OTM 507: Neuro

Neurons

receive info, process info, generate output, basic structure for sending electrical signals throughout nervous systems

Cell body (soma)

synthesizes neurotransmitters, cell body of a neuron that produces neurotransmitters

Dendrites

main input sites for the cell, projections of a neuron (nerve cell) that receive signals (information) from other neurons

Axon

output unit of the cell

Presynaptic terminals

transmit elements of the neuron

Glia

glue, support cells for neurons

Macroglia

astrocytes, oligodendrocytes, Schwann cells

Astrocytes

release/recycle neurotransmitters, clean up crew, CNS

Neuron function

action potential comes down, goes from presynaptic terminal to postsynaptic terminal (connects at synaptic cleft), tells the next part to pass the message on,

Basic functions: reception, integration, transmission, transfer of info

Oligodendrocytes

myelin in CNS

Schwann cells

myelin in PNS

Microglia

immune cells of central nervous system, dying cells attract microglia for clean up, CNS

Ependymal cells

line cavities of ventricles, help with transport, CNS

Satellite cells

support, protect, provide nutrients in PNS, PNS

Myelin

Sheath is formed by oligodendrocytes in CNS or Schwann cells in PNS, covers the axons of neurons, myelinates the neurons when the sheath wraps completely around the axon, sheath of proteins and fats surrounding an axon, insulates, prevents current flow across axonal membrane, increases speed of action potential and distance a current can passively spread, thicker myelin leads to faster conduction

Resting membrane potential

no information is being transmitted

Depolarization

potential becomes less negative inside the cell, neuron is excitatory, electrical signal can be transmitted, due to influx of sodium ions into cell

Electrical potential

difference in electrical charge, carried by ions

Action potential

repeated generation of a depolarizing signal, signal is all or none, The change in electrical potential, associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

Nodes of ranvier

small area of myelinated axons that lack myelin, area for action potential allowing ion flow across the membrane, point of depolarization, action potential slows when crossing, a space between two consecutive myelin sheaths where an axon comes in contact with the extracellular fluid

Afferent neurons

carry sensory info from outer body to CNS, sensory, Afferent = ARRIVE, The type of nerve that carries sensory nerve impulses from the periphery towards the central nervous system (CNS)

Efferent neurons

relay commands from CNS to smooth and striated muscles and to glands, motor, Efferent = EXIT, A nerve that conveys impulses toward or to muscles or glands.

Interneurons

act throughout the nervous system, process info locally or conveying info short distances, largest class of neurons, between sensory and motor

Neuroinflammation

inflammation of neurons, CNS's response to infections, disease, and injury, causes death of neurons and oligodendrocytes, causes inhibition of neural regeneration

Peripheral nerves system demyelination

result of trauma, autoimmune, viruses (COVID?), pathologic change involving peripheral nerves, destruction of myelin, disrupt proprioception, tingling/numbness, pain, weakness

Guillain Barre syndrome

acute inflammation of Schwann cells resulting in demyelination, causes ascending weakness, rapid onset with complete recovery possible, difficulty chewing, swallowing, speaking, fascial expressions, treatment with plasmapheresis and intravenous immunoglobulin therapy

Multiple sclerosis

immune system produces antibodies that attack oligodendrocytes, causes weakness, lack of coordination, impaired vision, double vision, impaired sensation, slurred speech, disruption of memory, emotions, and attention, onset between 20 and 40, primarily affects women

Types of MS

Relapsing/remitting

Secondary progressive

Primary progressive

Progressive relapsing

Clinically isolated syndrome

Neurotransmitters

Chemicals that convey info among neurons, released by presynaptic neuron

Neuromodulators

released into extracellular fluid, adjust activity of many neurons

Myasthenia Gravis

Acetylcholine receptors destroyed in motor cells, autoimmune, normal amounts released but unable to bind, causes constant excitatory of muscles

Peptides

act as hormones, neurotransmitters, neuromodulators

Amines

dopamine, norepinephrine, serotonin, histamine

Dopamine

associated with reward and pleasure, leads to addictive behaviors, affects motor activity and behavior

Norepinephrine

excess can lead to panic/anxiety disorders, ptsd, alertness, fight or flight

Serotonin

low levels associated with depression, affects mood and pain perception

Agonists

drugs that bind to the receptor and mimic the effects of naturally occurring neurotransmitters

