, inadequate oral intake)

increase Ca excretion (renal failure, diarrhea)

What are clinical manifestations of hypocalcemia?

Chvostek's sign, Trousseau's sign, tetany, muscle twitching,

What are the three forms ECF Ca can exist?

ionized (50%)

protein bound (40%)

complexed (10%)

What is the normal range for phosphate?

2.5-4.5 mg/dL

Where is phosphate (PO4) located? and why is it important?

located in bone

provides energy for muscle contraction

Parathyroid hormone, vitamin D, and calcitonin work together to control _______ absorption and excretion.

phophate (PO4)

What are the causes and symptoms of hyperphosphatemia?

causes:

- decreased renal excretion (renal failure)

- increased intake

- hypoparathyroidism

symptoms:

-primarily related to low Ca levels (caused by high PO4 levels) SIMILAR TO HYPOCALCEMIA

What is the normal range of magnesium?

1.5-2.5 mEq/L

Why is magnesium important?

-intracellular cation

-acts as a cofactor in intracellular enzymatic reactions

- increase neuromuscular exitablity (helps muscles and nerves stay healthy)

What are the causes and effects of hypomagnesemia?

causes:

-malnutrition

-gastric suction

-malabsorption syndromes

-ALCOHOLISM

-urinary losses (loop diuretics, renal tubular dysfunction)

effects:

-anorexia

-neuromuscular irritability

- increase reflexes

-depression

-disorientation

What is an antidote for hypermagnesemia?

calcium carbonate

What three systems are involved in acid-base balance?

chemical buffer system (HCO3-H2CO3)

kidneys (HCO3)

lungs (CO2)

What is normal pH?

7.35-7.45

How can acid be eliminated?

-By lungs as CO2 gas

-By the renal tubules with the regulation of bicarbonate (HCO3- )

-By regulating secretion of H+ into the urine.

What is a buffer? What are the most important plasma-buffering system?

-a chemical that can bind excessive H+ or OH- with out a significant change in pH

- the carbonic acid (H2CO3) - bicarbonate (HCO3) pair

What is the normal ratio of bicarbonate (base) to carbonic acid (H2CO3) ?

20 to 1

What are the two systems that can compensate when the pH is altered?

respiratory and renal systems

low pH =

acidosis

high pH =

alkalosis

What is normal PaCO2?

35-45 mmHg

What is normal HCO3 level?

21-28 mEq/L

What is normal PaO2 level?

80-100 mm Hg

When the HCO3 is low and pH is low this is?

metabolic acidosis

When the HCO3 is high and pH is high this is?

metabolic alkalosis

What are the causes and clinical cause of metabolic acidosis?

caused by:

-increased metabolic acids

-inability of kidneys to excrete acids

-excess loss of HCO3 via kidneys/GI

clinical causes:

- over production of acids (DIABETIC KETOACIDOSIS)

- severe loss of HCO3 (SEVERE DIARRHEA)

-KUSSMAL RESPIRATIONS (COMPENSATORY HYPERVENTILATION)

What are the causes and clinical causes of metabolic alkalosis?

causes:

- increased HCO3 administration

- excess loss of acid via kidneys/GI

-increase HCO3 levels by concentration of ECF via hypokalemia and hypochloremia

clinical causes:

-COMPENSATORY HYPOVENTILATION

-TREMORS, MUSCLE CRAMPS, TINGLING OF FINGERS AND TOES

-SEVERE VOMITING

-EXCESSIVE GI SUCTIONING

-excess base loading (antacids, ringers lactate)

-loss of acid (gastric suctioning, vomiting, THIAZIDE/LOOP DIURETICS)

-contraction of ECF ( decrease in ECF due to vomiting/NGT suction leads to loss of Cl and reabsorption of Na and HCO3)

When the PcCO2 is high and the pH is low this is

respiratory acidosis

When the PaCO2 is low and the pH is high this is

respiratory alkalosis

What are the causes and symptoms of respiratory alkalosis?

causes:

-hyperventilation (increased CO2)

-central stimulation of respiratory center (anxiety, pain)

-stimulation of peripheral pathways to respiratory center

-hypoxemia

symptoms:

-NUMBNESS AND TINGLING OF EXTREMITIES

- hyperventilation

What is the name of this abnormal ABG?

pH = 7.30

PaCO2 = 50

HCO3 = 24

respiratory acidosis

What is the name of this abnormal ABG?

pH = 7.48

PaCO2 = 44

HCO3 = 32

metabolic alkalosis

What is the name of this abnormal ABG?

ph = 7.10

PaCO2 = 50

HCO3 = 15

mixed acidosis

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