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
26
Q
Near response or adjustment to close-range vision process
A
- 3 processes to focus an image on the retina:
- Convergence of the eyes
- Constriction of the pupil
- Accommodation of the lens
27
Q
Neural components
A
-
Retina
- The only part of the brain that can be viewed without dissection
- Attached at two points: optic disc & ora serrata
-
Optic nerve
- Optic disc contains no receptor cells and produces a blind spot
28
Q
Neuropathic pain
A
- Stems from injuries to the nerves, spinal cord, meninges, or brain
- Two types of nerve fibers mediate pain
- Fast pain: immediate, sharp pain
- Slow pain: originates in small unmyelinated type C nerve fibers. Delayed and more burning/aching feel, and harder to identify where the pain is coming from
29
Q
Nociceptive pain
A
- Stems from tissue injury such as cuts, burns, and chemical irritations
- Associated with tissue inflammation
- Subdivisions
- Visceral pain: arise from internal organs
- Deep somatic pain: arise from bones, joints, muscles
- Superficial somatic pain: arise from the skin
30
Q
Olfaction
A
- Cranial nerve I
- Sense of smell in response to airborne chemicals called odorants
- Odorant molecules activate the receptors
31
Q
Olfactory mucosa cells
A
- Contains same cell types as those in gestation:
- olfactory cells: chemoreceptors
- basal cells: regenerating cells
- supporting cells: homeostasis
32
Q
Olfactory projection pathways
[DRAFT]
A
- Only sense that does not go through the thalamus
33
Q
Optical components
A
- Transparent elements that admit light rays, bend/refract them, and focus images on the retina
- Components
- Aqueous humor: serous fluid secreted by the ciliary body
- Lens: composed of flattened, compressed lens fibers
- Vitreous body: transparent jelly that fills the vitreous chamber
34
Q
Outer ear
A
- Conducts sound waves
- Auricle (pinna): elastic cartilage
- Auditory canal: terminates at the tympanic membrane
- External acoustic meatus: guard hairs, cerumen
35
Q
Pain
A
- An uncomfortable perception of tissue injury or noxious stimulation
- A symptom of an underlying condition
36
Q
Pain categories
A
- Nociceptive
- Neuropathic
37
Q
Pain projection pathways
A
- Pain signals reach the brain by 2 main pathways
- Signals from the head travel to the brainstem by way of four cranial nerves: V, VII, IX, X
- Pain signals from the neck and below travel by way of three ascending spinal cord tracts:
- spinothalamic tract
- spinoreticular tract
- gracile fasciculus
38
Q
Photopupillary reflex
A
- Pupillary constriction in response to light
- Mediated by an autonomic reflex arc
- When light intensity rises, signals are transmitted from the eye to the pretectal region of the upper midbrain
- Preganglionic parasympathetic fibers travel by way of the oculomotor nerve to the ciliary ganglion in the orbit
- From the ganglion, postganglionic fibers continue into the eye, where they stimulate the pupillary dilator
39
Q
Physiology of hearing
[HOLD p583]
A
- Sound waves enter the auditory canal on one side and nerve signals exit the inner ear on the other
- Connected by the middle ear because the tympanic membrane moves air & vibrates easily
- Stapes push against the perilymph of the inner ear; fluid that resists motion more than air does
- By concentrating the energy of the vibrating tympanic membrane on an area 1/18 that size, the ossicles create a greater force per unit area at the oval window and overcome the intertia of the fluid
- The auditory ossicles not not provide any mechanical advantage/sound. Vibrations of the stapes against the inner ear normally have the same amplitude as vibrations of the tympanic membrane against the malleus
- Hearing is based on movement of the cochlear hair cells relative to stationary structures nearby
40
Q
Pitch
A
- Sense of whether a sound is high or low (bass)
- Determined by the frequency at which the sound source, eardrum, and other parts of the ear vibrate
- Measured in hertz (Hz)
41
Q
Presbyopia
A
- Reduced ability to accommodate for near vision with age
- Caused by declining flexibility of the lens
- Corrected with bifocal lenses or reading glasses
42
Q
Primary taste sensations
A
- Salty
- Sweet
- Umami (savory)
- Sour
- Bitter
43
Q
Projection pathways
A
- Pathways followed by sensory signals to their destinations in the CNS
- Most travel by way of first-, second-, and third-order neurons
