Animal Phys Lecture 14: Sensory Systems

Sensory transduction

the conversion of stimulus energy into electrical energy

sensory receptor molecules

• membrane proteins that are sensitive to sensory stimulus

• converts stimuli in the environment into action potentials in the nervous system

• sensory transduction and occurs in all sensory systems

Stimulus

a form of external energy of stimulus into electrical signals

sensory receptors

sensory transduction begins at _______ with specialized cells that are able to detect environmental stimuli

photoreceptors

detect light

chemical receptors

in the tongue and nose to detect odors and taste

mechanoreceptors

detect touch

hair cells

detect sound

environment; body

receptor cells respond to stimuli from the ______ and _______

sensitivity

ability to distinguish among stimuli of different INTENSITIES

specificity

the ability to distinguish among stimuli of different TYPES

sensory modality

(subjective matter) mechano-, vestibular-, osmo-, auditory-, thermo-, electro-, gustatory-, olfactory-, photo-, and magneto-

chemical, mechanical and electromagnetic

what are the 2 types of stimulus?

ionotropic and metabotropic

what are the 2 types of transduction?

in exterorecpetors and interoceptors

where are ionotropic and metabotropic receptors located?

neural coding

one common way the nervous system encodes complex information by labeled line coding. One cell encodes for one type of sensory quality (neurons specifically tuned to one stimulus)

pain

receptor is activated, resulting sensation will be this, regardless of how it’s stimulated

WILL NOT

if receptor-cell type was dysfunctional the sensation ______ be perceived

active

the brain identifies the stimulus based on which labeled pathway is ______ rather than the intensity of the signal

any kind of stimulus

every receptor cell can be stimulated by _________ if there’s enough energy; the wiring of the receptors is what really matters

mechanoreceptors

they operate via sensitivity of stretch-activated (SA) ion channels. They open in response to stretching of the nearby plasma membrane (insect sensory bristle)

steps of mechanoreception

1. bristle movement stretches the membranes at the base of the bristle

2. membranes connect to mechanoreceptor dendrites

3. stretch-gated channels open allowing influx of Na+ and probably K+ too

4. produces receptor potential (RP)

5. if RP is above threshold it generates an action potential

6. action potentials from the neuron travel to CNS for processing

frequency; strength

action potential _______ encodes ______ of the stimulus

labeled line

(cell identity) tells CNS that the stimulus is a mechanical deflection of a particular sensory bristle on the body

vestibular system

balances organs

statocysts

many invertebrates have these sensory organs and they contain mechanoreceptors that function in their sense of equilibrium

pressure waves

sound equals ______

tympanal organs

flexible cuticle that can resonate in response to sound waves

vestibula organs

balance, detection of acceleration/motion, head position and orientation

lateral line system

detects water flow and other stimuli

auditory sustem

hearing