Biomedical instrumentation Flashcards
Cornea
Hoornvlies, layer around the whole cell
Myopia
Shortsighted, focal plane towards middle of eyeball, concave lens to cure it
Myperopia
Farsightness, focal plane outside eyeball, convex (bol) lens to cure it
Astagmatism
Eye has the form of a rugbyball, cylindrical glasses to cure it
Presbyopia
Bad accomodation (changing of thickness cell), reading glasses needed
Retina
Netvlies
Rods
Very sensitive, coupled, detect contrast
Cones
Detect details and colours, three different types: L (red), M (green), S (blue)
Spatial resolution
The smallest resolution the eye can see in high contrast–> result of this test is calles the visual acuity
Visual acuity
Result of testing the spatial resoluting with the formula: VA = d/D. d = testing distance, D = denominator of Snellen (only very high in the center of the retina)
Spherical aberrations
Optical quality reduction due to large pupil size
Chromatic aberration
White light entering the lens –> colours divided –> only one colour will be sharp at a time
Eccentricity
Distance from the center of the retina to the peryphery
Macular degeneration
Visual acuity is decreased due to blood inside the eye (mostly elderly)
Optic atrophy
Optic nerve has died so no more signals toward the brain
Threshold contrast
Lowest contrast that can be seen
Contrast sensitivity
1/threshold contrast
Perimetry
A test to measure the visual field (‘folow the finger’)
Deutan
Colour blindness with abscence of green cone
Protan
Colour blindness with abscence of red cone
EPSP
Excitatory post-synaptic potentials, depolarisation after influx Na+
IPSP
Inhibitory post-synaptic potential, hyperpolarisation by Cl-
EEG
Electroencephalography, measures electrical potential difference over time, measures activity of areas, salt paste inproves contact with skin (measured on head)
EEG artifacts
unwantes recorded activity due to biological (blinking eye) or technical (movement) reasons
Carpal tunnel syndrome
Pressure on the median nerve when carpal tunnel is too small –> tingling, weakness (aangeboren, hormonal, trauma)
ENG
Electroneurography, test for carpal tunnel syndrome, nerves stimulated –> AP –> arrival at atter point along nerve is measured (muscle contraction) (velocity = distance/time)
CAMP
Compound muscle action potential, many muscle fibers contract
Latency
Time it takes between stimulus and reaction
Amplitude in an ENG
Number of activated muscle fibers
Axonal degeneration
Individual axons are lost –> CMAP amplitude lower
Segmental demyelination
Myeline sheets are lost –> broader CMAP
Conduction block
Signal stops
DSL
Distal sensory latency, time between stimulation of the nerve and recording of the AP
EMG
Elctromyography, electical activity due to muscle contraction, measured on skin or in muscle (needle), used to find diseases
Multiple sclerosis
Demyelinating disease of the CNS by own immune system, first the optic nerve
Evoked potential
Measuring electrical activity in certain areas, demonstrating abnormal sensory functions (but always background activity, so it’s an avarage) activity can be tones (BAEP), shocks (SEP) or visual (VEP)
VEP
Visual evoked potential, flashes
Optic chiasm
Cross of medial optic nerves in central of the brain
Left retina
Half field stimulation of the eyes (left) (left virtual cortex AP)
Right eye full-fiels stimulation
One eye covered, other fully stimulated –> left and right cortex AP
SSEP
Somatosensory evoked potential, electrical stimulation in wrist or ankle, electrone placed on clavicle (erb’s point) and C7 vertebra, SSEP is used during surgery to monitor somatosensory system
BAEP
Brainstem auditory evoked potential, very short clicks, detecting auditory diseases
Fourier analysis
Describing a signal with a bunch of sinusoids with differen frequences
Pinna
External part ear
Cochlea
Slakkenhuis, basilar membrane vibrates (high frequencies at start, low at end), scala vestibula –> oval niche
Middle ear
Air vibration –> mechanical vibration –> fluid vibration, bony ossicles (protects from pressure changes)
Haircells
When basilar membran vibrates (inside cochlea) –> electro vibration (nerve impulse)
Inner hair cells
Detecting sounds innervated by type 1 spiral ganglion neurons
Outer hair cells
Deliver sound energy innervated by type 2 SGN, recieving infromation of the brainstem
Interaural attenuation
Theshold of vibration of the skull with headphones (40 dB), should be as high as possible when you want to exclude one ear
Otoacoustic emissions
Nearly inaudible sount that OHC echo back into the middle ear
BERA
Brainstem evoked response audiometry, detects electical activity of inner ear
ASSR
Same as BERA but the mid latency response is evaluated
