Central Nervous System pt 2 Flashcards
define neural pathways
series of neurons connected by synapses, that make a line of communication for a specific task
define a reflex
an automatic patterned response
define a reflex arc
neural pathways for reflexes
what is the process of a reflex arc
- stimulus triggering a sensory receptor
- information is sent to the CNS integrating centre through an afferent neuron
- information is sent to an effector organ by an efferent neuron to produce a response
what are the classes of reflexes
- spinal vs cranial
- somatic vs autonomic
- innate vs conditioned
- monosynaptic vs polysynaptic
describe a stretch reflex
- spinal
- innate
- somatic
- only known monosynaptic reflex in body
- EX hitting a hammer on a joint sends info from muscle spindle thru afferent neuron to brain; info goes thru efferent neuron to muscles
define a withdrawal reflex
automatic response to a painful stimulus
how can reflexes be overidden or inhibited
brain activates inhibitory neurons in spinal cord to suppress reflex
- post-synaptic potentials sum so if inhibitory influence from brain is greater than excitatory influence from nociceptor, then the withdrawal reflex is inhibited
describe pupillary light reflexes; what classes of reflexes does it include
- autonomic
- cranial
- innate
- polysynaptic
- reflex arc EX photoreceptors info goes thru afferent neurons to midbrain nuclei, info goes thru efferent neurons to pupils
what are the four components of voluntary motor action
- idea
- program
- execution
- feedback
in voluntary control, what parts of the CNS control the idea component
- limbic system
- association areas
- supplementary motor area
in voluntary control, what parts of the CNS control the program component
- supplementary motor area
- premotor area
- primary motor cortex
in voluntary control, what parts of the CNS control the execution component
- pyramidal tract
- extrapyramidal tract
- motor neuron
in voluntary control, what parts of the CNS control the feedback component
- sensory systems
- cerebellum
- thalamus
- basal nuclei
- brainstem
what is another name for pyramidal tracts (double check)
upper motor neurons
describe pyramidal tracts
- tract axons begin in primary motor cortex and terminate in ventral horn of spinal cord
- most cross to contralateral side in medullary pyramids
- also have collaterals that travel to other motor areas
what do pyramidal tracts control
fine control of voluntary movement of distal extremities (especially forearms, hands, fingers)
describe extrapyramidal tracts
- all motor pathways outside pyramidal tracts
- indirect input to motor neurons
- several pathways
what do extrapyramidal tracts support
voluntary movement of proximal extremities
what types of contributions and importance does the cerebellum have for the CNS
- critical to motor coordination
- provides feedback control of motor function
- contributes to muscle tone
- stores programs for remembered activities
describe the role of basal nuclei in motor control
- functions similar to cerebellum
- feedback control of voluntary movements
- select purposeful over unwanted movements
- damage leads to disease
describe Huntington’s chorea
- genetic disorder of basal nuclei
- pathway from basal nuclei to thalamus is lost
describe parkinson’s disease
- disease of basal nuclei
- lack of dopamine in substantia nigra (inhibitory area of midbrain)
what are the two language areas of the association cortex
- wernicke’s (comprehension) and broca’s (expression)
describe wernicke’s aphasia
- can speak but words don’t make sense
- difficulty understanding written and spoken language
describe broca’s aphasia
- cannot speak or write but can fully understand words
purpose of sleep
- body and brain rest
- enhances memory and learning
- immune system function support
sleep is a(n) ________ process
active
what is an EEG
electroencephalography; finds electrical activity of brain
what are the 2 types of sleep identified by EEGs
- slow-wave
- REM
describe slow-wave sleep in EEG
- multiple stages of low frequency waves
- muscle tone present but less compared to wake state
- occasional burst of involuntary activity occur every 10-20 min (spinal reflexes present)
describe REM sleep in EEGs
- high frequency waves and periodic bouts of rapid eye movement
- overall increase in brain activity occurs in comparison to slow wave sleep
what is the forebrain responsible for in sleep
induction of slow-wave sleep
describe ascending reticular activating system; what is it important for
- important in maintaining alert wakefulness
- part of reticular formation
- projections to thalamus, hypothalamus, forebrain
what are the sleep- and wake neurotransmitters
awake: acetylcholine, norepinephrine, dopamine
sleep: adenosine, acetylcholine
where is acetylcholine found in awake and sleep state
- ARAS
- mimicked by nicotine;
- REM sleep
- pons
where is norepinephrine and dopamine in awake state
- ARAS
- mimicked by amphetamines and cocaine
describe adenosine in sleep state
- SWS induced by forebrain
- blocked by caffeine
what types of EEG waves are made in alert awake state
beta; many neurons at different times
what types of EEG waves are made in resting awake state
alpha; more synchronization of electrical activity
describe stage 1 sleep in EEG
lightest sleep; lowest arousal threshold
describe stage 2 sleep in EEG
light sleep
describe stage 3 sleep in EEG
moderate sleep
describe stage 4 sleep in EEG
deep sleep (highest arousal threshold)
describe heart rate during the REM sleep stage; sleep stages 1-4
highest (similar to awake state);
decreases from stages 1-4
what are the types of non-associative learning
habituation and sensitization
what is memory
retention of information, skills, thoughts
what is learning; what part of brain is important
acquisition of new info; hippocampus
describe associative learning
making connection between two or more stimuli
whether you become habituated or sensitized to a stimulus depends on
circumstances; important = sensitized, unimportant = habituated
what are the memory processes
procedural (implicit) and declarative (explicit)
describe procedural memory; what part of the brain is involved
- learned motor skills and behaviours
- automatic response
- cerebellum involved
describe declarative memory; what part of the brain is used for this
- learned facts, events, experiences
- needs conscious effort for recall
- hippocampus
how can information be stored
short-term or long-term memories
describe short-term memory; what part of the brain is important for this
- lasts seconds to hours
- info lost unless consolidated
- frontal lobe is important
describe long-term memory; what parts of the brain are important
- lasts years to lifetime
- temporal lobe and hippocampus important
define plasticity
limited ability to alter anatomy and function in response to changes in activity patterns (EX long term potentiation)
define long-term potentiation
repetitive stimulation of a synapse that leads to increase in strength of synaptic connection (i.e. increases chance that AP will be triggered in postsynaptic cell)
what happens with synapses and neurons that allow for learning and memory to occur
- development of new synapses
- long-term modulation of existing synapses
- new neurons develop
describe the relationship of exercise and the brain
- may increase metabolic activity
- increased blood flow to brain
- improve mood disorders at any age
- improves cognitive function and slows dementia in alzheimer’s patients
what does plasticity do for potentials in the nervous system (double check)
- leads to increases in synaptic strength because EPSP generation size increases in post synaptic cell
- increase in sensitivity of PS cell due to increased amount and/or sensitivity to NT released at synapse
what are AMPA and NMDA to e/o
antagonists(?)
