Week 5 Review Chem/Phys Flashcards

Question

Name 3 clinical applications of La Place's Law.

Answer 1

1. normal alveoli and the need for surfactant during expiration 2. vascular pathology - aneurysm rupture due to increased wall tension 3. ventricular volume and work of the heart - a dilated ventricle has greater tension in its wall (end diastolic pressure rises)

Answer 2

**6.02 x 10²³molecules** = 1 mole **Hypothesis**: If you have *2 different gas containers* containing *2 different gases* at the _same temp and pressure_, then they contain the _same number of molecules_ _1 mole is 1 gram multiplied by the molecular weight:_ **i.e.** 1 mole O2 = 32 grams 1 mole of any substance occupies 22.4 L, so 6.02 x 1023 molecules of O2 = 32 grams and occupies 22.4 L

Answer 3

Total pressure of a gas mixture is the sum of the partial pressure of each gas In a mixture of gases, the pressure exterted by each gas is the same as that which it would exert if it alone occupied the container

Answer 4

* **Artifact** * ambient light * low perfusion * motion * dyshemoglobins * **Dyshemoglobins** * **carboxyhgb**: falsely high * **methgb**: Sat ~85% * **polythycemia**: no effect * **methylene and isosulfan blue**: falsely low * **blue nail polish**: falsely low

Answer 5

* Describes the relationship between **rate of flow** and * pressure gradient across the length of tube - **direct** * radius⁴ of the tube (r⁴) - **direct** * length of the tube (L) - **inverse** * viscosity of the fluid (n) - **inverse** **Q = π r⁴ "delta P" / 8 n L**

Answer 6

* contain a coiled tube that expands as pressure is applied * linkage connects the coil to a rotating arm that records the pressure * gauge pressure is **zero** referenced to *atmospheric pressure* and reads *0 at 760 mmHg* at sea level * **Gauge pressure** = **absolute pressure** *minus* **atmospheric pressure**

Answer 7

* **enantiomers** * mirror images of one another * cannot be superimposed on each other * possess similar chemical and physical properties * optically active and can rotate polarized light in a *clockwise fashion* (denoted by the prefix + or dextro) * or *counterclockwise fashion (denoted by the prefix - or levo)* * **diastereomers** * *not* mirror images * may have *_differing_* physical and chemical properties

Answer 8

* molecules that have the same chemical formula, but different structures * the number and type of atoms and bonds are the same in isomers, but the arrangement of the atoms is different * **two types** * structural isomers * stereoisomers

Answer 9

* A gas diffuses at a rate that is *inversely proportional* to the square root of its *molecular weight* * As **molecular weight increases**, the **rate of diffusion decreases** * *Smaller molecules diffuse faster*

Answer 10

* **Inversely** related to temperature * as temperature increases, less gas is able to dissolve into a liquid * increased temperature represents **greater** kinetic energy → **greater** kinetic energy allows dissolved gas molecules to escape and prevents further dissolving * lower temperature **slows** the kinetic energy of the gas molecules, allowing them to dissolve in liquids * i.e. hypothermic patients receiving volatile agent general anesthetic * slower wake up * **directly** proportional to pressure

Answer 11

* absorption of radiation by a given thickness of a solution of a given concentration is the same as that of twice the thickness of a solution of half of the concentration **(Beer)** * Each layer of equal thickness absorbs an equal fraction of the radiation that passes through it **(Lambert)**

Answer 12

* Strain gauges in pressure transducers * thermistors

Answer 13

Air = 21% O₂ and 79% N₂; atmospheric pressure is 760mmHg **Calculate the partial pressue of each gas:** Partial pressure of nitrogen is 79% x 760 mmHg = 600 mmHg Partial pressure of oxygen is 21% x 760 mmHg = 160 mmHg

Answer 14

* **Macroshock** * current distributed through the body * **culprit**: faulty wiring, improper grounding * **Microshock** * current applied in or near the heart * **culprit**: pacing wires, faulty equipment during cardiac cath

Answer 15

Macroshock complete physiologic damage

Answer 16

* contraindicated in patients with *pneumothorax* or where air filled cavity expansion is undesirable * middle ear surgery * retinal surgery * long bowel cases - think of bowel distension * neurosurgeries * nitrous oxide can diffuse into endotracheal cuffs, increasing volume, and cause tracheal mucosal damage

Answer 17

* contain **50% of the levo** form of the isomer and **50% of the dextro** form of the isomer * i.e. racemic epinephrine used to treat laryngeal edema

Answer 18

**.067ml/100ml** blood/mmHg partial pressure \*\*CO2 is 20x more soluble in blood than O2\*\*

Answer 19

10.2 cm H2O

Answer 20

* Metal is a good conductor, your patient is lying on a metal bed, surgery causes bleeding, blood is wet, the room is full of electrical equipment → RISK TO THE PATIENT → BURNS * Electrocautery

