Nervous system II Flashcards
is the process
initiated by stimuli acting on
sensory receptors.
Sensation
is the conscious
awareness of those
sensations.
Perception
are the means by
which the brain receives
information about the
environment and the body
Senses
have receptors distributed over a large part of the body. General senses are touch, pressure, stretch, heat, cold, and pain. Receptors for general senses are located throughout the body.
General senses
are localized to localized to specific organs that have specialized receptors. Special senses are taste, smell, hearing, equilibrium, and vision. Special sense organs are located in the head.
Special senses
detect heat and cold.
Thermoreceptors
detect touch,
vibration, stretch, and pressure. They are stimulated by
mechanically disturbing the dendrite
of the neuron.
Mechanoreceptors
are pain receptors that detect tissue injury or potential tissue injury. These receptors may be stimulated by a chemical, temperature, or mechanical disturbance.
Nociceptors
respond to
changes in chemical concentrations.
Chemoreceptors
respond to light.
Photoreceptors
Are bare dendrites with no associated
connective tissue.
Free nerve endings
It widespread throughout the skin and mucous
membranes.
It functions as thermoreceptors for heat and
cold nociceptors for pain
Free nerve endings
It is located at dermal papillae of the skin; highly
concentrated in the fingertips and palmar skin.
Tactile corpuscles
It functions as
mechanoreceptors for light
touch and texture.
Tactile corpuscles
These are bare dendrites with
no associated connective tissue.
Hair receptors
It functions as
mechanoreceptors for any light
touch that bends a hair
Hair receptors
Single dendrites surrounded by flattened Schwann cells that in turn are surrounded by fibroblasts, giving a layered appearance like tree rings.
Lamellar corpuscles
It functions as
mechanoreceptors for deep
pressure, stretch, and vibration
Lamellar corpuscles
It is long, flattened capsules with
a few nerve fibers.
Bulbous (Ruffini) corpuscles
It functions as
mechanoreceptors for heavy
touch, pressure, and stretching
of the skin.
Bulbous (Ruffini) corpuscles
It functions as
mechanoreceptors for light touch.
Tactile disks
is the term for taste.
Gustation
There are approximately ____
taste buds in the human mouth.
10,000
The surface of the tongue is covered with
bumps called
lingual papillae.
These are banana-shaped and have
hairlike microvilli (taste hairs) on their
surface.
Taste cells
Taste hairs are exposed to molecules
taken into the mouth through a taste
pore of the taste bud.
Taste cells
These are stem cells in the taste bud
that develop to replace taste cells as
they die.
Basal cells
- They physically support the 50 to 150
taste cells in the taste bud. - They do not have a sensory role
Support cells
This taste sensation is caused
by ions from salts binding to the taste
hairs.
Salt
This taste sensation is
caused by sugars
Sweet
This taste sensation is
associated with acids.
Sour
This taste is associated with
alkaloids such as caffeine, nicotine,
and quinine found in tonic water. It is
also associated with spoiled food.
Bitter
This meaty taste is derived from some amino acids binding to the taste hairs. An example of umami is the taste of beef or chicken broth.
Umami
carries sensory
messages from taste buds in the
anterior two-thirds of the tongue
The facial nerve (CN VII)
carries sensory messages from taste
buds on the posterior one-third of the
tongue
The glossopharyngeal nerve (CN IX)
carries sensory messages for taste from the other taste
buds in the mouth..
The vagus nerve (CN X)
sense of smell
Olfaction
receptors for
olfaction that are located in the mucous
membranes of the roof of the nasal cavity,
called
Olfactory mucosa
The rest of the
mucous membrane lining the nasal
cavity. It has no sensory function.
Respiratory mucosa
Bipolar neurons.
Olfactory cells
is the interpretation of sound
waves travelling in air
Hearing
is measured in cycles per second, called Hertz (Hz)
Pitch
treble
High pitch
bass
Low pitch
is determined by the size of the
sound wave and therefore the size of the
vibration
Volume
Physical reactions initiated by the
hypothalamus
is responsible for
emotional reactions to odors.
amygdala
external ear flap composed of elastic
cartilage. It directs sound waves into the ear.
Pinna
leads an opening in the
temporal bone, called external auditory
meatus, to the tympanic membrane, commonly
known as the eardrum.
Auditory canal-
Contains three tiny bones called ossicles- the
malleus, incus, and stapes
MIDDLE EAR
attached to the tympanic
membrane, and it forms a synovial joint with
the incus.
Malleus
also forms a synovial joint with the
stapes
incus
comes in contact with a
membranous oval window located at the
beginning of the inner ear
Stapes
leads from
the middle ear to the nasopharynx. It is normally
flattened and closed, but it opens during
yawning or swallowing to allow air to enter the
middle ear.
Auditory tube/ Eustachian tube-
It is a complicated mass of fluid-filled
semicircular canals and a spiral tube
embedded in a bony labyrinth (labyrinth
means “maze”) of the temporal bone.
