nsci 2101 exam 3 flashcards from quizlet

where does CNS output go

somatomotor system (striated skeletal muscles) and autonomic motor system (heart, digestive tract, blood vessels etc.)

what are UMNs and where are they

upper motor neurons start in the cerebral cortex and target lower motor neurons

what are LMNs and where are they

lower motor neurons start in the brainstem for the cranial nerves or the spinal cord for spinal neurons and directly target muscles

do LMNs synapse directly on the muscle

yes

what is the neuromuscular junction

point of contact between a motor neuron and a skeletal muscle cell, acetylcholine release from the neuron causes muscle contraction

describe the structure of skeletal muscle

made of muscle fascicles which contain fibers. one fiber per one neuromuscular junction

what does botox do in a neuromuscular junction

it blocks acetylcholine release at the neuromuscular junction (so injection into muscles causes paralysis)

describe the start of muscle contraction

acetylcholine released from neuron activates receptors on the muscle fiber. this causes depolarizion so sodium enters the muscle fiber and potassium exits. this spreads along the fiber like an action potential and calcium is released inside the fiber. the calcium activates the muscle complex that contracts the muscle

what form the stripes in striated muscle

alternating bands of motor proteins actin and myosin

describe muscle contraction

using ATP, myosin slides across actin molecules which shortens the muscle fiber

describe the difference between type I and type II muscle fibers

type I have more mitochondria than type II. a given motor neuron only innervates one type of muscle fiber

size, speed, force, and fatigability of type I muscle fibers

thin, slow speed, low force, slow fatigue

size, speed, force, and fatigability of type IIa muscle fibers

thick, intermediate speed, intermediate force, intermediate fatigability

size, speed, force, and fatigability of type IIb muscle fibers

thick, fast, high force, rapid fatigue

what kind of muscle fiber goes with slow, sustained exercise?

type I: long and thin muscles that are fatigue resistant

what kind of muscle fiber goes with short, intense exercise?

type II: short, bulky muscles that fatigue quickly

what is a motor unit

A motor neuron and all of the muscle fibers it innervates

muscle groups with high dexterity have (small/large) motor units

small

muscle groups with low dexterity have (small/large) motor units

large

what are lower motor neurons controlled by?

local circuits (reflexes and interneurons in the spinal cord) and upper motor neurons

where do the upper motor neurons for voluntary muscle originate?

the cerebral cortex

where do the upper motor neurons for fine tuning originate?

vestibular nuclei, superior colliculus, red nucleus, reticular formation of the pons and medulla

where is the primary motor cortex

precentral gyrus of the frontal lobe. somatotopically organized.

what is the premotor cortex

the part of the brain relevant to the planning, selection and execution of actions

describe the corticobulbar tract

it controls head and neck muscles, goes to bilateral brainstem cranial nerve motor nuclei

describe the corticospinal tract

controls bodylimb movements. lateral goes to entire contralateral spinal cord. ventral/anterior goes to bilateral cervical and upper thoracic spinal cord. descend through the pyramids of the medulla

what tract contains lower motor neurons that target cranial nerve nuclei in brainstem

corticobulbar tract

what tract contains the descending route from motor and premotor cortices

corticospinal tract

does the lateral corticospinal tract cross the midline? if so, where

yes, lower medulla

does the anterior/ventral corticospinal tract cross the midline? if so, where?

no

what are the first four loci the corticospinal tract travels through on its way down

internal capsule, cerebral peduncle, pons, pyramids

where are the LMNs for limb muscles

the ventral horn of the spinal cord

where are the LMNs for trunk muscles

medial ventral horn of the spinal cord (targeted by the corticospinal tract)

what would damage to the right motor cortex hurt?

movement on the left side of the body

what is the rubrospinal tract

goes red nucleus to spinal cord, coordinates fine limb movements

what is the vestibulospinal tract

vestibular nucleus to spinal cord for balance and head position adjustments

what is the reticulospinal tract

reticular formation to spinal cord for postufal control and learned limb movements

what is the tectospinal tract

superior colliculus to the cervical spinal cord for coordinating hand and eye movements

What is amyotrophic lateral sclerosis?

Progressive, degenerative disease with loss of upper and lower motor neurons

what does primary lateral sclerosis affect

UMNs

what does progressive muscle atrophy affect

LMNs

describe paralytic polio

motor neurons are killed by poliovirus, causing muscle atrophy and paralysis

describe the relationships between sensory input, thalamus, cortex, basal ganglia and motor output

sensory>thalamus>cortex(>basal ganglia>thalamus)>motor output

whats the main input and output for the basal ganglia

input: cortex

output: thalamus

what are the parts of the basal ganglia

striatum (caudate nucleus, putamen, nucleus accumbens), globus pallidus, subthalamic nucleus, and substantia nigra

what are the functions of the basal ganglia

voluntary movements and action selection, skill learning, motivation and emotion, informs cortex via thalamus of appropriate actions and details of skilled actions

what divides the striatum

the internal capsule

tell me about dopamine neurons in the substantia nigra pars compacta

major dopamine center, dopamine neurons contain lots of neuromelanin so they are black/brown

describe corticospinal neurons and basal ganglia circuitry

corticospinal neurons project to striatum where they use glutamate to excite medium spiny neurons

what are the main outputs for the basal ganglia and what do they do

the globus pallidus internal and substantia nigra pars reticulata signal ventral interior and ventral lateral nuclei of the thalamus with GABA

what does the thalamus do with the basal ganglia input

integrates the signals and sends excitatory projections to the cortex

are the rat and human midbrains similar

ya

what can basal ganglia degeneration lead to?

