The Nervous System

Two ComponentsCentral Nervous System• Brain

oCerebrumFrontal LobeParietal LobeTemporal LobeOccipital Lobe

oCerebellumoMedulla

• Spinal Cord

Peripheral Nervous System•  Nerves

o movement, senses, etc.

• Neurotransmitters

Cerebrum• Divided into two hemispheres• Majority of what is considered "brain"• Made up of 4 lobesoParietal LobeoTemporal LobeoFrontal LobeoOccipital Lobe

• Major functionsoMovement

Conscious movement

Cerebrum cont'd...

o Senses Processes information from body (smell, sight,

feel, taste, sound)oSpeech

ComprehensionCommunication

oLearning and Memory•  Made of nerve cells (grey matter)• White nerve fibers connect signal from nerve

cells and other parts of brain/ body

Cerebellum

• "little brain"• Two hemispheres, folded to achieve

more surface area• regulation and coordination of

voluntary movement• posture• balance

Medulla• Lower portion of brainstem• Controls involuntary movement

oHeartbeatoBreathingoSwallowingoVomitingoDefecation oReflexes

Occipital Lobe

• Function:oVisionoPerception

http://www.neuroskills.com/tbi/boccipit.shtml

http://www.sci.uidaho.edu/med532/occipita.htm\

Temporal Lobe

Function:• Sense of Hearing• Aspects of Memory• Emotional Behavior

http://www.sci.uidaho.edu/med532/temporal.htm

Temporal Lobe Epilepsy (TLE)• Two Types:

o Mesial TLEo Lateral TLE

• Etiologies:o Relation with febrile seizures (seizures that result from increases in body

temperature, common in infants whose temperature maintenance is immature)o Generally related to prolonged seizure

• Symptoms:o Simple Partial Seizures (SPS)o Complex Partial Seizures (CPS)o Secondarily Generalized Tonic-Clonic Seizures (SGTCS)

• Treatmentso Medication 

Phenytion, Carbamezepine, Calproate, and Phenobarbital Newer drugs, though, like gabapentin, topiramate,Levetiracetam andlamotrigine

, promise similar efficacy with fewer side-effects.  Basically such medication functions by decreasing the excitation of neurons or

by enhancing their inhibitiono Excision Surgery

http://en.wikipedia.org/wiki/Temporal_lobe_epilepsyhttp://www.sci.uidaho.edu/med532/temporal.htm

Frontal Lobe Functions

•  Motor activity• Speech• Reasoning• Emotions• Problem Solving• Spontaneity• Memory • Language• Initiation

• Judgment• Impulse Control• Social Behavior• Sexual Behavior

Frontal Lobe Fun Facts • Very vulnerable to injury and the most

common region of injury due to location and size

• Reaches full maturity around age 25• Frontal Lobe damage can result in...

o  Little spontaneous facial expressiono Difficulty speakingo Increase or decrease in socialization o Dramatic decrease in creativity and problem

solving skillso Mental flexibility and spontaneity impairment

Parietal Lobe Functions• Processes information about

oTouchoTasteoPressureoPainoHeat/cold

Functions:• Movement• Orientation• Recognition• Language Processing

Parietal Lobe Fun Facts• Parietal Lobe is divided into two functional

regionsoOne integrates info to form a single

perceptionoThe other lets the body know where it is in

space in relation to the world                    around it

• Damage to the Parietal Lobe may                causeoNeglecting part of the body or               space

(makes it hard to care oneself)o Inability to perceive objects

          normally

Hippocampus http://www.psycheducation.org/emotion/hippocampus.htm

• part of the limbic system (emotion system of the brain)o in charge of transferring information into memory

•  part of the temporal lobe (inside fold; not visible from outside)• Necessary for making new memories [Alzheimer's disease

(mentioned later) affects the hippocampus first and severly]• involved in severe mental illnesses•  Directly affected by estrogen

o estrogen increases "synaptic density" or the number of connections to other nerve cells

Hypothalamus http://webspace.ship.edu/cgboer/limbicsystem.html

• maintains homeostasis • regulates hunger, thirst, response to pain, levels of pleasure, sexual

satisfaction, anger, aggresive behavior and more • regulates functioning of parasympathetic and sympathetic nervous

systems (regulates pulse, blood pressure, breathing,etc.)• It recieves info from...

