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Week 1

Lecture Outline:

I.  Matter and Energy: Matter occupies space and has mass. It cannot be created or destroyed and it exists in 3 states.

1. States of matter

a. Solids – have definite shape and volume.
b. Liquids – have definite volume but are variable in shape
c. Gas – has no definite shape or volume.

2. Specific volume

3. Types of Energy

  1. kinetic energy actual movement or work being done
  2. potential energy is amt. of energy stored within a substance ready to produce some work.

4. Molecular structure and weight. All matter can be broken down into elemental units, which are atoms. Each element has an atomic # and weight relating to the # of protons in the nucleus of the atom. There are also an equal # of neutrons here and a specific # of electrons circling the core. The atomic weight of the atom is the "mass" of the atom and can be calculated using the total # of protons and neutrons. There are isotopes which share characteristics and # of protons but may have one or two less or more neutrons.

5. Atomic # and electron distribution – as above. The electrons circle the nucleus of an atom. The # of them depends on the substance and can be related to its position on the periodic table. Each horizontal row designates a new shell while each vertical row adds an electron to the atom as one travels left to right. The molecules on the far right are inert gases with full shells of electrons thus have no need to combine with other molecules. Their shells are full and they are happy! The theory of octet is what this phenomenon is about. The most unstable of elements are the 1st row on the left. The stability increases as one moves across to the right. The # of electrons that are able to react are called valence electrons. Anything with a valence electron of 3 or less is considered to be a metal and are highly reactive. IE. Lithium has an atomic # of 3. Its 1st shell has 2 electrons and is full but its second shell has only 1. It will donate that 1 electron to another element to keep its 1st shell full and happy. Potassium has atomic # of 19. # of electrons is 2 in the 1st shell, 8 in the 2nd and 3rd shells and only 1 in the 4th shell. Carbon can go either way has +/- 4 electrons. This whole area can also be referred to as the Bohr model.

6. Classification and reactivity of elements – reactivity will be dependent on the amt. of valence electrons available in the outer shell.

7. Types of bonding – Chemical bonds can be an ionic bond where the electron in the outer shell will leave the shell and go to another molecule. Sodium would give off one electron and chloride would take one. The result is a very stable bond. In covalent bonds the electrons are shared so that the electrons are circulating and sharing between the molecules. This bond can be polar (with a + and – end) or nonpolar (with and equal distance btw electrons or centers of the atoms. There can also be univalent bonding where the + valence # means they’ll donate electrons and anything that accepts electrons is know as a – valence.

8. Molecular motion and phases of matter – Cohesion is motion of matter. Solids move a little, liquids move more and gases move a great deal. Molecular motion increases as energy is added. Molecules exhibit a force of mutual attraction – closer they are to each other the greater the force is. This force btw like molecules is cohesion. The strongest state of cohesion will be in solid form. Cohesive force diminishes as molecules become further apart. Adhesion is a similar concept but with unlike molecules and it is the force that keeps the unlike substances together.

9. Temperature – can be measured in Fahrenheit, celsius or Kelvin. Kelvin is used in the ideal gas laws. To convert F to C: 9/5 x C + 32 = F K = C + 273.16

C to F: F – 32 x 5/9 = C

0 degrees K is the temp at which energy stops moving. It is very cold! The definition of temp is the way of measuring the average of the kinetic energy of molecules of the substance. Molecules that move fast will have higher temps while slow moving molecules will have lower temps.

