Ch.2, Nervous System Cont. Flashcards
Why does info enter the posterior root of the dermatome?
Bc posterior root is sensation; it is afferent and transmits to spinal cord
Posterior root ganglion
The spinal ganglion contains the cell bodies of sensory neurons situated in the posterior root of each spinal nerve (except for spinal nerve C1). These neurons are known as first-order neurons of the somatosensory system and carry sensations related to touch, vibration, proprioception, pain and temperature.
Matter organization in dermatomes
White matter outside; grey matter inside = opposite of the cerebrum
Difference between white matter and grey matter; difference in function
Grey matter consists of neuronal l cell bodies and their dendrites. The dendrites are short protrusions (like little fingers) that communicate with neurons close by. In contrast, your white matter consists of the long axons of neurons that transmit impulses to more distant regions of your brain and spinal cord.
GREY MATTER FUNCTIONS: Because grey matter has a large number of neuronal bodies (which contain the nucleus of the cell), this is where information processing happens. The grey matter is the seat of a human’s unique ability to think and reason. The grey matter is the place 1 J where the processing of sensation, perception, voluntary movement, learning, speech and cognition takes place.
WHITE MATTER FUNCTION: White matter’s role is to provide communication between different grey matter areas and between grey matter and the rest of your body.
How does info leave the dermatome?
Through anterior root (efferent)
What does the law of Bell aMnd Magendie not apply to?
does not apply to Vision or hearing
Propriosensation
awareness of where body is in space I the
What does somatosensation not include?
Not vision, olfaction, taste or auditory
PNS vs. ANS with breathing and urination
ANS: relaxes airway to get more air in
PNS: constricts airway bc we don’t need as much air
ANS: contracts base of bladder to restrict urination
PNS: stimulates bladder for urination
What are reflexes?
Don’t involve brain only spinal cord, more simple circuits l
What does it mean to say that neuronal circuits are the functional units of the nervous system
Functions of the nervous system are carried out by series of neurons connected to one another: neurons don’t work in isolation
Sensory and motor divisons pervade the nervous system means
Posterior is typically always sensory, anterior is always motor
Anterior/ventral (spinal cord): efferent
Posterior/dorsal root=afferent
Why can we use anterior/ventral and posterior/dorsal as interchangeable in the spinal cord but not brain?
Because spinal cord depends on whether you’re talking about a biped or quadruped (anterior side of the spinal cord would be ventral in dogs)
Neocortex, motor input vs output /
Layer IV: receives sensory inputs
Layers V and VI send motor outputs
Additions to the CNS; adaptations over time
= some simpler animals only have spinal cords, but over time as animals become more complex = brainstems and forebrains were added. noire complex = more structures
Brain systems are organized hierarchy and parallel
multiple hierarchal organized circuits acting in parallel allow the performance of simultaneous behaviors
(Primary – secondary – tertiary)
What is the exception to crossed brain circuits?
Olfactory, AND EVERYTHING IN THE AUTONOMIC, SOMATIC, AND ENTERIC NERVOUS SYSTEM: PNS IS NEVER CROSSED
What does it mean to say that some brain functions are localized and distributed?
Some brain functions are localized to one specific region: fear is localized to the amygdala
How is memory parsed apart and processed in parallel in different regions?
Memory: different memories are processed differently but episodic memory tends to be localized in the hippocampus
What does lateralized mean?
Language is usually lateralized to one side; spatial functions are usually lateralized to the right: not every function is bilateral
What is the difference between excitation and inhibition?
The brain uses excitation to produce some action and inhibition to prevent others
What does the spontaneous rate of activity of neurons mean?
Baseline rate of activity without any excitation or inhibition
Why does brain injury typically result in either a loss or release of behavior? Example of Parkinsons
Because the excitation and inhibition balance has been messed up: Parkinson’s can either cause rigidity of muscles (a lack of excitation to get them moving fluidly) or tremors (not enough inhibition to stop muscle shakes)
How are object recognition pathways and motor control pathways distinct?
V1 (primary visual cortex) has the ventral stream and dorsal stream
Ventral: CONSCIOUS, controls the what pathway, object recognition DAMAGE = usually damage to the temporal lobes, they cannot recognize what should be familiar objects, in rare cases they can’t even see it
Dorsal: UNCONSCIOUS, where pathway, how to interact with objects, vision for action DAMAGE = can’t reach for objects
Explain how a right hand touch would transmit somatosensation to the spinal cord.
right hand would transmit to right spine, somatic is not crossed
Dermatome
structures that are posterior = almost always sensory
structure that are anterior= almost always motor
What does numbness vs inability to move mean when considering spinal cord damage?
For instance, if a person has numbness in the fingers of the left hand but can still move the hand fairly normally, one or more of the posterior (dorsal) nerves in spinal cord segments C7 and C8 must be damaged. In contrast, if sensation in the hand is normal but the person cannot move the fingers, the anterior (ventral) roots of the same segments must be damaged. Clinical Focus 2-4, Bell Palsy, further explores the loss of motor function.
- Two sets of SNS nerves, the and the , receive sensory information or send motor signals to muscles, or both.
sensory and motor nerves
SNS nerves on the left side of the spinal cord control ——function on the side of the body.
SUBCORTICAL REGIONS
Subcortical regions make intimate reciprocal connections with cortical areas that process sensory, perceptual, cognitive, and motor functions. When the cortical areas perceive a threat, such as an angry dog, they communicate with subcortical regions that have already begun to increase breathing and heart rate via the sympathetic nervous system. This relation between the cortical and subcortical areas illuminates another principle of CNS organization: redundant and overlapping functions exist at many levels of the nervous system.
How does the wrist analogy explain the situation of the midbrain, hindbrain, and diencephalon?
fist: diecephalon
wrist: midbrain
Forearm: hindbrain; longest/thickest part
3 main functions of the basal ganglia
1: movement fluidity
2: connecting sensory regions to motor regions
3: associative learning which is needed for motor learning
How does the ANS interact with the CNS AND SNS?
through ganglia, act as mini brains to control the organs
Difference between polysynaptic and monosynaptic circuits
poly: means there is at least one interneuron between a sensory neuron and a motor neuron (WITHDRAWING HAND FROM HOT OBJECT)
mono: means there is not an interneuron here (THE CIRCUIT RESPONDS FASTER) INCLUDES THINGS LIKE THE PATELLAR REFLEDX
