Neurolgia Katie Van Keuls Lauren Kesselring Shela Fobellah.

Neurolgia

Katie Van KeulsLauren KesselringShela Fobellah

Neurolgia of the Central Nervous System

Makes up one half of the volume of the nervous system

Four Types of Neuroglia Cells1. Ependymal Cells2. Astrocytes3. Oligodendrocytes4. Microglia

Cerebrospinal Fluid

*Cerebrospinal Fluid (CSF) fills the central passageway the extends along the longitudinal axis of the spinal cord and brain.

*CSF provides a protective cushion and transports dissolved gases, nutrients and waste

Central Canal and Ventricles

*Central Canal-The narrow passageway in the spinal cord

*Ventricles-enlarged chambers of the passageway in the Brain

*Both are filled with Ependymal Cells

Ependymal Cells

An epithelium known as the ependyma

During embryonic development the free surfaces are covered by cilia

In Adults the cilia is just in the ventricles in the brain to help with circulation on CSF

Contains stem cells that can divide to produce additional neurons

Ependyma

Have slender processes that branch extensivly and make direct contact with neuroglia

The function of the connection is not known

Astrocytes

The largest and most numerous neuroglia in the CNS

Have slender cytoplasmic feet that wrap around capillaries

There is the break in the surrounding of the capillaries where the neuroglia come in contact with the capillary walls

Functions of Astrocytes: Maintaining the Blood-Brain Barrier

General circulating blood can not come into contact with CNS because hormones and chemicals in the blood can alter the neuron function

Endothelial cells create a blood-brain barrier to isolate CNS from the general circulation

Other Functions

Creating a tree-Dimensional Framework for CNS

Repairing Damaged Neural Tissue Guiding Neuron Development Controlling the Interstitial

Environment

Oligodendrocytes

Their cytoplasm extends to expose surfaces of neurons. Most neurons completely covered

Contributing Factors

*Myelin- lipids and proteins that make up the membrane wrapping a neuron Increase speed at which action

potential travels along the axon*Myelin Sheath- found along length of an

axon, presence increases impulse flow. oliogodendrocytes contribute

Internodes- large areas of the of the axon located in between the nodes

Nodes- (Nodes of Ranvier) axon branches originate from here, impulses jump from node to node

White Matter- group of myelinated axons, the sheaths make the structures appear white

Grey Matter- Made up of neuron cell bodies, dendrites, and unmyelinated axons. Unmyelinated means no myelin sheath. Unmyelinated axons are typical where short axons from synapses.

Microglia Cells

It is the least numerous and smallest neuroglia in the CNS

Microglia appear early in the embryonic development

Microglia migrates into the CNS as the nervous system forms

They remain isolated in neural tissue

Neuroliglia of the PeripheralNervous System

The cell bodies of neurons in the PNS are clustered in masses called ganglia

There are 2 types of Neuroglia. Satellite cells also called amphicytes Schwann cells also called neurilemmal

cells

Satellite cells

Surround neuron cell bodies in ganglia.

They regulate the environment around neurons

Schwann cells

Form a sheath around peripheral axons Axons covered by Schwann cells are

called neurilemma Most axons in the PNS whether

myelinated or unmyelinated are shielded from contact with fluids by Schwann cells

Only myelinate one segment of a single axon

Next show

Ion Movement and Electrical Signals

Abby, Abbey, Mohamed, McKenzie, and Rachel

Passive forces acting Across the Membrane

Chemical gradients K+ ion move out of cell Na+ ions move into cell Movements caused by concentration

gradients http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi

?book=neurosci&part=A132

Passive Forces Acting Across the Membrane

Electrical gradient Cystol (- charge) separated from extracellular

fluid (+ charge) by a chemical membrane + and – charges held apart: potential

difference Inner surface negatively charged compared

to exterior Measured in Volts and Millivolts


Current: movement of charges to eliminate a potential difference + and – charges attract

