Intro to senses Flashcards
What is sensory information?
Sensory information
- Continuously surrounds us
- Gives information about inside and outside environment
- Detected by receptors and sent to the brain
- Comes in multiple forms
* touch, taste, hearing, vision, smell, equilibrium
- Receptors classified in multiple ways
What are receptors?
Receptors
- Respond to stimulus
- Initiate sensory input to CNS
- Range from simple structures to complex structures, sense organs
What are stimuli ?
Stimuli
- Changes in sensory information
- Detected by receptors
- Some pleasurable
* e.g., tasty meal
- Some alert to danger
* e.g., detecting hot object
- Others with moment-to-moment information
* e.g., air temperature
What is sensation?
Sensation
- Conscious awareness of sensory information
- Only stimulus that reaches cerebral cortex
- Aware of only a fraction of stimuli
- Much input relayed to lower areas of the brain
* response initiated without awareness
* e.g., stimuli regarding blood pressure or carbon dioxide levels
For a stimulus to be consciously perceived, the sensory input must be sent to what area of the brain?
cerebral cortex
What must recptors do ?
Transduce
- Change one form of energy into a different form
- Original energy specific to type of receptor
* e.g., light energy in eye, sound energy in ear
- Energy transduced to electrical energy
* conducted along a sensory neuron
What is required to be a tranducer?
Two criteria necessary
1) maintenance of resting membrane potential across plasma membrane
2) modality gated channels within plasma membrane
- open in response to stimulus
What is a recptive field?
- Area of distribution of sensitive ends of receptor
- Inverse relationship between field size and ability to identify location
- If field small, precise location determined easily
- Broad field, only general region detected
What is a Tonic receptors?
Tonic receptors
* respond continuously to stimuli at constant rate
* e.g., balance receptors in inner ear
* sensitiVity stays same over time
What is a phasic receptor?
Phasic receptors
* detect new stimulus or change in stimulus
* sensitivity decreases over time
* e.g., tactile receptors of skin
* can undergo adaptation
- reduction in sensitivity to continuously applied stimulus
* e.g., loss of awareness of pressure while sitting in a chair
How does a receptor function as a transducer?
Transducers change one form of energy (e.g., light, sound) into electrical energy conducting along sensory neurons.
What are the classes of receptors?
- Stimulus type
- Location
- Structural complexity
Examples of recptors classified by stimulis type.
- Mechanoreceptors-respond to touch, pressure, vibration, stretch, and itch
- Thermoreceptors-sensitive to changes in temperature
- Photoreceptors-respond to light energy (e.g., retina)
- Chemoreceptors-respond to chemicals (e.g., smell, taste, changes in blood chemistry)
- Nociceptors-sensitive to pain-causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals)
Examples of receptors classified by location?
- Exteroceptors
- Respond to stimuli arising outside the body
- Receptors in the skin for touch, pressure, pain, and temperature
- Most special sense organs - Interoceptors (visceroceptors)
- Respond to stimuli arising in internal viscera and blood vessels
- Sensitive to chemical changes, tissue stretch, and temperature changes - Proprioceptors
- Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
- Inform the brain of one’s movements
Examples of receptors based on Structural Complexity.
- Complex receptors (special sense organs)
- Vision, hearing, equilibrium, smell, and taste - Simple receptors for general senses:
- Tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense
- Unencapsulated (free) or encapsulated dendritic
endings
