Kuliah4-anatomi2-Nervous sistem

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NERVOUS SYSTEM

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Nervous System =

Systema Nervorum

• _{A complex mechanism by which the}

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Parts of the nervous system

1. Central Nervous System (CNS):

– _{Brain (Encephalon)}

– _{Spinal cord (Medulla spinalis)}

2. Peripheral Nervous system

– _{Cranial and spinal nerves with their}

ganglia

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The nervous system is divided into the

1. peripheral nervous system (PNS) and the

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The PNS consists of:

• sensory neurons running from stimulus receptors

that inform the CNS of the stimuli

• motor neurons running from the CNS to the muscles and glands - called efectors - that take action.

The CNS consists of:

• the spinal cord and the

• brain

The peripheral nervous system is subdivided into : • the sensory-somatic nervous system and the

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The Sensory-Somatic Nervous System

• _{The sensory-somatic system consists}

of 12 pairs of cranial nerves and

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The cranial nerves

Nerves Type Function I

Olfactory sensory olfaction (smell)

II

Optic sensory

vision

(Contain 38% of all the axons connecting to the brain.) III

Oculomotor motor* eyelid and eyeball muscles

IV

Trochlear motor* eyeball muscles

V

Trigeminal mixed

Sensory: facial and mouth sensation

Motor: chewing

VI

Abducens motor* eyeball movement

VII

Facial mixed

Sensory: taste

Motor: facial muscles and salivary glands

VIII

Auditory sensory hearing and balance

IX

parasympathetic nervous s ystem

(PNS)

XI

Accessory motor

swallowing; moving head and shoulder

XII

Hypoglossal motor* tongue muscles

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Structure of Neuron cell

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The Spinal Nerves

• _{All of the spinal nerves are "mixed";}

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The Autonomic Nervous System

The autonomic nervous system consists of sensory neurons and motor neurons that run between the central nervous

system (especially the hypothalamus and

medulla oblongata) and various internal organs such as the:

•_heart

• _lungs

• _viscera

• _{glands (both exocrine and}_endocrine₎

It is responsible for monitoring conditions in the internal

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The actions of the autonomic nervous system are largely involuntary (in contrast to those of the sensory-somatic system). It also difers from the

sensory-somatic system is using two groups of motor neurons to stimulate the efectors instead of one.

• _{The frst, the}_{preganglionic neurons}_{, arise in the}

CNS and run to a ganglion in the body. Here they

synapse with

• _{postganglionic neurons}_{, which run to the efector}

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The autonomic nervous system has two subdivisions,

• _the_{sympathetic nervous system}

and the

• _{parasympathetic nervous}

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The Sympathetic Nervous

System

• _The_{preganglionic}_{motor neurons of}

the sympathetic system (shown in black) arise in the spinal cord. They

pass into sympathetic ganglia which

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The preganglionic neuron may do one of three things in the sympathetic ganglion:

1. synapse with postganglionic neurons (shown in white) which then re-enter the spinal nerve and ultimately pass out to the sweat

glands and the walls of blood vessels near the surface of the body. 2. pass up or down the sympathetic chain and fnally synapse with

postganglionic neurons in a higher or lower ganglion

3. leave the ganglion by way of a cord leading to special ganglia (e.g. the solar plexus) in the viscera. Here it may synapse with

postganglionic sympathetic neurons running to the smooth muscular walls of the viscera. However, some of these

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Functional work

• _{Neurons send signals to other cells as}

electrochemical waves travelling along thin fbres called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses

• _{A cell that receives a synaptic signal may be}

excited, inhibited, or otherwise modulated.

• _{Sensory neurons are activated by physical}

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Functional Work (2)

• Motor neurons, situated either in the central nervous system or in peripheral ganglia, connect the nervous system to muscles or other efector organs.

• Central neurons, which in vertebrates greatly

outnumber the other types, make all of their input and output connections with other neurons.

• The interactions of all these types of neurons form neural circuits that generate an organism's

perception of the world and determine its behavior.

• Along with neurons, the nervous system contains other specialized cells called glial cells (or simply

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From Signals



to behavior

Neuron axon

Signal

(electrochemi

cal wave _neurotra

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Structure of Neuron cell

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Cell structure

• _Neuron:

– _{Unit utama dari sistem syaraf}

– _{Sel besar, inti dan bagian-bagian} – _{Sering ada penjuluran (prosesus)}

axon

– _{Fungsi bagian-bagian sel : seperti sel}

lain (kromosom: pembawa sifat

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Ada dua macam prosessus

• _Dendrit:

– pendek, bentuk dan ukuran berbeda

– Fungsi: menerima rangsangan (impuls)

• _Axon:

– Panjang, tidak bercabang

– Tunggal

– Cabang: collateral

– Akhiran: telodendron

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Selubung syaraf

• _Myelin

– _{Mengelilingi axon,} – _Lipoid

– _{Dikelilingi oleh selubung brkt} Schwann cell (neurolemma)

– _{Sering selubung myelin mengalami pelekukan}  nodus Ranvier

– _{Fungsi Schwann cell:}

• _{Regenerasi axon} • _{Sumber nutrisi}

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Secara struktural neuron dibagi:

• _{Unipolar: mempunyai satu prosesus}

• _{Bipolar: dua prosesus dengan dua}

arah yang berlawanan

• _{Pseudo unipolar: pada awalnya}

bipolar, multipolar dengan arah

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Divisi sensoris – reseptor sensoris

• _{Rangsangan (impuls)} sensoris 

reaksi segera

• _{Atau dapat disimpan dalam otak}

reaksi kemudian

• _Informasi sistem syaraf (nervus

spinalis)  ke medula spinalis 

medula oblongata  pons 

cerebrum  thalamus  daerah

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Divisi motorik - efektor

• Tugas pokok sistem syaraf adalah mengatur

kegiatan tubuh, dicapai dengan mengatur:

– _{Kontraksi otot rangka;}

– _{Kontraksi otot polos dalam organ internal;} – _{Sekresi kelenjar eksokrin dan endokrin}

• Ini disebut fungsi motorik dari sistem syaraf

• Syaraf, otot dan endokrin disebut

• Bagoam sistem syaraf yang langsung

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Peranan sinaps

• _{Sinaps: tempat hubungan satu}

neuron dengan neuron berikutnyua

• _{Suatu tempat menguntungkan untuk}

mengatur penghantaran sinyal

• _{Menentukan arah penyebaran sinyal}

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Peranan muscle spindle (otot dan

tendo)

• _{Muscle spindle} mendeteksi

perubahan panjang serabut otot dan perubahan kecepatan panjang

• _{Tendo golgi} mendeteksi

ketegangan yang bekerja pada tendo otot selama kontraksi otot atau

pereganan otot.

• _{Bekerja pada tingkat bawah sadar}

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Sistem syaraf otonom

• _{Mengatur fungsi viseral tubuh}

• _{Membantu mengatur tekanan arteri,}

motilitas dan sekresi gastrointestinal, output urin, berkeringat, suhu tubuh, dll.

• _{Impuls dikirim dengan sistem}

– _{Simpatis (epineprin dan norepineprin)}

– _{Parasimpatis (jantung, paru, esophagus,}

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Refek otonom

• _{Sistem syaraf otonom mengatur}

fungsi viceral  dengan memakai

refek otonom – gastrointestinal

• _{Bagian atas:}

– _{Bau makan}__{selera makanan melalui}

syaraf dalam hidung  nukleus vagus 

glosofaringeus  salivarius batang otak.

– _{Ke syaraf parasimpatis ke kelj sekretor}