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Technological Sciences for the Operating Room Physics for the Surgical Technologist Why Study Physics? Physics involved in all aspects of O.R. No longer sufficient to only know how to operate machines Basic concepts of equipment design must be understood Surgical technologist must evolve as the O.R. advances into the future Surgical Applications Physicists have contributed to practice of medicine – Wilhelm Conrad Röntgen: Discovered X-rays – Thomas Edison: Further X-ray technology EKG: measures electrical activity of heart EEG: measures electrical activity of brain Surgical Applications CAT Scan – Uses X-rays for detailed imaging of tissues MRI – Uses radio frequencies to excite protons in tissue – Protons return to equilibrium, emit RF signal analyzed as image Ultrasound Imaging – Transforms sound waves into images – Tissue reflects source signal – Image is created from “echoes” Surgical Applications PET – Patient consumes radiopharmaceutical agent that emits positron – When positron meets electron, both are destroyed – Gamma rays are emitted – Detectors locate each destruction event; creates colored image indicating activity Mechanics Study of objects in motion – Dynamics: Study of motion & forces that cause it – Kinematics: Study of objects in motion; does not include study of the forces that caused motion Speed and Velocity Speed: – Describes how fast something is moving Important: Direction is not considered – Average Speed = distance traveled ÷ time taken to travel distance Velocity – Involves direction and speed Acceleration Acceleration: – Object’s velocity has changed – Change in velocity over time Involves change in direction, speeding up, slowing down Projectile Motion Motion of any object launched into air at an angle – Projectile launched vertically – Comes back to launching level in accelerated motion Satellite – Projectile since gravity acts upon it – Falls toward earth, but does not complete descent due to earth’s curvature Newton’s Laws of Motion First Law – Expresses physical concept of inertia – Object will not move unless outside force acts upon it – Object moving at constant velocity will continue so in a straight line until acted upon by an object Second Law – External force causes an object to accelerate Newton’s Laws of Motion Third Law – Also called Law of Conservation of Momentum – Whenever force is exerted, equal and opposite force occurs in reaction Momentum A force exerted on an object causes force on other object in opposite direction – Cannon recoils after shooting cannonball Total momentum before event is equal to momentum after event – Before cannonball is fired, momentum of cannon and ball is zero Recoil of cannon after firing gains opposite direction momentum; equalizes momentum Simple Harmonic Motion Object displaced from equilibrium will oscillate about its equilibrium position Work and Energy Work – Force acting upon an object to cause displacement Energy – Forms of energy that produce changes in matter Light, electricity, sound, and heat are forms of energy Mechanical Energy – Most common form of energy – Energy that makes objects move – Measured by amount of work object can do Potential Energy Energy object has stored due to position relative to zero position – Gravitational Potential Energy Cart on top of a hill. – Chemical Potential Energy Batteries, firecrackers – Elastic Potential Energy Bungee cords Kinetic Energy Kinetic Energy – Energy of Motion Cart rolling down the hill Power Rate at which work is done – Watt: Standard metric unit of power – Horsepower = 750 W Atom Structure: Bohr Model Electrons: Negative charge Protons carry a positive charge Atomic Number indicates number of protons Equals number of electrons (usually) Protons and neutrons compose atomic mass; reside in nucleus Neutrons carry a neutral charge Elements All matter made up of elements – 92 natural elements – Periodic Table of Elements – Living organisms are composed of chemically reactive gases like hydrogen, carbon, nitrogen, oxygen Elements Atom Electron Configuration – Atoms seek electron stability – Obtain stability by losing, sharing, gaining electrons Ionization of Atoms – Gain or loss of electrons Loss: Atom is + charged ion Gain: Atom – charged ion Molecules Groups of atoms joined by chemical bonds Molecular Weight – Equals the sum of atomic weights of atoms in a molecule Matter Three States – Solids: has definite shape and volume – Liquids: has volume, but no shape – Gases: has no volume or shape – Plasma High-energy form of matter Sometimes defined as a fourth state Matter Matter in continual state of flux – Physical Changes: ice to water; reversible Identifying characteristics retained – Chemical Changes: irreversible identifying characteristics altered Pressure Can be evaluated for solids, liquids, gases – Pressure exerted by object against a surface depends on area of contact Liquid – Exerts pressure on sides of container – Exerts pressure on object placed inside Pressure Gas – In addition to pressure other properties that can be measured are temperature, mass, volume Related & values determine state of gas – Boyle’s Law Boyle studied relationship between pressure and volume of confined gas at constant temperature Observed volume is inversely proportional to temperature When pressure is increased, the volume is decreased. Heat Transfer Temperature is the degree of heat or cold of an object upon touch Thermal Equilibrium – Two objects touch, one cold, other warm Cold object warms up, warm object cools down Reach point when no change occurs Conduction – Transference of thermal energy by contact Heat Transfer Convection – Liquid and gases poor conductors – Transfer heat through convection – Movement of energetic molecules in liquid or gas Thermal Radiation – Does not require contact for transfer of heat – Sun warming the earth; wood stove fire – Greenhouse effect Waves General Properties Transfers energy Wave: repeating and periodic disturbance moving through medium –Wave temporarily displaces particles in medium; seek original position –Unique property of wave is ability to transfer energy without transporting matter Electromagnetic Waves Visible Light originates in electric and magnetic fields Electromagnetic waves – Include radio waves, microwaves, infrared waves, visible light, ultraviolet light, x-rays, gamma rays – Listed in order of vibration – slow to fast Electromagnetic Waves Wavelength – Ultraviolet Region includes short waves, beyond violet end of spectrum – Infrared Region includes long waves, beyond red end of spectrum ROY G. BIV X-rays Waves shorter than ultraviolet Discovered by Wilhelm Röntgen Pass thru objects made visible on fluorescent screen Thomas Edison invented fluoroscope X-ray Machine – Cathode Tube (Coolidge tube) Aims accelerated electrons at heated atoms (Tungsten filament) – Anode: electrons strike metallic electrode – Electrons slow down – Electrons penetrate metal – Stopping of electrons produces X-rays Sound Wave Produced by vibrating object causing air molecules to vibrate Oscillating air molecules create pressure wave of compressions and rarefactions – Compressions are regions of high pressure – Rarefactions are regions of low pressure – Sound Wave: alternating compressions and rarefactions Sound Wave Number of waves in one second – Equals number of vibrations per second sent by vibrating object Cycle – One wavelength is the distance between two successive areas in same state of compression Hertz (Hz) is wave cycles per second – 1 Hz = 1 cycle per sec. – Human Ear: perceive 20 Hz to 20,000 Hz – Megahertz (MHz): ultrasonic frequencies; 1 million cycles/sec. Sound Wave Longitudinal and Transverse Waves – Sound wave travel thru solids – Gases and liquids: only longitudinal waves Speed increases with temperature and depends on level of humidity – Speed of sound depends on temp. of medium – Speed of sound thru air: 770 mph – Speed of sound thru water: 4,820 ft/sec. Doppler Effect Shift in frequency and wavelength of waves resulting from source that is moving. – Train approaching and passing. Light Speed of Light – 186,000 miles per second Light travels in straight line; cannot bend Light wave can be – Absorbed, converted to heat – Reflected – Transmitted Reflection Law of Reflection – Angle of reflection = angle of incidence Specular Reflection – Light travels to mirror in one direction & reflects from mirror in one direction Diffuse Reflection – Objects send light in all directions – Irregularities on surface of object larger than wavelength of light send light in many directions Refraction Bending of light ray as it passes from one substance to another Color Dispersion Separation of light into different wavelengths show colors of visible light – Longer wavelengths: red – Shorter wavelengths: violet – Spectrum of wavelengths is range between red and violet – White All wavelengths of spectrum strike eye at same time – Black Absence of the wavelengths of visible light spectrum Laser Light Amplification Stimulated Emission of Radiation Device that transforms energy into electromagnetic radiation – Light with electrons that radiate in synchronous vibration Laser Components Pump Source – Sets particles from energy source in motion – Energy emitted from laser as electromagnetic radiation Gain Medium – Made of solid, liquid, or gas – Amplifies light as it passes thru material – Determines type of laser: solid state, semiconductor or liquid – Solid State: Pulse beam has the most power output Laser Components Resonator Cavity – Mirrors that direct and redirect particles through the gain medium Nuclear Physics Study of the properties of atomic nucleus Nucleons are protons and neutrons – Quarks: Subatomic particles that make up nucleons Repulsive Force – Keeps tightly packed nucleons from overlapping – Nucleus appears as closely packed spheres, almost touching – Binding Energy: Forces apart nucleons Nuclear Physics Relationship of Energy and Mass – Einstein’s Equation E = mc² Mass and energy are same thing Small amount of mass holds a lot of energy Matter can be converted from one energy form to another – Particle accelerators and nuclear reactors Physics for the Surgical Technologist QUESTIONS? I DON’T’ THINK SO!