Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
NU 624
Exam 3 - Pressure/Surface Tension/Pascale/LaPlace/Fluids
| Question | Answer |
|---|---|
| How is pressure measured under the Systeme Internationale? | Newton/meter sq., or Pascale |
| How is the Pascale usually referred to as? | kPa |
| What does Pascale's principle state? | Pressure applied to a completely enclosed fluid is transmitted undiminished to all parts of the fluid and its enclosing walls |
| What do we now know about pressure in a fluid that is enclosed in a container? | There are differences in wall tension in different parts of the fluid |
| What is an aneurysm? | Localized enlargement of an artery caused by weakening of the artery wall |
| The pressures exerted on the walls of an aneurysm are (lesser/greater) than the pressures exerted on the surrounding arterial walls. | greater |
| Why are the dilated walls of a vessel more prone to rupturing or dissection? | The forces exerted at the weak point are greater than elsewhere in the vessel that do not have a weak point |
| What does LaPlace’s Law state? | Wall tension increases with vessel radius |
| What are four physiologic scenarios where LaPlace's Law is seen? | COPD, difficulty of a baby's first breath, alveolar role in exhalation, aneurysms |
| LaPlace's Law explains the relationship between what three factors? | Pressure, surface tension, radius |
| What is the LaPlace equation? | P=2T/R |
| Pressure and surface tension are expressed as _________. | dynes/cm sq |
| The Law of LaPlace describes the magnitude of (inward/outward) pressure. | Inward |
| What is the implication of LaPlace’s Law in regards to alveoli? | Larger surface tension involves a larger force pushing inward into the alveoli and with 2 alveoli connected in the airway, it is implied that the smaller alveoli would collapse and push its gases into larger alveoli (smaller radius=more pressure) |
| What prevents the collapse of contents of smaller alveoli into larger alveoli? | surfactant |
| What does pulmonary surfactant decrease and where does it have a greater effect? | decreases surface tension; greater effect in smaller alveoli |
| Increased wall tension is described by ________ Law, but offset by the effects of ________. | LaPlace's; surfactant |
| What is the function of the aortic cross clamp in open heart surgery? | Divert blood to the cardio-bypass machine |
| What determines LV response to the aortic cross clamp? | Length-tension-velocity relation of the myocardium |
| Tension is obtained by multiplying what two factors? | pressure & radius |
| What are the principle determinants of afterload? | ventricular dimensions (radius) and systolic intraventricular pressure |
| What are two other surgical scenarios that utilize cross-clamping? | Abdominal aneurysmectomy and infrarenal aortic cross-clamping |
| Tubes are pathways in which the ________ is greater than the _______. | Length; diameter |
| An orifice is a pathway whose ______ is greater than its ______. | Diameter; length |
| What are the 5 factors that determine the rate of flow through a tube? | 1)Cross section (radius) 2)proximal to distal pressure gradient (P1-P2) 3)tube length 4)fluid viscosity 5)solution density |
| What is the definition of the “flow” of fluid? | Quantity of fluid (gas or liquid) passing through in a unit of time |
| What is the equation for flow? | F=Q/T |
| What must be present in order for flow to occur through a tube? | Proximal to distal pressure gradient |
| Flow rate is (directly/indirectly) proportional to pressure. | directly |
| How much is flow reduced if the diameter of a tube is reduced to ½ the original size? | Reduced to 1/16th the original value |
| How does flow change if a tube is cut in half? | Flow is doubled |
| What has more influence on flow through a tube: altering the diameter or the length? | Diameter |
| What is the definition of the meniscus? | A curve in the surface tension of a liquid caused by the contact of liquid against the sides of a container |
| What are two possible shapes of a meniscus? | Concave or convex |
| When does a convex meniscus occur? | When the molecules of the liquid repel the molecules of the container or object |
| Where can a convex meniscus be seen? | mercury barometers |
| When does a concave meniscus occur? | When the molecules of a liquid attract those of the container |
| When can an example of a concave meniscus be seen? | water in a glass |
| What property creates the concave meniscus of water up the sides of a glass and downward in the center? | surface tension |
