Body Fluids, Electrolytes, and Acid-Base Balance

Comprehensive vocabulary flashcards covering fluid compartments, electrolyte compositions, fluid movement, IV solutions, regulatory hormones (ADH, Aldosterone, ANP, BNP, RAAS), and acid-base balance mechanisms and disorders.

Intracellular Fluid (ICF) fraction of total body fluid

Fluid located inside cells that constitutes approximately 2/3 of total body fluid. [Slide 2]

Physical boundary separating Intracellular Fluid (ICF) from Extracellular Fluid (ECF)

The plasma membrane. [Slide 2]

Extracellular Fluid (ECF) fraction of total body fluid

Fluid located outside cells that constitutes approximately 1/3 of total body fluid. [Slide 2]

Two main subcompartments of Extracellular Fluid (ECF)

Interstitial fluid (IF) and blood plasma. [Slide 2]

Interstitial fluid (IF) proportion of Extracellular Fluid (ECF)

$\frac{2}{3}$ of ECF. [Slide 2]

Blood plasma proportion of Extracellular Fluid (ECF)

$\frac{1}{3}$ of ECF. [Slide 2]

What separates blood plasma from interstitial fluid?

Capillary walls. [Slide 2]

Total body water volume in an average body

$42\,L$ [Slide 5]

Intracellular Fluid (ICF) total volume in an average body

$28\,L$ [Slide 5]

Extracellular Fluid (ECF) total volume in an average body

$14\,L$ [Slide 5]

Interstitial fluid volume in an average body

$10\,L$ [Slide 5]

Blood plasma volume in an average body

$3\,L$ [Slide 5]

Transcellular fluid volume in an average body

$1\,L$ [Slide 5]

Major solutes enriched in Intracellular Fluid (ICF)

Potassium ($K^+$), magnesium ($Mg^{2+}$), phosphate ($PO_4^{3-}$), and negatively charged proteins. [Slide 6]

Cellular processes that control Intracellular Fluid (ICF) composition

Cell processes and membrane transport ($Na^+/K^+$ pump). [Slide 6]

Major solutes enriched in Extracellular Fluid (ECF)

Sodium ($Na^+$), chloride ($Cl^-$), and bicarbonate ($HCO_3^-$). [Slide 6]

Protein difference between blood plasma and interstitial fluid within the ECF

Blood plasma contains proteins, whereas interstitial fluid has very little or no protein. [Slide 6]

movement of fluid between compartments is due to

Osmolarity (solute concentration). [Slide 8]

water moves by osmosis (mvmnt of fluid between compartments)

From hypotonic (more water) $\rightarrow$ hypertonic (less water). [Slide 8]

Fluid shift pathway when drinking enough water

Blood becomes hypotonic, causing water to shift: Blood $\rightarrow$ Interstitial fluid $\rightarrow$ Cells. [Slide 8]

Fluid shift pathway during dehydration

Blood becomes hypertonic, causing water to shift: Cells $\rightarrow$ Interstitial fluid $\rightarrow$ Blood. [Slide 8]

Cellular morphological effect of a hypertonic solution

More salt than water in solution, causing cells to SHRINK. [Slide 9]

Cellular morphological effect of an isotonic solution

Equal parts water and salt in solution, causing cells to STAY THE SAME. [Slide 9]

Cellular morphological effect of a hypotonic solution

More water than salt in solution, causing cells to SWELL. [Slide 9]

Hypertonic IV fluid concentration definition and examples

Anything ABOVE $0.9\%$; examples include $3\%$ Normal Saline and $10\%$ Dextrose. [Slide 9]

Isotonic IV fluid examples

$0.9\%$ Normal Saline and Lactated Ringers. [Slide 9]

Hypotonic IV fluid concentration definition and examples

Anything BELOW $0.9\%$; examples include $0.45\%$ Normal Saline and $0.33\%$ Normal Saline. [Slide 9]

Tonicity behavior of 5% Dextrose (D5W) after infusion

STARTS as isotonic and becomes HYPOtonic when metabolized. [Slide 9]

