Fluids and Electrolytes
What Are Fluids
Fluid: molecules that are able to move freely and are changeable; adapt to shape of containers; fluid composition is
critical for your body’s ability to function; between 50% and 70% of our body weight is fluid.
Intracellular fluid: two thirds of our body fluid is held within the walls of our cells; when our cells lose fluid they shrink
Extracellular fluid: remaining third of our body fluids that flow outside the cells; three types -
1) Tissue fluid: flows between the cells that make up a particular organ (such as muscle fibres or the liver)
2) Plasma: extracellular fluid that causes your blood to drip; it is the liquid portion of blood; carries red blood cells
3) Digestive juices: secreted by cells in the pancreas, stomach and small intestine.
Electrolytes: body fluids are made of water with electrolytes dissolved in it; mineral salts.
Ions: electrically charged particles.
What Do Fluids Do?
1) Dissolve and transport
substances: transports all
carbohydrates, amino acids,
minerals, medication; water
insoluable substances such as
fat are transported with the
help of water soluble proteins.
2) Account for blood volume: you
need enough blood volume to
maintain healthy fluid levels;
this makes it possible for the blood transport of oxygen, nutrients and hormones.
3) Help maintain body temperature: water isn’t easy to heat; being made of mostly water helps keep us cool.
4) Protects and lubricates our tissues: cerebrospinal fluid cushions the brain and spinal cord; amnionic fluid
protects a fetus; creates saliva, tears and mucus.
What Do Electrolytes Do?
- Help regulate fluid balance through osmosis; they draw water towards areas where they are concentrated; this
continues until the solutes are equal on both sides of the cell membrane.
- Ions are the sparks that stimulate nerves and causes muscle contractions; critical to body functioning. How Do We Lose Water
Insensible water loss: evaporation, sweat, breath
Hypothalamus: cluster of nerve cells in this part of the brain tell us we are thirsty; stimulate d by:
- High concentrations of salt or other dissolved substance in our blood.
- Low blood volume or blood pressure
- Dryness in the mouth
*problem: we drink until we are not thirsty but this is often not enough to achieve fluid balance.
How Do We Get Fluids?
- Chemical reactions in the body; metabolic water:
formed by breakdown of fat, carbs and protein, adenosine
triphosphate (ATP); makes up 10-15% of our daily water
- Food and beverages.
- Making triglyceride and peptide bones creates