Resistance: how much the membrane restricts ion movement if a barrier (cell membrane) separated + and – charges High resistance, small current Low resistance, large current


Electrochemical gradient: sum of the chemical and electrical forces acting across the cell membrane

Active Forces Across the Membrane

Membrane channels control movement of ions across the cell membrane

Two types of channels Passive and Active Passive channels (leak)

Always open Permeability varies because proteins change shape in

response to local conditions

Active Forces Across the Membrane

Active Channels (gated) open or close in response to specific stimuli

Channel has 3 stages 1. Closed but capable of opening 2. Activated- open 3. Inactivated- Closed and not capable of

opening 3 Classes of gated channels

Types of Gated Channels

Chemically Regulated- open or close when they bind specific chemicals

Receptors that bind acetylcholine (Ach) at the neuromuscular junction are chemically regulated channels

Most abundant on the dendrites and cell body of a neuron where synaptic communication occurs


Voltage Regulated- open and close in response to changes in the transmembrane potential

Most important are sodium, potassium, and calcium channels

Sodium channels have two gates


Activation GateOpens on

stimulationLets sodium

ions into cell

Inactivation GateClosesStops the entry

of sodium


Mechanically Regulated- open or close in response to physical distortion of membrane surface

Important in sensory receptors that respond to touch pressure or vibration

Gated Channels

Figure 12.13

Graded Potentials

Depolarization- a change in a cells membrane potential, usually making it more positive. A large depolarization of the neuron can result in an action potential.

Graded Potentials cont.

Repolarization- change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential previously changed the membrane potential to a positive state

Graded Potentials cont.

Hyperpolarization- prevents neuron from receiving any other stimulus right after an action potential.

Prevents axons receiving stimuli to not shoot an action potential in the opposite direction

Graded Potentials

Figure 12.14.1

Graded Potentials

Figure 12.14.2

Figure 12.15

Depolarization and Hyperpolarization

Action Potentials: All-or- Nothing Principle

A single nerve cell, just like a single muscle fiber, transmits an action potential.

If a stimulus is strong enough to generate nerve action potential, the impulse is conducted along the entire neuron at maximum strength.

This is true unless it is altered by conditions, such as toxic waist.

Generation of Action Potentials

NT= Neurotransmitters 1. A chemical message from presynaptic neuron to postsynaptic neuron. 2. NT bind to receptors. 3. NT produce an EPSP or an IPSP 4. The EPSP’s and IPSP’s come together – either spatially or temporally. 5. The soma becomes more positive. 6. The more positive charge reaches the axon hillock. 7. Once the threshold of excitation is reached the neuron will fire an action

potential. 8. The Na+ channels open and Na+ is forced into the cell by the

concentration gradient and the electrical gradient. 9. The neuron depolarizes. 10. The K+ channels open and K+ is forced out of the cell by the

concentration gradient and the electrical gradient.

Generation of Action Potentials Cont.

11. The neuron continues to depolarize. 12. The Na+ channels close at the peak of the action potential. 13. The neuron starts to repolarize. 14. The K+ channels close, but they close slowly and K+ leaks out. 15. The terminal buttons release NT to the postsynaptic neuron. 16. The resting potential is overshot and the neuron falls to a -

90mV (hyperpolarize). 17. The Na+/K+ pump then starts to pump 3Na+ ions out for every

2K+ ions it pumps in. 18. The K+ not pumped in, is diffused in the synapse. 19. The neuron begins to repolarize. 20. The neuron returns to resting potential.

