Clinical Neuroscience Test 1

Name some of the Nervous system Functions (10)

• Initiating

• Sequencing

• Completing

• Cognition

• Emotions

• Dreams

• Homeostasis

• appetite

• secretions

• Process Sensations

White Matter Job and Places?

Transmits Information

• Myelin Sheaths

• Limbic System

• Columns of Spinal Cord

Grey Matter Job and Places?

Processes Information

• Dendrites

• Roots of the spinal cord

• Surface of the brain

⭐️(Soma makes up Grey Matter)

12 Cranial Nerves

Olfactory(s), Optic(s), Oculomotor(m), trochlear(m), trigeminal(b), Abducens(m), facial(b), vestibulocochlear(s), glossopharyngeal(b), vagus(b), accessory(m), hypoglossal(m)

Olfactory

Smell

Optic

Vision

Oculomotor

Eye Movement, constricts pupil and adjusts shape of lens or eye for focus

Trochlear

Eye Movement

Trigeminal

Sensations for the face and head, chewing

Abducens

Eye movement

Facial

Facial Expression, closes eye, tears, salivation

Vestibulocochlear

sensation of head position and head movement, hearing

Glossopharyngeal

Sensation from pharynx. posterior tongue, middle ear, swallowing, salivation

Vagus

sensation from pharynx, larynx, skin in external ear canal, sensation, and motor to viscera

Accessory

Elevates shoulder, turns head

Hypoglossal

Moves Tongue

Myasthenia Gravis

Autoimmune Disorder, targets synapses between nerves and muscles

Results in ptosis(droopy eye) and diplopia(Double vision)

oculomotor, Abducens, Trochlear

Brachial Plexus

C5-T1

Forms peripheral nerves supplying the upper limb

• Axillary

• Musculocutaneous (Bicep)

• Radial (Extension)

• Median

• Ulnar

Afferent Neuron

Enters CNS posteriorly, Sensory

Efferent Neuron

Exits CNS Anteriorly, Motor

Once cranial Nerves exit the brain they become…

Peripheral nervous system nerves

Median Nerve Job

Finger Flexion

Radial Nerve Job

Elbow and Forearm

Wrist Extension

Ulnar Nerve Job

Flexion and Extension of Fingers and Wrist

Sciatic Nerve Job

External Rotation and Adducanalion of the Hip

How are all the nervous system functions possible?

Communication between nerve cells (Neurons) and glial cells

Functional unit of the nervous system

Neurons

Provides services to help neurons communicate with eachother and nourish, support, and protect neurons

Glial Cells

What does an Axon do?

Transmits information

Neuromuscular Junction

Muscular Contraction

Tinels Test

tapping the median nerve at wrist to cause numbness in thumb and index fingers to test for carpal tunnel

Phalens Manuever

Pressing posterior wrists together to test for carpal tunnel

Brainstem connects…

Cerebral region and spinal cord

Midbrain, pons, and medulla do what…

Regulate in-voluntary functions like,

• breathing

• heart rate

• blood pressure

• balance

• swallowing

• sleep and wakefulness

Cerebellum Job

Coordination, movement and posture, balance, fine muscle control

Cerebrum Region

2 hemispheres that divide into 6 lobes (we need to know 5)

occipital

frontal

temporal

limbic

parietal

Lobe Jobs

Frontal: problem-solving, voluntary motor activity, Reasoning, judgment, speaking

Temporal: behavior, memory, hearing, comprehending language

Parietal: Right from left, sensation, reading, orientation

Occipital: vision, color perception

Limbic: Homeostasis, memory, emotions, olfaction

Brain stem job

Breathing, body temp, digestion, alertness and sleep, swallowing

Whats in the Limbic system?

Cingulate Gyrus, Basal Ganglia, Hypothalamus, Amygdala, Corpus Callosum, Thalamus, Hippocampus, Cerebellum

Hypothalamus: sleep, mood, hunger and thirst, arousal, blood pressure, temp, HR

Thalamus: Sensory information

Amygdala: Emotions

Hippocampus: Memories

Structure of Neurons

Reception→Integration→Transmission

Interneurons

Any nerve cell that signals to another neuron (CNS)

process information locally or convey information short distances

Estimation for how many cortical Neurons there are

16 BILLION

Neurons have the same basic components of what kind of cell?

Animal cells

• Nucleus

• Mitochondria

• Endoplasmic Reticulum

4 main components of a typical neuron

Soma(cell body), Dendrites(Input), Axon(output), Presynaptic terminal(Bouton)

The Soma, cell body, is the site of what?

Protein Synthesis

The dendrites, input unit, do what?

Receive incoming signals

The Axon, output unit, arises from what?

a specialized area of cells, AXON HILLOCK

The presynaptic terminal, Bouton, do what?

point at which signal is transmitted to another neuron, muscle cell, or gland

Synaptic cleft does what?

the Presynaptic neuron releases a neurotransmitter into it which diffuses from one side of the cleft to another

Where are neurotransmitters produced and where are they transported to?

Produced in the SOMA and transported to the presynaptic terminal

What is the process of moving neurotransmitters to the presynaptic terminal called?

Axoplasmic transportation

What is the process of moving material from the Axon→presynaptic terminal called?

Anterograde transport

Materials returning to the Soma travel by what kind of transport?

Retrograde Transport

What kind of transport slows with aging?