10. Heat

11. Methods of physiologic heat loss: van’t Hoff’s Law

I.  Gas laws


  1. Gas – the gas laws work for ideal gases only but there aren’t any, they don’t exist other that theoretically. The molecules are far apart and have no attraction for each other. Rare gases exist in labs; these molecules are still far apart but have negligible cohesiveness. Real gases behave like ideal gases. They have cohesive and adhesive forces present. With a high temp. and a low pressure these will elicit the behavior of ideal gases but still have cohesive and adhesive forces.
    1. Pressure – the force exerted on the container walls. Ie. A cylinder will have many collisions of molecules against each other and this will increase the pressure. Oxygen bang in to each other and this will increase the pressure in the cylinder as more collisions occur. Barometric pressure, the measure of the atmosphere or a BP cuff will actually measure the pressure by using a column of mercury (Hg). If you reduce the volume of gas or reduce the container size, these will increase the pressure of the gas if you maintained a constant temp and atm.
    2. Compression
    3. Expansion
    4. Mean free path
    5. Van der Waal’s forces – the mutual attractions brought about by electrical charges. These need to be overcome to be able to separate molecules or changing the shape of molecules. Forces occur when shape and pattern of electrical charges are aligned so one end is relatively + and one end is +. Must overcome these forces to change from a liquid to a vapor.

2. Temperature conversions as above

3. Standard temp and pressure – 0 degrees C and 760mmHg (atm pres. at sea level)

4. Boyle’s Law – deals with pres. and vol. with temp as constant. At constant temp, pres. and vol. will vary inversely. This applies only to ideal gases. P1 x V1 = P2 x V2

Ie. Squeezing the ambu bag. Raise the press in the bag, the volume will go out of the bag. As the pressure in the lungs increase the volume will go into the lungs. A spontaneously breathing person breathes by the press in the lungs decreasing and the volume increases. This law expresses compressibility of gases at constant temps.

5. Charles’ Law – Volume and temp at constant pressure. Volume is directly proportional to absolute temp at constant pressure. V1/T1 =V2/T2

ie. Laryngeal mask airway uses a cuff. When it is steam sterilized is must have the air removed from the cuff first since it will expand when heated.

6. Gay Lussac’s Law – pressure is directly proportional to absolute temp (in Kelvin) if volume is constant. P1/T1 = P2/T2

7. Avagadro’s Law – one mole of any gas at same temp has same # of molecules. Equal volumes of gases under same pressures and temps contain the same # of molecules

Avogadro’s Number is 6.02 x 10 to the 23rd molecules.

8. Gram molecular weight and volume - GMW is expressed in grams. One mole of any substance = 1 gm. Of molecular weight. Gram molecular volume is GMW divided by wt per liter. Ie. O2 has 32 grams per mole. 32/1.429gm/liter = 22.4L

9. Ideal Gas Law – is a combination of Charles, Gay Lussac’s and Boyle’s Laws thus

PV = nRT

10. Definitions -

  1. Density - is mass divided by volume. Gases are always expressed in liters.
  2. Specific gravity –
  3. Baricity - deals with the density of a specific solution. Ie. The density of a local anesthetic solution divided by the density of the CSF. CSF is 1.001 –1.005 gm/l at 37 degrees C.

    Isobaric – will have the same baricity of CSF and will stay where you put it.

    Hypobaric – will be lighter than CSF and will travel upward

    Hyperbaric – will be heavier than CSF and will travel downward or sink

  4. Viscosity
Diffusion and Humidification
  1. Graham’s Law - When gases are liberated they dispense quickly in order to fill the space they are occupying. The goal is to achieve equal pressures in both places. This especially applies to anesthetic gases. The rate of diffusion of one gas compared to another varies inversely with the square root of molecular weight. A large gas will take more time to diffuse than a smaller gas. Ie. CO2 is offloaded into the lungs. CO2 is 4-6x faster than O2 in the lungs due to its molecular weight.
  2. Dalton’s Law of Partial Pressures – the total pressure exerted is made up of the sums of all gases in a container. P1 + P2 + P3 =
    1. Ie. Atmos of sea level thus P =760mmHg. O2 has 21% of 760 and N has 79% The total of the two will equal 760. Ie. If a flask has 100% of O2 and isofluorane is added, what will the concentration of O2 be in the flask. Would need to know the vapor pressure of inhalation agents.