o vagus nerve; gives info about blood pressure and how full the stomach is

o reticular formation of brainstem; gives info about skin temp.o optic nerve; gives info about light and darknesso unusual neurons lining the ventricles, it gets info about contents of

the cerebrospinal fluid incluidng toxins that lead to vomitingo limbic system/olfactor nerves; give info that regulate eating and

sexuality o it's own receptors; give inof about ion balance and temp of the blood

Hypothalamus• Sends instructions by...

o autonomic nervous system control of blood pressure, heartrate, breathing, digestion,

sweating, and all sympathetic/parasympathetic functionso pituitary gland

 neurally and chemically connected to this gland gland pumps hormones releasing facors into blood stream hormones regulate growth and metabolsim

Amygdala http://thalamus.wustl.edu/course/limbic.html

• FEARo couples a learned sensory stimulus (dog snarling = danger) to an

adaptive response (fight or flight)• Sensory input

o visualo auditoryo somatosensory cortices (the part of the brain where sensory

signals are sent)•  Outputs

o hypothalamuso brainstem

• involved in mood and conscious emotional response to an event• damage (rare)

o no response to fearful events o inability to recognize fear in the facial expression of others

 

Spinal Cordhttp://faculty.washington.edu/chudler/spinal.html

• Pathway connecting brain + peripheral nervous system

• Protected by spinal column    ( bone )

omade up of 31 segments 8 cervical12 thoracic 5 lumbar5 sacral1 coccygeal

opair of spinal nerves exit from each segment

Neurons • Neurons are specialized to carry "messages"

through electrochemical processes• Like all cells of the body, neurons

o Are surrounded by a cell membraneo Have a nucleus that contain geneso Contain cytoplasm, mitochondria, and other

organelleso Carry out basic cellular processes such as

protein synthesis and energy production

Neurons • Neurons are different from other cells because...

oThey have specialized extensions called dendrites and axons

oCommunicate with each other through electrochemical processes

oContain specialized structures (ex. Synapses) and chemicals (ex. Neurotransmitters)  

Anatomy of Neurons

• Dendrites bring info TO the cell body o Many to a cello No myelin insulation o Branch near cell body

• Axons take info AWAY from cell body o Generally only one to a cello Usually have myelino Branch further from cell body

• Myelin Sheath is made of electrically-insulating material and surrounds the axon of a neuron. The myelin sheath increases the speed at which impulses travel along the axon.

Dendrites

AxonMyelin Sheath

Terminal buttonOr terminal end

Soma

It’s a neuron!

Impulse Transmission• A synapse is a small gap separating neurons

o Types of synapses (axodendritic, axosomatic, axoaxonic)

• In order for neurons to communicate, an electrical impulse must travel down an axon to the synaptic terminal (the “bulb” end of an axon)

Impulse Transmission cont.• At the synaptic terminal, the

electrical impulse will trigger the release of neurotransmitters into the space between neurons

• The neurotransmitters then bind with receptor sites on the postsynaptic ending (the membrane on the other neuron)

The binding to receptor sites influences the electrical response in the post synaptic neuron

NeurotransmittersNeurotransmitters can be… excitatory or inhibitory• Excitatory neurotransmitters increase the probability

of the electrochemical impulse being transmitted to the adjoining cell

• Inhibitory neurotransmitters decrease this probability• A balance is necessary…. If a stroke or trauma

damages the tract of inhibitory motor neurons (neurons not able to inhibit neurotransmitters to other motor neurons) … result is excessive contractions of muscles

• Remember: a typical neuron may have many synaptic connections with the synaptic terminals of many different axons

Sum Up of Neurons

Brain Abscesses• What is a brain abscess?

o a mass of immune cells, pus, and other material due to a bacterial or fungal infection

• What are its etiologies? or causes?oA bacterial or fungal infection that did not start in

the brain...for example, an ear infection could cause a brain abscess if the bacteria travels through the blood (to brain) most common source is a lung infection

o sometimes parasiteso introduction of infectious organism through injury   

(ex. knife wound) or surgery

Brain Abscesses• Inflammation develops as a result of this infection • Infected brain cells, white blood cells, and

live/dead microorganisms collect in a limited area of the brain which may be enclosed by a membrane

• This immune response is good to isolate the infection, however...oThe brain swells and the mass may put pressure

on delicate brain tissueo Infected materials can block vessels of the brain

Brain Abscess Symptoms

• Headache• Stiff or aching neck, shoulder, or back• vomiting• change in mental status (ex. drowsiness, confusion,

instability, slow thought process, coma• seizures• fever and chills• vision changes • loss of muscle function

• Decreased sensation• weakness• language difficulties• loss of coordination

Brain Abscess Treatment

Brain Abscesses may be a serious medical emergency... If pressure in skull becomes high enough it may cause death• Medication

oEspecially broad spectrum antibiotics that work against a number of different bacteria

oAnti-fungal medication may be used (if infection is caused by fungus)

• Surgery (procedure depends on size and depth) oOpening and draining abscessoEntire abscess may be removed if small enough and

enclosed in a sac

Brain Abscess Treatment cont.