Retrograde transport,

Alzheimers, Huntingtons, and Amyotropic Lateral Sclerosis (ALS)

Multipolar Cells

• Most Common

• Multiple dendrites from same Soma and single axon

• Mostly MOTOR NEURONS

• Massive amounts of input

• 8,000 on dendrites, 2000 on Soma

• Purkinje Cells 150,000

Purkinje Cells

150,000

in Cerebellum

large

play an inhibitory role in the coordination of movement

Bipolar Cells

• 2 major processes

• dendritic root

  • Many branches

• Axon

  • Conducts signal toward the presynaptic terminal

Pseudopolar Cells

• Single projection from the cell body that divides into 2 axonal roots

• NO true dendrites

• Mostly SENSORY NEURONS

  • Communicate from the periphery to the cell body

  • A central axon then transmits that sensory info back to the spinal cord

• One Soma supports both axons

How do Neurons send messages?

Electrochemically

What does electrochemically mean in regards to neurons sending messages?

Chemical concentrations (Ions) inside and outside a nerve cell cause a state of rest or cause the nerve to generate an electrical signal

Important Ions in nerve cell environment are…

NA+: Sodium

K+: Potassium

CA²+: Calcium

Cl-: Chloride

How are the fundamental electrical properties of all nerve cells determined?

A Distribution of Ions across the nerve cell membrane

• A nerve cell membrane allows some ions to pass through and block the passage of other ions

For a neuron to generate an electrical signal due to an ion movement, what must happen?

A stimulus must cause a gated channel to open

Ligand-gated Channel

Open due to the binding of a neurotransmitter (Acetylcholine) to a pocket on the post synaptic membrane

• Excitatory

Voltage-gated Channel

open/close in response to changes in the electrical potential across the cell membrane. Open instantly and close just as fast.

• Important to the release of neurotransmitters and the propagation of action potentials

  • Gava and Glutamate

Modality-gated Channel

Specific to sensory neurons, open in response to mechanical forces

• Touch, pressure or temperature

• Finger touching something

Leak Channels

No Gates but always open to allow small numbers of ions through cell membrane

• Water

What does the membranes electrical potential mean?

The difference in charge across the cell membrane

• measured in mV

What are the 3 types of electrical potentials?

Resting membrane potential

• No signal is occurring

Local Potential

• Slight trickle of activity or signal

Action Potential

• A full blown signal occurs

At rest, what is a neurons charge?

More Negative inside, Less positive outside

• Polarized

What is the resting polarity of a cell at resting membrane potential?

-60mV to -90 mV

The resting membrane potential is maintained how?

By a variety of cellular process that require energy (ATP)

How do changes from resting potential occur?

Electrically charged ions pass through gated channels and change the distribution of electrically charged ions inside and outside the nerve cell

How does a nerve cell become depolarized?

The membrane potential becomes less negative than the resting potential

• Depolarization: increases likelihood that the neuron will generate a transmittable signal and be EXCITATORY

What is hyperpolarization?

The membrane potential becomes MORE NEGATIVE that the resting potential

• Hyperpolarization: reduced likelihood that the neuron will generate a transmittable signal and be INHIBITORY

When does action potential occur?

A neuron transmits information rapidly and over longer distances. It is an explosion of electrical activity that is created by a depolarizing current which causes the resting potential to move toward 0mV.

Once the depolarization reaches -55mV, a neuron will fire and AP. ALL OR NOTHING

Once AP is generated, it spreads______along the axon to the adjacent regions of the membrane

Occurs in one direction

In multipolar neurons, propagation is toward the presynaptic terminal

passively

In pseudopolar neurons, propagation in the distal axon is toward the ____ and propagation in the proximal axon is toward the ____.

Soma CNS

Some axons are specialized for faster AP propagation because of 2 adaptation____

Larger Diameter Axons

Myelination

Multiple Sclerosis attacks what?

Myelin Sheaths

Neuronal Divergence

Single neuronal axon have many branches that terminate on a multitude of cells

i.e. stepping on Nail causes you to activate many muscles that moves the limb away from the nail

Neuronal Convergence

Multiple inputs from a variety of different neurons terminate on a single neuron

i.e. reaching around a room in the dark as sensation input from your hand are sent via afferent fibers to sensory association areas of the cerebrum fro processing/understanding

Glial Cells

Supporting Glue and functions of: myelinating, signaling, cleaning, nourishing, and defending

Oligodendrocytes and Schwann Cells

Form myelin the protects and insulates axons for better propagation/communication of electrical current (Action potentials)

Oligodendrocytes

CNS myelination

Schwann

PNS Myelination

Astrocytes

Star shaped cells that have many supporting roles. Mostly in CNS

Astrocyte Roles

• directly signal with neurons, oligodendrocytes, microglia, and astrocytes

• Regulate communication at a synapse

• cleaning up neuronal environment, including activation of microglia

• Provide nutrients to neurons

Microglia Job

Function as part of the immune system and phagocytes cleaning up the neuronal environment (injured/aging neurons, infections, bacteria, and disease)

Essential for healing

Neuroinflammation

immune response and inflammation of nervous tissue within CNS triggered by injury, infection, toxins, or protein aggregation

PNS: Peripheral Neuropathy

any pathological change in the peripheral nerves due to disease or trauma

Effects Axons or Myelin

Characterized by destruction of the myelin sheath and motor tracts leading to decreases in proprioception, pain, numbness, and weakness

PNS: Gullian-Barre Syndrome

Autoimmune disease, polyneuropathy, involves acute inflammation and demyelination of peripheral sensory and motor fibers leading to ascending muscle weakness of the limbs producing a symmetric flaccid paralysis. Paresthesia and numbness also accompanies loss of motor function. The cranial nerves are often affected aiding the severity of the condition. Attacks Schwann

CNS: Multiple Sclerosis

Autoimmune neuroinflammatory that attacks Oligodendrocytes producing patches of demyelination or plaques along nerve axons in the CNS which results in a systemic slowed or blocked transmission of signals