Physiology 2130 Lecture Notes - Lecture 2: Body Water, Extracellular Fluid, Fibrinogen
20 May 2018
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Module 2 – Bodily Fluids
Intro:
• Our eternal environment is bathed in fluids
• Because of homeostasis the volume and ion concentrations of these fluids remain relatively stable
Body Fluid Compartments:
• The body is divided into two major fluid compartments
o Intracellular fluid compartment (ICF) – inside all the cells
o Extracellular fluid compartment (ECF) – everything outside the cell
• The extracellular fluid can be further divided
o The interstitial fluid compartment – fluid directly outside, bathing the cells
o The plasma – watery portion of the blood
• Fluid makeup in an average 70 kg (154 lb) person
o Total body water (TBW) is 42 litres or 11.1 gallons
o The ICF contains 28 L or 7.4 gallon
o The interstitial compartment contains 11 L or 2.9 gallons
o The plasma contains 3 L or 0.8 gallons
Plasma:
• Plasma is a pale-yellow fluid
• Consist of
o 92% water
o 8% other – ions, nutrients, gases and wastes
• Plasma is a colloidal solution: liquid containing suspended substances that do not settle out of solution
o Most of these suspended substances are plasma proteins (including albumins, globulins and fibrinogen)
• Plasma volume remains relatively constant
o Normally water intake matches water loss
Chemical Composition of the Body Fluids:
• Important ions in the body and their approx. concentrations in each fluid compartment
• Note: important to remember the relative distribution of the ions
o Big differences between the inside and outside of the cell
o Small differences between the plasma and interstitial fluid
• Sodium: Na+
o Interstitial – 150 mOsm/L H20
o Intracellular – 15 mOsm/L H20
o Plasma – 148 mOsm/L H20
o More inside than out
• Potassium: K+
o Interstitial – 5.0 mOsm/L H20
o Intracellular – 150 mOsm/L H20
o Plasma – 4.8 mOsm/L H20
o More inside than out
• Calcium: Ca+
o Interstitial – 2.4 mOsm/L H20
o Intracellular – 0 mOsm/L H20
o Plasma – 2.5 mOsm/L H20
o More outside than in
• Chloride: Cl-
o Interstitial – 125 mOsm/L H20
o Intracellular – 9 mOsm/L H20
o Plasma – 102 mOsm/L H20
o More outside than in
Know relative
distribution, not
exact numbers
Know relative
distribution, not
exact numbers
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Intro: our eternal environment is bathed in fluids, because of homeostasis the volume and ion concentrations of these fluids remain relatively stable. The body is divided into two major fluid compartments. Intracellular fluid compartment (icf) inside all the cells: extracellular fluid compartment (ecf) everything outside the cell. The extracellular fluid can be further divided: the interstitial fluid compartment fluid directly outside, bathing the cells, the plasma watery portion of the blood. Intracellular 15 mosm/l h20: plasma 148 mosm/l h20, more inside than out, potassium: k+ Intracellular 150 mosm/l h20: plasma 4. 8 mosm/l h20, more inside than out. Know relative distribution, not exact numbers: calcium: ca+ Intracellular 0 mosm/l h20: plasma 2. 5 mosm/l h20, more outside than in, chloride: cl- Intracellular 9 mosm/l h20: plasma 102 mosm/l h20, more outside than in, proteins: pr, plasma 1. 2 mosm/l h20. Chemical composition of the body fluids: why do we see these differences in ionic compositions, due to the cell membrane.
