Nervous System1

8/2/2019 Nervous System1

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The Nervous SystemThe Master System


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Nervous SystemNervous SystemBy the end of the lesson you should be able to

Describe the transmission of impulses from

senses to central nervous system and back tomuscles.

Describe the reflex action and the pathwayof the reflex arc.

Describe the function of reflex response.

Describe the role of the central nervoussystem.


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The System


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A system that controls all of theactivities of the body.

The nervous system is made of:

The brain

The nerves

The spinal cord

The senses


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nervous system


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Anatomy

http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Image/0,,239033_1582296_,00.html

Central Nervous System PeripheralNervous System

(CNS) (PNS)

-Brain -Nerve Network of the

Body-Spinal Cord


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Basic Neurons

Sensory neurons carry signalsfrom the outer parts of your body(periphery) into the centralnervous system.

Motor neurons (motoneurons)carry signals from the centralnervous system to the outer parts(muscles, skin, glands) of yourbody.

Interneurons connect variousneurons within the brain andspinal cord.

Receptors sense the environment(chemicals, light, sound, touch)and encode this information intoelectrochemical messages thatare transmitted by sensoryneurons.

http://health.howstuffworks.com/brain2.htm

http://healthmad.com/conditions-and-diseases/brain-

anatomy-for-nurses-made-simple-self-learn-series/

Bipolar

(Interneuron)Pyramidal Cell

Motor Neuron

(multipolar)

Sensory Neuron

(unipolar)


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Basic nerve cell structureBasic nerve cell structure


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3 main types of nerve cells3 main types of nerve cells

sensory

neuronrelay

neuron

motor

neuron


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Classifying Neurons

The nerve cell bodies are generally located ingroups. Within the brain and spinal cord, thecollections of neurons are called nuclei andconstitute the gray matter, so-called because oftheir color. Outside the brain and spinal cord thegroups are called ganglia. The remaining areasof the nervous system are tracts of axons, thewhite matter, so called because of white myelin

sheath. Tracts carrying information of a specifictype, such as pain or vision, generally havespecific names.

http://webschoolsolutions.com/patts/systems/nervous.htm

http://www.cerebromente.org.br/n07/fundamentos/neuron/rosto_i.htm


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Sensory neuronsSensory neurons

Carries impulses from receptors e.g painreceptors in skin to the CNS( brain or spinalcord)


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Relay neuronRelay neuron

Carries impulses from sensory nerves tomotor nerves.


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Motor neuronMotor neuron

Carries impulses from CNS to effector e.g.muscle to bring about movement or gland to

bring about secretion of hormone e.g ADH


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The CellularComponents

Neurons

-Function: transmit

information

-There are 28 billion inthe human body

-Longest neuron is alittle over 1 meter

Glial Cells

-Function: support neurons in

place and provide insulation

-These cells outnumber the

neurons by 1 to 10 ratio


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Transmission of signals


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The Synapse

parkinsons

parkinson


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NERVOUS SYSTEM

CNS (Central Nervous System)

SegmentationPNS (Peripheral Nervous System)Spinal NervesNeuron Types

Autonomic Nervous System

(how many nervous systems are thereanyways?)


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Central Nervous System (CNS)

Brain and Spinal CordCentral CommandPNS (Peripheral Nervous System) arenerves that go out to targets in body


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The Central Nervous System controls all of the bodys activities.

* The Central Nervous System is made of two main organs.

1. The brain

2. The spinal cord


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The Central Nervous System is made of the brain and the spinal cord.

The Central Nervous System controls everything in the body.


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An organ that controls your emotions, your thoughts, and everymovement you make.


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Peripheral Nervous System (PNS)

All nerves that leave the CNSTwo Modalities:

Sensory/Afferent

(info. In)

Motor/Efferent

(commands out)

Somatic

Visceral/Autonomic

Somatic

Visceral/Autonomic

--smooth mm.

--heart--glands


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BrainCranial Cavity of SkullSpinal Cord

Vertebral ArchesCranial Nerves I-XII (offbrain)Spinal Nerves

C--8 prs (L,R)T--12 prsL--5 prsS--5 prs


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Transverse View (x-section)

vertebral body

vertebral arch

vertebral foramen

spinal cord


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Sagittal View

vetebral body, arch

intervertebral discspinal cordspinal nerves (where?)


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Zebra-Man

DermatomesEach is sensory area ofone spinal nerve


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Segmental Spinal nerve


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Autonomic Targets

All have dual

sympathetic and

parasympathetic

innervation


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The nervous system also allows you to react to a stimulus.

A stimulus is a change in the environment.

Example: A hot stove

Or tripping over a rock


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Your reactions are automatic.

Automatic means that you do not have to think about your reactions.

Example: If a bug flies by your eye,

you will blink.


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The Outer Nervous System is made of the nerves and the sense organs.

Nerves Sense organs


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Messages carried throughout the body by nerves.


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The Neuron

-the cell body, containing the nucleus (genetic material)

-dendrites, hair-like structures surrounding the cell body,which conduct incoming signals-the axon (or nerve fiber), varying in length from a millimeter

to a meter, which conduct outgoing signals emitted by theneuron. Axons are encased in a fat-like sheath, calledmyelin, which acts like an insulator and, along with theNodes of Ranvier, speeds impulse transmission



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Glia

-Astrocyte - provides physical and nutritional support for

neurons; digests part of dead neurons as well as regulates theextracelullar fluid around the neuron.

-Microglia - digests part of dead neurons

-Oligodendroglia - provides insulation for neurons (myelin)

-Satellate cell- provides physical support for neurons in PNS

-Schwann cell- provides insulation for neurons (myelin)

http://library.thinkquest.org/C0126536/main.php?currentchap=1&currentsect=neuron.htm&pagenum=6


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How does it work?

When at rest a neuron ispolarizedthat is, it has anegative charge on theinside of the cell relativeto the outside of the cell.This is because it has a

higher concentration ofnegatively charged ionson the inside. Whenstimulated, the nerve cellmembrane becomespermeable to sodium ions,which rush in temporarilycausing a positive chargeto build up on the insiderelative to the outside.When the electricalimpulse reaches the endof the axon it istransferred to the nextnerve cell so the messagehttp://www.naturalhealthschool.com


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More Shapes and Sizes

http://www.mind.ilstu.edu/curriculum/neurons_intro/neurons_intro.php


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Somatosensory Receptors

Input (afferent system) to the nervous system is in the formof our five senses: touch/pain, vision, taste, smell, andhearing. Pain, temperature, and pressure are known assomatic senses. Sensory receptors are classified

according to the type of energy they can detect andrespond to.

Mechanoreceptors: hearing and balance, stretching.

Photoreceptors: light.

Chemoreceptors: smell and taste mainly, as well asinternal sensors in the digestive and circulatory systems.

Thermoreceptors: changes in temperature.

Electroreceptors: detect electrical currents in thesurrounding environment.



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Physiology (function)

http://webschoolsolutions.com/patts/systems/nervous.htmhttp://www.biologymad.com/NervousSystem/nervoussystemintro.htm

In the PNS, collections of

neurons are called ganglia

In the CNS, collections of

neurons are called nuclei

Involuntary Control Voluntary Control


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Physiology ofAutonomic Nervous

System

http://www.biologymad.com/NervousSystem/nervoussystemintro.htm

Sympathetic

(stimulate

function)

Parasympathetic

(calms)


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Thank you


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Nervous System1

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