Somatic senses and special senses Flashcards
(134 cards)
1
Q
Define sensation
A
Activation of sensory receptor cells at the level of the stimulus. It is a conscious or unconscious awareness of the external or internal stimuli
2
Q
Define perception
A
Central processing of sensory stimuli into a meaningful pattern. It is a conscious awareness and interpretation of sensations.
3
Q
What is adaptation in the context of sensation?
A
The change in sensitivity (usually a decrease) to a long-lasting stimuli.
4
Q
What are general senses vs special senses?
A
General senses have receptors distributed throughout the body and has receptor cells within the structures of other organs. Special senses have a specific organ devoted to it.
5
Q
What is included in general senses?
A
Somatic and visceral senses
6
Q
What are somatic senses?
A
Senses that arise from the skin, muscles, joints or connective tissues.
7
Q
What are the classifications used to describe sensory receptors?
A
Structural (cell type, or position in relation to stimuli), or function (transduction of stimuli)
8
Q
Describe the types of sensory receptors based on cell type
A
Free nerve endings, encapsulated nerve endings at the dendrites of first order sensory neurons, or specialized cells that synapse with first-order sensory neurons.
9
Q
Give examples of each type of cell type for the sensory receptors
A
Free nerve endings: pain and temperature receptors in the dermis of the skin.
Encapsulated nerve endings: lamellated corpuscules that respond to pressure and touch in dermis of skin.
Specialized cells: photoreceptors of the eye
10
Q
What are tactile sensations?
A
Pressure, touch, vibration, itch and tickle.
11
Q
What are the tactile receptors?
A
- Tactile corpuscule (Meissner’s corpuscule)
- Hair root plexuses
- Type 1 and type 2 cutaneous mechanoreceptors (Merkel’s discs and Ruffini’s corpuscule, or bulbous corpuscule)
- Lamellated corpuscules (Pacinian corpuscule)
- Free nerve endings
- Muscle spindle
- tendon stretch organ
12
Q
What is the difference between crude touch and discriminative touch?
A
Crude touch is the ability to perceive that something has simply touched the skin, and discriminative is the ability to recognize what point of the body is touched
13
Q
Where are free nerve endings located, and what stimuli do they respond to ?
A
Demis, cornea, tongue, joint capsules, visceral organs. They respond to pain, temperature, itch and tickle
14
Q
Where are Merkel’s discs located, and what stimuli do they respond to ? Are they fast or slowly adapting receptors?
A
Epidermal-dermal junction, mucous membranes. Low frequency vibration, pressure. Slowly adapting
15
Q
Where are bulbous corpuscules located, and what stimuli do they respond to ? Are they fast or slowly adapting receptors?
A
Dermis, joint capsules. Stretch, touch. Slowly adapting.
16
Q
Where are tactile corpuscules located, and what stimuli do they respond to ? Are they fast or slowly adapting receptors?
A
Papillary dermis, especially in the fingertips and lips. Light touch, low frequency vibration. Rapidly adapting.
17
Q
Where are lamelated corpuscules located, and what stimuli do they respond to ? Are they fast or slowly adapting receptors?
A
Deep dermis and subcutaneous tissue. Deep pressure, high frequency vibration. Rapidly adapting.
18
Q
Where are hair follicle plexus located, and what stimuli do they respond to ? Are they fast or slowly adapting receptors?
A
Wrapped around hair folllicules in the dermis. Movement of hair, touch. Rapidly adapting.
19
Q
Where are muscle spindles located, and what stimuli do they respond to ?
A
In line with skeletal muscle. Muscle contraction and stretch.
20
Q
Where are tendon stretch organs located, and what stimuli do they respond to ?
A
In line with tendons. Stretch of tendons.
21
Q
Describe pressure.
A
Sustained sensation felt over a large area than touch. Results from the stimulation of tactile receptors in deeper tissues, they are longer lasting and have less variation in intensity than touch .
22
Q
What is the only sensation that you cannot elicit yourself?
A
Tickle
23
Q
What are thermoreceptors?
A
Free nerve endings.
24
Q
Describe the utility of pain
A
Provides information on tissue damage stimuli that can be used for diagnosis of disease or injury
25
What are pain receptors called and what are they made of ?
Nociceptors, and they are free nerve endings located everywhere in the body.
26
What are the two kinds of pain?
Fast and slow
27
What is referred pain?
When pain is felt from an area far from the stimulated organ
28
What is phantom pain?
Sensation of pain related to a non existend limb that has been amputated. The brain interprets the nerve impulses that arise in the remaining proximal portions of the sensory nerves as coming from a nonexistant limb.
29
What are the three parts of somatosensation?
