BIOC32H3 Lecture Notes - Lecture 13: Withdrawal Reflex, Lateral Inhibition, Nociception

19 views5 pages
5 Jul 2018
School
Course
Professor
BIOC32
LECTURE 13
Sensory Physiology I
Processing of Sensory Stimuli
โ— Special senses (always conscious)
โ—‹ Vision
โ—‹ Hearing
โ—‹ Taste
โ—‹ Smell
โ—‹ Equilibrium (balance)
General Properties of Sensory Systems
1. Activated by a stimulus (physical energy)
2. Stimulus activates sensory receptor
โ— Converts stimulus to intracellular signal
โ— Signal transduction
โ— Changes in membrane potential (Vm) known
as generator or receptor potential (same as
graded potential)
3. If threshold is reached, conduction of action
potential to CNS
4. Integration of signal in the CNS
โ— somatosensory cortex (conscious)
โ— brain stem (unconscious)
Types of Sensory receptors: Classified by Structure
Types of Sensory Receptor: Classified by the
Stimulus that they are Most Sensitive To
โ—Chemoreceptors๎€:๎€ respond to chemical
stimuli that bind to receptors e.g taste, smell,
O๎€2๎€, glucose, pH
โ—Mechanoreceptors๎€:๎€ ๎€mechanical stress๎€ or
mechanical strain๎€ such as pressure
(baroreceptors), vibration, gravity, cell
stretch (osmoreceptors), acceleration
(proprioceptors), sound
โ—Thermoreceptors๎€: temperature
โ—Photoreceptors๎€: ๎€light
โ—Nociceptors:๎€ ๎€respond to painful stimuli
โ—Adequate stimulus๎€: the form of energy to
which that receptor is most responsive
โ— Sensory receptors can respond to other
forms of energy if stimulus intensity is high
enough e.g photoreceptors respond to
pressure
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in
BIOC32
LECTURE 13
1. Determination of Location of Stimulus
โ†’ (Somatic and Vision sensory neurons have
receptive fields)
โ— Somatic and visual stimuli are activated by
stimuli that falls within physical area : the
receptive
๎€
๎€field
โ— 1 receptive field may be associated with 1
secondary sensory neuron
โ— Receptive fields may overlap
โ—‹ Several primary neurons converge
onto one secondary neuron
โ— Convergence decreases ability to locate the
stimulus accurately
โ†’ Two-Point Discrimination: Convergence
โ— Stimulation of 2 primary neurons
โ— Convergence onto ๎€1๎€ secondary neurons
โ— Receptive field is large โ€“ less sensitive
โ— OUTCOME: will seem like compass only
pricked one area on skin
โ— e.g arms, legs, back
โ†’ Two-Point Discrimination: Small receptive Field
โ— Stimulation of 2 primary neurons
โ— 2 secondary neurons activated
โ— Receptive fields small: more sensitive
โ— OUTCOME: allows 2 separate pin to be
decoded as 2 separate touches
โ— e.g fingertips
Coding of Auditory Info Doesnโ€™t Require receptive
Fields to Locate Stimulus
โ— Ear sensitive to different frequencies of
sound waves
โ— No receptive fields in ear
โ— Instead timing of stimulation used to
compute location
โ— Time difference taken for sound stimuli to
reach the 2 sides of auditory cortex is
registered and used to locate the sound
source
โ—OUTCOME:๎€ source is on left side of body
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in

Document Summary

General properties of sensory systems: activated by a stimulus (physical energy, stimulus activates sensory receptor. Changes in membrane potential (vm) known as generator or receptor potential (same as graded potential) threshold is reached, conduction of action. 3. potential to cns: integration of signal in the cns somatosensory cortex (conscious) brain stem (unconscious) Adequate stimulus : the form of energy to which that receptor is most responsive. Sensory receptors can respond to other forms of energy if stimulus intensity is high enough e. g photoreceptors respond to pressure. Mechanoreceptors : mechanical stress or stimuli that bind to receptors e. g taste, smell, O 2 , glucose, ph mechanical strain such as pressure (baroreceptors), vibration, gravity, cell stretch (osmoreceptors), acceleration (proprioceptors), sound. Lecture 13: determination of location of stimulus. (somatic and vision sensory neurons have receptive fields) Somatic and visual stimuli are activated by stimuli that falls within physical area : the receptive field.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents

Related Questions