Unit 5: Ch 16 (Sense Organs) Flashcards
1
Q
Accessory structures of the eye
A
- Orbit: eye socket
- Eyelids/palpebrae: enhance nonverbal communications
- Eyelids/palpebrae: block foreign objects from the eye
- Conjunctiva: mucus membrane that covers the inner surface of the eyelid and anterior surface of the eyeball
- Lacrimal apparatus: contains the lacrimal gland and a series of ducts that drain the tears into the nasal cavity
- Extrinsic eye muscles: attach to the walls of the orbit & external surface of the eyeball
- Orbital fat: surrounds the eye on the sides and back; cushions the eye
2
Q
Anatomy of the ear
A
- Sections
- Outer: the part you can see, ceruminous glands
- Middle: vibrations, auditory ossicles
- Inner: where the NS components are housed
- The outer and middle sections are concerned only with transmitting sound to the inner ear, where vibration is converted to nerve signal
3
Q
Astigmatism
A
- Inability to simultaneously focus light rays that enter the eye on different planes
- Caused by a deviation in the shape of the cornea
- Corrected with cylindrical lenses
4
Q
Cochlea
A
- Organ of hearing
- 3 fluid-filled chambers separated by membranes
- Scala vestibuli: superior chamber
- Scala tympani: inferior chamber
- Scala media: middle chamber; triangular shaped (aka cochlear duct)
5
Q
Emmetropia
A
- A state in which the eye is relaxed and focused on an object without effort (normal vision)
6
Q
Endolymph
[HOLD]
A
- High Potassium fluid; K+ ions are secreted into the endolymph by cells around the circumference of the cochlear duct
- Strong electrochemical gradient from the endolymph to the hair cell cytoplasm
- This gradient provides the potential energy that enables the hair cell to work
- Each upward movement of the basilar membrane pushes the inner hair cells closer to the stationary tectorial membrane. This forces the stereocilia to bend in the direction of the tallest one
- K ions flow into the hair cell and depolarize it
- The hair cell releases a burst of neurotransmitter, exciting the sensory processes of the cochlear nerve cells below it
- Thus a signal is generated in the cochlear nerve and transmitted to the brain
7
Q
Equilibrium
A
- The sense of body orientation, movement, and balance
8
Q
Equilibrium hair cells & supporting cells
A
- The saccule and utricle each contain a patch of hair cells and supporting cells called a macula
- Macula sacculi: vertical movement (respond to vertical acceleration and deceleration)
- Macula utriculi: horizontal movement (determines tilt of head)
9
Q
Equilibrium projection pathways
A
- Hair cells of the macula sacculi, macula utriculi, and semicircular ducts synapse at their bases with sensory fibers of the vestibular nerve
- The vestibular nerve and the cochlear nerve merge to form CN VIII (Vestibulocochlear)
- Vestibular nuclei process signals about the position and movement of the body and relay information to 5 targets
- Cerebellum
- Reticular formation
- Spinal cord
- Thalamus
- Nuclei of the oculomotor
10
Q
Equilibrium types
A
-
Static equilibrium
- The perception of the orientation of the head in space (whether it is erect or tilted)
-
Dynamic equilibrium
- The perception of motion or acceleration
- 2 kinds
- linear acceleration: a change in velocity in a straight line, as when riding in a car
- angular acceleration: a change in the rate of rotation, as when your car turns a corner
11
Q
Eye layers
A
-
Fibrous layer
- 2 regions
- sclera & cornea
- 2 regions
-
Vascular/uvea layer
- 3 regions
- choroid
- ciliary body
- iris
- 3 regions
-
Inner layer
- Consists of the retina and the beginning of the optic nerve
12
Q
Frequency
A
- The number of cycles per second (cycle is the movement of a vibrating object back and forth)
- 2 types
- infrasonic: below 20 Hz
- ultrasonic: above 20,000 Hz
13
Q
Gustation
A
- Chemical stimulation of sensory cells clustered in taste buds
- The chemical stimuli are called tastants
14
Q
Hair cells of inner ear
A
-
Inner hair cells (IHCs)
- sensory neurons
- all we hear comes from the IHCs, which supply ~90% of the sensory fibers of the cochlear nerve
-
Outer hair cells (OHCs)
- sensory & motor neurons
- adjust the response of the cochlea to different frequencies and enable the IHCs to work with greater precision
15
Q
Hearing
A
- A response to vibrating air molecules
16
Q
Hearing & equilibrium
A
- Cranial nerve VIII (vestibulocochlear)
- Vestibulor: equilibrium
- Cochlear: hearing
- Hearing and equilibrium senses reside in the inner ear
- Use mechanoreceptors
17
Q
Hyperopia
A
- Farsightedness
- Condition in which the eyeball is too short
- Retina lies in front of the focal point of the lens, and the light rays have not yet come into focus when they reach the retina
- Corrected with convex lenses
18
Q
Information transmitted by sensory receptors
A
- Modality: type of stimulus or sensation produced
- Location: encoded by which nerve fibers issue signals to the brain
- Intensity: whether a sound is loud/soft, light is bright/dim, a pain is mild/severe, etc.
- Duration: how long a stimulus lasts
19
Q
Inner ear
A
- Maze of temporal bone passages called the bony labyrinth
- Lined by tubes called the membranous labyrinth (in the temporal lobe)
- Neural tissue
20
Q
Light & dark adaptation
A
-
Light adaptation
- Pupils constrict to reduce pain and intensity
- Color vision and acuity below normal for 5-10 mins
-
Dark adaptation
- Dilation of pupils occurs
- In 1-2 mins, night (scotopic) vision begins to function
21
Q
Lingual papillae
A
- Visible bumps on the tongue
- Types
- Filiform papillae: spikes without taste buds. Responsible for the rough feel of a cat’s tongue
- Foliate papillae: form parallel ridges on the sides of the tongue where most chewing occurs and most flavor chemicals are released
- Fungiform papillae: widely distributed taste buds concentrated at the tip and sides of the tongue
- Vallate papillae: large, arranged in a V, contain up to half of all taste buds
22
Q
Loudness
A
- The perception of sound energy, intensity, or the amplitude of vibration
- Expressed in decibels (dB)
- 0 dB defined by a sound energy that corresponds to the threshold of human hearing
- Every 20 dB step up the scale represents a sound with 10x greater intensity
23
Q
Middle ear
A
- Help coordinate speech with hearing
- Conducts vibrations
- Tympanic membrane (eardrum) nerves V & VIII: innervated by sensory branches of the vagus and trigeminal nerves
- Tympanic cavity: contains auditory ossicles
- Auditory (eustachian) tube: equalizes air pressure on both sides of the tympanic membrane. Serves to aerate and drain the middle ear
- Auditory ossicles: connect the tympanic membrane to the inner ear (malleus, incus, stapes)
24
Q
Myopia
A
- Nearsightedness
- Condition in which the eyeball is too long
- Light rays come into focus before they reach the retina and begin to diverge again by the time they fall on it
- Corrected with concave lenses
25
Q
Near point of vision
A
- The closest an object can be and still come into focus