Sistem sensorik
Dr. Shofa Nur Fauzah
Divisi Fisiologi Fk UNSWAGATI
Tujuan Instruksional Umum :
1. Mahasiswa mampu menjelaskan reseptor-
reseptor sensorik
Tujuan Instruksional Khusus :
1. Mahasiswa mampu menjelaskan mengenai
reseptor sensorik dalam mengolah informasi
Sistem Sensorik
12 psg saraf
kranial
Somatik
31 psg saraf
spinal
Sistem saraf
perifer
Simpatik
autonom
parasimpatik
Saraf Spinal
Terdiri dari
• divisi afferen : reseptor afferen dorsal MS
jaras sensorik cerebrum/cerebellum
Classification of Neurons (by function)
Sensory Neurons –
(afferent) have
specialized receptor ends
that sense stimuli and
then carry impulses from
peripheral body parts to
brain or spinal cord.
Can be unipolar or
bipolar.
Sensory Receptors
• are specialized epithelial cells or neurons that
transduce environmental signals into neural
signals.
• The environmental signals that can be
detected include mechanical force, light,
sound, chemicals, and temperature
KLASIFIKASI TIPE STIMULUS
Mekanoreseptor Thermoreseptor Fotoreseptor
(sentuh, tekanan,
regangan, getaran) (perubahan suhu) (cahaya)
Kemoreseptor
(penciuman, rasa, Nosiseptor (kerusakan
perubahan kimia cairan jaringan)
intersisitial dan darah)
Classsification by Location
• Exteroceptors (ek0ster-o-sep9torz) are sensitive to stimuli
arising outside the body (extero 5 outside), so most
exteroceptors are near or at the body surface. They include
touch, pressure, pain, and temperature receptors in the
skin and most receptors of the special senses (vision,
hearing, equilibrium, taste, smell).
• Interoceptors (in0ter-o-sep9torz), also called
visceroceptors,
respond to stimuli within the body (intero 5 inside), such as
from the internal viscera and blood vessels. Interoceptors
monitor a variety of stimuli, including chemical changes,
Nonencapsulated (Free) Nerve
Endings
• Present nearly everywhere in the body,
nonencapsulated (free) nerve endings of
sensory neurons are particularly abundant in
epithelia and connective tissues.
• Most of these sensory fibers are
nonmyelinated, small-diameter group C fibers,
and their distal endings (the sensoryterminals)
usually have small knoblike swellings.
Nonencapsulated (Free) Nerve
Endings
• Temperature cold (10–40°C, or 50–104°F) are
located in the superficial dermis. Those responding to
heat (32–48°C, or 90–120°F) are deeper in the dermis.
• Painful stimuli by Nociceptors plasma membrane
protein called the vanilloid receptor. This protein is an
ion channel that is opened by heat, low pH, and various
chemicals including capsaicin, the substance found in
red peppers
• Tissue movements caused by pressure
• Itch Located in the dermis, the itch receptor escaped
detection for years because of its thin diameter
Nonencapsulated (Free) Nerve
Endings
• Tactile (Merkel) discs, which lie in the deepest layer of
the
epidermis, function as light touch receptors. Certain
free
nerve endings associate with enlarged, disc-shaped
epidermal cells (tactile or Merkel cells) to form tactile
discs.
• Hair follicle receptors, free nerve endings that wrap
basket like around hair follicles, are light touch
receptors that detect bending of hairs. The tickle of a
mosquito landing on your skin is mediated by hair
follicle receptors.
Encapsulated Nerve Endings All
encapsulated nerve endings
• Virtually all encapsulated receptors are
mechanoreceptors, but they vary greatly in
shape, size, and distribution in the body.
• Tactile corpuscles or Meissner’s corpuscles
• Lamellar corpuscles, also called Pacinian
corpuscles
• Bulbous corpuscles or Ruffini endings
• Muscle spindles, joint knees, tendon organ.
• Ujung saraf bebas dihantarkan mll serabut
saraf C (unmyelinated, 2m/det) dan Að
(myelinated,5-30m/s)
• Ujung rambut, Ruffini, Corpuscle
Meissner,Diskus Merkel(reseptor Iggo Dome)
dihantarkan mll serabut saraf A β (30-
70m/sec)
Somatosensory
• Three main levels of neural integration
operate in the somatosensory (or any sensory)
system
1. Receptor level: sensory receptors
2.Circuit level: processing in ascending pathways
3. Perceptual level: processing in cortical sensory
areas
Reseptor sensory
• Reseptor primer potensial aksi dihasilkan
dari potensial reseptor
• Reseptor sekunder potensial aksi dihasilkan
oleh pelepasan neurotransmitter dari reseptor
Steps in sensory transduction
a. Stimulus arrives at the sensory receptor. The
stimulus may be a photon of light on the
retina, a molecule of NaCl on the tongue, a
depression of the skin, and so forth.
b. Ion channels are opened in the sensory
receptor, allowing current to flow.
Usually the current is inward, which produces
depolarization of the receptor
• The change in membrane potential produced
by the stimulus is the receptor potential, or
generator potential .
• If the receptor potential is large enough, the
membrane potential will exceed threshold and
an action potential will fire in the sensory
neuron.
• Receptor potentials are graded in size
depending on the size of the stimulus
• Reseptor dapat beradaptasi secara lambat atau
cepat
• Adaptasi : penurunan sensitivitas oleh stimulus
yang berulang
1. Reseptor tonik adaptasi lambat/tidak
beradaptasi, terus-menerus memberikan
stimulus.mis:kekuatan otot dan proprioseptif
sendi
2. Reseptor fasik adaptasi cepat. Mis:reseptor
taktil
• Area Asosiasi somatosensori area
broadman 5 & 7
Daftar Pustaka
• Seeley’s.Anatomy&phisiology. Mcgrew-Hill.
2011.US
• Guyton&Hall. Buku Ajar Fisiologi Kedokteran.
EGC.Jakarta.2006