hypo or hyperkinesia

what are some types of hypokinesia

akinesia: impaired initiation of movements

bradykinesia: slowed/reduced movement

rigidity: stiffness/resistance

what are some types of hyperkinesia

chorea: rapid/jerky movements

athetosis: slow writhing

ballism: flailing

gimme some facts on parkinson's disease

symptoms arise from degeneration of dopamine neurons in substantia nigra pars compacta. impaired movement, resting tremor, muscle agidity. presents in 1% of people over 60

what does L-Dopa do

its a dopamine precursor molecule that crosses the blood brain barrier and is converted to dopamine inside the brain

what does deep brain stimulation do

a stimulating electrodes are implanted usually into the GPi or subthalamic nucleus (for parkinsons) to restore movement sometimes

gimme some facts on Huntington's

degenerationof MSNs in striatum. caused by inheritance of a dominant mutation producing a mutant protein that kills MSNs. produces hyperkinesia (involuntary, random rapid movements)

gimme some facts on Tourettes

dysfunction in striatal and frontal cortical circuits causes uncontrollable movements and vocations (tics)

what is dystonia

uncontrollable sustained muscle rigidity and contractions

What is the tentorium cerebelli?

sits between occipital lobe and cerebellum and is dura mater

what are the general functions of the cerebellum

movement synergy, muscle tension and movement speed and fluidity

describe the anatomy of the cerebellum

anterior lobe and posterior lobe divided by the primary fissure. the flocculonodular lobe is like a little dangly thing off the anterior. midline cerebellum is the vermis, external surface is the cerebellar cortex. two hemispheres. have medial-lateral running folia

how does the cerebellum connect to the brainstem

the superior peduncle connects it to the midbrain, the middle peduncle connects to the pons, the inferior peduncle connects to the medulla

what are the two main locations that cerebellum neurons are located

cerebellar cortex surface layers and deep cerebellar nuclei (fastigial nuclei (medial), interposed nuclei, dentate nuclei (lateral, is longer))

What is the main output of the cerebellum?

deep cerebellar nuclei

what are the three layers of cerebellar cortex

molecular (axons, dendrites, and smaller neurons), purkinje (purkinje cell bodies), and granular (granular cell bodies)

what is the most numerous neuron type in the brain

granule cells

where do the axons of granule cells in the cerebellum go

the molecular layer of cerebellar cortex

is the granule layer dense

ya

describe a purkinje cell

huge fan shaped dendritic arbor, 2D, reaches into molecular layer, sends axons to deep cerebellar nuclei

compare and contrast directions of granule cell and purkinje cells

granule cells: axons to molecular layer, axons split and run in both directions parallel to the folia

purkinje cells: dendrites to molecular layer and fan out in single plane perpendicular to the direction of the folia

what are the two inputs of the cerebellum

climbing fibers (from medulla, contact purkinje fibers)

mossy fibers (from many places, contact granule cells)

describe climbing fibers

come from inferior olivary nucleus of the medulla and wrap around one purkinje cell's dendrites like a vine

what are the three cerebellar functional domains

cerebrocerebellum, spinocerebellum, and vestibulocerebellum

what are the main inputs of the spinocerebellum

spinocerebellar tracts and cranial nerves carrying proprioceptive info

what does the spinocerebellum do

sends info on position and tension of muscles in the body

spinocerebellum output?

interposed nuclui>red nucleus>spinal cord and cranial nerve nuclei

cerebrocerebellum main input?

from cerebral cortex via the pontine nuclei (pontine nuclei send axons to contralateral cerebellum via the middle cerebellar peduncle

cerebrocerebellum output?

to dentate nucleus then ventrolateral nucleus of the thalamus then to the cerebral cortex

function of the cerebrocerebellum

coordinating movement planning, learned movement, and cognition

vestibulocerebellum input?

from vestibular nuclei and vestibulocochlear nerve

vestibulocerebellum output?

fastigial nucleus and vestibular nucleus to spinal cord and cranial nerves

vestibulocerebellum function?

maintain balance and coordinate eye movements

common effects of cerebellar pathology

ataxia (inaccuracy in speed and force movements, inaccurate estimates of distances)

tremor, nystagmus (involuntary movements of the eyes), stroke and neurodegenerative diseases can affect the cerebellum

what does alcohol do to the cerebellum

it inhibits its activity which leads to motor and coordination impairment

what are the three components of the autonomic nervous system

parasympathetic nerv sys, sympathetic nerv sys, enteric nerv sys

describe the neurons and ganglia in the parasympathetic and sympathetic nervous systems

pre ganglionic neurons CNS neurons synapse in ganglia outside the CNS then project their post ganglionic axons to targets that are not skeletal muscle (glands, smooth muscle, cardiac muscle, etc)

what is the enteric nervous system good for

it is intrinsic to the gut and does gut secretion and motility

what does the cns originate from

the neural tube

what does the pns originate from

the neural crest or placodes