Force, Heat And Pressure Flashcards
Force
Interaction, when unopposed, that will change the motion of an object
Can be acceleration (push) or deceleration, (pull)
Force = mass x acceleration
Most common is gravity
Pressure
Main force in healthcare
Pressure = force ÷ area
Can be exerted in solids, liquids and gases
Pressure in solids- pressure sores - decubitis ulcere
Caused by reduction of blood flow
Pressure in solids
pressure sores - decubitis ulcers
Caused by reduction of blood flow
Pressure in liquids
Blood pressure - beating heart creates pressure in blood vessels
Blood pressure measured by sphygmomanometer
Pressure in gases
Breathing -
Moving from high pressure to area of low pressure
Creating areas of higher/lower pressure in the chest to facilitate air movement in and out of the lungs
Boyles law: pressure of a given qty of gas varies inversely with its volume
Heat
Atoms and molecules always vibrating
More vibration = more heat = quicker chemical reaction and expansion
Applies to heating and cooling of medications and foods
Body decreases heat by increasing blood flow to the skin
High heat- interupts molecules, especially proteins, which can kill the cell eg) cooking food, sunburn
Kills micro-organisms - basis for heat sterilisation: boiling, hot oven or autoclave (water under pressure heated to 122 degress to kill bacterial endospores
Electricity
Is the flow of charged particles, usually electrons or protons
Conductors (can flow through) - fluids, nerve cells, pacemaker wires
Insulators (cannot flow through) - dry skin, myelin sheath, plastic covering around wires
Currents and voltage
Current - flow of electrical charge in a circuit
Voltage - potential differncr in charge between 2 points in an electrical field
Voltage is the cause, current is the effect
Electrocution
When the body becomes part of an electrical circuit.
Risk depends on - amount of current, duration of current, voltage, frequency, resistance
Usual cause of death - ventricular fibrillation. Outside impulses disturb normal pattern and loss of pumping
Electricity Therapy
Defibrillators (heart) > 100 milliamp
Electric Shock Therapy (brain) 0.5 to 1.5 amps
Electrocautery - control blood flow in surgery - burn tissue rather than cause muscle contraction
Radiation
Emission or travel of energy as particles (nuclear radiation) or as electromagnetic waves.
Radiation is absorbed, reflected or passed through depending on the type of radiation and the type of material
Electromagnetic waves - different properties accodding to how far apart the waves are (wavelength)
Short wavelength has more energy - xrays and gamma rays which can damage the molecules
Some radiation has low energy and causes minimal damage such as radio waves, microwaves and infrared
Eg) microwave causes water molecules to spin faster which increases temp of materials containing water
Can be used to kill cancer cells
Nuclear radiation
Nucleus of an atom consists of protons and neutrons
Protons - positively charged
Neurtrons - no charge
Nuclear radtion is the release of radiations due to the breakdown of an atoms Nucleus (nuclear decay)
Nucleus is generally stable but some are prone to breaking apart.
They are called radioisotopes
Nuclear decay produces 3 types of radiation- alpha rays, beta rays and gamma radiation.
Alpha - large particles that can be stopped by paper
Beta - smaller than alpha and will travel further. Can be stopped by thin metal eg) foil
Gamma - requires lead shielding
Xrays are similar to gamma rays - walls are shielded with lead. Travel through tissue, absorbed by bones.
Nuclear decay
Nuclear decay produces 3 types of radiation- alpha rays, beta rays and gamma radiation.
Alpha - large particles that can be stopped by paper
Beta - smaller than alpha and will travel further. Can be stopped by thin metal eg) foil
Gamma - requires lead shielding
Xrays are similar to gamma rays - walls are shielded with lead. Travel through tissue, absorbed by bones.
Radiation damage to cells
Direct - radiation rays physically collide with components of the cell and break them apart. Damages DNA, proteins or cell membrane.
Indirect - damage molecules that makes them reactive and causes damage elsewhere
Radiation and DNA
If DNA is damages it can:
- repair itself
- apoptosis - programmed cell death
- mutation to cell
Mutation might be benign or could cause uncontrolled replication- tumour
