Special senses Flashcards
Humans perception is limited by?
- receptor types
- sensitivity
- central processing
Control centre in the brain?
2 things it controls
Cerebral cortex
1. Sensation
2. Perception
Receptor definition
structure within afferent neuron that responds to stimulus
Sensory transduction
conversion of stimulus to electrical energy
Peripheral nervous system
nerve fibres carrying info between CNS and other parts of the body
Afferent neurons have sensory receptors at the end of peripheral endings
Adequate stimulus
the stimulus that the receptor is specialised to respond to
Types of receptors and their adequate stimulus
Peter Malark Obviously Never Takes Chemicals
- Photoreceptor (light)
- Chemoreceptors (chemicals)
- Mechanoreceptor (pressure)
- Osmoreceptor (concentration of solutes)
- Thermoreceptors (temps)
- Nocireceptors (pain)
Intensity of stimulus determined by?
- number of receptors
- frequency of action potentials
Response changes - body adjusts to stimulus in 3 ways:
- Receptor Adaptation
- Neuron Habituation
- Neuron Sensitivity
Receptor Adaptation
What is it and 2 types
Receptors decrease extent of depolarisation
Repetition of stimulus results in fewer action potentials
1. Tonic Receptors
- adapt slowly or not at all
- Phasic Receptors
- adapt rapidly (watch)
Sensory discrimination
Large vs Small
Large diffuse receptive fields = least sensitive
Small dense receptive fields = most sensitive
Somatic senstation
What?
Where is it processed?
Types of tactile receptors (5)
Sensation of body surfaces
Somatic processing: spinal cord & brain
1. Hair
2. merkels disc
3. pacinian corpuscle
4. ruffini endings
5. meissners corpuscles
Pain Sensation
describe
3 Categories of Nocireceptors
more than a direct response. behaviour and emotions play a role
it is personal and multidimensional
1. Mechanical noceceptors
2. Thermal noceceptors
3. Polymodal noceceptors (damaging stimuli)
EYE
2 main muscles in contraction & relaxation
what occurs in bright light
Circular muscles
Radial muscles
In bright light the circular muscles contract and radial muscles relax, and the pupil constricts
Eye accomodation
what is it?
explain process
Observation of nearby objects
The ciliary muscles contract -> suspensory ligaments slacken -> lens more convex -> light rays more refracted
Rods VS Cones
Rods:
- more sensitive
- low acuity
- shades of grey
- photopigment
Cone:
- less sensitive
- sharp
- colours
- 3 photopigments (red, green & blue)
Visual Acuity Test
formula?
VD = d/D
(d = 6 meters)
(D = distance at which eyes should be able to read it)
EAR
3 main sections
- External ear
- Middle ear
- Inner ear
Pitch, Intensity and Timbre
Pitch = frequency changes
Intensity = amplitude changes
Timbre = overtones
External Ear Structures (3)
- Pinna
- External auditory meatus (canal)
- tympanic membrane (eardrum)
Middle Ear Structures (3)
MIS
Ossicles
1. Malleus
2. Incus
3. Stapes
Inner Ear (1 main & NB compartment)
Cochlea
1. Organ of Corti
Pitch discrimination
Depends on where it vibrates maximally on the basilar membrane
Loudness discrimination
Depends by how much the basilar membrane vibrates
Conductive deafness
What
& possible causes
Sound waves are not conducted through external and middle ear
Blockage
ruptured ear drum
ear infection
restricted ossicular movements
Sensorineural deafness
What
& where possible defects may lie
Sound waves are transmitted to inner ear but not translated to nerve signals
1. Organ of corti
2. in auditory nerves
3. in ascending auditory pathways
Equilibrium
Vestibular aparatus and their roles (2)
- Semi-circle canals
- rotation / angular acceleration - Otolith canals
- upside down sloth (position of head to gravity)
Taste
receptors?
protrusions on tongue?
5 primary tastes
Chemoreceptors
Papillae
- sweet 2. sour 3. bitter 4. umami 5. salty
Smell (olfactory mucosa)
3 cell types
- olfactory receptors cells
- afferent neuron - basal cells
- detect odours - supporting cells
- secrete mucous
