Senses - UniMAP

GENERAL SENSES
Dr. Hj. Abdul Rashid Hj. Said.
Consultant Psychiatrist
Hospital Tuanku Fauziah,
Kangar, Perlis.
Introduction
• Sense is the ability to perceive stimuli.
• Sight, smell, taste, touch and hearing
• General senses – distributed over a large part of
the body eg. Pain, touch, temperature, vibration,
itch and proprioception.
# somatic
# visceral
• Special senses - localized to specific part of the
body eg. Smell, taste, sight, hearing and
balance.
RECEPTORS
• Sensory nerve endings or specialized cell
capable of responding to stimuli by
developing action potential.
• Mechanoreceptors – respond to
mechanical stimuli such as bending or
stretching.
• Chemoreceptors – respond to chemicals
such as odour molecules
RECEPTORS…..
• Photoreceptors – respond to light.
• Thermoreceptors – respond to
temperature changes.
• Nociceptors – respond to stimuli that result
in sensation of pain
PAIN
• Two types of pain sensation.
– 1. Sharp well localized, pricking or cutting
pain. Faster action potential
2. Diffuse, dull, burning or aching pain.
Slower action potential
Referred Pain
• A painful sensation perceived to originate
in the region of the body that is not the
source of the pain stimulus.
Areas of referred pain
Suppression of Pain.
• Local anaesthesia - blocking the action
potential by using chemical agents.
• General anaesthesia – Pain sensation
can also be suppressed if loss
conciousness is produced. Chemical
agent that block the reticular formations
PHANTOM PAIN
• Occurs in people with appendages
amputated.
• Perceive intense pain in the amputated
structure as if it were still there.
• Integration of cerebral cortex results in
perception of pain that is projected to the
site of sensory receptor for that pathway.
SPECIAL SENSES
• OLFACTORY (SENSE OF SMELL)
• SENSE OF TASTE
• SIGHT / VISION
• HEARING AND EQUILIBRIUM
Special Senses
• SENSE of TASTE
VISION.
Lacrimal apparatus
Lacrimal apparatus
Neuronal Pathways for Vision
• 1. Each visual field is divided into a
temporal and nasal half.
• 2. Light from each half of the a visual field
projects to the opposite side of the retina.
• 3. An optic nerve consists of axons
extending from the retina to the optic
chiasma.
Neuronal Pathways for Vision
• 4. In the optic chiasma axons from the
nasal part of the retina cross and project to
the opposite of the brain. Axons of the
temporal part does not cross.
• 5. An optic tract consists of axons that
have passed through optic chiasma to the
thalamus.
Neuronal Pathways for Vision
• 6. The axons synapse in the thalamus.
Collateral branches of the axons in the
optic tracts synapse in the superior colliculi.
• 7. An optic radiation consists of axons from
thalamic neurons that project to the visual
cortex.
• 8. The right part of each visual field projects to
the left side of brain and vice versa.
Eye Disoders
• Myopia (Nearsightedness) – Rabun jauh.
• Hyperopia (Farsightedness) – Rabun
dekat
Rabun jauh
Rabun dekat
Conjunctivitis
• Infection of the conjunctiva
HEARING AND BALANCE
• The ear - External Ear
- Middle Ear
- Inner ear
Hearing.
Neuronal Pathways for Hearing
• 1. Sound waves strike the tympanic
membrane and cause it to vibrate.
• 2. Vibration of the tympanic membrane
causes the three bones of the middle ear
to vibrate.
• 3. The stapes vibrates in the oval window.
• 4. Vibration of the stapes causes the
perilymph in the scala vestibuli to vibrate
Neuronal Pathways for Hearing
• 5. Vibration of the perilymph passes
through the vestibular membrane and
causes vibration of the endolymph in the
cochlear duct.
• 6. Vibration of the endolymph causes
displacement of the basillar membrane
Neuronal Pathways for Hearing
• 7. Vibration of the perilymph in the scala
vestibuli and of the endolymph in the cochlear
duct are transferred to the perilymph of the scala
tympani.
• Vibrations in the perilymph of the scala tympani
are transferred to the round window, which is
flexible and allows movement of the entire fluid
column of the perilymph.
Ear Disorders
• Otitis Media – infection of the middle ear.
Equilibrium
• Static equilibrium – associated with the
vestibule and is involved in evaluation the
position of the head relative to the gravity.
• Kinetic equilibrium – associated with
semicircular canal and is involved in
evaluating changes in the direction and
rate of head movements.
Semicircular Canal
Effects of Aging on the Special
Senses
• Presbyacusis - As the age increasing, the
number of hair cells in the cochlear
decrease. The decline doesn’t occur
equally in both ears.
• Old people tends to fall due to decrease in
number of hair cells in the saccule, utricle
and ampullae.
Example of Questionnaires
• Multiple Choice Questionaires.
• 1. Berikut adalah sel-sel sistem saraf
pusat.
A. Microglia
T/F
B. Limfosit
T/F
C. Neutrophil
T/F
D. Astrocytes
T/F
E. Ependymal cell
T/F
• 2. Berikut adalah perkara-perkara yang
benar mengenai action potential selsel saraf.
A. Resting membrane potential berlaku
kerana perbezaan cas negetif dan
positif. T/F
B. Depolarization adalah proses
permulaan impulse. T/F
C. Action potential sel-sel saraf bergerak di
kedua arah. T/F
D. Pencetusan pergerakan action potential
berdasarkan hukum “all in one law”. T/F
E. Repolarization adalah proses permulaan impulse.
T/F.
Contoh soalan nota pendek.
• 1. a. Nyatakan fungsi-fungsi utama sistem
saraf pusat. (4 markah)
b. Bagaimanakah sistem saraf periferi
berintegrasi dengan sistem saraf
pusat ( 3markah).
c. Berikan contoh khusus untuk soalan 1b.