CVS 1 - Static Fluid and Fluid Pressure Flashcards
A fluid is…
a substance that conforms to the shape of its container. i.e., liquids and gases
Usually, the study of fluids is divided into 2 parts which are…
Hydrostatics: (Study of fluids at rest )
Pascal’s Principle, and Archimedes principle (Buoyancy)
Hydrodynamics: (Study of fluids in motion)
Continuity equation and Bernoulli equation
(the physics of the cardiovascular system)
Density is often used instead of mass when dealing with liquids.
Density is defined as…
mass per unit volume, unit kg/m3
𝜌=𝑚/𝑣
𝜌_𝑤𝑎𝑡𝑒𝑟=1000 𝑘𝑔/𝑚^3
𝜌_𝑏𝑙𝑜𝑜𝑑=1060 𝑘𝑔/𝑚^3
Pressure is defined as…
rce per unit area, unit is the pascal (Pa)
𝑃=𝐹/𝐴
Pascal’s principle states that…
any change in pressure applied to a completely enclosed fluid is transmitted undiminished to all parts of the fluid and the enclosing walls.
Approximately 5 cm^3 of aqueous humor is produced within the eye every day, and normal intra-ocular pressure is around…
12-24 mmHg
In a normal eye, excess fluid can be released through the trabecular meshwork.
In glaucoma, the fluid cannot…
escape and causes a significant increase in the intra-ocular pressure (up to ~85 mm Hg). This can result in permanent damage to the optic nerve and, if untreated, blindness.
The unborn baby is surrounded by amniotic fluid within the womb.
This is excellent for…
diffusing or distributing the effect of any sudden force applied to the abdomen of a pregnant woman.
Cerebrospinal fluid (CSF) is an enclosed fluid (~150 cm3) which surrounds the brain and spinal cord.
A brain tumour will cause…
a reduction in the volume in which the CSF is contained, resulting in an increase in the fluid pressure of the CSF.
The pressure of the CSF can be determined by…
inserting a spinal tap (connected to a water manometer) between the 3rd and 4th lumbar vertebrae.
Define Decubitus Ulcers (bedsores)
These are pressure ulcers caused by patients spending prolonged periods in the same position.
They tend to occur around bony regions such as elbows, heels, hips, shoulder blades (i.e. those regions in ‘contact’ with mattress etc. where pressure is applied), and result from restricted blood flow in these regions.
Laplaces Law states that…
the larger the vessel radius is, the larger the wall tension required to withstand a given internal fluid pressure.
Filling the bladder with a fluid will…
exert a pressure on the wall of the bladder and generate a stress within the wall.
Contraction of the muscle will…
generate a pressure on the fluid within the lumen.
The magnitude of the pressure change depends on…
the dimensions of the lumen, P=T/r
Pressure and volume law compliance V~r
