Week 4 Flashcards
Describe the key elements of a sensory system
First step in sensation involves accessory structures which collect and modify sensory stimuli.
Second step is transduction, converting incoming energy into nerve cell activity; accomplished by neural receptors.
What is sensory adaptation
Sensory adaptation takes place when the receptors receive unchanging stimulation, nerve cell activity is transferred through the thalamus and onto the cortex.
Explain transduction
Transduction is the process of converting incoming energy into nerve cell activity
Explain Encoding
Encoding is the translation of a stimulus’ physical properties into a pattern of neural activity.
Explain visible light
Visible light is electromagnetic radiation that has a wavelength from just under 400 nanometres to about 750 nanometres (a nanometre is one-billionth of a metre).
Explain light intensity
Refers to how much energy the light contains and determines the brightness of light.
Explain light wavelength
What colour you see depends mainly on light wavelength, different wavelengths produce sensations of different colours.
Explain the eye
Light enters through the cornea.
Light then passes through the pupil.
The iris adjusts the amount of light allowed into the eye by contracting to reduce the size of the pupil/
The lens is directly behind the pupil.
Both cornea and lens are curved so that can bend light rays.
Light rays are focused into an image on the retina
Describe photoreceptors
Photoreceptors are specialised cells in the retina that convert light energy into nerve cell activity.
Describe the two basic types of photoreceptors
Rods and Cones
Rods use photopigment rhodopsin, which is more light-sensitive than cones
Cones use one of three isospin photopigments each is sensitive to different light wavelengths.
Describe sound
Sound is a repetitive fluctuation in the pressure of a medium, such as air. Vibrations of an object produce the fluctuations in pressure that create sound. A wave is a repetitive, rhythmic variation in pressure that spreads out in all directions.
Describe amplitude
or intensity is the difference in air pressure from a wave’s baseline to its peak.
Describe wavelength
is the distance from one peak to the next.
Describe frequency
is the number of complete waveforms, or cycles, that pass by a given point in space every second. One cycle per second is 1 hertz (Hz)
Describe Auditory Accessory Structures
The pinna is the crumpled part of the ear visible on the outside of the head that funnels sound down through the ear canal.
At the end of the ear canal, the sound waves reach the middle ear, where they strike a tightly stretched membrane known as the eardrum or tympanic membrane.
The vibrations of the tympanic membrane are transferred through a chain of three tiny bones named for their shapes, the malleus (hammer), incus (anvil) and the stapes (stirrup).
These bones amplify the changes in pressure produced by the original sound waves by focusing the vibrations of the tympanic membrane onto the oval window, a smaller structure.
Describe Auditory Transduction
After sound passes through the oval window, it enters the inner ear reaching the cochlea. The cochlea is the structure in which transduction actually occurs.
The cochlea is wrapped into a coiled spiral. A fluid filled ‘tube’ runs the length of it.
The asilar membrane forms the floor of this long tube.
When a sound wave passes through the fluid in the tube, it moves the basilar membrane, and this movement deforms hair cells of the organ of Corti, a group of cells that rests on the membrane.
These hair cells make connections with fibres from the acoustic nerve (auditory nerve), a bundle of axons that go into the brain. When the hair cells bend, they stimulate neurons in the auditory nerve to fire in a pattern that sends the brain a coded message about the amplitude and frequency of the incoming sound waves, senses as loudness and pitch.
Describe Psychological Dimensions of Sound
Loudness is determined by the amplitude of the sound wave
Pitch, how ‘low’ or ‘high’ a tone sounds, depends on the frequency of sound waves.
Timbre is sound’s quality. It is caused by complex wave patterns that are added onto the lowest, or fundamental, frequency of a sound. This enables you to tell the difference between a note played on a flute and a note played on a clarinet.
Describe taste perception
Taste perception (gustatory perception or sense of taste) is the chemical sense system in the mouth. The receptors for taste are in taste buds, which are grouped together as papillae in the mouth and throat.
Describe Olfactory perception
Olfactory perception (or sense of smell) detects chemicals that are airborne, or volatile. Accessory structures include the nose, the mouth and the upper part of the throat. Odour molecules can reach receptors either through the nose or through an opening in the palate at the back of the mouth.
Explain cutaneous senses
somatic senses or somatosensory systems) are located throughout the body, rather than in a localised, specific organ. These include the skin senses of touch, temperature, and pain as well as proprioception,
Describe stimulus and receptors for touch
Skin, hairs receptors that transduce pressure into neural activity are in or just below the skin.
Describe Proprioception
The proprioceptive senses provide information about the position of the body and what each part of the body is doing.
Describe the Trichromatic Theory of Colour Vision
The trichromatic theory or Young-Helmholtz theory of colour vision states that there are three types of visual elements in the eye, each most sensitive to a different wavelength, and information from these three elements combines to produce the sensation of colour.
Which cones respond most to light in the blue range?
Short-wavelength cones
