Sensory Reception Chapter 31
Mar 27, 2015
Sensory Reception
Chapter 31
Sensation and Perception
• Sensation is conscious awareness of a
stimulus
• Perception is understanding what a
sensation means
Types of Receptors
Mechanoreceptors
Thermoreceptors
Pain receptors
Chemoreceptors
Osmoreceptors
Photoreceptors
Assessing a Stimulus
• Action potentials don’t vary in amplitude
• Brain tells nature of stimulus by:
– Particular pathway that carries the signal
– Frequency of action potentials along an axon
– Number of axons recruited
Recordings of Action Potentials
Sensory Adaptation
A decrease in response to a stimulus that is being maintained at constant
strength
Somatic Sensations
• Touch
• Pressure
• Temperature
• Pain
• Motion
• Position
Somatosensory Cortex
Hearing
• Ear detects pressure waves
• Amplitude of waves corresponds to
perceived loudness
• Frequency of waves (number per
second) corresponds to perceived pitch
Anatomy of Human Ear
cochlea
auditory nerve
eardrumauditory canal
hammer
anvilstirrup
Sound Reception
• Sound waves make the eardrum vibrate
• Vibrations are transmitted to the bones
of the middle ear
• The stirrup transmits force to the oval
window of the fluid-filled cochlea
Sound Reception
• Movement of oval window causes waves in the fluid inside cochlea ducts
Sound Reception
• Fluid movement is sensed by the organ of Corti
• Hair cells are bent against overlying tectorial membrane and fire
Balance and Equilibrium
• In humans, organs
of equilibrium are
located in the
inner ear
• Vestibular
apparatus
Vision
• Sensitivity to light does not equal
vision
• Vision requires two components
– Eyes
– Capacity for image formation in the
brain
Camera Eyes
• Characteristic of octopuses, squids, and all vertebrates
• Eye is structured like a camera– Interior is dark chamber– Light enters through pupil– Lens focuses light on photoreceptors
Human Eye sclera
choroid
iris
lens
pupil
cornea
aqueoushumor
ciliary muscle
vitreous body
retina
fovea
opticdisk
part ofopticnerve
Pattern of Stimulation
Visual Accommodation
• Adjustments of the lens
• Ciliary muscle encircles lens, attaches to it
• When this muscle relaxes, lens flattens, moves focal point farther back
• When it contracts, lens bulges, moves focal point toward front of eye
The Photoreceptors
• Rods – Contain the pigment rhodopsin
– Detect very dim light, changes in light intensity
• Cones– Three kinds; detect red, blue, or green
– Provide color sense and daytime vision
To the Visual Cortex (2)
Visual cortex
Taste
• A special sense
• Chemoreceptors
• Five primary
sensations
– Sweet, sour, salty,
bitter, and umami
Smell
• A special sense
• Olfactory receptors
• Receptor axons lead to olfactory lobe
olfactorybulb
receptor cell
Sensory Perception
• Sensory Cortexes; visual, auditory, smell, taste, somatosensory.Register current incoming sensory signals.
• Sensory Association Areas for each sense store sensory memory and automatically compare current with past to provide meaning.
Common Integrating Area(CIA)
• Integrates messages from sensory cortexes and association areas to understand.
• Also known as the gnostic area = knowing
• CIA capacity is limited = what your looking at and/or listening to.
Memory
• CIA must Recall memory from the sensory association areas. Facilitated pathways help.
• The the CIA Remembers (puts the separate sensory messages back together)
Thought Process
• CIA is in command
• Sensory Association Areas provide memory
• Frontal Lobes provide temporary storage, i.e., train of thought
• Limbic System provides emotional imput