Chapter 15 Flashcards
used to describe sensitivity to:
-5 things
- temp
- pain
- pressure
- vibration
- proprioception
4 basic types of receptors
- nocicpetors
- thermoreceptors
- mechanoreceptors
- chemoreceptors
nocicpetors
- definition
- where are they found
- difficulty in what
- pain receptors
- everywhere
- hard to pin point exactly where stimulus is because there are large receptive fields
thermoreceptors
- definition
- where are free nerve ending found
- temperature receptors
- found in dermis, skeletal muscles, liver, and hypothalamus
mechanoreceptors
- when does stimulus occur
- 3 types
-occurs when plasma membrane is distorted
-1. tactile receptors
2, baroreceptors
3. proprioceptors
tactile receptors
- definition
- where are they found
- how sensitive?
- how large are receptive fields
- touch, pressure and vibration
- in skin
- very sensitive
- narrow
baroreceptors
- definition
- found where
- pressure changes
- blood vessels. lungs, digestive, reproduction and urinary tracts
proprioceptors
- definition
- tension in
- state of
position of joints
- tension in tendons and ligaments
- state of muscular contractions
chemoreceptors
- definition
- ex
detects changes in concentration of particular chemicals or compounds
-O2, pH
3 general considerations of sensory pathways
- decussation
- relay
- symmetry
decussation
most pathways cross over
relay
most pathways have 2 or more neurons relaying the signal
symmetry
all pathways are paired symmetrically
sensory pathway
-5 steps
- neuron in primary sensory area (post central gyrus)
- third order neuron (thalamus)
- second order neuron (interneuron in the spinal cord or brain)
- first order neuron
- detected by receptor
what happens in between the third order neuron and the second order neuron
it crosses from left to right
where is the first order neuron located
the cell body of this sensory neuron is in the dorsal root ganglion
posterior column pathway
carries sensations of highly localized touch, pressure, vibration, and proprioception
anterior spinothalamic pathway
carries sensations of poorly localized touch and pressure
lateral spinothalamic pathway
carries poorly localized sensation of pain and temp
what happens to the ____ in the posterior column pathway?
- 1st order neuron
- 2nd order neuron
- 3rd order neuron
- Ascends through posterior column and synapse in medulla
- ascends through medulla, crosses over and synapses thalamus
- travels to postcentral gyrus
what happens to the ____ in the anterior spinothalamic pathway?
- 1st order neuron
- 2nd order neuron
- 3rd order neuron
- synapses within the posterior gray horn
- crosses over and ascends through anterior column to synapse in thalamus
- travels to post central gyrus
what happens to ____ in the lateral spinothalamic pathway?
- 1st order neuron
- 2nd order neuron
- 3rd order neuron
- synapses within the posterior gray horn
- crosses over and ascends through lateral columns to synapse in thalamus
- travels to post central gyrus
2 types of pain
- somatic
2. visceral
somatic pain
pain associated with muscles and skin
visceral
- what is pain associated with
- highly or poorly localized?
- referred pain
- cause
- organs
- poorly localized
- may be felt in areas not commonly associated with that organ
- multiple sensory neurons converge on a single ascending tract
what does this mean:
-multiple sensory neurons converge on a single ascending tract
brain is unable to distinguish visceral signal from somatic signal
descending tracts
-2 types of neurons
- upper motor neuron
2. lower motor neuron
upper motor neuron
pyramidal cells of primary motor cortex
lower motor neuron
- definition
- what does it trigger
cell bodies are located in motor nucleus of brain stem or spinal cord
-muscle contraction
extrapyramidal system
additional centers in cerebrum, diencephalon and brain stem that issue somatic motor commands at subconscious level
