Lecture 5: Special and general senses Flashcards
(160 cards)
1
Q
Where are general senses found
A
- all over the body
- pain, touch, temp
2
Q
Where are specialized senses found
A
- in specific areas
- they have specialized and complex receptors
- smell, taste, vision, hearing, and balance
3
Q
What is sensation
A
- the activation of specialized cells/ receptors which send impulses to the CNS
- there is no “experience” of the sensation
4
Q
What is perception
A
- the integration of sensory info at the level of the brain (thalamus)
- allows for the “experience” of the sensation
5
Q
When do you get the experience of sensation
A
only when the activation of sensory receptors are integrated by the brain
6
Q
What is the all or nothing principle
A
- neurons (& receptors) will either fire or not
- no “half potential)
7
Q
What is adaptation
A
- decreased response from a receptor over time
- speed depends on receptor (ex. touch= fast, proprioception= slow)
8
Q
What is graded response
A
- arises from critical threshold
- receptor will only respond to stimulus greater than threshold
- these thresholds can be altered
9
Q
What are somatic senses
A
-senses that present throughout the body
= the genral senses
-distribution is not uniform
-two-point discrimination
10
Q
Name some examples of the general senses / somatic senses
A
skin, mucosa, muscles, tendons, joints, viscera, etc..
11
Q
What senses are specific to one area of the body
A
special senses
ex. photoreceptors (retina)
12
Q
What are the 3 different ways to classify receptors
A
- location
- stimulus
- structure
13
Q
What are the 3 different kinds of receptors classified by location
A
- Exterocaptors
- Visceroceptors
- Proprioceptors
14
Q
What are Exteroceptors
A
- on or near surface of body
- respond to external stimuli
- includes special sense organs
- pain, touch, temp
15
Q
what are Visceroceptors
A
- located internally, within viscera
- typically stimulated by pressure, stretching, chem changes
- mediate hunger and thirst
16
Q
what are proprioceptors
A
- special type of visceroceptor
- limited to skeletal muscle, tendons, joints
- info bat movement, orientation
- tonic vs phasic
17
Q
What are the 6 different kinds of receptors classified by stimulus
A
- Mechanoreceptors
- Chemoreceptors
- Thermoceptors
- Nociceptors
- Photoreceptors
- Osmoreceptors
18
Q
What stimulates mechanoreceptors
A
mechanical stimulus changes shape or position of receptor
19
Q
What stimulates chemoreceptors
A
- respond to chemical compounds
- either total amount or change in concentration
20
Q
what stimulates thermoreceptors
A
changes in temp
21
Q
what stimulates nociceptors
A
- respond to tissue damage which is perceived as pain
- toxins, light, sound, pressure, heat
22
Q
what stimulates photoreceptors
A
respond to light
23
Q
what stimulates osmoreceptors
A
- respond to osmotic pressure
- large concentration in hypothalamus
24
Q
What are the 2 kinds of receptors classified by structure
A
- Free nerve endings
- Encapsulated nerve endings
(somatic receptors only )
25
What are the free nerve endings
- simplest, most common, widely distributed
- located on surface and internally
- fibres terminate in enlarged dendritic knobs
26
What are encapsulated nerve endings
- have some type of CT that surrounds dendrites
- most are primary mechanoreceptors
- vary in size and distribution
27
What are tactile (Meissner) corpuscles
- encapsulated nerve ending / exteroceptor
- activation stimulus: mechanical, light pressure
- function: touch and low frequency vibration
28
What are Bulboid (krause) corpuscle
- encapsulated nerve ending / exteroceptor
- activation stimulus: mechanical
- function: touch, texture and low frequency vibration
29
What are Bulbous (ruffini) corpuscle
- encapsulated nerve ending / exteroceptor
- activation stimulus: mechanical
- function: crude and persistent touch
30
What are Lamellar (pacinian) corpuscle
- encapsulated nerve ending / exteroceptor
- activation stimulus: mechanical, deep pressure
- function: deep pressure, high frequency vibration, stretch
31
What are muscle spindles
- encapsulated nerve ending / visceroceptors
- activation stimulus: mechanical, stretch