Touch, proprioception and interoception
30
What is proprioception?
A sense that provides awareness of the activities of muscles, tendons, joints and balance + equilibrium.
31
Where are the proprioceptive receptors located?
Skeletal muscles, tendons, joints, and in the internal ear.
32
What are the five special senses?
Smell, taste, hearing, vision and balance
33
Where are the olfaction receptors located?
In the nasal epithelium in the superior portion of the nasal cavity
34
What are the sensory receptors in olfaction?
Free nerve endings in the apical layer of the mucous membrane in he nasasal epithelium
35
What is the responsive portion of the sensory receptors in olfaction?
The cilia of all the cells contain an olfactory receptor protein
36
What is the use of epithelial cells in the nasal epithelium?
Supporting cells and basal stem cells produce new olfactory receptors
37
How is olfactory adaptation?
Very quick, the threshold of smell is low
38
Describe the olfactory pathway
1. Odorant binds to olfactory receptors creating a signalling cascade that creates a depolarization of the neuron cell membrane
2. With sufficient depolarization, it creates an action potential
3. Axons of nerves go to the olfactory bulb, where they synapse with mitral cells, who also synapse with cells from the brain.
4. The axons form the olfactory tract, which goes to the primary olfactory cortex, located in temporal lobes
5. The primary regions project to other regions like the lymbic system and hypothalamus
39
What is required for molecules to be tasted?
That they are dissolved in saliva
40
What are the classes of taste ?
Salty, sweet, sour, bitter and umami
41
What are the sensory receptors for taste and where are they located?
Gustatory receptor cells, located in taste buds
42
What are taste buds?
They are strucures found in the papillae of the tongue, they consist of supporting cells, gustatory receptor cells, and basal cells, as well as taste hairs and taste pores
43
What is the responsive portion of taste buds?
The receptors in the microvili of the gustatory cells
44
What are the different papillae of the tongue ?
Fungiform, circumvallate, filiform or foliate
45
Which papillae does not contain taste buds?
Filiform
46
What is the order of taste thresholds?
Bitter, sour, salty and sweet
47
How long is taste adaptation?
1-5 minutes
48
Describe the gustatory pathway for sweet, bitter, and umami
1. Chemical stimulus binds to a G protein coupled receptor on the cell membrane (in the taste hairs of the cell), creating a reaction cascade
2. The cascade releases Ca ions from the smooth endoplasmic reticulum
3. The ions release stimulates exocytosis of vesicules containing neurotransmitters in the synaptic cleft
4. The nerves generate an action potential traveling in cranial nerves 7, 9 or 10
5. The signal goes to the medulla, thalamus, and the insula
49
Describe the gustatory pathway for salty and sour
1. Specific ion channels react with Na or H ions, which causes depolarization of the membrane
2. When the threshold is attained, Ca ion channels open
3. The ions release stimulates exocytosis of vesicules containing neurotransmitters in the synaptic cleft
4. The nerves generate an action potential traveling in cranial nerves 7, 9 or 10
5. The signal goes to the medulla, thalamus, and the insula
50
What are the accessory organs of the eye?
Eyelids, conjunctiva, eyelashes, eyebrows, lacrimal apparatus and 6 extraocular muscles
51
What is the function of eyelids?
Shade the eyes during sleep, protect them from excessive light and foreign objects, spread lubricating secretions over the eyeball
52
What is the function of the conjunctiva?
It is a thin mucous membrane that lines the inner aspect of the eyelids and is reflected onto the anterior surface of the eyeball. It serves as lubrication and protection.
53
What is the function of the eyelashes and eyebrows?
Help protect the eyeballs from foreign objects, perspiration and direct rays of the sun
54
What is the lacrimal apapratus?
Structures that produce and drain tears.
55
What are the three tunics of the eyeball?
The fibrous tunis, the vascular tunic, and the retina
56
What are the two parts of the fibrous tunic ?
The posterior sclera and the anterior cornea
57
Describe the posterior sclera and its use
The white of the eye. A white coat of fibrous tissue that covers everything but the iris. It gives the shape to the eyeball and protects its inner parts.
58
Describe the posterior cornea and its use
A non vascular transparent fibrous coat through which the iris can be seen. The cornea refracts light .
59
What are the parts of the vascular tunic?
Choroid, ciliary body and iris
60
Describe the choroid and its use
A vascular layer that absorbs light rays so that they are not reflected and scattered within the eyeball, it also provides nutrients to the posterior surface of the retina.
61
Describe the ciliary body and its use
It consists of the ciliary processes and the ciliary muscles. The processes are protusions (or folds) of the internal surface of the ciliary body where epithelial lining cells secrete aqueous humor. The ciliary muscle is a smooth muscle that alters the shape of the lens for near of far vision.
