Sistem saraf adalah sistem yang berfungsi untuk mengatur dan mengkoordinasikan tubuh manusia. Ada 2 sistem regulatorik yang berperan: sistem saraf dan sistem endokrin (hormon). Perbedaan dari sistem saraf dan sistem endokrin dilihat dari responnya: Sistem saraf:cepat,singkat,spesifik. Sistem endokrin: Lambat,lebih lama, spesifik.

1. Introduction to Nervous system
M. Djauhari Widjajakusumah
Departement of Physiology
Faculty of Medicine University of Indonesia
Introduction to Nervous system
M. Djauhari Widjajakusumah
Departement of Physiology
Faculty of Medicine University of Indonesia

2. ORGANIZATION OF THE NERVOUS SYSTEM
• The nervous system is divided into two parts
o The central nervous system (CNS)
o The peripheral nervous system (PNS)
 afferent (or sensory) neurons
 efferent (or motor) neurons
• Information flow through the nervous system follows the basic
reflex pattern
Silverthorn Human Physiol 5e, 2010

3. ORGANIZATION OF THE NERVOUS SYSTEM
o The central nervous system (CNS)
 the brain and the spinal cord
 the integrating center for neural reflexes
 integrates information that arrives from the afferent branch of
the PNS and determine whether a response is needed
 sends output signals directing an appropriate response (if any)
that travel through efferent neurons to their targets, which are
mostly muscles and glands
Silverthorn Human Physiol 5e, 2010

4. ORGANIZATION OF THE NERVOUS SYSTEM
o The peripheral nervous system (PNS)
 Afferent (or sensory) neurons
• Sensory receptors continuously monitor conditions in the internal and
external environments
• Sensory receptors send information along afferent neurons to the central
nervous system
 Efferent neurons
• Somatic motor division,
– controls skeletal muscles
• Autonomic division,
– controls smooth and cardiac muscles, exocrine glands, some
endocrine glands, and some types of adipose tissue
– also called the visceral nervous system  it controls contraction and
secretion in the various internal organs [viscera, internal organs].
– divided into sympathetic and parasympathetic branches
Silverthorn Human Physiol 5e, 2010

5. FIGURE 8-1 Organization of
the nervous system.
The peripheral nervous
system (PNS) sends
information to the central
nervous system (CNS)
through afferent
(sensory) neurons and takes
information from the CNS
to target cells via efferent
neurons. The enteric
nervous system can act
autonomously or can be
controlled by
the CNS through the
autonomic division of the
PNS.
Silverthorn Human Physiol 5e,
2010

6. ● FIGURE 5-1 Organization of the nervous system.

7. FUNCTIONAL CLASSIFICATION
• Based on the direction in which a neuron transmits a nerve impulse.
• Neurons found in the peripheral nervous system are of two basic
functions:
(1) Afferent neurons carry impulses towards the central nervous
system (brain or spinal cord)
(2) Efferent neurons carry impulses away from the central nervous
system
All afferent neurons carry sensory information, so they are also called
sensory neurons
All efferent neurons affect the activity of muscles or glands, they are
also called motor neurons
sensory = afferent
motor = efferent

8. PERIPHERAL NERVOUS SYSTEM ORGANIZATIONPERIPHERAL NERVOUS SYSTEM ORGANIZATION

10. Types of Fibres in Peripheral and Cranial NervesTypes of Fibres in Peripheral and Cranial Nerves
Afferent
• Somatic
 General: sensory from cutaneous and muscle receptors
 Special: vision, hearing
• Visceral
 General: sensation from viscera
 Special: smell, taste
Efferent
• Somatic
 General: motor to skeletal muscle
 Special: efferent to eye, ear
• Visceral
 General: autonomic motor
 Special: motor to brachiomeric musculature
Afferent
• Somatic
 General: sensory from cutaneous and muscle receptors
 Special: vision, hearing
• Visceral
 General: sensation from viscera
 Special: smell, taste
Efferent
• Somatic
 General: motor to skeletal muscle
 Special: efferent to eye, ear
• Visceral
 General: autonomic motor
 Special: motor to brachiomeric musculature

18. Vander et al.: Human Physiology: The Mechanism of Body Function,Vander et al.: Human Physiology: The Mechanism of Body Function,
8th Ed, 20018th Ed, 2001

19. Silverthorn Human Physiol 5e, 2010

20. Motor neuron with a myelinated axon. A motor neuron is comprised of a cell body (soma)
with a nucleus, several processes called dendrites, and a long fibrous axon that originates from
the axon hillock. The first portion of the axon is called the initial segment. A myelin sheath
forms from Schwann cells and surrounds the axon except at its ending and at the nodes of
Ranvier. Terminal buttons (boutons) are located at the terminal endings.

