Physiology 2130 Lecture Notes - Lecture 2: Body Water, Extracellular Fluid, Fluid Compartments
29 May 2018
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Module 2 – Outcomes
Make a simple diagram of two cells and a nearby capillary. Label the intracellular fluid compartment, extracellular fluid
compartment, interstitial fluid compartment, plasma, and cell membrane. Indicate the relative size of each of the
compartments in terms of percent of total body water.
• Total body water: 42 L
o Intracellular enviro - ~30 L (70%)
o Extracellular ~12 L (30%)
▪ Interstitial - ~10 L (25%)
▪ Plasma - ~2 L (7%)
Describe the chemical composition of the intracellular fluid, interstitial fluid, and plasma in
terms of sodium, potassium, chloride, and proteins. (You do not need to memorize the
exact amount, just their relative levels.)
• Sodium:
o extracellular (interstital and plasma)
o intracellular
• Potassium
o extracellular (interstital and plasma)
o intracellular
• Calcium
o extracellular (interstital and plasma)
o intracellular
• Chloride
o extracellular (interstital and plasma)
o intracellular
Explain what accounts for the differences in chemical composition of the intracellular and interstitial fluids and plasma.
• Why do we see these differences in ionic compositions?
o Due to the cell membrane
• The cell membrane forms a physical barrier between the intercellular and extracellular fluids
• This membrane is selectively permeable
o Some substances can cross very easily, and some cannot cross at all
• The membrane can be selective because it contains channels, pores and special transport systems that regulate the
passage of molecules across the membrane
If you were to design a 'Sports Drink' for athletes (like Gatorade). What would you include and why?
• Sugar – energy boosts
• Electrolytes like Na, Cl, K, and Ca – maintain muscular responses and water distribution
A simple mnemonic used to remember the relative chemical composition between intracellular and interstitial fluids is the
'Salt Baaa”. Eplai wh this eoic is useful. Draw a diagra to help eplai our aswer. Ca ou suggest a
better mnemonic that uses all the ions described in the module?
• “alty hoolate overed anana
o Outside – salt & choclate
▪ Na, Cl and Ca
o Inside – banana
▪ K
Extracellular
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Document Summary
Make a simple diagram of two cells and a nearby capillary. Label the intracellular fluid compartment, extracellular fluid compartment, interstitial fluid compartment, plasma, and cell membrane. Indicate the relative size of each of the compartments in terms of percent of total body water. Intracellular enviro - ~30 l (70%: extracellular ~12 l (30%) Interstitial - ~10 l (25%: plasma - ~2 l (7%) Describe the chemical composition of the intracellular fluid, interstitial fluid, and plasma in terms of sodium, potassium, chloride, and proteins. (you do not need to memorize the exact amount, just their relative levels. ) Sodium: extracellular (interstital and plasma, intracellular, potassium, extracellular (interstital and plasma, intracellular, calcium, extracellular (interstital and plasma, intracellular, chloride, extracellular (interstital and plasma, intracellular. Explain what accounts for the differences in chemical composition of the intracellular and interstitial fluids and plasma: why do we see these differences in ionic compositions, due to the cell membrane.