- function: sense of muscle length
32
What are the Golgi tendon receptors
- encapsulated nerve ending / visceroceptors
- activation stimulus: mechanical, tendon stretch, contraction strength
- function: sense of muscle tension
33
What detects pain
Nociceptors
34
What are the 2 types of nociceptor fibres
acute and chronic
35
What type of fibre carries somatic pain and from where
- acute fibres, fast
| - concentration in skin, mucosa, superficial areas
36
What type of fibre carries visceral pain and from where
- chronic fibres, slow
| - originates in visceral structures
37
where are there no nociceptors
brain tissue
38
what is typically the first indication of injury of disease
the nociceptors detection of pain
39
what is referred pain
- misinterpretation of nerve signals
| - pain perceived at a location other than the site of the painful stimulus/ origin
40
Characteristics of thermoreceptors (5)
- free nerve endings
- receptive fields ~1mm
- detects hot or cold but not both
- not uniformly distributed
- rapid adaptation
41
when do thermoreceptors start firing and increase to in heat stimulus
around 25° C, increase in rate until 45 ° C
42
when does heat temp in thermoreceptors start causing pain
Temperatures above 48° C start to cause pain
43
When are thermoreceptors most active to cold
Most active between 10° C and 40° C
44
when do thermoreceptors start lacking ability to fire in cold
Lack of firing below 10° C
45
what mediates light touch
-tactile disks (merkel disks)
46
what are the 2 components of merkel disks
- tactile epithelial cell
| - tactile disk
47
what are 4 characteristics of light touch
- subtle detection in exact areas of skin
- epithelial cell is stiff and easily deformed
- slow adaptation
- can also detect contours and surfaces
48
What is characteristics of Bulbous corpuscles
- flat shaped, located deep in dermis
- slow adapting
- crude, persistent touch
- deep touch
49
what are characteristics of Lamellar corpuscles
- thick laminated C.T.
- found in deep dermis
- abundant in hands and feet, joint capsules
- fast adapting
- high freq. vibration and stretch
- deep touch
50
what are 3 additional touch sensations
- skin movement
- itch
- tickle
51
Describe skin movement
- slight movement on or in skin
- movement of hair causes sensation
- mediated by root hair plexuses
52
describe itch sensation
- caused by chem irritation of free nerve endings
- histamine, bradykinin
- can also be induced by suggestion
53
describe the tickle sensation
- tactile stimulation by someone else
- mediated by free nerve endings
- interaction of neural circuits in thalamus, cerebellum, and cortex
54
what is proprioception
location of body parts w/o visual info
55
what informs proprioception
- muscle spindles
| - golgi tendon receptors
56
what are intrafusal fibres that compose muscle spindles
- striated ends that contract
- central portion contains nucleus and sensory fibres
- found btw and parallel to extrafusal fibres
57
what is structure and function of muscle spindles
- composed of 5-10 intrafusal fibres
- 2 sensory nerve fibres
- monitor changes in muscle length
- special gamma motor neurons can cause contractions (stimulated to maintain posture - stretch reflex)
58
What are the 2 sensory nerve fibres
- wrapped perpendicular to intrafusal fibres
- type I (rapid) & type II (slow)
- encircle central are of each spindle
59
Where are golgi tendon organs located
at junction btw muscle and tendon
60
what 2 things does golgi tendon organ consist of
-dendrites (golgi tendon receptors)
-sensory fibres (type
I b)
61
structure and function of golgi tendon organ
Surrounded by connective tissue capsule
Stimulated by excessive stretch in tendon
Antagonistic to muscle spindles
Causes skeletal muscle to relax – Golgi tendon reflex
Prevent muscle tearing
62
What are the 4 special senses
- taste
- smell
- vision
- hearing / balance
63
What 2 senses are intimately linked
taste and smell
- breathing collects chemicals to specialized sense organs for taste
- chemoreceptors are activated to give info about toxic & chem properties
64
What % of sense of taste comes from the sense of smell?
