Neuro 9 Flashcards
True or false: both the posterior and anterior pituitary are neural tissue
No 1 just the posterior
What are considered special senses?
Vision, hearing, taste, smell, equilibrium
What are the somatic senses?
Touch, temperature, pain, itch
What’s visceral stimuli
Blood pressure , blood glucose concentration, internal stuff
What is the purpose of the sensory system?
Provide us with information about our external environments
What is the ending of a somatic sensory neuron? (Simple neuron)
Bare endings
What’s a complex neurons receptor? What do they sense?
Nerve endings enclosed in connective tissue capsules
They sense touch
What’s special about special senses?
They have a non neuronal cell that contains receptors
What are chemoreceptors activated by?
Chemicals
What are mechanoreceptors activated by
Mechanical stimulus
What are photoreceptors activated by?
Light
What are thermoreceptors activated by?
Temperature
What are physical stimuli transduced into?
Receptor potentials (basically graded potentials)
What do mechanically gated channels do?
Convert mechanical stimulus into electrical signal
What does a primary sensory neuron do?
Recieves stimulus
What does a tertiary neuron do?
Carries info to region of cerebral cortex
What’s the neuron steps to get information from the Skin to the cerebral cortex
Primary sensory neuron
Secondary sensory neuron
Tertiary neuron
What stimuli always cross the midline at the medulla?
Fine touch, vibration, proprioception pathways
What is an inhibitory neuron?
A primary sensory neuron that gets activated but doesn’t become a perceived stimulus
What are receptive fields?
A physical area that a sensory neuron can respond with
What is convergence?
Convergence creates large receptive fields
Overlapping of neuron receptors
What happens with a large receptive field?
There is no two point discrimination because there is a convergence of primary neurons that sum to one secondary sensory neuron
What are two stimuli that fall within the same secondary receptive field perceived as?
A single point → because only 1 signal goes to the brain
Where are small receptive fields found?
More sensitive areas such as finger tips
When fewer neurons converge, what happens?
Secondary sensory neurons are much smaller and there is 2 point discrimination
Where is visceral sensory incorporated
Into the brainstem and spinal cord
Where is special and sensory information routed through?
Thalamus
what does the thalamus do with information
relays it to cortical centres
where do equilibrium pathways primarily project?
cerebellum
which senses have dedicated cortical regions
special senses
which senses are integrated into the primary somatosensory cortex?
somatic senses
which sense does NOT go through the thalamus
smell - it goes through the olfactory bulb to the olfactory cortex
what are the 4 properties that the CNS uses to distinguish a stimulus
modality
location
intensity
duration
what does modality describe
the physical stimuli being sensed and determined by the sensory receptor being activated (temp vs touch receptors and where the pathways terminate in the brain)
what does the amount of space dedicated to each body part on the somatosensory cortex mean?
the amount of space for the body part is proportional to the sensitivity of that part (think of the weird guy with huge hands)
how is the location of the stimulus determined?
they are coded according to which receptive fields are being activated
what is a receptor potential?
a) an action potential
b) a graded potential
c) the resting membrane potential of a receptor cell
a graded potential
what does lateral inhibition help with?
helping the brain very accurately pinpoint where a stimulus is coming from
what is lateral inhibition?
when the pathway that is the closest to the stimulus inhibits the neighbouring neuron’s/pathways (inhibition of lateral neurons)
does an action potential ever die off
it is always regenerated
what is intensity of a stimulus determined by ?
the numbers of receptors being activated
and the frequency of action potentials coming from those receptors
(population coding and frequency coding)
what is population coding? and what does it play a part in determining?
it is overall number of receptors that is being activated (so the overall number that is providing input)
it helps with determining the intensity of a stimulus
what is frequency coding? and what does it play a part in determining?
it is the frequency of an action potential firing
it helps with determining the intensity of a stimulus
what is the duration of a stimulus determined by
it is determined by how long action potentials are being activated
what is the frequency of an action potential proportional to?
stimulus intensity
what makes neurotransmitter release vary?
the pattern of action potentials arriving at the axon terminal
what type of receptors does duration depend on? (2)
tonic receptors
phasic receptors
what are tonic receptors
they are slowly adapting receptors that respond for the duration of the stimulus
what are phasic receptors
they are receptors that rapidly adapt to a constant stimulus and turn off once stimulus is constant
they require a stimulus change to activate again
True or false: each receptor is most sensitive to a particular type of stimulus
True
How can the brain tell the origin of each incoming signal?
Each sensory pathway projects to a specific region Of the cerebral cortex dedicated to a particular receptive field.
What is the autonomic nervous system?
Involuntary control of smooth muscle, cardiac muscle and many glands
What are the subdivisions of the autonomic nervous system?
Sympathetic and parasympathetic
What activity does parasympathetic activity dominate?
Rest and digest
What activity does sympathetic activity dominate?
Fight or flight
What are atomic responses important for?
Homeostasis
What is an example of an autonomic response?
Embarrassed or becoming flushed
Is there a definite cellular response for parasympathetic and sympathetic activity?
No
What initiates autonomic and behavioural responses?
Hypothalamus, pons, and medulla
What is a ganglion!
Group of cel’s that exist outside of the CNS
How many neurons do autonomic pathways consist al?
Two that synapse in an atomic ganglion
Is it possible for 1 preganglionic neuron to synapse with 8 or 9 postganglionic neurons? Or is it 1:1
Yes that is possible in autonomic pathways
Where does the preganglionic neuron start and extend to in the autonomic system?
Starts in the spinal cord or brainstem to ganglion
Where does the postganglionic neuron start und end in the autonomic system?
Extends from ganglion out to the target tissue
How does sympathetic and parasympathetic pathways differ (2)
By point of origin in the CNS
Location of ganglia
Where are sympathetic ganglia found?
Mainly found in two ganglion chains running alongside the vertebral column
Where do preganglionic neurons originate for the sympathetic pathway
Thoracic and lumbar regions
What’s the length of pre and post ganglionic neurons for the sympathetic pathway
Short preganglionic, long post ganglion
Where is ganglia located in the parasympathetic system?
Ganglia us located on or near their target organs
Where do preganglonic neurons originate in the parasympathetic system?
The brain stem or the sacral region of the spinal cord
What’s the length of the pre and post ganglionic neurons in the parasympathetic region
Long preganglionic, short postganglionic
What contains 75% of all parasympathetic neurons?
Cranial nerve x (vagus)