Antagonists

drugs that prevent the release of neurotransmitters or bind to the receptor and impede the effects of a naturally occurring transmitter

Reuptake inhibitor

slows breakdown in synaptic cleft toallow more time for neurotransmitter to bind

Neuroplasticity

ability of neurons to change function, chemical profile, structure

New learning, relearning, Memory

Habituation

decrease in response to a repeated, benign stimulus,

PT/OT uses to decrease neural response to a stimulus for autism, complex regional pain syndrome, visual/vestibular disorders

Experience dependent plasticity

long lasting changes in strength of synapses between neurons and in neural networks, learning curve, brain initially works harder and when skill is learned less brain activity is required

Collateral sprouting

neighboring axons branch to reinnervate, exercise stimulates regeneration, PNS injuries

Regenerative sprouting

axon and target cell damaged, axon sends branches to new target, exercise stimulates regeneration, PNS injuries

Axon injury in CNS

damage on cellular level, axon swells, breaks, cell body dies, no regeneration in CNS

Recovery: edema/ischemic reduction, other receptor sites become more sensitive, increased neurotransmitter released through intact axons, silent synapses used, neurogenesis through stem cells

Silent synapses

unused synapses in brain waiting for a job, develop new functions

Reorganization of cerebral cortex

brain activity shifts to surrounding areas, explains stroke recovery, explains why other senses are more sensitive when others are defected

Metabolic effects of brain injury

Neurons die due to deprivation of oxygen, no known cures for stroke, TBI, or neurodegenerative disease, drugs minimize effects

Rehab after brain injury

recovery influences by intensity and timing of rehab, early rehab is necessary, avoid bed rest (could cause other brain areas to suffer), task specific training

Constraint induced movement therapy

treatment used in stroke, unaffected limb is constrained, forces affected limb to function, allows for functional reorganization, Avoid intense CIMT (could increase damage)

Neurotransmitter

A chemical that is released by the pre-synaptic element of the neuron upon stimulation and activates post-synaptic receptors

Membrane potential

the electric potential that exists on the two sides of a membrane or across the wall of a cell

depolarization

when the membrane potential become more positive then when it is at resting potential

repolarization

when the membrane potential returns back to resting state by decreasing the voltage

Saltatory conduction

Characterized by an action potential "jumping" between Nodes of Ranvier as it is propagated down the axon

voltage gated channel

transmembrane proteins that open when the neuron gets depolarized or when the voltage of the membrane changes sufficiently

Ligand gated channel

group of transmembrane ion-channel proteins which open to allow ions to pass through the membrane in response to the binding of a neurotransmitter

Hyperpolarization

when the membrane potential becomes more negative than when it is at resting potential

Synapse

site where an arriving action potential, through excitation-secretion coupling involving Ca2+ influx, triggers the release of one or more neurotransmitters into the synaptic cleft

absolute refractory period

The time period from the beginning of the action potential to the return of the resting state during which the membrane will not respond normally to an additional stimuli.

Dorsal root

One of two nerve roots that emerge from the spinal cord carries sensory information towards the spinal cord and connects with the ventral root to combine and form the spinal nerve

Ventral root

one of the two nerve roots of a spinal nerve that passes anteriorly from the spinal cord to send motor signals to muscle and organs

Dorsal horn

grey longitudinal columns found within the spinal cord; primarily acts as the termination of primary afferent sensory fibers via the dorsal roots of the spinal nerves.

Ventral horn

one of the grey longitudinal columns found within the spinal cord; contains the cell bodies of the lower motor neurons which have axons leaving through the anterior spinal roots on their way to innervate muscle fibers

Tracts

bundles of axons that travel to and from the body and cortex and carry specific sensory or motorinformation

Dorsal root ganglion

cluster of neuron that contain the cell bodies of sensory neurons

Gray commissure

A cross bar of gray matter in the spinal cord that connects the dorsal horns and ventral horns and surrounds the central canal in the spinal cord. Contains mostly interneurons

Vertebral bodies

bony segments of the spinal column; functions as a protective layer for the spinal cord

Frontal lobe

part of the cerebral cortex in either hemisphere of the brain, lying directly behind the forehead; involved in a wide range of "higher" cognitive functions

Temporal lobe

Portion of the cerebral cortex that is above the ears, and involves in hearing, language processing and memory

