Neurophysiology Flashcards
What is the structura overview of the Nervous system?
What are the ascending and descending tracts?
What is the motor system compromised of?
Explain the motor control system
What is the hierarch of motor control within the CNS?
determine the goal of movements in the CNS
Association cortex and the basal ganglia
determine the correct sequence of commands that will allow the goal to be achieved in the CNS
primary motor cortex and cerebellum
implement descending commands in the CNS
Neuronal circuits in the spinal cord
What are the three inputs to alpha motor neurons that determine which muscle will contract?
- upper motor neuron
- spinal interneurons
- sensory neurons
input from the cortex or brainstem regulate voluntary movements
upper motor neurons
interneuron form an extensive circuitry within the spinal cord. Basic motor programs are encoded in spinal circuits known as central generators
spinal interneurons
neurons from muscle proprioceptors provide feedback about muscle length and tension
sensory neurons
a motor neuron annd all the muscle fibers it innervates
motor unit
What is the size principle and how does it relate to motor units?
includes conscious sensation derived from receptors in the skin and joint capsules
proprioception
Unconscious sensation and muscle length tension is relayed from?
muscle spindles and golgi tendon organs
provide information to the CNS about muscle stretch (length) and the speed with which muscle length is changing
muscle spindles
What do muscle spindles consist of?
large myelinated axons and have very fast conduction
sensory fibers
provide the motor supply to contractile filaments within muscle spindles
gamma motor neurons
Where are the cell bodies of gamma motor neurons located?
ventral gray matter of the spinal cord
Explain th myotatic reflex arch
What causes areflexia?
a lesion in any part of the myotatic reflex circuit
What are the deep tendon reflexes?
brachioradialis, biceps, triceps, knee, and ankle
Explain the myotatic reflex circuitry
sensory nerve terminals that are encapsulated within tendons
golgi tendon organs
arranged in series with extrafusal muscle fibers, with one end attached to the extrafusal muscle fibers and the other end attached to the collagen fibers of the tendon
golgi tendon organs
Sensory axons from GTOs are smalled that type ___ and are designated type _
type la
type lb
Explain the golgi tendon reflex
Explain the flexor and crossed extension reflexes
What are the two major groups of descending pathways?
- lateral pathways
- ventromedial pathways
concerned with voluntary movement of the distal muscles (muscles of the arm and hand)
lateral pathways
What are the two major lateral pathways?
Where does the corticospina tract originate?
primary motor cortex
Where does the rubrospinal tract orginates?
brainstem(midbrain region)
originates in the brainstem and innervates the proximal and axial muscles to help maintain head position and posture
ventromedial pathways
What are the three ventro medial pathways?
For the lateral corticospinal tract what is the function and location?
Location: medulla
Function: fine control of limbs
For the anterior corticospinal tract what is the function and location?
Function: fine control of limbs
Location: spinal cord
For the lateral vestibulospinal tract what is the function and location?
Location: None
Function: Balance and posture
For the medial vestibulospinal tract what is the function and location?
Location: medulla
Function: control of head position
For the rubrospinal tract what is the function and location?
Location: medulla
Function: upper limb movement
In the pyramidal pathways the motor cortex in each hemisphere controls the muscle on the _
contralateral side of the body
In the pyramidal pathways the fibers descend through the internal capsule and upper brainstem to the _, where the tract cross the _
medullary pyramids
midline (dessucate
in the spinal cord the lesion above the medullary pyramids will result in?
contralateral muscle weakness
In the spinal cord the lesions below the pyramidal decussation will produce a _
ipsilatearl muscle weakness
Where does the rubrinospinal tract originate?
the red nucleus of the midbrain, which in turn recieves input from the motor cortical areas
When are rubrospinal tracts active?
in mediating flexion, which can help to diagnose the site of neurologic injury in comatose patients
characterized by excessive flexion of the elbows and wrists and supination of the arms
decorticate posturing
Where is the damage in decorticate posturing?
anterior to the red nucleus of the midbrain. an intact red nucleus allows the upper extermities to undergo flexion via the rubrospinal neurons
characterized by excessive extension of the elbows and wrists with pronation
decerebrate posturing
Where does decerebrate posturing occur?
indicates midbrain lesion that involves the level of the red nucleus
provides sensory information from the visual and vestibular systems about the body position and balance
ventromedial pathways
Where does the vestibulospinal tract originate and function?