80%
| -thus nasal congestion reduces ability to taste
65
What is a taste bud
- taste receptor
- ~10,000 of them
- located on tongue in papillae
66
What 4 additional structures other than tongue have sensors for taste?
- soft palate
- internal surface of the cheeks
- pharynx
- epiglottis
67
What are papillae?
- little bumps on the top of tongue that help grip food while your teeth chew
- contain taste buds
- gives a rough texture to the tongue (abrasive feel)
68
What are the 4 types of papillae
- filiform
- fungiform
- circumvallate
- foliate
69
describe filiform papillae
- thread-like, abundant (anterior 2/3)
| - no taste buds
70
Describe fungiform papillae
- mushroom shaped, abundant (anterior tip & sides)
| - taste buds on the top
71
Describe Circumvallate papillae
- round, not abundant (10-12 placed like an inverted V at the back)
- taste buds are on it's sides
72
Describe Foliate papillae
- ridge like
- taste buds on side wall
- Rudimentary in human (lots in other mammals)
73
What are the 3 types of epithelial cells that make up taste buds
1. supporting (support) cells
2. Basal cells
3. Gustatory or taste cell
74
What are supporting cells of taste buds
-isolates the taste cell and provides structural support
75
what are basal cells of taste buds
-stem cells which give rise to support cells which then give rise to taste
76
What is Gustatory or taste cells of the taste buds
- have long microvilli (receptive part) that emerges from a taste pore & are bathed by saliva
- surrounded by sensory dendrites that bring the nervous impulse up to the somatosensory area of the tongue passing by the medulla oblongata & the thalamus
- renewed every 10-14 days (exposed to the elements)
77
What are the 5 basic taste sensations
- sweet: sugar, alcohol, certain amino acids
- Salty: inorganic salts (NaCl)
- Sour: H+ ions
- Bitter: alkaline
- Umami: glutamate, MSG
78
Most foods are a combo of which of the primary taste sensations
all 5
| -there is evidence that suggests humans can experience more than the 5 types of taste
79
Describe the pathway in which we experience taste (6 stages)
1. chem or compound dissolved in saliva
2. substance links to the membrane receptors on the microvilli of the taste cell
3. initiates depolarization the mechanism of action is diff for each taste sensation
4. encourages release of neurotransmitter from vesicles of the taste cell
5. = depolarization & (AP) of sensory neurons associated w/ the taste cell
6. sensory impulses for taste are conducted to the brain by a) facial nerves b) Glossopharyngeal c) Vagus
80
Which area of brain transmits perception of taste
Gustatory area (insular cortex) via the thalamus
81
Which are of the brain determines the appreciation for the taste sensations
hypothalamus & limbic system
82
Where are the cells of the olfactory epithelium
- located in the roof of the nasal cavities
| - penetrate the cribriform plate and dangle in the nasal conchae
83
What are the 3 types of cells that make up the olfactory epithelium
1. basal cells (stem cells at base of the epithelium)
2. supporting cells (secrete mucus w/ the olfactory glands in the c.t.)
3. olfactory receptor cells (primary receptors for odorants)
84
What is the name of the bundles of olfactory nerves formed above the cribriform plate of the ethmoid bone
glomeruli (glomerulus)
85
what is the cribriform plate
roof of nasal cavity and part of ethmoid bone
86
how many diff types of olfactory receptors
thousands
| - explains the complexity & subtlety of the sense of smell
87
Most receptors of the olfactory system are which type?
chemoreceptors
88
what do the nociceptors of the olfactory epithelium respond to?