Hypertonic components

More salt than water in solution

Hypotonic components

More water than salt in solution

Net fluid movement direction during dehydration (Review Question)

From cells $\rightarrow$ blood. [Slide 11]

Fluid balance

State where fluid intake = fluid output, maintaining normal distribution of water and solutes in ICF and ECF. [Slide 12]

Four organ systems that maintain fluid balance

Urinary, digestive, cardiovascular, and endocrine systems. [Slide 12]

Ingested water volume and sources

From food and drinks, totaling approximately $2300\,mL/day$. [Slide 13]

Metabolic water volume and production mechanisms

Produced inside the body during cellular respiration and dehydration synthesis, totaling approximately $200\,mL/day$. [Slide 13]

Body's largest route of fluid output

Urination (~$1500\,mL$, about $60\%$ of total loss). [Slide 14]

Five routes of water loss from the body

Urination, breathing (lungs), sweating, cutaneous transpiration (skin evaporation), and defecation. [Slide 14]

Cutaneous transpiration definition

Water loss through skin evaporation, distinct from sweating. [Slide 14]

Percentage of fluid output lost collectively via skin, lungs, and feces

Remaining $40\%$ of fluid loss. [Slide 14]

Three factors that cause fluid output variation

Physical activity, environment (heat, humidity), and body condition. [Slide 15]

How does the body maintain balance

Fluid intake MUST equal fluid output

Reason for administration of IV solution

Means to increase fluid input directly into the blood

Common anatomical sites for clinical IV needle placement

Veins in the hand or the antecubital region. [Slide 16]

Two most common clinical IV solutions

A $0.9\%$ saline solution and a $5\%$ dextrose (D5W) solution. [Slide 16]

0.9% Saline Solution exact chemical composition

$0.9\,g$ of sodium chloride to every $100\,mL$ of sterile water. [Slide 17]

Physiological reason 0.9% saline is the standard fluid replacement IV solution

It is isotonic to blood plasma and will not typically cause a net shift of fluid between compartments. [Slide 17]

5% Dextrose (D5W) Solution exact chemical composition

$5\,g$ of dextrose sugar to every $100\,mL$ of sterile water. [Slide 18]

Tonicity of 5% Dextrose (D5W) in holding bag and clinical utility

Hypertonic to blood in the holding bag; metabolized in the body to maintain normal fluid concentration, supplying water and energy (glucose). [Slide 18]

Antidiuretic Hormone (ADH / Vasopressin) source, trigger, action, and overall effect

Source: Hypothalamus $\rightarrow$ Posterior pituitary;

Main trigger: $\uparrow$ Osmolarity (dehydration), $\downarrow$ blood volume;

Main action: $\uparrow$ Water reabsorption in kidneys (collecting ducts);

Overall effect: Keeps WATER (not excess water is lost in urine). [Slide 19]

Aldosterone source, trigger, action, and overall effect

Source: Adrenal cortex;

Main trigger: $\downarrow Na^+$, $\downarrow$ BP, $\uparrow K^+$;

Main action: $\uparrow Na^+$ reabsorption, $\uparrow K^+$ excretion $\rightarrow$ water follows $Na^+$;

Overall effect: Keeps SALT + WATER. [Slide 19]

Angiotensin II trigger, actions, and overall effect

Trigger: $\downarrow$ BP, $\downarrow$ blood volume (via RAAS mechanism);

Main action: Vasoconstriction + stimulates ADH & aldosterone;

Overall effect: Raises BP quickly. [Slide 19]

Atrial Natriuretic Peptide (ANP) source, trigger, action, and overall effect

Source: Heart (atria);

Main trigger: $\uparrow$ Blood volume / pressure;

Main action: $\downarrow Na^+$ reabsorption $\rightarrow \uparrow$ water loss;

Overall effect: Loses SALT + WATER. [Slide 19]

Brain Natriuretic Peptide (BNP) source, trigger, action, and overall effect

Source: Heart (ventricles);

Main trigger: $\uparrow$ Ventricular stretch;

Main action: Similar to ANP;

