Structures of Nervous System Flashcards
neural pathways
series of neurons that send signals to each other and process info
- enable signals to be sent to diff parts of nervous system
- linked by axons
convergent pathway
has two inputs
can help integrate diff kinds of input to crease one image
divergent pathway
has output to two cells
can help send same signal to cause different outcomes
what does the multisynaptic pathway converging on hippocampus enable it to create?
hippocampus can integrate diff info
-> converge to crease memory with smell, vision, and hearing
white matter
areas in CNS that are largely comprised of myelinated axons
afferent vs efferent
afferent: toward the nervous system
efferent: away from the nervous system
features of neural pathways
- synaptic relays
- pathways process info in parallel
- brain has organizational structure that reflects environment (topographically organized)
PNS: Somatic Nervous system
- the 12 cranial nerves
- coordinate muscle and sense receptors of head and neck
- is the brain’s direct communication with body (doesnt have to send signals through spinal cord)
- some are sensory, motor, or both
PNS: Somatic Nervous system
- the spinal nerves
31 pairs carry sensory/motor signals to/from CNS via spinal cord
- are in topographic organization (map onto the certain parts of the body)
- are top down, so if you injure spine near the neck the signal wont go further down meaning paralyzed from neck down
each spinal nerve is the fusion of two distinct branches:
- dorsal root
- ventral root
dorsal root (in spinal cord)
- is an afferent nerve
- carry sensory information from body to spinal cord
ventral root (in spinal cord)
- is an efferent nerve
- carry motor info from spinal cord to muscles
why can paralyzed people blink
cranial nerves (#7) control blinking. this means the signaling is direct and does not have to go through the spinal cord
regeneration of nerves in PNS after injury
axonal regrowth occurs at a rate of 1 cm/week in humans
regeneration of nerves in CNS
regeneration inhibitor molecules limit axon growth
- astrocytes put up physical barriers for regrowth (contain inhibitory molecules)
- macrophages do not clear cellular debris
(regeneration) CNS cells in PNS
axons from neurons in the spinal cord and regenerate within PNS grafts
PNS: autonomic nervous system
- supported by autonomic ganglia (clusters of cells in pns)
- supply major organs with nerves
preganglionic fibers -> ganglia -> postganglionic fibers -> organs
sympathetic nervous system
- activation prepares the body for fight/flight response
- neurotransmitter is norepinephrine
- ex: increased heart rate and breathing, lower digestion, pupils dilated to gather more info
parasympathetic nervous system
activation is often in opposition to sympathetic activity (rest and digest)
- neurotransmitter is acetylcholine
- ex: decreased heart rate and breathing, higher digestion, pupils less dilated
CNS axial organization
dorsal: superior
ventral: inferior
rostro: anterior
caudal: posterior
medial: middle (towards/into brain)
lateral: side (away from brain)
three views of the brain (types of cuts)
horizontal: through the face horizontally
sagittal: splits two halves of brain
coronal: slices from top down
what info does a horizontal cut provide?
helps visualize symmetry
what info does a saggital cut provide?
helps see projection from spinal cord to brain
what info does a coronal cut provide?
helps see important sections of the brain
ex: The corpus callosum. The lobes of the brain.
the cns develops from the
neural tube
three subdivisions of the brain
forebrain, midbrain, hindbrain
forebrain develops into
- telencephalon [ cerebral hemispheres (cortex, basil ganglia, limbic system) ]
- diencephalon (thalamus and hypothalamus)
midbrain develops into
mesencephalon
hindbrain develops into
- metencephalon (cerebellum and pons)
- myelencephalon (medulla)
medulla
transitions signals from the spinal cord to higher parts of the brain and in controlling autonomic activities, such as heartbeat and respiration
- contains cranial nerve nuclei for head/neck
- nuclei that regulate breathing, heart rate, sleep
damage is fatal
a big medulla plays a large role in
physical moves
pons
- communicates with cerebellum (motor control)
- contains motor control and sensory nuclei
- relaxes muscles during REM
cerebellum
- involved in motor coordination and learning
Granule cells
are the smallest and most numerous type of neurons in the brain
Parallel fibers
are the axonal extensions of granule cells, with each fiber making single synapses on hundreds of thousands of Purkinje cells
Purkinje fibers
play a major role in electrical conduction and propagation of impulse to the ventricular muscle
superior colliculi (tectum)
- midbrain sensory and motor systems
- visual reflexes and eye movements
a paired structure in the rostral midbrain that is involved in incorporating environmental stimuli and coordinating gaze shifts involving both eye and head movements
- eyes move to different areas of visual field to create a 3D image
inferior colliculi
- midbrain sensory and motor systems
- auditory signals; sound localization, frequency
involve sound localization, frequency determination, and integration of auditory with nonauditory systems.
substantia nigra
neurons release dopamine
is a basal ganglia structure located in the midbrain that plays an important role in reward and movement.
critical brain region for the production of dopamine
reticular formation
play crucial role in regulating sleep, arousal, consciousness, and motor control
thalamus
cluster of nuclei that relay sensory/motor info
- sits on top of brainstem
hypothalamus
nuclei produce hormones to coordinate the autonomic nervous system and the activity of the pituitary
- control vital functions such as sleep, body temp, thirst, hunger, growth, sleep, sex
gray matter
- cell bodies and dendrites decide whether to send signals
- do computations
gyri
sulci
Outside bump
Valley
what are the four lobes
frontal: controls cognitive tasks and voluntary movement
parietal: enables body sensation somatosensory cortex
occipital: visual reception and interpretation
temporal: handles memory, hearing, and language
Brodmann’s Area
divided cortex into 52 areas
basal ganglia
are important in motor control
- direct intentional movements
limbic system
important for learning, memory, cognitive functions, emotional regulation, sense of smell
functions to facilitate memory storage and retrieval, establish emotional states, and link the conscious, intellectual functions of the cerebral cortex with the unconscious, autonomic functions of the brain stem
lowkey shaped like an earlobe in the middle of the brain
ventricular system
series of chambers with cerebral spinal fluid that provides support
- built like ram horns
cerebral spinal fluid
- acts as a shock absorber
- provides an exchange medium between blood (transfer macromolecules)
- clear waste (metabolic biproducts)
- does that washing out stuff at night
blood-brain barrier
large molecules are blocked but some pathogens such as syphilis could still pass through.