  3. Fick’s Law of Diffusion: gases and non-gases - the diffusion rate is proportional to differences in partial pressures. A gas always diffuses from an area of high pressure to an area of low pressure.
  4. Pressure gradient – the diffusion rate is directly proportional to partial pressure gradient, the area of membrane available to diffuse through and the solubility of gases to the membrane. CO2 is larger but it diffuses 20x faster than O2 since it is more soluble than O2. P1 – P2 x area x solubility/membrane thickness square root of molecular weight.
  5. Humidity and Humidification: Absolute and Relative. Humidity refers to presence of water molecules in the gaseous state in a mixture of gases. The gaseous water molecules are considered vapors at temp. below the critical temp. of water expressed as relative and absolute. Absolute is water content of gas expressed as wt. Of water per volume of gas. Units are mg of h2o /liters of air. Relative humidity is the ratio of absolute humidity to the saturated humidity at a given temp. (Saturated humidity is related to the maximum vapor capacity.) Humidification in vapor pressure is important to avoid dryness being inhaled. Amt. of evaporation of liquid water is directly proportional to its temp. If ambient temp is less than water temp is then water vapor will recondense back in to water and "rainout" will occur like the glugging of water collecting in the vent tubing. The temp of the room is cooler so the vapor in the tube will fall below 37 and condense again. This has led to the development of filters or traps to utilize their own exhaled vapors to humidify the air. HME’s are the name.
    1. Humidification is important due to the heat loss experienced in the OR from 1.radiation, 2.convection, 3.conduction, and 4.evaporation.

      Water vapor in the alveoli is always constant and is = to 47mmHg. Will have to subtract this pressure when figuring out aA gradients and pO2’s.

  6. Hypothermia – Increases consumption of O2 and can decrease production of CO2. For every one degree of C change there is a decrease or increase of 7.9% in O2 consumption. Oxyhemoglobin dissociation curve comes in here. If hypothermic will cause a shift to the left where hemoglobin will hold O2 and not release it to the tissues thus tissue hypoxia develops. There can also be a shift in the pH of .01 per decrease in temp by 1 degrees C. This will decrease the amt. of anesthesia necessary. Blood viscosity will increase 2-3% per change in C. If temp is cool and you check an H&H will show hemoconcentration and be higher than the actual value. There can also be clotting problems with hypothermia, tend to bleed. The other thing to watch for is shivering since this increase O2 consumption 400-500%.
  1. Pressure and tension, liquefaction and solubility
  1. Pressure units and conversions – Use the metric system of grams for weight, liter for volume and meter for length. Standard temp is 0 degrees C. and stand pressure is 760mmHg
  2. Cylinders and Bourdon gauges - The bourdon gauge is a way of measuring high pressures relative to the atmospheric pressure say in a cylinder.
  3. Joule-Thompson Effect – This has to do with why cylinders cool to allow gas to escape. If they didn’t cool then the heat from the escaping gas would cause an explosion. The gas is released slowly and it will expand. If this occurs in a small closed space then heat is emitted in the space. If gas is released in a large space there will be a cooling effect. Stated in Hall’s piece this effect is seen if gas is allowed to expand in a vacuum; then energy is lost in overcoming intermolecular attraction and the gas cools. An example is seen by opening an O2 tank into a room, the valve will be cool and water vapor could condense near this.
  4. Adiabatic compression and expansion – volume changes without heat loss or gain from the environment. All gases cool during expansion and heat during compression. This is true for a closed system only and this conversion to expand or compress is reversible or else it would be the Joules-Thompson effect. The heat of the cylinder will change according to pressure.
  5. Law of LaPlace – tension is defined as an internal force generated by a structure. For cylinders T =Pr where r is the radius. T is the wall tension and P is the pressure of fluid in the cylinder. A sphere would be T=Pr/2. Spheres are alveoli.
  6. Critical temperature and pressure – Gases will liquefy if sufficient pressure is applied and temp. is below a critical value. If a gas is above its critical temp you cannot liquefy if even by varying pressures. O2 is compressed gas. Could not maintain the liquid O2 since its crit temp is –119degrees C. Nitrous oxide is liquid compressed cylinder since its crit temp is 36.5. You will always have a reading on the gauge of 745 until the liquid N2O is used up and then the gauge will cut in half while there is just compressed gas left but that will be used very quickly and the tank will now read empty. Must always measure the tanks to check for fullness.
  7. Raoult’s Law
  8. Henry’s Law


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