| The force exerted by atoms and molecules is defined as __________. | Pressure |
| How is pressure generated? | kinetic energy |
| Kinetic energy is produced by atoms and molecules that are in __________. | motion |
| What is the equation for pressure? | force/area |
| The English unit of pressure, the pound, is a unit of (mass/force). | force |
| What are two ways that the English unit of pressure is measured? | lbs/ft sq; lbs/sq in |
| What is the international unit of pressure? | newton/meter sq or "Pascal" |
| 1 atmosphere of pressure is equivalent to _______ kPa or _______ lbs/sq in. | 101.3 kPa; 14.69 lbs/sq in |
| When is pressure exerted at the molecular level? | When molecules of gases collide |
| What is cylinder pressure? | The sum of molecular forces in a closed container |
| How is cylinder pressure measured? | lbs per square in. gauge (PSIG) |
| What two values are equal when a gas cylinder is empty? | cylinder and atmospheric pressures |
| A full E cylinder of oxygen measures _________ PSIG. | 1900-2200 |
| A full tank of N2O measures __________ PSIG. | 745 |
| What does the Bourdon Gauge measure? | Pipeline or cylinder pressures |
| What type of measurement is the Bourdon Gauge based on? | Aneroid |
| An aneroid gauge operates (with/without fluid). | without |
| What governing body sets standards for the readings on Bourdon-type gauges? | ASTM |
| What do the terms mmHg and cmH20 measure? | Pressure of a gas other than compressed gas |
| mmHg is also referred to as ______. | torr |
| The tourniquet applied during knee surgery utilizes _______ as a form of measurement since it is not a compressed gas. | mmHg or torr |
| High pressure and continuing pressure in an anesthesia machine is measured in units of _______. | cmH20 |
| What are the three physics principles that apply to pressure in a liquid source? | 1)pressure in a liquid at a certain level is proportional to the height of the liquid 2)pressure in a liquid increases with the depth below the surface 3)pressure in a liquid is the same in all directions at the same depth |
| Patients undergoing TURP are at risk of developing ____________. | Dilutional hyponatremia |
| Why are TURP patients at risk of developing dilutional hyponatremia? | High-hanging bags of irrigation lead to absorption of irrigating solution by open venous channels |
| What is the function of the pressure relief valve near the CGO? | Prevents transmission of high-pressures in the anesthesia machine to the patient |
| What safety feature on the anesthesia machine may limit the ability to provide adequate jet ventilation? | Pressure relief valve |
| What are the features in the anesthesia machine that ensure unidirectional flow of gases toward the patient from machine and away from the patient on exhalation? | Inspiratory and expiratory valves |
| How is incompetence of unidirectional valves prevented? | Opening, cleaning, and if necessary, replacing discs |
| What is the function of the pressure regulator (pressure reducing valve)? | Reduce pressure and control gas supply from the pipeline or cylinder |
| How do pressure regulators function? | Balances force of a spring against the force of the compressed gas |
| What is surface tension? | Attractive forces that occur between molecules at the surface of a liquid |
| Where does surface tension occur? | At the air-liquid interface |
| Surface tension creates a strong barrier between ______ and _____ molecules. | Air; liquid |
| What property prevents fast evaporation of water as well as certain insects to walk on water? | Surface tension |
| The dyne is a unit of (force/mass). | Force |
| How is surface tension measured and at what temperature is it measured at? | Dynes/cm at 20 degrees celsius |
| What lines the walls of alveoli in the lungs? | Thin film of liquid |
| How does the surface tension of fluid in the lungs influence the alveoli? | The surface tension of the liquid influences the alveoli to want to collapse |
| What endogenous chemical prevents the collapse of alveoli? | Surfactant |
| Lung surfactant is secreted by _____________. | Type 2 alveolar epithelial cells |
| What does the lung surfactant decrease? | Cohesive force of the liquid film, or surface tension |
| What are the three physiological benefits of lung surfactant? | 1)increases lung compliance 2)reduces the tendency of small alveoli to empty into larger ones (collapse) 3)reduce fluid leak from pulmonary capillaries into alveoli |
Created by:
philip.truong
Popular Nursing sets