Costanzo Neurophysiology - General Sensory Systems Flashcards
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?
- Mechanical force
- Light
- Sound
- Chemicals
- Temperature
What are the 4 types of sensory transducers?
- Mechanoreceptors
- Photoreceptors
- Chemoreceptors
- Nociceptors
What are 5 examples of mechanoreceptors?
- Pacinian Corpuscles
- Joint receptors
- Stretch receptors
- Hair cells in auditory and vestibular systems
- Baroreceptors in carotid sinus
What are some examples of photoreceptors?
Rods and cones in of the retina
What are 4 examples of chemoreceptors?
- Olfactory receptors
- Taste receptors
- Osmoreceptors
- Carotid body O2 receptors
What detects extremes of temperature and pain?
Nociceptors
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?
- Stimulus arrives at sensory receptor
- Ion channels are opened in the sensory receptor
- 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
Pressure
slow pain
How do slowly adapting/tonic receptors behave?
Respond repetitively to prolonged stimulus
Detect a steady stimulus