- Their axons are called first- through third-order nerve fibers
44
Q
Receptor classification by distribution of receptors in the body
A
- General: widely distributed receptors located throughout the body
- Special: limited to the head, are innervated by the cranial nerves, and employ complex sense organs
45
Q
Receptor classification by origin of stimulus
A
- Exteroceptors: sense stimuli external to the body
- Interoceptors: detect stimuli in the internal organs
- Proprioceptors: sense the position and movements of the body or its parts
46
Q
Receptor classification by stimulus modality
A
- Thermoreceptors: respond to heat/cold
- Photoreceptors: respond to light
- Nociceptors: respond to pain
- Chemoreceptors: respond to chemicals, odors, tastes, body fluid composition
- Mechanoreceptors: respond to physical deformation of a cell or tissue caused by vibration, touch, pressure, stretch or tension
47
Q
Receptor potential
A
- The initial effect of a stimulus on a sensory cell
- A small local electrical change
48
Q
Receptor types
A
-
Unencapsulated endings
- free nerve endings: pain, heat, cold
- tactile discs: light touch, pressure
- hair receptors: light touch, movement of hairs
-
Encapsulated nerve endings
- tactile corpuscles: light touch, texture
- bulbous corpuscles: heavy/continuous touch
- lamellar corpuscles: deep pressure, stretch, tickle, vibration
- muscle spindles: muscle stretch
- tendon organs: tension on tendons
49
Q
Referred pain
A
- Pain in the viscera that is mistakenly thought to come from the skin or other superficial sites (ie arm pain that could be an indicator of a heart attack)
50
Q
Refraction
[HOLD]
A
- Image formation depends on refraction, the bending of light rays
51
Q
Retina principal cell layers
A
-
Photoreceptor cells
-
Rods: night, scotopic or monochromatic vision (peripheral vision)
- Outer segment contains rhodopsin
- Inner segment contains organelles atop cell body with nucleus
- Cones: color, photopic, or day vision (centralized vision)
-
Rods: night, scotopic or monochromatic vision (peripheral vision)
- Bipolar cells
- Ganglion cells
52
Q
Semicircular ducts
A
- Detects angular/rotary movements
- Housed in the semicircular canals of the temporal bone
- Filled with endolymph
53
Q
Sensation
A
- A subjective awareness of a stimulus
54
Q
Sensory adaptation
A
-
Phasic receptors
- Generate a burst of action potentials when first stimulated, then quickly adapt and reduce or stop signaling even if the stimulus continues
-
Tonic receptors
- Adapt more slowly and generate signals more steadily than phasic receptors
55
Q
Sensory projection
A
- The transmission of information from a receptor to a specific locality in the cerebral cortex, enabling the brain to detect and identify the stimulus
56
Q
Sensory receptor
A
- Any structure specialized to detect a stimulus
57
Q
Sound
A
- Any audible vibration of molecules
- Can be transmitted through water, solids, or air, but not through a vacuum
58
Q
Taste cell types
A
- Taste cells: chemoreceptors
- Basal cells: neurons that regenerate taste buds
- Supporting cells: support taste & basal cells to support homeostasis
59
Q
Taste projection pathways
A
- Facial nerve VII collects sensory information from taste buds of the anterior 2/3 of tongue, the glossopharyngeal nerve IX and X
- All taste fibers project to a site in the medulla oblongata (solitary nucleus)
- Second-order neuron arise here and relay the signals to 2 destinations
- nuclei in the hypothalamus and amygdala
- thalamus
60
Q
Transduction
A
- The fundamental purpose of any sensory receptor
- Conversion of one form of energy to another (ie light, sound, heat, touch, vibration, or other forms of stimulus energy into nerve signals)
61
Q
Vision
A
- The perception of objects in the environment by means of the light they emit of reflect
- Light is visible electromagnetic radiation
62
Q
Visual pigments
A
-
Rods (contain rhodopsin)
- Two major parts of molecule: opsin & retinal (retinene)
-
Cones (contain photopsin)
- Retinal moiety same as in rods
- Opsin moiety contains different amino acid sequences
- Identifies red, blue, and green colors
63
Q
Visual projection pathway
A
- Optic nerves arise from the retinal ganglion cells and leave each orbit through the optic canal
- Converge to form an X on the optic chiasm
- Beyond this, the fibers continue as a pair of optic tracks