Where does the tectospinal tract originate and function?
Where does the reticulospinal tract originate and function?
distal muscles of the limbs are represented most _
laterally
axial muscles of the trunk are represented _
medially
motor neurons for the proximal limb muscles are located in an _
intermediate position
Upper motor neuron lesions are characterized by ?
spastic paresis (incomplete paralysis), hyperreflexia, hypertonia
Lower motor neuron lesions are characterized by ?
flaccid paralysis, areflexia, hypotonia, muscle twitches, atrophy, no reflex arch
What is an example of pure lower motor neuron lesion?
Poliomyelitis
What is an example of upper and lower motor neuron lesions?
amyotrophic lateral sclerosis
What are the following areas?
What areas of the body have the most gray matter/motor function?
lips/ fingers
movements we decide to make volitionally
somatosensory association area
encoding movement intention and the selection of the movements based on environmental sensory inputs
premotor cortex
What supplies the majority of the lateral surface of the cortex, including the section of primary motor conrtex, including the primary motor cortex and is responsible for movements of the face and upper externities?
middle cerebral artery
an occlusion of the middle cerebral artery will cause?
contralateral spactic paresis of the face and upper extremities
What artery supplies the area responsible for the lower extremities?
anterior cerebral artery
occlusion of the anterior cerebral artery will cause?
spastic paresis of the lower extremities
a group of subcortical nuclei located primarily in the base of the forebrain
the basal ganglia
What are the components of the basal ganglia?
the striatum (divided into the caudate nucleus and putamen), globus pallidus, subthalamic nucleus
What is the function of the basal ganglia?
modulation of cortical output
is degenerationof the dopaminergic neurons that project from the substantia nigra to the striatum
parkinsons disease
a fatal autosomal dominat disorder affecting the huntingtin gene. severe idopathic degeneration of gabaergic neurons affecting the indirect pathway of the basal ganglia
huntingtons disease
Where is the gray matter and white matter located?
white matter is deeper and gray matter is superficial, but the basal ganglia is gray matter that is deep
What are the functional cerebellar subdivisons?
cerebellar lesions produce a characteristic movement disorder called?
ataxia
in which movements become inaccurate and are poorly coordinated; there is also decreased muslce tone is called?
hypotonia
What is the function of the thalamus?
What is the function of the hpothalamus?
body temperature regulation
What is the function of the cerebellum?
What is the function of the brainstem?
Different areas of the hypothalamus have different ___
functions
Circadial rhythms are generated by?
endogenous body clock
body clocks are created by neurons of the?
suprachiasmatic nuscleus, the activity of which oscillates spontaneously in a daily cycle
proved information about daylight to entrain the circadian rhythm
retinohypothalamic tract
What does the pineal gland secrete?
the hormone mealtonin in the hours of darkness, which helps to synchronize the day/night and sleep cycles
monitors the surface electrical activity of the brain waves and produces wave patterns
EEG
Why are EEGs useful?
Explain the sleep stages and brain activity
What are the four major diffuse modulatory systems?
-noradrenergic system
-serotonergic system
-dopaminergic neurons
-cholinergic neurons
Neurons in the reticular formation have what type of connectivity throughout the CNS?
widespread connectivity
the anatomic concept that describes columns of neurons that extend throughout the core of the brainstem
reticular formation and diffuse modulatory systems
the concept of reticular formation that has a strong influence on wakefullness
Reticular activating system
consciousness requires proper functioning of what?
reticular activating system and both cerebral hemispheres
What occurs in unconsciousness or comas?
lesions that damage the reticular activating system or when there is diffuse, damage to both cerebral hemispheres
How are the diffuse modulatory systems catergorized by? and what utilizes it?
utilized by the reticular formation
categorized by the principal neurotransmitter
Noradrenergic system:
-originates where?
-function?
-distribution?
Serotonergic system:
-originates where?
-What does it release?