- menthol (e.g. halls)
| - spicy (e.g. peppers)
89
nerve impulses follow the olfactory nerves to the olfactory tract and end in what 2 areas
- olfactory areas: parts of frontal lobe and piriform cortex (smell interpreted consciously)
2. hypothalamus, amygdala, limbic system (emotional aspect of the smell.. ex. smoke = danger = fight or flight)
90
what is the only sensory modality that does not go through the thalamus before reaching the cortex
smell
91
What are the 5 accessory structures of the eye
1. eyebrow
2. eyelid
3. conjunctiva
4. Lacrimal apparatus
5. the muscle of the eye
92
Describe the structure of the eyelid
-thin folds covered w/ skin
-internally has 2 sheets (tarsal plates made of dense c.t.)
-embedded btw the sheets of the tarsal plates ~Meibomian (tarsal) glands
~secretes an oily substance to increase moisture
93
What is conjunctiva
transparent mucous membrane w/ 2 vascularized sheets
| -does not cover the cornea just the sclera (secretes mucous that lubricates the eye)
94
What is conjunctivitis
inflammation of the conjunctiva = red eyes
| -caused by a congestion or vasodilation of the blood vessels
95
How does lacrimal apparatus produce and distribute tears
- lacrimal glands
- secrete tears via excretory ducts
- release onto conjunctiva
- tears collected lacrimal puncta (2) (near medial canthus)
- flows to the lacrimal sac by lacrimal ducts
- goes to nasolacrimal duct
- empties nasal cavity (level of the inferior nasal meatus)
96
What are the 6 muscles of the eye
1. superior oblique
2. inferior oblique
3. medial rectus
4. lateral rectus
5. superior rectus
6. inferior rectus
97
what is the function of the superior oblique
abducts, depresses and internally rotates the eye
98
what is the function of the inferior oblique
abducts, elevates and externally rotates the eye
99
what is the function of medial rectus
adduction of the eye
100
what is the lateral rectus
abduction of the eye
101
what is the superior rectus
elevation and assists in internal rotation
102
what is inferior rectus
depresses, adducts and assists w/ external rotation of the eye
103
The bulb (globe) of the eye is made of what 3 tunics
1. fibrous tunic
2. vascular tunic
3. sensory tunic
104
What are the 2 portions of fibrous tunic of the bulb of the eye
1. anterior portion = Cornea (1/6)
| 2. posterior portion = Sclera
105
What are the 3 parts of vascular tunic of the bulb of the eye
- Choroid
- Ciliary body
- Iris
106
what is the structure of the choroid
- posterior part of eye bulb/ globe
- richly vascularized
- lines almost all of internal surface of sclera
- contains melanin
107
What is the structure of the ciliary body
- made of ciliary processes & muscles
| - anterior extension of the choroid
108
what is the structure and function of the iris
- continuity of the ciliary processes
- takes the form of a ring, made of smooth muscles
function: contracts and relaxes to adjust the diameter of the pupil
109
What is the sensory tunic of eye bulb
- Retina
- lines the posterior caity of the bulb of the eye
- responsible for the reception of light rays
- contains the photoreceptor cells (rods and cones)
110
What is the optic disc
- blind spot
| - retina does not detect light here because optic nerve, central artery & vein of the retina pass through this section
111
What is the yellow oval spot on lateral side of the optic nerve (at end of optic axis)
macula lutea
112
What is structure of macula lutea
- has central pit called Fovea centralis where cones dominate
- no rods in this central pit
- low density of rods in macula lutea
- # of rods increases towards the periphery of the retina while the # of cones decreases
113
What are the 2 cavities of the eye
- the lens and it's suspensory ligament separate the eye into 2 segments
1. Anterior cavity
2. Posterior cavity
114
What are the 2 chambers of the Anterior cavity of the eye
1. anterior chamber (btw cornea & iris)
2. posterior chamber (btw iris & lens)
- filled w/ aqueous humor formed by epithelial cells of ciliary processes
115
What is structure and function of the posterior cavity of the eye
- from the lens to the retina