• Needle Aspiration (for deep abscess)oInject medication directly into mass

• Diuretics and steroids may be used to reduce swelling

Traumatic Brain Injury http://www.ninds.nih.gov/disorders/tbi/tbi.htm

• Sudden trauma to the brainohead is jolted/ hits an object oobject pierces skull

• Mild cases -oLoss of consciousness, headache, confusion,

lightheadedness, dizziness, blurred vision, ringing in the ears, bad taste in mouth, fatigue, behavioral changes, trouble with memory/concentration/thinking

TBI cont'd...

• Severe casesoSame symptoms as beforeoAlso, headache that does not go away,

 repeated nausea, convulsions, inability to wake up from sleep, dilation of one or both pupils, slurred speech,  weakness or numbness, loss of coordination, increased confusion

TBI cont'd...• Treatment

o quick medical attention - stabilize the patient to prevent further injury

o Not much can be done to reverse the initial injuryo Possible neurosurgery to remove hematomas (ruptured blood

vessels)o Disabilities - problems with thinking, memory, senses,

communication, mental health, o Coma - unconscious, unarousable, unresponsive, unawareo Vegetative state - unconscious, unaware, but periods of alertnesso Persistent Vegetative state - vegetative state for more than one

month

New Treatment Idea for TBI http://www.technologyreview.com/blog/editors/22189/ Technology Reviews Nov 2008• Some of the neural damage that accompanies TBI results from the impact. However, most occurs over days, weeks, or months later. The impact triggered a chemical cascade that triggered the inflammation and cell death. Scientists are trying to come up with treatments that prevent this slow degeneration.

•  Instead of targeting neurons, like scientists have in the past to solve the degeneration problem, scientists are now targeting astroglia (or astrocytes)o these cells are thought to support neurons

• Eli Gunnarson, of the Karolinska Institute in Sweden, has found red-blood-cell booster hormone erythropoietin (EPO) protects against swelling by closing a channel that normally imports water into astroglia

• David Meaney and his colleagues at the University of Pennsylvania, have found that right after injury, astroglia receive a flood of calcium ions; which is toxic to neurons. If a drug could be developed that stops the flood by inhibiting the specific receptor on the cell's surface the degeneration could be stopped (a class of compounds has already been found to do this)

Other Diseases!

• Alzheimer's Diseaseo More common in women than meno Caused by atrophy of cerebral cortex and other forebrain

territoryo In some serious cases, the brain can weigh less than 1000

grams at death.•  Wallenberg Syndrome

o Difficulty swallowingo Hoarsenesso Caused by paralysis of vocal cords

• Wernicke Aphasiao Impairment in the comprehension of written and spoken

languageo  Inability to speak substantive language

http://www.sci.uidaho.edu/med532/dorsalat.htm

http://www.sci.uidaho.edu/med532/alzheimer.htmhttp://www.sci.uidaho.edu/med532/wallenberg.htmhttp://www.sci.uidaho.edu/med532/wernickes_aphasia.htm

Possible New Treatment for Alzheimer'shttp://www.sciencedaily.com/releases/2009/02/090202174818.htm  Science Daily Feb 2009

 • Northwestern University research team found that insulin may

slow or prevent damage and memory loss caused by toxic proteins in Alzheimer's disease, by shielding memory-forming synapses from harm

•  Therapeutics designed to increase insulin sensitivity in the brain may help treat the disease; sensitivity to insulin decreases with age (a risk factor for Alzheimer's)

•  Sergio T. Ferreira, member of research team, commented, "Recognizing that Alzheimer's disease is a type of brain diabetes points the way to novel discoveries that may finally result in disease-modifying treatments for this devastating disease

So How is the Nervous System Interrelated, Interconnected, and Interdependent with other systems??

• The Nervous System works very much with the following systems and organs:

Skin Eyes Ears Mouth Endocrine System Muscular System Skeletal System Circulatory System Respiratory System Immune System

CAN YOU EXPLAIN HOW??