Chapter 46 Flashcards
What are the modalities of transmission of the follwing receptors: Mechano-, thermo-, nocicetors, electromagnetic, and Chemo?
Mechano: detech mechanical compression on stretching
Thermo-: detect changed in tempurature (either cold or warmth)
Nociceptors: detect damage to tissues
Electromagnetic: detect light in the retina
Chemo-: taste, smell, oxygen, osmolarity, CO2, basically respond to chemical stimulation
What is the purpose of the “labeled line” principle?
Explains how different nerve fibers transmit different modalities of sensation when a nerve is stimulated.
e.g. why does pain feel like pain and hot feel like hot
Explain the “labeled line” principle:
-each nerve tract terminates at a specific point in the CNS, and the type of sensation felt is determined by the point in the nervous system to which the fiber leads
–> the pain receptor is just reponding to a stimulus that ‘should’ cause pain, so the fiber runs to a point in the CNS that elicits the ‘feeling’ of pain from that action potential.
How does receptor potential relate to action potential within the sensory neuron?
When the receptor potential rises above threshold, then an action potential occurs and propagates down the sensory neuron
How does the frequency of action potentials trasmitted from a sensory receptor relate to the action potentials in the seonsory neuron? What is the significance?
the frequency of action potential transmitted from a sensory receptor increases approximately in proportion to the increase in receptor potential.
-this allows receptors to have a response ranging from a very weak stimulus to a very stong stimulus
What are the two different kind of adaptation observed in receptors?
-Tonic (slow adapting) and Phasic (rapidly adapting)
How does adaptation occur in a mechanoreceptor like a paccinian corpuscle?
- the viscoelastic structure results in action potential whenever the receptor is deformed.
- once the motion or deformation is stabilized the action potentials stop and the receptor has therefore adapted
What are some exmples of tonic receptors?
- muscle spindles and golgi tendons
- slow adapters
What are examples of phasic receptors?
paccinian corpuscles
-rapidly adapting and only react when the stimulus strength changes
What is ther difference between type A and type C fibers?
Type A (MS, GTO, Vibration and discrimination) fibers are large and medium sized myelinated fibers which carry information very quickly while type C fibers are small and unmyelinated and carry information more slowly (pain and temp)
What is the dischargin zone?
all of the neurons stimulated by an incoming fiber
What is the discharging zones inhibitory counterpart?
-inhibitory zone
What is facilitation?
-large numbers of input terminals must discharge on the same neuron either simultaneously or in rapid succession to cause excitation.
Has to do with neuronal pools
What is the difference between convergence and divergence?
Convergence: multiple inputs unite to excite a single neuron
Divergence: excitation of great numbers of neurons leaving the pool (2 kinds)
–> amplifying divergence: number of neurons going to a specific place is amplified in the pool
–> divergence into multiple tracts: the signal is split into multiple directions and tracts (e.g. is dorsal columns taking info to the cerebellum and the thalamus)
What is the role of an inhibitory interneuron in a normally excitatory pathway?
-reciprocal inhibition circuits