22. GENERAL PROPERTIES OF SENSORY SYSTEMS
• Begin with a stimulus, in the form of physical energy that acts on a
sensory receptor.
• The receptor is a transducer that converts the stimulus into an
intracellular signal, usually a change in membrane potential.
• If the stimulus is above threshold, action potentials pass along a sensory
neuron to the central nervous system, where incoming signals are
integrated.
– Some stimuli pass upward to the cerebral cortex, reach conscious
perception
– Others are acted on subconsciously, without our awareness.
• At each synapse along the pathway, the nervous system can modulate
and shape the sensory information.
Silverthorn Human Physiol 5e, 2010

23. Silverthorn Human Physiol 5e, 2010

25. Vander et al.: Human Physiology: The Mechanism of Body Function, 8th Ed, 2001Vander et al.: Human Physiology: The Mechanism of Body Function, 8th Ed, 2001

26. FIGURE 10-1 Sensory receptors.
(a) Simple receptors may have
myelinated or unmyelinated
axons. (b) This illustration
shows a Pacinian corpuscle,
which senses touch. (c) The cell
illustrated is a hair cell, found in
the ear.
Silverthorn Human Physiol 5e,
2010

27. Sensory Transduction Converts Stimuli into Graded Potentials
• Receptors convert diverse physical stimuli, into electrical signals.
– transduction: the conversion of stimulus energy into information that can
be processed by the nervous system.
• In many receptors, the opening or closing of ion channels converts
mechanical, chemical, thermal, or light energy directly into a change in
membrane potential.
• Some sensory transduction mechanisms include signal transduction and
second messenger systems that initiate the change in membrane potential.
• The change in sensory receptor membrane potential is a graded potential
called a receptor potential.
– In some cells, the receptor potential initiates an action potential that
travels along the sensory ber to the CNS.
– In other cells, receptor potentials influence neurotransmitter secretion by
the receptor cell, which in turn alters electrical activity in an associated
sensory neuron. Silverthorn Human Physiol 5e,
2010

28. An afferent neuron with a receptor ending. The receptor potential arises at the nerve ending 1, and
the action potential arises at the first node of the myelin sheath 2. (Vander et al.: Human Physiology:Vander et al.: Human Physiology:
The Mechanism of Body Function, 8The Mechanism of Body Function, 8thth
Ed, 2001, Fig 9-2)Ed, 2001, Fig 9-2)

29. Vander et al.: Human Physiology: The Mechanism of Body Function, 8th Ed, 2001Vander et al.: Human Physiology: The Mechanism of Body Function, 8th Ed, 2001

30. FIGURE 10-7 Sensory neurons use action potential frequency and duration to code stimulus
intensity and duration; Silverthorn Human Physiol 5e, 2010

37. Synaptic transmission

44. Somatic Spinal Reflexes

52. General organization of the somatosensoryGeneral organization of the somatosensory
system.system.
The three basic levels of neural integration are the receptorThe three basic levels of neural integration are the receptor
level, the circuit level, and the perceptual level. The circuitlevel, the circuit level, and the perceptual level. The circuit
level involves noncortical CNS centers, while thelevel involves noncortical CNS centers, while the
perceptual level involves cortical sensory centers.perceptual level involves cortical sensory centers.
The first-order neurons are at the bottom of the figure andThe first-order neurons are at the bottom of the figure and
include the sensory receptors. The third-order neurons areinclude the sensory receptors. The third-order neurons are
the uppermost neurons in the figure, with cell bodies in thethe uppermost neurons in the figure, with cell bodies in the
thalamus and terminals in the somatosensory cortex.thalamus and terminals in the somatosensory cortex.
Second-order neurons connect the first- and third-orderSecond-order neurons connect the first- and third-order
neurons.neurons.
FIGURE 13.2FIGURE 13.2

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