- is filled w/ vitreous humor (gelatinous transparent substance)
function:
- maintains the form of the eye (pressure)
- maintains the retina in place
116
what takes a direct line in optic path
the optic axis
117
what are the 3 main types of neurons in the optic path
- photoreceptors
- bipolar cells
- ganglion cells
118
Describe the optic pathway in order
- photoreceptors (receive visual info/ collect light signal = photons)
- transform light energy into nerve (electrical) impulses
- transmit impulses to the bipolar cells
- impulses travel to the ganglion cells
- -axons of these cells penetrate the optic disc & form the optic nerve
- nerves cross in the optic chiasm then travel as the optic tract
- pass via thalamus
- visual cortex of the occipital lobe
119
What do horizontal and amacrine cells do in the optic pathway
- modify the signal sent by the photoreceptors
| - communicate w/ other types of cells
120
What are the 3 major parts of the ear
- external (outer) ear
- middle ear (tympanic cavity)
- internal (inner) ear (labyrinth)
121
What are the 3 parts of the external ear
1. Auricle (pinna)
2. External auditory canal
3. Tympanic membrane
122
What is the Auricle (pinna) of the external ear
- captures the sounds (funnel amplifier)
- focuses sounds to the tympanic membrane via the external auditory canal
- changes in ear structure changes the sound
123
What is the external auditory canal of the ear
- conducting tube leading to the tympanic membrane
| - contains: hairs & ceruminous glands (wax) to catch dust and waste and prevent particle accumulation
124
What is the tympanic membrane of the ear
- fine membrane of c.t.
- integral for channeling sound waves
- separates the external ear from middle ear
- sound waves (pressure) cause the tympanic membrane to vibrate (moves the bones of middle ear, transmit the sound to internal structures)
125
What is the structure of the middle ear
- filled with air
- has 2 windows:
1. oval or vestibular
2. round or cochlear
126
what is the round or cochlear window of the middle ear
- openings that are sealed and separated from internal ear
- contains the auditory tube (a flattened tube narrowed at it's center that closes the opening) (also links the middle ear to the nasopharynx)
127
What is the function of the auditory tube
- essential to equilibrate the pressure on each side of the tympanic membrane
- helps to allow for free vibration
- prevents tearing
128
Why do ears pop sometimes when yawning or swallowing
because the flattened part of the round / cochlear window opens and allows pressure to equilibrate
129
What is the structure of the ossicles
3 small bones:
- Malleus (hammer)
- Incus (anvil)
- Stapes(Stirrup)
130
What is the function of the Ossicles
transmit sound of the external ear to the internal ear
131
What is the hammer ossicle fastened to
to the tympani membrane, its head articulate with the anvil, which in turn articulates with the stirrup
132
What is the structure of the internal ear
-consist of a bony labyrinth = external (houses the membranous labyrinth internal)
-
133
What does the bony labyrinth of the internal ear contain
Perilymph
134
What does the membranous labyrinth of the internal ear contain
Endolymph
135
What is the function of the internal ear
- transformation of vibration to a nerve impulse for hearing
| - perception of the position of the head for the balance
136
What is the bony labyrinth
a series of channels housed in the bony part of the temporal bone
137
What are the 3 parts of the bony labyrinth
1. Semicircular canals (equilibrium)
2. Vestibule(equilibrium)
3. Cochlea (hearing)
138
What are the semicircular canals of the bony labyrinth
- 3 canals all at right angles to one another
- at their bottom lies the ampulla (house the crista ampullaris which is receptors for equilibrium and rotational movement)
139
What is the name of the two distinct structures of the vestibule of the bony ear
together = Otolithic Organ
- Saccule (on the side of the cochlea)
- Utricle (on side of semicircular canals)
140
What are the Maculae in the vestibule of bony labyrinth
receptors of equilibrium (react to gravity)