62
Describe the iris and its use
The colored portion of the eye seen through the cornea. It includes the circular iris and radial iris smooth muscle fibers that are arranged in a donut shaped structure. The pupil is the black hole at the center of the iris through which the light enters. The principal function is to regulate the amount of light entering the posterior cavity of the eyeball.
63
What is the retina?
The inner coating of the eye, it lines the 3/4 of the posterior part of the eyeball and it is the begining of the visual pathway.
64
What is the optic disc?
Where the optic nerve enters the eyeball
65
What are the layers of the retina?
A pigmented epithelial layer (non visual portion), a neural portion layer of photoreceptors, bipolar cells, and ganglion cells (visual portion)
66
What is the role of the pigmented layer of the retina?
Aids the choroid to absorb the light rays
67
Where is the lens of the eye and what is its use?
Behind the iris, to fine tunes the focusing of light rays using the ciliary muscles.
68
What are the two photoreceptors of the eye ?
Rods and cones
69
Describe the function of rods
Specialized for black and white vision, dim light, shades of grey, see shapes and movements.
70
Describe the function of cones
Specialized for color vision, sharpness of vision in bright light.
71
What is the macula lutea ?
The exact center of the posterior portion of the retina, the visual axis of the eye, where there is the least cones
72
What is the fovea?
The area with the sharpest vision due to its high concentration of cones.
73
Where are rods located in the eye?
Mostly in the periphery of the retina, and they are absent from the fovea and the macula lutea
74
Explain why we possess a blind spot
Because the optic disc does not contain rods or cones, it is where all the axons of the retinal ganglion cells pass through the retina. Therefore, no image can be formed there.
75
What are the two cavities of the eye and what separates them
The anterior cavity and vitreous chamber, separated by the lens
76
Describe the anterior cavity
Lies behind the cornea and before the lens. It is filled with a watery fluid called aqueous humor, which is produces by the ciliary processes behind the iris continually.
77
Describe the flow of aqueous humor
The anterior cavity is divided between the posterior chamber and anterior chamber. The aqueous humor flows from the posterior chamber through the pupil into the anterior chamber, and drains into the venous sinus (canal of Schlemm) and then into the blood.
78
What is the function of aqueous humor?
It produces intraocular pressure, which maintains the shape of the eye, keeps the retina smoothly applied to the choroid to produce clear images.
79
What is glaucoma?
Excessive intraocular pressure, it causes degeneration of the retina and blindness
80
What is contained in the vitreous chamber?
Vitreous body, a gel formed during embryonic life and never replaced
81
What are the three steps required in image formation in the anatomy of the eye?
1. Refraction of the light rays. by the cornea and the lens
2. Accomodation of the lens
3. Constriction of the pupil
82
What is refraction and what portions of the eye are involved?
Bending of light rays at the interface of two different media. The anterior and posterior surfaces of the cornea and the lens refract incoming light so it exactly focuses on the retina
83
What is accomodation in the eye?
An increase of the curvature of the lens, initiated by the cilliary muscles to enable the lens to focus on nearby objects
84
What is presbyopia?
Inability to read print at close range
85
What is myopia?
Nearsightedness
86
What is hypermetropia?
Farsightedness
87
What is the use of pupil constriction in image formation ?
It narrows the diameter of the hole through which light enters the eye. It occurs simulatenously with the accomodation of the lens and functions to prevent light rays to enter through the periphery of the lens.
88
What is convergence in image formation?
When both eyes focus on a single object
89
What is astigmatism?
A refraction abnormality due to an irregular curvature of either the cornea or the lens.
90
Discuss the physiology of vision
1. Light is absorbed by the photopigments in the retina
2. The retinal is converted in the disc of the photoreceptor, which releases the opsin
3. The opsin release creates a reaction cascade that ends up closing ligand gated ion channels, which created hyperpolarization of the photoreceptor membrane, which stops releasing glutamate.
3. The low concentration of glutamate created an excitatory post synaptic potential in the bipolar neuron, which releases glutamate
4. The graded potential creates an action potential in the ganglion cells, which travels to the optic nerve.
5. The nerve impulses travels to the optic chiasma, the optic tract, than the thalamus and the occipital lobes of the cortex
91
What is the single photopigment present in rods?
Rhodopsin
92
What is the photopigments in cones?
Photopsins
93
What are rhodospins and photopsins made of ?
Retinal, a vitamin derivative, and opsin.
94
How many types of opsins are there ?
4
95
What are the three parts of the ear?
The external ear, the middle ear, the inner ear
96
What are the parts of the external ear?
