Summary
Summary NUR 323 Final Exam Study Guide
- Course
- NUR 323
- Institution
- University Of Rhode Island
This is a comprehensive and detailed exam study guide on finals for Nur 323. *Essential Study Material!!
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Fluid and Electrolyte DisturbancesAcid-Base Balance
Body normally maintains steady balance between acids produced during metabolism and
bases that neutralize or promote excretion of the acids
Increased CO2 or H+ hyperventilation
o Leads to acidity
Decreased CO2 and H+ hypoventilation
o Leads to alkaline solution
The lower the pH, the higher the H+ concentration
pH of solution (ranges from 1-14)
o pH 7 neutral
o pH <7 acidic
o pH >7 alkalosis
Normal blood pH is 7.35-7.45 (slightly alkaline)
o <7.35 is acidosis
o >7.45 is alkalosis
Buffer system primary regulator
Acid-Base Regulation
Buffer System
o Fastest-acting and primary regulator in the body
o Buffers act chemically to change strong acids to weaker acids; bind acids to
neutralize their affect
o Cells can act as buffer system by shifting H+ in and out of cells
Respiratory System
o Responds in minutes, maximum effectiveness in hours
o Helps maintain pH by excreting CO2 and water (by-products of metabolism)
When released into circulation, CO2 enters RBC and combines with water
to form H2CO3 (CO2 + H2O)
Carbonic acid dissociates into H+ and HCO3-
H+ is buffered by hemoglobin and HCO3- diffuses into plasma
In capillaries this process is reversed, CO2 is formed and excreted
by the lungs
The amount of CO2 in the blood directly relates to carbonic acid
concentration and subsequent H+ concentration
Increased respirations more CO2 expelled and less in blood
less carbonic acid less H+
Decreased respirations more CO2 in blood more carbonic
acid more H+
Rate of CO2 excretion is regulated by medulla in brainstem
Increased CO2 or H+ hyperventilation (blow off CO2)
Decreased CO2 or H+ hypoventilation (retain CO2)
Renal System
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, o 2-3 days for maximal response but can maintain balances indefinitely in chronic
imbalances
o Normal conditions kidney reabsorbs and conserves all bicarbonate they filter
o Kidneys can generate additional bicarbonate or eliminate excess H+ as a
compensation for acidosis
Normal urine acidic pH 6
Compensatory mechanism urine can decrease to pH 4 or increase to pH
8
Alteration in Acid-Base Balance
Occurs when ratio of 1:20 between acid and base content is altered
o NORMAL ACID-BASE BALANCE IS 1:20
o Primary disease or process may alter one side of ratio
o Compensatory process attempts to maintain the other side of ratio
When compensatory mechanism fails, acid-base imbalance results
Because of pathophysiology or not enough time for mechanism to
function
o Ex: CO2 retention in pulmonary disease
Increased renal bicarbonate reabsorption
Increased H+ excretion
Respiratory Acidosis (excess carbonic acid)
o Occurs with hypoventilation
CO2 builds up and subsequent carbonic acid
o To compensate, kidneys conserve bicarbonate and secrete H+ in urine
Respiratory Alkalosis (Carbonic Acid Deficit)
o Occurs with hyperventilation
Hypoxemia from pulmonary disorders, anxiety, CNS disorders,
mechanical ventilation
o Compensated respiratory alkalosis is rare, must treat cause
o May get buffering by shifting bicarbonate (HCO3-) into cells in exchange for Cl-
Metabolic Acidosis (Bicarbonate Deficit)
o Occurs when acid (other than carbonic acid) accumulates in body or when
bicarbonate is lost from body fluids
Ketoacids with ketoacidosis
Lactic acid with shock
Severe diarrhea results in loss of bicarbonate
Renal disease, kidney loses ability to reabsorb bicarbonate
o Compensatory mechanism increase CO2 excretion
Hyperventilation; Kussmaul breathing
Metabolic Alkalosis (Bicarbonate Excess)
o Occurs in loss of acid or gain of bicarbonate
Prolonged committing or gastric suction
Ingestion of baking soda
o Compensatory mechanism
Decreased respiratory rate to increase plasma CO2 hypoventilation
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, Renal excretion of bicarbonate
Metabolic acidosis correct with hyperventilation
Metabolic alkalosis correct by hypoventilation
Carbonic acid respiratory
Bicarbonate metabolic
Examples of Acid-Base Balance
1. pH is 7.54
a. alkalosis (pH is >7.45)
b. respiratory rate will decrease
c. retain CO2 (an acid) and correct the alkalosis
2. pH is 7.28
a. acidosis (pH is <7.35)
b. respiratory rate will increase
c. to rid body of CO2 (acid) and correct acidosis
ABGs: Analyzing Blood Gases
Diagnostic Studies
Arterial Blood Gas (ABG)
o Measures PaO2, PaCO2, acidity (pH), and bicarbonate (HCO3) in arterial blood
o SaO2 is either calculated or measured
o Specimen obtained from arterial puncture; usually radial or femoral
o Risk for bleeding; risk for infection; painful
Normal ABG Levels
pH: 7.35-7.45
PaCO2: 35-45 mmHg
Bicarbonate (HCO3): 22-26 mEq/L
PaO2: 80-100 mmHg
SaO2: 95%
Base excess: +/- 2.0 mEq/L
Analyzing Arterial Blood Gases
Determine if its acid or base
Analyze PaCO2 to determine if respiratory acidosis or alkalosis
Analyze bicarbonate to determine if patient has metabolic acidosis or alkalosis
Determine if CO2 or HCO3- changes match the pH alteration
Decide if body is trying to compensate
Acidic Normal Alkaline
pH <7.35 7.35-7.45 >7.45
Resp. PaCO2 >45 35-45 <35
Met. HCO3 <22 22-26 >26
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, Fluid and Electrolytes
Key Terms:
Homeostasis
o Equilibrium in the body
Intracellular fluid
o Fluid inside the cells; 2/3
Extracellular fluid
o Fluid outside the cells; 1/3
Cations
o Positively charged ions
Anions
o Negatively charged ions
Active transport
o Molecules move against concentration gradient using energy
o Move from low to high concentration
ex: Na+/K+ pump
Na+ moves out, K+ moves in
Diffusion
o Movement from high to low concentration through semipermeable membrane
o Requires no energy
Facilitated diffusion
o Use of carrier protein to pass larger molecules though membrane (high to low
concentration)
No energy, passive
Osmosis
o Movement of water from region of low solute concentration to high solute
concentration
o Higher the concentration the stronger the pull (osmotic pressure)
o Requires no energy
o Osmolarity fluids outside the body
Sodium-Potassium Pump
o Active transport
o Sodium moves out
o Potassium moves in
o Energy used ATP produced in cells mitochondria
Colloids
o Version of crystalloids but with larger particles that cannot cross membrane
Crystalloids
o Water and small particles
Hypotonic
o Solutions in which solutes are less concentrated than the cells
o Swells
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