141
What is Cochlea translated from latin
snail
142
What is the structure of the Cochlea
- spiral bony canal that makes about 3 turns around a bony pillar called Modiolus
- divided into 3 canals (separated by membranes)
143
Where is the organ of Corti located
within the cochlea
- separated from scala vestibuli by the vestibular membrane of cochlear duct
- separated from scala tympani by the basilar membrane of the cochlea
144
How is the organ of Corti responsible for the sensation of hearing
- the "hair" / stereocillia touch the tectorial membrane of the cochlear duct
- the base of the stereocillia synapse with the neurons of the cochlear nerve (a division of vestibulocochlear nerve)
145
What are the 2 components of a wave in hearing
1. Amplitude (intensity of sound, volume ; 0-140dB)
| 2. Frequency (speed of vibration; determines pitch.. 20-20,000 Hz
146
What is the unit of measure for sound
decibel (dB)
0=barely audible
90+=possible long term damage
140+=very painful
147
Where do high freq, med freq, and low freq sound displace the basilar membrane
- high freq = near base
- med freq = middle
- low freq = near apex
148
What is the route that sound takes in the physiology of hearing
-pina captures sound & directs it in external auditory canal
-tympanic membrane vibrates
-stimulates the ossicles
-stapes raps on the vestibular window
creates hydraulic waves in the perilymph of the scala vestibuli
-the waves propagate themselves up to the scala tympani
-the waves also moves the vestibular membrane of the cochlear duct
-pressure changes of endolymph moves the basilar membrane
-increased pressure in scala tympani pushes the perilymph towards the cochlear window
-movement of the hair depolarize the neurons of nerve VIII (vestibulocochlear)
-the nerve impulse end up in the medulla oblongata (cochlear nuclei)
-crosses to opposite side
-goes toward the midbrain
-to end up in the thalamus & in the auditory areas of the temporal lobes
149
What is the pathway in physiology of equilibrium : static equilibrium
- head movement moves the otholithic membrane bcs of the weight of the otholithic
- hair (stereocillia) movement
- obtain depolarization or hyperpolarization of their membrane
- release of the neurotransmitter
- synapse w/ sensory neurons w/ the vestibular division nerve VIII (vestibulocochlear)
150
in dynamic equilibrium when do endolymph canals move
when there is acceleration or deceleration
151
What is the pathway in physiology of equilibrium : dynamic equilibrium
- ampullae of the canals have crista ampullaris
- contain hair cells
- cupula (gelatinous substance) perceives movement of the endolymph
- when cupula moves, the hairs are bent
- this leads to the generation of a nerve impulse in the neurons of the vestibular division nerve VIII (vestibulocochlear)
152
What is the pathology of diplopia (double vision)
- paralysis or congenital weakness of certain muscles of the bulb of the eye
- eyes not perfectly coordinated
153
What is the pathology of Strabismus (weak eyes)
- congenital weakness of the muscles of the bulb of the eye, defect of the parallelism of the eyes
- the brain can neglect the nerve impulse coming from the deviating eye
154
What is the pathology of Glaucoma
- accumulation of aqueous humor
- intraocular pressure gets to a dangerous level & get a compression of the retina & the optic nerve
- can lead to blindness
155
What is the pathology of cataracts
- opaqueness of the lens
| - causes: ageing, disease, tobacco, sun
156
what is the pathology of achromatopsia (color blindness)
- hereditary abnormality with a congenital deficiency of at least 1 type of cone
- link to sex especially males
157
What is the pathology of Trachoma
- contagious infection of the conjunctiva & cornea
- chlamydia trachomatis - bacteria; STD
- leads to blindness
158
what is Otalgia
ear pain
159
What is Otitis externa
inflammation or infection of the external auditory canal by bacteria & fungi
160
What is Anosmia
- absence of odors
- causes: genetic, ageing, physical obstruction of nasal cavity, severed olfactory nerve, inflammation of the nasal cavities
