Module 8 Flashcards
light pathway
• First refracted by lens and cornea
• Focused onto the retina
• Once light has been converted to an electrical impulse by retina neurons, the signal exits the eye via the OPTIC NERVE
o No photoreceptors=BLIND SPOT
Accommodation
• Lens contributes to the ability to focus on both near and distant objects
o Distant objects: LENS IS FLAT
o Near objects: CILIARY MUSCLES BEND AND ROUND OUT THE LENS
emmetropia
- Light focuses directly on retina
* 20/20 vision
myopia
- light is focused just short of the retina bc of mis-shaped lens or eyeball
- near sighted
- Cornea: imperfect curvature
- Eyeball is too long
- Need bi-concave lens
hyperopia
- far sighted
- light is focused just behind the retina
- lens accommodation is too thin
- cornea: imperfect curvature
- eyeball is too short
- need bi-convex lens
retina
• neural portion of the eye
two types of photoreceptors
- rods and cones
* sensitive to light
rods
o activated when light levels are low
o if one loses rod function=night blindness
cones
o activated when light levels are high
o contribute to color vision
o loss of cone function: legally blind
o 3 different types which respond to different colors (red, blue, green); lacking=colorblindness
astigmatism test
- All lines equally dark=no astigmatism
* Opposite=astigmatism
color blindness test
- Ishihara plates
- Each plate consists of colored spots and concealed number or shape
- Say what each plate has
- Depending on the amount of correct=determines colorblindness
auditory system
converts pressure waves (sound) into a neural signal
Pathway of auditory system
• Sound first reaches the external ear and enters the external auditory canal
• Vibrations then travel to the tympanic membrane which vibrates
o Attached are three auditory ossicles
• Malleus
• Incus
• Stapes
• These three exert a force onto the oval window
• Oval window transmits the sound to the inner ear
cochlea
inner ear
o Most critical structure for hearing
o Movement of oval window causes movement for cochlea fluid (action potentials are generated
if a person has hearing loss
one can determine if the cause is related to bony transmission or neural deficits by applying a vibrating tuning fork to the skull
conduction deafness
o If a patient can hear the tuning fork, the neural structures are intact
nerve deafness
o If individual cannot hear anything when the tuning forks are against the sku
Weber test
- Strike a tuning fork against the heel of a hand
- Place stem of fork in the middle of subject’s forehead
- If sound is more loudly heard in one ear, conduction deafness or nerve deafness is present in one of the subject’s ears
rinne Test
- Determines if deafness is nerve or conduction related
- Plug one ear with an ear plug
- Place fork directly on mastoid process (bump of bone behind ear) until sound is no longer heard
- Then place tuning fork just outside the ear
- If sound cant be heard, patient may have conduction deafness
olfaction
o Begins in the epithelial tissue
o Olfactory receptor neurons convert the chemical signals into neural impulses
• When an odorant molecule binds to a specific olfactory receptor, it activates that receptor and results in an action potential
Each receptor is specific to a type of odorant
olfactory fatigue
olfactory receptors adapt quickly to odo
Gustatory receptors
located in the taste buds of the tongue, soft palate, epiglottis, and pharynx
• Receptors are specific to certain taste sensations
• Neural impulses from receptors are transmitted to the medulla by the facial nerve, glossopharyngeal nerve, and vagus nerve
• Signal is then transmitted through the thalamus to the parietal lobe of the cerebral cortex
Olfactory fatigue test
o Block the left nostril with an ear plug
o Hold a bottle of oil of wintergreen under right nostril
o Inhale through the right nostril and exhale through the mouth
o Measure how long it takes for the sensation to disappear
heredity and taste test
o Place a piece of PTC paper on your tongue and allow it to mix with your saliva
o Sensation can be positive or negative
CNS
- Central nervous system
- Brain and spinal cord
- Information is processed and incorporated with other incoming info from the body
- Can transmit a signal back to the PNS for all necessary responses via motor neurons
PNS
- Peripheral nervous system
- Sensory and motor neurons outside of the CNS
- Receives information from environment and sends it to brain or spinal cord
Somatic division
- Innervates skeletal muscle
* Make a decision to move your arm
autonomic division
- Innervates smooth muscle, cardiac muscle, and glands
* Get nervous and heart rate increases or begin to sweat
neurons
o Excitable nerve cells and can transmit signals throughout the nervous system
afferent neurons
receive info from environment and send it to CNS aka sensory neurons
interneurons
receive signal from afferent neurons and send the info to other local interneurons or motor neurons
efferent neurons
send info away from the CNS to various effectors aka muscle or glands; motor neurons
Glia
o Nervous system cells which do not transmit neural signals
o Necessary for proper functioning of neurons
o Responsible for the uptake of certain chemicals which affects the ability of neurons to send signals
o Form a myelin sheath which surrounds axons of neurons and ensures rapid conduction of nerve impulses
reflex
occurs when nerve impulses travel over a simple neuron pathway called a reflex arc
reflex arcs have 5 basic parts
- Receptors detect stimulus and create impulse
- Sensory neurons create impulse
- Interneurons: conduct nerve impulses
- Motor neurons: sent impulses to motor cortex and pre-frontal cortex
- Effectors carry out a response to a nerve impulse
cortex
outer region of the brain
gyri
raised ridges of the brain
sulci
indentations
central sulcus
divides the frontal lobe from parietal lobe
frontal lobe
personality, emotions, motor control
temporal lobe
: hearing, recognition
parietal lobe
sensory information, speech
occipital lobe
vision, speech
cerebellum
muscle control
superior colliculi
• Superior colliculi: superior
inferior colliculi
processing auditory information
corpus callosum
: fiber ttract that connects the two brain hemispheres
thalamus
mass of gray matter that receives all sensory info and projects to various cortical structures
hypothalamus
controls hunger, thirst, and circadian rhythyms
fourth ventricle
fluid-filled cavities that contain cerebrospinal fluid
choroid plexus
spongy tissue that produces CSF
pons
motor control, consciousness and sleep
medulla
maintains vital body functions such as heart rate and breathing
