Lec 17 Flashcards
What are the three levels of processing sensory information?
- The receptor level
- The circuit level
- The perceptual level
What are the 4 criteria to create a signal at the receptor level?
- The stimulus energy must match the receptor specificity
- The stimulus must be applied within the receptive field
- Transduction needs to occur
- Graded potentials need to reach the threshold
What is the difference between a generator potential and a receptor potential?
The receptor potential is found in special senses and has a separate cell that releases a chemical messenger to the neuron fiber, and generator potentials for free or encapsulated dendrites are all one cell.
What is adaptation of reception?
It is the reduction in sensitivity to a constant stimulus that is not painful.
What are the two types of reception adaptation?
- Peripheral adaptation happens at the level of the receptor and reduces the amount of information sent to the CNS
- Central adaptation happens at the level of the neural pathway and involves brain nuclei
What are the two types of receptors that differ in adaptation? Give some examples of each.
Phasic receptors are fast acting eg. lamellar and tactile corpuscles and gives information on rate of change, and Tonic receptors are sustained responses with little to no adaptation eg. nociceptors and proprioceptors.
What happens in first order neurons?
Information is sent to the CNS, and branches, some of it goes to second order neurons and some may lead to motor reflexes
Where do second order neurons lead?
The brain (thalamus/cerebellum)
What do third order neurons do?
They take info from the thalamus and send it to the appropriate brain area.
What are the three main pathways for information to ascend the spinal cord?
- Dorsal column-medial lemniscal pathways
- Spinothalamic pathways
- Spinocerebellar pathways
What kind of information is sent up the dorsal column-medial lemniscal pathways?
Mostly single type of receptor specific information such as discriminative touch, proprioception, or vibrations
What kind of information is sent up the spinothalamic pathways?
Less precise things such as pain, temperature, coarse touch and pressure.
What kind of information is sent up the spinocerebellar pathways?
information about muscle/tendon stretch
Where do the different ascending pathways dessicate?
The dorsal column-medial lemniscal pathways desiccate at the medulla, the spinothalamic pathways desiccate in the spinal cord, and the spinocerebellar pathways do not desiccate.
What is the difference between sensation and perception?
Sensation is the noticing in changes in the environment, and perception is the interpretation of that information. Perception drives response.
What are the six properties of sensory perception, and what do they mean?
- Perceptual detection is the awareness of an input or sum of inputs.
- Magnitude estimation is the determination of the intensity of the stimulus based on action potential rate
- Spatial discrimination is the localization of the stimulus
- Feature abstraction is the coming together of multiple features to come together for the sensory experience.
- Quality discrimination is the ability to distinguish sub modalities of a sensation like taste.
- Pattern recognition is the recognition of familiar things.
What chemicals can cause pain or the transmission of pain?
histamine, K, ATP, acids, bradykinin
What is sharp pain?
Pain carried by the smallest of myelinated sensory fibers, A delta fibers
What is burning pain?
It is carried more slowly by non myelinated fibers called C fibers and are indicative of an inflammatory reaction.
What are the pain neurotransmitters? What tract does pain take up the spinal cord?
Neurotransmitters are glutamate and substance P. Pain takes the spinothalamic tract up the 2nd order neuron.
What are the endogenous opioids (painkillers)?
Endorphins and enkephalins
What part of the midbrain is involved in pain supression?
The periaqueductal grey matter
What is the difference between pain threshold and pain tolerance?
The same amount of stimulus is needed to generate the sensation of pain (threshold), but the ability to withstand high levels of pain varies on a lot of factors (tolerance)
What is somatic/musculoskeletal pain?
It is aching/throbbing/cramping that is associated with innervated bones and muscles.
What is visceral pain?
Pain associated with the organs of the thorax or abdomen, it can be aching or burning and is associated with problems such as muscle spasms or irritating chemicals.
What is referred pain?
Pain from one area of the body that comes from somewhere else.`
What is hyperalgesia?
Pain amplification