Overall effect: Reduces volume (like ANP). [Slide 19]

Meaning of the RAAS acronym

Renin-Angiotensin-Aldosterone mechanism. [Slide 19]

Aquaporins definition

The proteins that transport water molecules in kidney collecting duct cells under the influence of ADH. [Slide 20]

Action of ADH in form of flowchart

Dehydration→increased plasma osmolarity→hypothalamus signals P.P.G to secrete→ADH→kidney collecting duct→ Aquaporins inserted→water reabsorption→concentrated urine→ normal hydration

Hormone memory trick: ADH

ADH $\rightarrow$ "Aqua" $\rightarrow$ Water – saves water. [Slide 21]

Hormone memory trick: Aldosterone

"Salt hormone" – saves salt and water. [Slide 21]

Hormone memory trick: ANP and BNP

"Anti-volume hormones" (removes salt and water). [Slide 21]

Hormone memory trick: Angiotensin II

"Emergency BP booster". [Slide 21]

Acid-Base Buffer Systems (Bicarbonate,protein,phosphate) site of action, speed, action, and simple effect

Acts in: Blood & cells;

Speed: Immediate (seconds);

Main action: Bind or release $H^+$ ions;

Simple effect: First control (instant control). [Slide 22]

Respiratory System acid-base control site of action, speed, action, and simple effect

Acts in: Lungs;

Speed: Fast (minutes);

Main action: Controls $CO<em>2$ by changing breathing rate;

Simple effect: Blow off acid ($CO</em>2$). [Slide 22]

Renal System acid-base control site of action, speed, action, and simple effect

Acts in: Kidneys;

Speed: Slow (hours–days);

Main action: Excrete $H^+$, reabsorb/generate $HCO_3^-$;

Simple effect: Final control (strong, long-term). [Slide 22]

Buffer system

Main: bicarbonate buffer (HCO3-/H2CO3)

Prevents sudden pH changes

Works immediately

Respiratory control

CO2→H2O→carbonic acid

Fast breathing=decrease in CO2→decrease acid→increase pH

Slow breathing=increase in CO2→increase acid→decrease pH

Renal control

Kidneys remove H+ (acid) and keep/make HCO3-(base)

Most powerful but slow

Acid-Base control mechanisms speed hierarchy memory trick

Buffers = FIRST, Lungs = FAST, Kidneys = FINAL. [Slide 23]

Respiratory Acidosis cause, pH, main change, compensation, and examples

What's wrong: Not breathing enough; pH: $\downarrow$; Main change: $\uparrow CO<em>2$ (acid); Compensation: Kidneys keep $HCO</em>3^-$; Examples: COPD, asthma, drug overdose (opioids), airway obstruction; Think: $CO_2$ builds up = acid $\uparrow$. [Slide 24]

Respiratory Alkalosis cause, pH, main change, compensation, and examples

What's wrong: Breathing too fast; pH: $\uparrow$; Main change: $\downarrow CO<em>2$; Compensation: Kidneys remove $HCO</em>3^-$; Examples: Anxiety/panic attack, high altitude, fever; Think: $CO_2$ lost = acid $\downarrow$. [Slide 24]

Metabolic Acidosis cause, pH, main change, compensation, and examples

What's wrong: Too much acid OR loss of base; pH: $\downarrow$; Main change: $\downarrow HCO<em>3^-$; Compensation: Lungs breathe fast ($\downarrow CO</em>2$); Examples: Diarrhea, diabetic ketoacidosis (DKA), kidney failure; Think: Base is low = acid wins. [Slide 24]

Metabolic Alkalosis cause, pH, main change, compensation, and examples

What's wrong: Too much base OR loss of acid; pH: $\uparrow$; Main change: $\uparrow HCO<em>3^-$; Compensation: Lungs breathe slow ($\uparrow CO</em>2$); Examples: Vomiting, antacid overuse, diuretics; Think: Base is high = pH high. [Slide 24]

Meaning of the COPD acronym

Chronic Obstructive Pulmonary Disease. [Slide 24]