Lecture 22: The PNS- Sensation Flashcards
Transduction Pathway
Energy, sensory receptor, signal to brain
Types of energy: Transduction Pathway
Chemical, mechanical, thermal, light
Types of Sensory Receptors: Transduction Pathway
Simple, Complex, Special Sensory
Cognition
When the signal reaches the cerebrum (most go through the thalamus)
Mechanoreceptors
Detect mechanical deformation which stretches the membrane to open ion channels
Baroreceptors
Senses pressure
Proprioceptors
Senses body position (joints/muscles)
Thermoreceptors
Change in temperature which alters the permeability of the membrane
Cold receptors respond if temperature < body temperature
Warm receptors respond if temperature > body temperature to 45C
> 45C: Nociceptors
Photoreceptors
Electromagnetic radiation that changes the membrane characteristics
Chemoreceptors
Application of chemical ligands which also opens ion channels
(Taste, smell, CO2, O2, H+)
Subconscious
Processed in spinal cord or brain stem
Special Senses
Vision, hearing, taste, smell, equilibrium
Somatic Senses
Touch, temperature, pain, itch, proprioception
Somatic Stimuli
Muscle length + tension, proprioception
Visceral Stimuli
Blood pressure, distension of GI tract, blood glucose concentration, internal body temperature, osmolarity of body fluids, lung inflation, pH of CSF, pH + oxygen content of blood
Where do equilibrium pathways primarily project to?
The cerebellum
Where do most sensory pathways go through?
The thalamus
Receptive Fields
Area monitored by a single receptive cell
What increases receptive field size?
Convergence of primary neurons onto secondary neurons increase receptive field size
Where are smaller receptive fields located?
More sensitive areas
Labeled Line
1:1 association of a receptor to a sensation
Larger receptive fields
More difficult to localize stimulus
Lateral Inhibition
Enhances contrast and makes a stimulus easier to perceive
Intensity
Frequency of action potentials
More frequent action potentials= longer and stronger
Duration
When action potentials are firing
Tonic Receptors
Slowly adapting receptors that respond for the duration of a stimulus
Phasic Receptors
Rapidly adapt to a constant stimulus and turn off