The auricle, the external auditory canal, and the tympanic membrane
97
What is the function of the auricle?
Funnel sound into the auditory canal
98
What is the function of the auditory canal?
Direct sound to the tympanic membrane
99
What is the function of the tympanic membrane ?
Vibrate to the contact of sound
100
What is the function of the external ear?
Collect sound waves and pass them inwards
101
What are the parts of the middle ear?
Auditory eustachian tube, the auditory ossicles, the oval window
102
What is the function of the eustachian tube?
Connected to the throat, it allows to equalize pressure in the tympanic cavity
103
What is the function of the auditory ossicles?
They amplify the vibrations from the tympanic membrane
104
What are the auditory ossicles called ?
malleus, incus and stapes
105
What is the function of the oval window?
It is the area where the stapes pushes
106
What are the parts of the inner ear?
Round window, and labyrinth (outer bony labyrinth and inner membraneous labyrinth)
107
What is the labyrinth, and what are its three areas called?
A series of cavities in the temporal bone. Semicircular canals, vestibule and cochlea.
108
Describe the bony labyrinth
Lined with periosteum, it contains perilymph, chemically similar to cerebrospinal fluid
109
Describe the membraneous labyrinth
A series of sacs and tubes lying inside with same general form as the bony part. Filled with endolymph, chemically similar to intracellular fluid
110
What is the vestibule?
The central portion of the bony labyrinth
111
Describe the cochlea
A bony spiral that makes almost three tours around a bone called the modiulus
112
What are the channels in the cochlea
The scala vestibuli, scala tympani and the scala media
113
What is contained in the scala vestibuli and tympani ?
perilymph
114
Describe the scala vestibuli and the scala tympani
The scala vestibulli starts at the oval window, and the scala tympani stops ar the round window. They are separated apart from one point called the helicotrema.
115
What are the membranes separating the cochlear duct from the scalas?
The vestibular membrane and the basilar membrane
116
What part of the labyrinth is the cochlear duct part of ?
The membraneous labyrinth
117
What lies on the basilar membrane?
The organs of corti
118
What is the tectorial membrane ?
A flexible and gelatinous membrane that lies ober the hair cells of the organs of corti
119
What nerves are connected to the ear?
auditory nerve (vestibulocochlear)
120
What is a pitch ?
The frequency of the sound vibratio. Higher pitch sounds have shorter frequencies and vice versa
121
Why are the different pitch resonating at different places in the cochlea?
Because the basilar membrane is stiffer at the basal end, and floppier at the apex
122
Discuss the physiology of hearing.
1. The auricl directs sound waves into the external auditory canal
2. Sound waves strike te tympanic membrane, causing it to vibrate
3. Vibration conducts from the tympanic membranes to the ossicles (malleus, incus, and stapes)
4. Stapes pushes into the oval window
5. Movement of the oval window sets up fluid pressure wave in the perilymph of the scala vestibuli
6. Pressure wave transmitted to the scala tympani to the round window
7. As the pressure wave goes through, it pushes on the vestibular membrane, which deforms the cochlear duct through the endolymph
8. The pressure fluctuations of the endolymph move the basilar membrane, which moves the hairs of the spiral organ against the tectorial membrane, which releases neuro transmitters, which cause an action potential in the nerve fiebrs.
9. Nerve impulses frmo the cochlear branch of the vestibulocochlear nerve pass to cochlear nuclei in the medulla, then travel to the midbrain, thalamus and auditory area of temporal lobe.
123
Describe the parts of the vestibule
The utricule and sacule
124
Describe the semicircular canals
Each aranged approximately at right angles to each other. Anterior and posterior are vertical, lateral is horizontal. They each enlarge into the ampulla.
125
What are the two kinds of equilibrium ?
Static and dynamic
126
What is static equilibrium?
Maintenance of the position of body relative to gravity
127
What is dynamic equilibrium ?
Maintenance of body position in response to sudden movement like rotation, acceleration and deceleration
128
What are maculae ?
Organs of static equilibrium. They are hair cells that function as sensory receptors, and supporting cells.
129
What are the primary sense organs of dynamic equiibrium?
The cristae of the semicircular ducts
130
How is dynamic equilibrium maintained?
Rotation and acceleration with the semicurclar ducts, and the sacule and utricule for linear acceleration
131
What are the primary organs of static equilibrium?
The maculae of the utricule and sacule
132
How do maculae work?
The difference in intertia between hair stereocilia and otholitic membrane leads to a shearing force when the head it tilted.
133
What is the name of the organs that bends in rotation in the ampulla?
The cupula
134
What is the nerve pathway for equilibrium?
Pons, medulla, thalamus, parietal cortex and cerebellum.
