Module 3: The Peripheral Nervous System Flashcards
Identify key aspects to afferent neurons
- Small, round cell body
- Single long dendrite
- Short axons
Afferent nerve cell bodies are found in clusters called ___, found external to the spine
Ganglia
What is the primary purpose of the afferent division of the nervous system?
To carry nerve impulses from the peripheral receptors and special sense organs to the CNS
What is transduction?
The conversion of an environmental signal to an electrical signal
What do mechanoreceptors respond to?
Mechanical energy. Respond to vibration, acceleration, movement
Can neurons change the amplitude of an action potential? (T/F)
False! They cannot change amplitude of an action potential
How do neurons convey the strength of a stimulus?
They can code the intensity of a stimulus by firing a high frequency of action potentials
If a neuron conveys a high frequency of action potentials, will this illicit a strong or weak response?
Strong. High frequency of action potentials = stronger response
How does the brain identify the site of sensory stimulation?
It uses the location of the afferent nerves where the stimulation was picked up from
What is a receptive field?
A region of the environment where the neuron is sensitive to
How does the brain identify the location of a smell?
It uses gradients
What is receptor potential vs generator potential
The stimulation of a receptor that alters the membrane of the neuron to open nonselective cation channels. This is called receptor potential in specialized receptor cells and generator potential in the ending of an afferent neuron
What are the 4 properties that allow the CNS to differentiate between incoming signals
- Modality (receptor type, chemo/photo,etc)
- Intensity
- Location
- Duration
Describe tonic receptors
- Slow adapting or do not adapt at all
- Important in situations where a near constant signal from a stimulus is necessary
Describe phasic receptors
- Rapidly adapting
- The receptor will even stop rapidly generating action potentials even with the stimulus present
- Important for monitoring changes in stimulus intensity
What is an “off response”. What receptor is involved?
The depolarization of an action potential in a phasic receptor when a stimulus has been removed
What do mechanical nociceptors respond to?
Physical damage (cutting, crushing)
What do thermal nociceptors respond to?
Temperature, especially heat
What do chemical nociceptors respond to?
Noxious chemicals both external and internal to the body
Describe fast pain fibres
- Are a-delta fibres
- Perceived associated with these fibres are acute, sharp, and stabbing pain
Describe slow pain fibres
- are C-fibres
- Unmyelinated
- Perceived sensation associated is burning, aching and throbbing
How does glutamate and substance P aid in the sensation of pain?
- Is released from afferent pain fibre axons and is postsynaptic glutamate receptors on neurons on dorsal horn of spinal cord. Transmits the signal to higher levels for further processing
How are the hypothalamus and limbic system involved in the perception of pain?
- Allows for behavioural and emotional responses to the pain
How is the cortex involved in the perception of pain?
- Cortical somatosensory cortex processing localized pain to an area of the body where the stimulus has affected