Ch. 7 Sensory NS Pt. 1

what do Receptor cells excite?

afferent neurons so it can tell CNS about a stimulus

Chemoreceptors, Photoreceptors, Thermoreceptors, Mechanoreceptors, Nociceptors, Proprioceptors

Chemoreceptors→transduce chemical stimulus in environment/blood (taste & smell)

Photoreceptors→transducer light & darkness (ex// rods & cones)

thermoreceptors→transduce temperature

mechanoreceptors→transducer touch/pressure
nociceptors→transduce pain & extreme temperature (damaged tissue)
proprioceptors→transduce body positions

Phasic Receptors

example scenario?

rapidly adapting receptor “Something is changing!”
ex// light, touch, or smell

ex// bath water is hot when you first enter & then it feels okay because there’s no more action potentials firing

Tonic Receptors

example scenario?

slow adapting receptor; “something is still here”

ex// pain of when you break your leg

define coding

converting a stimulus into electrical signal that CNS can interpret

Let’s say I pinch you harder, will the action potential strength be greater?

NO, there will just be MORE FREQUENT action potentials

sensory unit

single afferent neuron with all its receptor endings

receptive field

the specific area where receptors monitor

Afferent sensory pathways are formed by _______

3 or more neurons connected by synapses that form ascending pathways to the CNS

what are the 3 ascending tracts to the CNS?

1) posterior column tract
2) spinothalamic tract

3) spinocerebellar tract

1st order neurons

-where is its cell body located?

deliver sensation to CNS

-cell body is in dorsal root ganglion(spinal nerves) & cranial sensory ganglion(cranial nerves)

2nd order neuron

an interneuron located in spinal cord/brain & sends message to thalamus

Third Order Neuron

sends message from thalamus to cerebral cortex

somatosensory cortex

receives info from sensory receptors of skin, bone, tendons, joints, skeletal muscle

Visual Cortex? Where is it located?

-receive info from eyes

-Occipital lobe

Auditory cortex? Where is it located?

-receive info from ears

-temporal lobe

Gustatory cortex? Location?

-receive info from taste buds of tongue

-next to somatosensory cortex

Olfactory Cortex? Location?

-receive info from olfactory receptors of nose
-located in parts of frontal & temporal lobe

association cortex

example scenario?

interprets & gives meaning to info

ex//

Primary cortex:
"Cold object touching my palm."

↓

Association cortex:
"That's an ice cube."

what does it mean that lips are two-point discrimination?

lips have 2 receptors close to each other so two points can be felt

(not the case with the BACK)

What is lateral inhibition?

concept that allows you to sense fine detail bc multiple receptors are playing a role