INNER EAR
the stapes of the middle ear that come in contact with the vestibule at a
membrane.
Oval Window
is perceived when the
head is stationary or moving in a straight line.
Static equilibrium
is perceived when the
head is rotating. The rotation would be in the
transverse plane if you were spinning in a
chair, the coronal plane if you were doing a
cartwheel, or the sagittal plane if you were
doing a somersault (forward tuck and roll).
Dynamic equilibrium
It is used to perceive vertical movement of the
head, as in going up and down in an elevator.
Saccule
Is used for horizontal movement of the head,
as in acceleration in a car.
Utricle
which initiates reflexes if
the position of the head changes
abruptly
Spinal cord-
which uses the information
to determine the position of the head for
coordination and posture.
Cerebellum
which coordinate eye movements.
Neurons in cranial nerves III, IV, and
VI-
which directs the sensory
messages of equilibrium to the frontal
and parietal lobes.
Thalamus
light to stimulate the
receptors of vision.
Photoreceptors
it is a phenomenon where in light
travels in straight lines but can be bent as it
passes through materials of different
densities.
Refraction
shade the eyes from the glare of the sun
and help prevent sweat from entering the
eyes
Eyebrows
blink periodically to distribute moisture
across the surface of the eyes. It contains
tarsal glands along its edge (tarsal plate),
which secrete an oil that helps lubricate the
eye.
Eyelids
help keep debris from entering the eye.
Eyelashes
s located deep to the skin, lateral and superior
to each eye. Its function is to produce tears.
Lacrimal gland
a thin, transparent membrane that lines the
eyelids and covers the white, exposed surface
of the eye. Its purpose is to secrete a mucous
film to prevent the eye from drying.
Conjunctiva
if they directly approach the front of the eye in
a straight line.
Rectus
- if they approach the eye at an angle to the
front of the eye.
Rectus
outermost layer, a tough, fibrous layer that
does not stretch. It can be seen as the white
of the eye. The anterior part of the sclera is
transparent.
Sclera
It needs to be transparent to allow
light to enter the eye.
cornea
middle layer
Uvea
is dark and has any
blood vessels to feed the neurons
located on the inner layer of the eye
The choroid layer
composed of smooth muscle and forms a ring around the lens. It also produces a thin, watery fluid called aqueous humor found in the anterior and posterior chambers of the eyes.
The ciliary body
seen as the colored part of the
eye. It is smooth muscle that regulates
the size of the pupil.
The iris
innermost layer. It lines the vitreous
chamber that is filled with vitreous humor, a
transparent, gel-like fluid.
Retina-
used for gray-scale (non color
vision) and low light conditions. They contain a
chemical rhodopsin that reacts to light to
initiate a local potential.
Rods-
used for color vision and are
responsible for the best visual acuity (sharpest
vision). They contain the chemical iodopsin
that reacts to light to initiate local potential.
Cones
primarily responds to one color, either
green, red, or blue.
cones
is located on the retina directly
posterior to the center of the lens. It has more
cones than rods
Macula lutea
is the area where blood vessels
enter the eye and the axons forming the optic
nerve leave the eye
Optic disc
appears as a small
depression in the center of the macula lutea. It
contains only cones, so it is the area of sharpest
vision.
Fovea centralis
if the cornea and
lens focused the image ahead the retina.
Myopia (nearsightedness)
if the cornea and
lens focused the image behind the retina.
Hyperopia (farsightedness)
if the cornea or the lens is not a
perfectly smooth curve, the light rays will not
refract correctly to produce a clearly focused
image on the retina
Astigmatism
When the eye is perfectly focused on the
retina whether it is near or far. This ability is
called
accommodation.
allows the brain to have depth
perception, knowing where the object is located
in space.
Binocular vision
The ciliary muscles and suspensory ligaments
are less able to accommodate the shape of the
lens with age, creating a condition called
presbyopia
Procedures in which a
tuning fork is used to
test for hearing loss
Rinne test Weber test
An eye chart used to
measure visual acuity
Snellen test
A procedure that
measures the pressure
inside the eye
Tonoetry
A disease of the eye in which the cells of the central portion of the retina (macula lutea) degenerate, eventually causing vision loss
Age-related macular
degeneration (AMD)
A progressive loss of
vision due to the clouding
of the lens of the eye.
Cataract
A genetic disorder that
results in the inability to
see certain colors.
Color blindness
Hearing loss caused by a lesion in the outer or middle ear that prevents the proper conduction of vibrations to the inner ear
Conductive hearing
loss
Inflammation of the
conjunctiva
Conjunctivitis
increased intraocular
pressure
Glaucoma
Various shapes of the
eye that affect vision
Myopia/hyperopia/
astigmatism
An inability of the eye to
accommodate for near
and far vision that occurs
with aging
Presbyopia
Infection of the outer ear
swimmer’s ear
Otitis externa
Infection of the middle
ear
Otitis media
Hearing loss caused by a
problem with the organ of
Corti or the auditory
nerve
Sensorineural hearing
loss