-Center of control for?
What makes up the reticular activating system?
noradrenergic system + serotonergic sysem
Cholinergic Neurons:
-origin?
-function?
What is the location of dopaminergic neurons?
widespread in the CNS
What are the two dopaminergic systems?
- nigrostriatal system
- mesocorticolimbic system
Nigrostriatal system:
- Location?
- importance?
Mesocorticolimbic system:
-origin?
-importance?*
What is the limbic system?
is connected to the highest centers of cognition in the prefrontal and association areas of the cortex
cingulate cortex
What occurs in the cingulate cortex?
sensations of emotions are perceived
What is the imprtance of the hippocampus?
in the conversion of short term memory to long term memory
What is the function of the amygdaloid nucleus?
involved in strong emotions, including fear and aggression and linking emotions with memories
What is the function of the hypothalamus in the limbic system?
What is the function of the mammillothalamic tract?
relay the activity of the hypothalamus to the cortex, therefore providing a pathway linking the expression with the sensation of emotions
Draw the limbic system
learning and memory is associated with changes in the structure and function of synapses
synaptic plasticity
repeated synaptic stimulation can result in a presistent increase in the sensitivity of a neuron
long term potentiation
long tern potentiation is associated with?
function?
What is the purpose of wernicke’s area?
understanding the meaning of words
output from wernickes area to brocas area occurs via what tract?
arcuate fasciculus
What is the function of broca’s area?
generates the commands needed to instruct the neighboring motor cortex to produce the movements of the mouth and tongue needed to speak
Lable the area of the brain
characterized by the inability to produce speech, comprehension is generally preserved
Broca’s aphasia
characterized by fluent production of speech, but the sentences lack meaning and comprehension of language is poor
Wernicke’s aphasia
Lable the skeletal muscle anatomy
Wha are the subunits of skeletal muscle?
a motor neuron and all the muscle fibers it innervates
motor unit
Draw out the neuromuscluar junction
Draw out the Sarcomere
How many actins encircle each myosin?
6 actins encircle each myosin thick filaments
thin contractile myofilament
actin
thick contractile myofilaments
myosin
head portion of the myosin filament that bridges the gap between myosin and actin during contraction
crossbridge
Dystrophin:
-Location?
-importance?
dystophin is an important scaffolding protein located between the sarcolemma and myofilaments
What protein is mutated in duchenne muscular dystrophy?
dystrophin
What are the two portion of the myosin heads?
actin binding site
ATP binding site
What are the functional filaments associated with the troponin-tropomyosin compex?
What are the neuromuscular junction diseases?
-myasthenia gravis (antibodies that stop enzymes from binding)
-botulism (prevents release of ace)
What are the drugs/toxins that affect Neuromuscular Transmission?
- Botulinum toxin- failure of ach release; flaccid paralysis of muscle
- neostigmine - prolongs action of ach at the end of plate
Explain what occurs in the excitation-contraction coupling
refer to slides
What occurs in the cross-bridge cycle?
What is the size principle?
What are the slow twitch and fast twitch muscle fibers?
What is the length-tension relationship?
What is the force-velocity relatioship?
lines the walls of hollow organs, no striations
smooth muscle
What does smooth muscle regulate?
blood flow, ventilation of the lungs, and gastrointestinal motility
Explain the structure of a smooth muscle cell
smooth muscle cells serves as attachments points for?
actin filaments (thick filaments overlap thin filaments in an irregular array)
What allows smooth muscle cells to generate force?
the irregular arrangement of actin and myosin
is the most common type of smooth muscle, cells within a bundle behave as a functional syncytium due to the presence of gap junctions
visceral smooth muscle
How are cells arranged in visceral smooth muscle?
large bundles
smooth muscle cells function individually since the cells are not connected by gap junctions
multiunit smooth muscle
What are the componets of the multiunit smooth muscle cells?
-a dense nerve supply from autonomic neurons
-fine control over force development in a manner similar to spatial summation in skeletal muscle
Explain the excitation-contraction coupling in smooth muscles
Explain the latch state of the crossbridge cycle
What are the two ways to induce smooth muscle relaxation?