Propagation of Action Potentials

spread to affect the entire excitability membrane

Message is relayed from one location to another in a series of steps where the message is repeated

Continuous and Saltatory Propagation


Continuous- mechanism which an action potential is propagated along an unmyelinated axon

Transmembrane potential becomes positive and current develops as Na+ ions move to cytosol and extracellular fluid

Current spreads, depolarizing adjacent portions of the membrane

Axon hillock can’t respond with action potential but initial segment of axon depolarized to threshold, developing an action potential

Process continues in a chain reaction


Saltatory- rapid propagation of action potential between successive nodes of a myelinated axon

Myelin increases resistance to flow of ions across the membrane resulting in only nodes can respond to depolarization

http://www.blackwellpublishing.com/matthews/actionp.html

Synaptic activity next

Synaptic Activity

By: Zack Ingram, Vince Calo, Morgan Brauner, and Faduma Mohamed

Electrical Synapses

Transmit information via the direct flow of electrical current at gap junctions

Found in all nervous systems, including the human brain

Synchronize electrical activity among populations of neurons

How it Works

Usual source of current is generated by the action potential

Current can flow in either direction across gap junction

Transmission is extraordinarily fast Passive current flow across gap

junction is virtually instantaneous so communication can occur without delay

Chemical Synapses

Junctions where cell of nervous system sends signals to muscles or glands

Found in neuromuscular junction Children have 10,000 trillion but this

declines with age Adults have 1,000-5,000 trillion

Electrical vs. Chemical

Space between pre- and postsynaptic neurons is greater at chemical synapses than at electrical synapses

Communication occurs virtually instantaneously at an electrical synapses and with a delay at a chemical synapses

Cholinergic Synapses

A synapse that uses acetylcholine as its neurotransmitter

Neurotransmitters relay, amplify, and modulate signals between a neuron and another cell

Other Neurotransmitters…

Serotonin

Linked to mood control, regulation of sleep, pain perception, body temperature, blood pressure, hormonal activity, sexual behavior, appetite, learning, memory, endocrinal functions, anxiety, depression, moods, muscular functions, and cardiovascular functions

Dopamine

Controls the flow of information to other parts of the brain

Connected with the pleasure system of the brain

Deregulation of the dopaminergic system has been linked to Parkinson’s Disease, Tourette’s syndrome, schizophrenia, ADHD, and the generation of pituitary tumors

Nor epinephrine

Increases the level of excitatory activity within the brain

Plays an important role in the sympathetic nervous system which coordinates the “fight or flight” response

Other Neurotransmitters

Works Cited

http://faculty.washington.edu/chudler/neurok.html

http://www.hubin.rog/facts/brain/texts/nervous_systems_en.html

http://www.bbc.co.uk/science/humanbody/body/factifiles.nervous_anatomy.shtml

http://web.sfn.org?BAW/SfNResources/SFN%20resources.html

Disease next

Diseases and Conditions

Naana BoatengShagail CoxDanielle Beard

Multiple Sclerosis

Definition: disease of the central nervous system

The immune system eats at sheath http://multiple-

sclerosis.emedtv.com/multiple-sclerosis-video/the-nervous-system-video.html

Multiple Sclerosis

Symptoms: blurred, double vision, red-green color distortion, blindness in one eye

Occur between the ages of 20 and 40

Multiple Sclerosis

Effects: muscle weakness, trouble w/ coordination and balance.

Most get paresthesias Speech impediment, tremors and

dizziness are frequent complaints

Multiple Sclerosis

Treatments: no cure Medications:

Novatronen(mitoxantrone)- for chronic MS

Steroids Physical therapy

Multiple Sclerosis

Facts: can be hereditary .100 in 100,000 cases in U.S.More common in European countries,

Russia, Southern Canada, Northern United States, New Zealand & Southeast Australia

Multiple Sclerosis

ResearchNational Institute of Neurological

Disorders and Stroke (NINDS) and other health institutes such as the NIH are conducting research.

Most promising info.- interferon (beta interferons)

Parkinson's Disease

Definition: Disease of the motor system. Loss of

dopamine producing brain cells.

