Chemistry 7 Pressure and Static Pressure Flashcards
How does pressure relate to health professionals?
Circulatory system (blood pressure) Breathing (gas pressure) Movementoffluids(gasesandliquids) Patientcare Equipmentused
What is pressure?
Definition: •Pressureisaneffectwhenforceisappliedonagiven area…
Pressure = Force
area
=Whenthesameforceisconcentratedinasmallarea, thepressureonthisareawillbegreater: when the pressure is applied over a larger area, the pressureon this area is less.
What states does this concept apply to?
Appliesequallyto •solids •liquids •gases
sincetheforceinvolvedmaybeappliedequallyby thesedifferentstatesofmatter
How is the SI unit shown?
(standard unit of pressure)
Name some examples of where it is used.
•Pascal(Pa)orkilopascal(kPa) •Normalairpressure=101.3kPa •Bloodgases:partialpressureofO2(pO2)=13.3kPa
How is British unit shown and where is it used?
Pounds/squareinch(psi) •Airincartyres(28psi=190kPa) •Gascylindersinoperatingtheatres
Atmospheric pressure
- Pressureexertedbythe atmosphereagainstthebody
- Measuredbythedisplacementof acolumnofliquid •mmHg=millimetresofmercury
- 1Atm=760mmHg
Name the instrument used to measure pressure in the body.
Manometer‐e.g. sphygmomanometer, used to measure blood pressure •The measurement is based on the effect that an external pressure (the inflated cuff) has on the arterial pressure.
What is blood pressure and where is it usually measured?
Pressurethatbloodexertsonthewallsofblood vessels
•Usuallymeasuredatbrachialartery
Outline steps used to measure blood pressure
Cuffofappropriatesizeisfittedandinflatedmanuallyby repeatedlysqueezingarubberbulbuntilthearteryis completelyoccluded •Listeningwiththestethoscopetothebrachialarteryatthe elbow,theexaminerslowlyreleasesthepressureinthecuff •Whenbloodjuststartstoflowintheartery,theturbulentflow createsa”whooshing”orpoundingsound(firstKorotkoff sounds);systolicbloodpressure •Thecuffpressureisfurtherreleaseduntilnosoundcanbe heard(fifthKorotkoffsound);diastolicbloodpressure
Explain Systole pressure in relation to the function of the heart
The systolic measurement is taken on the emptying of the lower heart chambers
Explain Diastole pressure in relation to the function of the heart
The Diastolic measurement is taken on the blood returning to the lower heart chambers
What are the normal ranges of Systolic and Disatolic blood pressure and what can change blood pressure
Systolic (90 -140 mm Hg) Diastolic (70 -90 mm Hg)
Blood Vessel Diameter and Cardiac output (blood volume)
Outline how a non-mercury Manometer works.
Notallmanometershavemercuryin them •Someusewaterorsaline,withthe heightofthecolumnbeingmeasured incmwater orcmsaline
•Centralvenouslines •Usedtorecordacontinuousblood pressurewithouttheuseof manualcuffs
Comparing pressure:
1kPa=7.5mmHg=10.2cmH2O
•Remember,Hgismoredensethanwater •SowoulditbesensibletouseaH2Omanometerto measurebloodpressure?
•140mmHg=1904mmH2O
Used when needing to measure other areas of the body.
Other areas where pressure plays a role
Respriation
Pressure sores: Ifapersonremainsbedboundforlongperiods… •Sustainedlowpressuretothebody •Deficiencyofbloodflowtotissue •PressureSores(DecubitusUlcers)
Give clinical example of applying understanding of pressure
In the case of broken limbs, would a wider or narrowing bandage give the best support?
