Sensory Physiology 1- Gehrral Properties

Question 1

What are sensory receptors?

Answer 1

• respond to a particular form of energy: adequate stimulus
• Transduce (convert) stimuli into electrical signals.
• respond to a stimulus by generating the receptor potential (a graded potential)
• have a threshold

Question 2

What are some examples of sensory receptors?

Answer 2

• chemoreceptors
• Mechanoreceptors
• photoreceptors
• thermsreceptors

Question 3

How do sensory receptors transduce?

Answer 3

Presence of stimulus activates ion channel or 2nd messenger to convert stimulus to neuronal signal

Question 4

How do sensory receptors have a change in membrane potential?

Answer 4

Stimulus causes receptor (ion channel or 2nd messenger) causes a change in membrane potential

Question 5

What happens if the threshold potential of sensory receptors is not meant?

Answer 5

No change in membrane potential (no action potential)

Question 6

What are the functions of encoding sensory signals?

Answer 6

• encoding stimulus intensity (amplitude)
• encoding stimulus duration
• encoding sensory stimulus location: a sensory neuron has a receptive field

Question 7

What are possible outcomes of encoding stimulus duration?

Answer 7

1. Slowly adapting/ tonic receptor

2. Rapidly adapting/ phasing receptor

Question 8

What is spatial summation?

Answer 8

Spatial summation: the adding together of EPSP’s generated simultaneously together at many different synapses on a dendrite

Question 9

What is convergence in sensory systems?

Answer 9

Presence of convergence influences the sensitivity of a region to a stimulus: Two-point discrimination (decreased)

Absence of convergence influences the sensitivity of a region to a stimulus: Two-point discrimination (increase)

Question 10

What are the somatic senses?

Answer 10

• Touch (fine and crude/coarse)
• proprioception
• nociception
• temperature

Question 11

Describe perception in contralateral primary somatic sensory cortex

Answer 11

Primary sensory neuron then message travels to secondary sensory neuron, then travels to tertiary sensory neuron

Question 12

What is the path to the cortex for somatic senses?

Answer 12

1. Crude touch, temperature, and nociception cross midline in the spinal cord
2. Fine touch, propioception, and vibration cross midline in the medulla oblangata
3. All sensory pathways (except olfaction)synapse in the thalamus before going to cortex
4. Sensations are perceived somato-sensory cortex in the parietal lobe of the brain