Physiology Unit 2-Sensory

• Transduction is a stimulus from outside of the cell membrane that signals an extracellular receptor to create a signal an intracellular signal.
• Stimulus

  physical energy act on sensory receptors
• Intracellular Signal open/close ion channel that changes the membrane potential
• Threshold an action potential from immense amount of stimulus to a sensory receptor that signal CNS
• Differences between Simple and Non-Neural?

  The difference is that non-neural is transduced by specialized cells rather than neurons.

  Also that simple has free nerve ending and non-neural does not
• 3 type of sensory neuron

  Simple, Complex, and Non-neural
• What will happen when the stimulus is activated on membrane?

  Bend the membrane opening the Na ion channel to let it inside which creates a graded potential

  
• What is receptor potential?

  It is a graded potential but the receptor- initiates action potential or neurotransmitter secretion which causes action potential in sensory neuron
• Step of receptors potential: non-direct

  Stimulus comes in

  Na ion channel opens and goes in

  Ions depolarize the cell open the Ca ion channel

  Ca ion goes in an exocytosis- vesicles move to the wall

  Neurotransmitter fire out to the receptors
• step receptor potential: Direct

  Stimulus comes in

  The Na ion channel opens and Na ion comes in

  Depolarized to create an AP
• How does sensory info travel? Gives simple step

  Receptors send signals through the spinal cord which goes to the brain. It goes through the thalamus synapse and goes to the cortex.

  
• How are intensity and duration encoded in neurons?

  Encoded by the action potential. Intensity is the frequency of action potential and duration is the series of action potential.
• What is the 2nd step of receptor potential

  The Na ion channel open, Na goes in
• Which pathway does not go through the thalamus?

  olfactory
• What does the thalamus do?

  Modify and relay information to the cortical center
• what is it called when there are many sensory that will not be noticed because you forgot about it?

  habituation
• Inhibitory modulation

  diminishes suprathreshold stimulus below the perceptual threshold.
• Action potential will always be the?

  Same no matter there is no strength or weakness only amount of series.
• Meissner corpusule


  respond to flutter stroking
• Pacinian Corpusule

  series of vibration
• Ruffini Corpusule

  Respond to skin stretch
• Merkei receptors

  sense steady pressure and texture
• Free nerve ending

  Nociceptor responds to noxious stimuli

  Hair Root sense hair movement
• What is a receptor that slowly adapts overtime?

  Tonic receptors
• What receptors adapt rapidly via stimulus and offset?

  Phasic receptors
• When pain happens at a single point hitting A, B, and C but B is the main focal point of the sensation?

  Stimulus goes through all three but B has the most response with neurotransmitters firing out. In the second phase, an inhibition will happen stopping A and C from responding distinguishing the one with the stimulus.
• What is the thing called that distinguishes between receptive field

  lateral inhibition
• Somatic senses: Steps on pathway for fine touch

  1.Cross midline into the medulla

  2. Synapse with thalamus

  3. Primary somatic sensory cortex
• Somatic Senses: Steps to pain

  1.Touch across spinal cord

  2.Synpase with thalamus

  3.Primary somatic sensory cortex
• There is no such thing as pain what is the stimulus for this and the receptor for it?

  Stimulus is noxious stimuli and receptors are nociceptors.
• What are the two fiber types for Nociceptors?

  A delta- fast fiber and C fiber- low fiber
• damage of tissue causes a release of:

  histamine, K, prostaglandins, serotonin, substances P
• Although pain does not go into CNS if it is emotion or hypothalamus it will go to the cortex
• What is referred pain?

  A pain that is sensed together from organs and the skin because of being close to one another.
• What is pain modulation?

  A touch that reduces the pain more by adding another neuron to the inhibitory
• Give me the olfactory pathway

  Nose - olfactory nerve - olfactory bulb - olfactory tract - cortex that split into limbic or cerebral.
• What happens in the olfactory bulb synapse? Simple term

  Odorant molecules first dissolve in the mucous layer (nasal cavity) before binding to the primary olfactory neuron synapse up to the secondary sensory neuron.
• What makes a new neuron(olfactory)?

  Basal cell layer include stem cell
• Give me olfactory signal transduction steps when synapse in the primary neuron.

  Odorant molecules dissolve in the mucous layer- olfactory epithelium

  Odorants bind to the olfactory receptor dendrites.

  The receptor GCPR activates adenylyl cyclase.

  Adenylyl cyclase makes ATP to cAMP.

  The cAMP increase causes an open Ca/Na ion channel.

  An increase of Ca/Na causes the Cl ion channel to open.

  Cl ion channel opens creating depolarization.

  Depolarization occur= receptor potential
• Amygdala hippocampal


  emotion/memory limbic system