Parietal lobe

located after the frontal lobe after the central sulcus and is responsible for processing information from the body's senses and awareness

Occipital lobe

located in the posterior part of the brain, which is responsible for visual information

Brainstem

an area of the central nervous system that connects the brain and spinal cord responsible for breathing, swallowing, heart rate, blood pressure, consciousness, and sleep wake cycle; consists of the midbrain, the pons, and the medulla oblongata

Midbrain

Connects the pons and diencephalon and is the upper part of the brainstem, important in motor control such as eye movements and processing vision and hearing, contains cranial nerves 3, 4

Pons

The the middle structure of the brainstem that coordinates face and eye movements, facial sensations, hearing, balance, and acts as a bridge between the cerebellum and the rest of the brain, contains cranial nerves 5, 6, 7, 8

Medulla oblongata

The lower part of the brainstem that coordinates cardiovascular control (blood pressure/heartbeat), breathing, head and eye movement, swallowing, reflexes, contains cranial nerves 9, 10, 12

Ventricles

hollow cavities of the brain, that contain the cerebrospinal fluid (CSF), which circulates within the brain and spinal cord.

Hypothalamus

Part of the diencephalon that regulates neuroendocrine function. It assists helps with eating, drinking, emotion, sexual behavior, regulating body temperature and other motivated behaviors.

Amygdala

art of the limbic system that is linked to emotion, smell, and motivation. Also know as the Amygdaloid nucleus. Responsible for the "fight or flight" response

Thalamus

small structure within the brain located just above the brain stem between the cerebral cortex and the midbrain and functions to relay motor and sensory signals to the cerebral cortex

Cerebellum

receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements coordinating voluntary movements like posture, balance, and speech

Glial cells

Their supportive functions help define synaptic contacts and maintain the signaling abilities and health of neurons; not involved in direct synaptic connections, a support cell in the nervous system classified into astrocytes, oligodendrocytes, and Schwann cells

Axon terminal

The end region of an axon and a site of synaptic contact with another cell (AKA presynaptic terminal)

World test/ digit span test

spell "world" backwards and forwards and list the letters in alphabetical order, recite a series of 5 numbers forwards and backwards

Declarative memory

problems due to damaged hippocampus, prefrontal cortex, and parietotemporal association cortex

working - give patient 3 words to remember, discuss other topics, then ask for 3 words again

recent - ask about activities from past couple days

long term - ask about past events in their life or in history

Goal directed behavior

deciding on a goal, planning, following through with plan, and monitoring progress

One minute naming test

generate as many words as possible that begin with a single letter in one minute

Consciousness level

the level of consciousness at which mental activities accessible to awareness occur

Alert

Lethargic

Obtunded

Stupor

Coma

Lethargic

lose track of conversations and tasks, falls asleep if little stimulation is provided

Obtunded

alert briefly to strong stimuli, no meaningful answers

Stupor

alert only during vigorous stimulation

Language and speech

Comprehension: relationships, instructions

Naming: objects, body parts

Reading

Writing

One minute category naming test

name as many objects as possible from one category in one minute

Aphasias

Language disorders, which are associated with Broca's and Wernicke's areas in the brain.

Wernicke's aphasia

receptive, impaired language comprehension, normal rate, rhythm, and grammar of speech but jumbled and nonsensical, word salad, often due to ischemic stroke, they are more likely confused

Broca's aphasia

expressive, speech is poorly articulated and difficult to get out, use primarily nouns and verbs and no linking words, disconnected speech w/ long pauses, easily frustrated, comprehends very well

Dysarthria

speech impairment causing difficulty articulating words

Orientation

Person: ask about the individual such as name, place of birth

Place: where you are now, what city/state

Time: what time is it, day of week, month, year

Situation: why are you here, what happened, why evaluating

A & O x3, A & O x4

Stereognosis

use light touch, proprioceptive, and movement information to identify an object placed in the hand

have patient close eyes, place common object (key, paperclip, pen) in their hand, have them tell what it is

Bilateral simultaneous stimulation

assess patient's awareness of stimuli presented at same time to both sides of body, touch and visual

Touch: close eyes, lightly touch one limb or both simultaneously and ask if left, right, or both were touched

Visual: show patient objects w/ one in right visual and one in left visual and ask for names of each