Answer 21

* *Thorpe Tube* is an older term for *flowmeters* * **At low flows** * annular shaped orifice around the float is relatively tubular so (according to Poiseuille's Law) flow is governed by **viscoisity** * **At high flows** * (indicated on the wider top part of the float tube), the annular opening is more like an orifice, and **density** governs flow

Answer 22

**Critical temp of O2** **= -119 C** Therefore, O2 cannot be liquefied at room temp no matter how mjch pressure is applied to it. \*\*Main supply of O2 in a hospital is in liquid oxygen stores. Huge quantities can be stored in this way and is more economincal. The containers are insulated from the outside and the temperature is kept at -160 C\*\* **Critical temp of Nitrous = 39.5 C** **Room temp = ~25 C** Therefore, pressure can be applied to liquefy nitrous at room temp, Hence, nitrous is stored at pressure of 745 mmHg and at room temp.

Answer 23

states that matter is made of minute particles called molecules that exist in various states (solid, liquid gas, or plasma)

Answer 24

* P1V1=P2V2 * *volume* is **inversely proportional** to *pressure* * _temperature constant_ * As pressue increases, volume decreases * APPLICATIONS * **squeezing resevoir bag** on anesthesia machine * apply pressure (squeezing it), volume decreases * **A full E Cylinder will empty 625-650 L into the atmosphere** * the relatively small volume of gas in the cylinder is at high pressure. When it is released to the atmosphere where there is a relatively low pressure, a large volume results * **Spontaneously breathing** * when intrapulmonary pressure becomes negative (decreases), intrapulmonary volume increases (taking a breath in) * **Bellows on a ventilator** * as pressure increases, the volume within thin the bellow decreases

Answer 25

* Relates **pressure** and **velocity** and how they interact * the *lateral wall pressure* is LEAST at the point of *greatest constriction* and the *speed* is the GREATEST * Thus, *flow will be faster* through the *constricted portions* and *lower* at the *wider portions* of a tube ## Footnote **Narrow diameter = _decreased_ lateral wall pressure = _increased_ speed** **Wider diameter = _increased_ lateral wall pressure = _decreased_ speed**

Answer 26

* **Expansion of a gas causes cooling** * **Clinical Application:** as gas leaves a cylinder, the expansion cools the surrounding air causing condensation of moisture on the cylinder

Answer 27

Calibration of vaporizers is done using Avagadro's hypothesis.

Answer 28

* fluid flows through different cross sectional areas in different portions of the tube * as tube narrows (V2), velocity of fluid increases, thus dropping pressure * Velocity of the fluid can be found by measuring the pressure

Answer 29

states that molecules are in constant motion (random motion) and have a degree of attraction between them called van der waals forces.

Answer 30

* At *constant temperature*: * The **amount of gas dissolved** in a liquid is **directly proportional to the partial pressure** of the gas in contact with the solution. * allows calculation of O2 and CO2 dissolved in blood * *Increasing FiO2* is an application of Henrys law * recall - most oxygen in the blood is bound to hgb rather than dissolved in the blood * *overpressurizing the vaporizer* is another example * we increase the concentration set on the vaporizer to speed up delivery to the blood, and therefore, the brain

Answer 31

* **pressure gradient** across the wall of a SPHERE or TUBE/CYLINDER (blood vessel, ventricle, alveolus) is related to * wall tension (T) - **directly** * radius (r) - **inversely**

Answer 32

* **IV flow** * gauge (r4) * shorter/longer catheter (L) * viscosity of fluid * **Airways** * **Vascular flow** * polythycemia vs anemia * **thorpe tubes** * at low flows

Answer 33

Reynolds Number = _velocity x density x diameter_ viscosity **Reynold's Number \> 2000** = _Turbulent Flow_

Answer 34

That **resistance** which will allow **one ampere of current** to flow under the influence of a potential of **one volt** ## Footnote **W (resistance) = Potential (volt) / Current (ampere)** **or** **E (Voltage) = I (current flow or amp) x R (resistance)**

Answer 35

*Pressure* of a gas is _directly proportional_ to the *temperature* (K) So, as temperature increases, pressure increases **Application**: full cylinder of compressed gas is moved from air conditioned hospital (70 degrees) to the loading dock (100 degrees F) → pressure in the tank increases!

Answer 36

* Continual diffusion of oxygen into the blood is driven by a concentration gradient that continually diffuses oxygen into the alveoli via the ventilator circuit * When *ventialtion* is _absent,_ we are dependent on this continual diffusion of oxygen * **This is the principle behind _apenic oxygenation_**

Week 5 Review Chem/Phys Flashcards

(68 cards)