Nervous System (Senses)
What types of sensory receptors are there?
Somatic
Mechanoreceptors
Visceral
Chemoreceptors
General
Thermoreceptors
Special
Nociceptors
Exteroreceptors
Photoreceptors
Enteroreceptors
Proprioceptors
Encapsulated
Unencapsulated
Nervous System (Senses)
What are the types of cutaneous sense organs?
Nervous System (Senses)
What is the network-like pattern on fish and tadpoles?
Neuromasts have
sensitive hair cells
with kinocilia
extending into a
cavity, fluid or a
cupula
Organized into
mechano- or
electroreceptive
structures
Pattern refered to as a
lateral line (canal) or
cephalic canal
Nervous System (Senses)
The Senses: Balance
Kinetic labyrinth
Responds to movement
of endolymph (fluid) in
semicircular canals i.e.
angular (rotational)
acceleration
Nervous System (Senses)
The Senses: Balance
Static labyrinth
Responds to
force of gravity
and linear
acceleration
Nervous System (Senses)
The Senses: Hearing
Auricle collects
sound waves
External
auditory
meatus (canal)
channels sound
waves
Tympanic mem.
& ossicles
conduct sound
waves
Nervous System (Senses)
The Senses: Hearing
The oval window
transfers sound
waves to the liquid
inside the cochlea
Three scala:
vestibuli
media
(cochlear duct)
tympani
Nervous System (Senses)
The Senses: Hearing
Sound waves
vibrate basilar
membrane
causing
microvilli to
bend
Bending causes depolarization in
hair cells that in turn create action
potentials in synapsing neurons
Nervous System (Senses)
The Senses: Hearing
Basilar membrane
stiff near vestibule,
responds to higher
frequency sounds
(20,000 Hz).
Lower pitches
picked up further in
to cochlear duct,
with lowest
Excess wave energy travels back down
frequencies (200
via scala tympani and out round
Hz) at apex
window
Nervous System (Senses)
The Special Senses: Olfaction (smell)
Nervous System (Senses)
The Special Senses: Gustation (taste)
Chemoreceptors
that detect
chemicals which are
in solution (saliva)
are taste buds.
Taste buds are
comprised of
specialized
epithelial cells that
Associated
mainly
with
papillae.
synapse with
neurons.
Also on lips etc.
Nervous System (Senses)
The Senses: Gustation (taste)
Types of papillae:
Circumvallate
Foliate
Fungiform
Filiform (most
numerous but
NO taste buds
here.
Foliate papillae
Nervous System (Senses)
The Senses: Gustation (taste)
Salty
Nervous System (Senses)
What are the layers of the eye and what are
their functions?
3 distinct layers
of tissue in eye:
Fibrous
Sclera & cornea
Vascular
Choroid, iris etc.
Nervous
Retina
Clear light pathway
Nervous System (Senses)
What is the external anatomy of the eye?
Nervous System (Senses)
What is the internal anatomy of the eye?
Nervous System (Senses)
How do our eyes control the amount
of light entering?
Cornea refracts light as it
head towards lens
Iris is attached to ciliary
body and consists of
contractile tissue (smooth
muscle). Coloration is due
to varying amounts of
melanin
Pupil is simply the hole in
the center of the iris
Nervous System (Senses)
How do we focus the image?
Ciliary body contains smooth
muscle fibers, which allow
the distortion of the lens via
suspensory ligaments.
Ciliary processes are very
vascular and produce
aqueous humor (watery
fluid in anterior
compartment).
Nervous System (Senses)
How is light converted into action potentials?
3 neuronal layers of the
retina:
Photoreceptors
Also bipolar neurons and
Ganglionic neurons
Nervous System (Senses)
Are all photoreceptors created equally?
Rods (~120 million each)
Cones (~6-7 million each)
Nervous System (Senses)
How is light converted into action potentials?
The Senses: Vision
Photoreceptors are rather
unique in that they are
hyperpolarized as a result
of stimulation.
In dark (no stimulus)
leaky Na+ channels.
In light (stimulus) Na+
channels close and
hyperpolarization occurs