LECTURE 7 Flashcards
8 Senses
Sight, Hearing, Taste, Touch, Smell, Movement, Balance, Interception
Interception
Sensation of knowing what is going on in the internal organs of our body
Variation in human sensory capacity is influenced by…
Genetics, Maturation, Circadian Rhythm, Experience, Fatigue, Injury
Categories of human sensory receptors
Chemoreceptors (chemicals), Mechanoreceptors (movement), Nociceptor (pain), Photoreceptor (light), Thermoreceptor (temperature), Phonoreceptor (sound)
STEP ONE OF SENSATION
Reception - ability of receptor to absorb energy of a stimulus
STEP TWO OF SENSATION
Transduction - conversion of stimulus energy into a membrane potential, a change in permeability of a post-synaptic membrane, transfers into a certain action potential.
STEP THREE OF SENSATION
Transmission - receptor potentials transmitted via AP’s to CNS
STEP FOUR OF SENSATION
Integration - CNS processing of frequency of receptor potentials
What is sensation coded as
Frequency of neurons firing
Accomodation of a stimulus occurs because…
A decrease in responsiveness by receptors due to continual stimulation
A uniformly maintained stimulus of constant intensity is pereived as what over time?
Progressively WEAKER over time (eg. when you put your clothes on in the morning you can feel them but this feeling dulls down throughout the day)
Variable intensity stimulus of shorter durations is perceived as what over time?
Perceived as progressively stronger over time
Sensation
Detecting the information
Perception
Understanding the information detected
Primary Somatosensory Cortex
- Integration of sensory information
- Provides meaning to our perceptions
- Topographically organised (sensory map)
Lesions of the Primary Somatosensory Cortex
Defective localisation, Loss of proprioception, Tactile Agnosia
Tactile Agnosia
Trouble identifying an object by touch alone
Why cant we tickle ourselves
Brain anticipates touch and turns down the sensitivity threshold
Three main types of receptors
Interoceptors, Proprioceptors, Exteroceptors
Interoceptors
States of our internal organs
Proprioceptors
Information about our own movements (Kinesthesis) - muscle receptors, joint receptors, cutaneous receptors, vestibular system
Exteroceptors
Information about the movement of objects in the environment
Proprioception
Sensation and perception of the position and movement of limbs, head and trunk
What are spindles parallel to
Muscle Fibres
When do spindles fire
When the muscle is stretched
What are Type II spindles sensitive to
Length
What are Type Ia spindles sensitive to
Velocity
When do Golgi Tendon Organs fire
When the muscle contracts
Where are Golgi Tendon Organs found
Within tendons
What are joint receptors
Sensory endings in the joint that provide information of the joint angle
What are cutaneous receptors
Receptors in the skin
What do mechanoreceptors measure
Measure deformation of skin eg. information about tough, pressure, displacement
Surgical Deafferentiation
Afferent pathways surgically severed/removed
‘Signals Balance’ - proprioception
Information about the position and movement of head
‘Location’ - proprioception
Middle inner ear deep within the temporal bone
How are sensors triggered - proprioception
By linear and angular acceleration of the head