Parkinson's Disease

Symptoms: Tremor Stiffness of limbs Slowness of

movement Impaired balance

and coordination Depression Difficulty

swallowing

Difficultly chewing Speaking problems Sleep disruption Skin problems Urinary problems Completing easy

tasks becomes difficult

Difficulty walking Difficulty talking

Parkinson’s Disease

Treatment No cure

Levodopa Anticholinergics Amantadine Surgery

Parkinson's Disease

Facts Most commonly seen in Japan Seen in people over 50 Average life expectancy is same for

people without disease. Gets worse over time Animal models are used to study

disease progresses and develop new drug therapies

Parkinson's Disease

Progression Stage One: Symptoms on one side of the

body Stage Two: Both sides of body are affected,

no impairment of balance Stage Three: Balance impairment, mild to

moderate, physically independent Stage Four: severe disability, still able to

walk or stand unassisted Stage Five: Wheel Chair bound or bed

ridden unless assisted

Tay-Sachs

Definition: is a deadly disease of the nervous system passed down through families.

Mostly appears in children from 3 to 6 months

Tay-Sachs

Symptoms: Seizures, behavior changes, listlessness, delayed mental and social skills

More serious symptoms:Blindness,deafness,loss of intellectual skills

Tay-Sachs

Causes: defective gene on chromosome 15.

Both parents have to carry the gene. Child must receive copies from both parents.

1 in every 27 members of the Ashkenazi Jewish population carries the Tay-Sachs gene.

Tay-Sachs

Treatment: There is no treatment.

Mercury and the nervous system

Definition: there are three types of mercury Elemental Inorganic Organic


Symptoms: tremors, emotional changes, insomnia, neuromuscular changes ,headaches, disturbances in sensations, changes in nerve responses,performance deficits on tests of cognitive function.

How Does Mercury Affect the Nervous System?Methyl mercury targets and kills neurons in specific areas of the nervous system including the:

Visual cortex

Cerebellum

Dorsal root ganglia

Several mechanisms have been proposed to explain how mercury kills neurons: 1.Protein inhibition 2.Disruption of mitochondria function 3.Direct affect on ion exchange in a neuron 4.Disruption of neurotransmitters 5.Destruction of the structural framework of neurons


Treatment: with DMSA frequent low dosages of ALA Immediate chelation therapy is the

standard of care


Facts: Minamata Bay (Japan) Iraq Faroe Islands (North Atlantic)

Work cited

group., a. W. (n.d.). Mercury. Oklahoma State University - Environmental Health & Safety - Home. Retrieved February 4, 2010, from http://ehs.okstate.edu/training

Ninds multiple sclerosis information page. (2010, February 1). Retrieved from http://www.ninds.nih.gov/disorders/multiple_sclerosis/multiple_sclerosis.htm Brawley, Dr. Otis. (2009, September 30). Is Multiple sclerois hereditary?. Retrieved from http://www.cnn.com/2009/HEALTH/expert.q.a/09/30/multiple.sclerosis.heredity.brawley/

index.html Tay-Sachs disease: MedlinePlus Medical Encyclopedia. (n.d.). National Library of Medicine

- National Institutes of Health. Retrieved February 4, 2010, from http://www.nlm.nih.gov/medlineplus

http://multiple-sclerosis.emedtv.com/multiple-sclerosis-video/the-nervous-system-video.html

http://www.mayoclinic.org/tay-sachs-disease/symptoms.html Multiple sclerosis:hope through research. (2010, February 1). Retrieved from http://www.ninds.nih.gov/disorders/multiple_sclerosis/detail_multiple_sclerosis.htm Health Effects | Mercury | US EPA. (n.d.). U.S. Environmental Protection Agency. Retrieved

February 4, 2010, from http://www.epa.gov/hg/effects.htm Neuroscience for Kids - Effects of Mercury on theNervous System. (n.d.). UW Faculty Web

Server. Retrieved February 4, 2010, from http://faculty.washington.edu/chudler/merc.html

Neurolgia Katie Van Keuls Lauren Kesselring Shela Fobellah.

Documents

Transcript of Neurolgia Katie Van Keuls Lauren Kesselring Shela Fobellah.