ECF & ICF

What is the fluid compartment?

A location that is largely separate from another compartment by some form of a physical barrier

Components of fluid compartment

ECF & ICF

Extracellular Fluid (ECF)

Outside and between cells

Intracellular Fluid (ICF)

Inside cells

ICF comprises

~67% TBW and ~40% overall body wt.

ECF comprises

~33% TBW and ~20% overall body wt.

ECF composition

Plasma, Interstitial fluid, transcellular fluid

Plasma Compartment

25% of ECF

5% of body wt

Held within blood vessel

Interstitial Fluid Compartment

70% of ECF

15% of body wt

Flows between cells

Transcellular Fluid Compartment

5% of ECF

Separated from plasma by epithelium

Transcellular fluid types

CSF, Intraocular, Pleural, Peritoneal,Pericardial, Synovial, Digestive secretions

Total Body Water

60-70% of total body wt.

Why do adult bodies have more water than adolescents?

Muscle tissue holds water; adults have more muscle tissue therefore a higher water concentration.

Where are extracellular outputs sent?

Kidney, lungs, feces, sweat, and skin

What does ECF contain more of compared to ICF?

Nutrients and waste products, and higher concentrations of Cl-, HCO3-, Na+.

What does ICF contain more of compared to ECF?

Proteins, and higher concentrations of PO4-, K+, and Mg2+.

pH of the Blood

7.2-7.4

What role does HCO3- play in ECF?

Performs as buffer; controlling pH of the blood

What nutrients are found in ECF?

O2, glucose, fatty & amino acids

What waste products are in the ECF?

CO2, urea, uric acid, ions & excess water

Most abundant component of both ICF & ECF

water

How much of the ECF is transcellular fluid?

0.1%

How are fluids controlled in the body?

Thirst, sweating, renal control, and neuronal control

How does thirst affect the body?

Dehydration

What hormone affects renal fluid control?

Aldosterone

What is aldosterone?

Secreted from the adrenal cortex and promotes sodium, chloride, and water reabsorption in the kidneys.

How is neuronal fluid controlled?

Osmoreceptors & Baroreceptors

Osmoreceptors

Track changes in osmotic pressure

Found in pituitary gland

Baroreceptors

Track changes in blood pressure

Found in carotid arteries

How much blood does the human body have?

5L, but can change based on environment

Dehydration

Loss of water from the body

How does dehydration affect the cell?

Decrease in ECF & ICF volumes

Increase in osmolarity

Signs of dehydration

Dry tongue, poor skin elasticity, soft eyeballs, decrease in BP, increased Hb & Hct

Why do the eyeballs soften when dehydrated?

Lowering of intraocular tension

Why do ECF & ICF volumes drop when dehydrated?

Water is pulled from ECF when sweating > Solute conc. increases > Water is pulled from ICF to counteract > Water lost to sweating > TBW decreased

How is water removed from the ECF?

Blood vessels

Osmolarity

total concentration of all solute particles in a solution; depends on ion concentration; largely Na+ ions

Normal Osmolarity

300-320 mOsm/L

What is the unit for osmolarity

Osm/L

Solution

Solute + solvent

Solute

Substance being dissolved

Solvent

Substance that dissolves another

Aqueous solution

A solution in which water is the solvent

Electrolyte solution

A solution containing a solute that dissociates into ions

ex. salt water

Non-electrolyte solution

Solution containing a solute that will not dissociate into ions

eg. glucose water

Normal saline solution

0.9% NaCl

Purpose of physiological saline

Maintain osmolarity

How does physiological saline work?

NaCl will dissociate into Na+ and Cl- > Na+ is used in fluid maintenance

Amount of solute is measured in?

Moles, equivalents, or osmoles

Concentrations of solute measured in?

Moles per liter (mol/L)

Equivalents per liter (Eq/L)

Osmoles per liter (Osm/L)

Relationship between moles, particles, and mass

Avogadro's number

6.022 x 10^23

Equivalence

Concentration of electrolytes in a solution

Eq = mol * valence

What is the equivalence of 1mol CaCl2?

CaCl2 dissociates into Ca (2+) & Cl2 (1-) > 1 mol * (2+) = 2 Eq/L