Costanzo Neurophysiology - General Sensory Systems Flashcards Preview

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Flashcards in Costanzo Neurophysiology - General Sensory Systems Deck (25):

What type of cells are sensory receptors?

Specialized epithelial cells

Occasionally primary afferent neurons - i.e. olfactory chemoreceptors


What do sensory receptors transmit?

Transduce environmental signals into neural signals


What environmental signals can be detected by sensory receptors?

1. Mechanical force
2. Light
3. Sound
4. Chemicals
5. Temperature


What are the 4 types of sensory transducers?

1. Mechanoreceptors
2. Photoreceptors
3. Chemoreceptors
4. Nociceptors


What are 5 examples of mechanoreceptors?

1. Pacinian Corpuscles
2. Joint receptors
3. Stretch receptors
4. Hair cells in auditory and vestibular systems
5. Baroreceptors in carotid sinus


What are some examples of photoreceptors?

Rods and cones in of the retina


What are 4 examples of chemoreceptors?

1. Olfactory receptors
2. Taste receptors
3. Osmoreceptors
4. Carotid body O2 receptors


What detects extremes of temperature and pain?



What is a receptive field? What makes an excitatory or inhibitory receptive field?

Area of the body, that, when stimulated, changes the firing rate of a sensory neuron. If the firing rate of the sensory neuron is increased the receptive field is excitatory. If the firing rate of the sensory neuron is decreased the receptive field is inhibitory.


What are the steps in initial sensory transduction?

1. Stimulus arrives at sensory receptor
2. Ion channels are opened in the sensory receptor
3. Change in membrane potential achieved


What is the typical ion flow in a sensory receptor? What is the exception?

Usually the current is inward = depolarization of the receptor

Exception is photoreceptor, light decreases inward current and causes hyperpolarization


What happens to the membrane potential if the receptor potential is depolarizing? How are receptor potentials graded?

It brings the membrane potential closer to threshold. If the receptor potential is large enough, the membrane potential will exceed threshold and an action potential will fire in the sensory neuron.

Receptor potentials graded in size depending on the size of the stimulus.


How are sensory receptors different in terms of adaptation?

Slowly adapting/tonic receptors

Rapidly adapting/phasic receptors


What are 3 examples of slowly adapting/tonic receptors?

Muscle spindle
slow pain


How do slowly adapting/tonic receptors behave?

Respond repetitively to prolonged stimulus
Detect a steady stimulus


What are 2 examples of rapidly adapting/phasic receptors?

Pacinian corpuscles
Light touch


How do rapidly adapting/phasic receptors behave?

Show a decline in AP frequency with time in response to a constant stimulus

Primarily detect onset and offset of a stimulus


Potentially, how many neurons can be involved in an afferent sensory pathway?

Sensory receptors
First-order neurons
Second-order neurons
Third-order neurons
Fourth-order neurons


What are first order neurons in an afferent sensory pathway? What do they do? Where are the cell bodies located?

Primary afferent neurons that receive the transduced signal and send the information to the CNS.

Cell bodies are located in the DRG or spinal cord ganglia.


Where are the second order neurons in an afferent sensory pathway located?

located in spinal cord or brain stem


What info do the second order neurons in an afferent sensory pathway receive?

Info from one or more primary afferent neurons in relay nuclei and transmit it to the thalamus


Where do the axons from second order neurons in an afferent sensory pathway go?

May cross the midline in a relay nucleus in the spinal cord before they ascend to the thalamus.

Sensory information originating on one side of the body ascends to a contralateral thalamus


Where are third order neurons in an afferent sensory pathway located? From here, where is the information transmitted?

In relay nuclei of thalamus.

Encoded sensory information ascends to the cerebral cortex.


Where are the fourth order neurons in an afferent sensory pathway located?

In appropriate sensory area of the cerebral cortex


What does reception of info from fourth order neurons result in?

Conscious perception of a stimulus