Special Senses Flashcards
Name general somatic senses
1) Touch
2) Proprioception
3) pain
4) temperature
What do mechanosensors sense?
Touch and proprioception
What is proprioception?
Body position
What do nociceptors sense?
Pain
What do thermoreceptors sense?
Temperature
How many somatosensory pathways are there?
4
Which neuron is closest to where a sensation is being felt?
1st order
What does a sensory neuron convert stimuli into?
Action potential
Where is cell body of 2nd order neuron located?
Spinal cord
Where does second order neuron send signal?
Up spinal cord white matter directly to brain stem
Where is the 3rd order neuron located?
Thalamus
What is the sensory “train station depot” in the brain?
Thalamus
Where is 4th order neuron located?
Somatosensory cortex
Where is somatosensory cortex located?
Cerebral cortex
What shaped neuron is the 1st order neuron?
Pseudo unipolar
Where are dendrites of 1st order neuron?
In skin
Where is cell body of 1st order neuron located?
Dorsal root ganglia
What is the area of skin that a single neuron is responsible for called?
Receptive field
What does a small receptive field yield?
High resolution (precision) sensitivity
What areas have the smallest receptive fields in the body?
Fingers and tongue
What is determined by frequency of nerve firing?
Stimulus strength
What does high frequency of nerve firing yield?
Strong stimulus
What is neuron frequency?
How many action potentials are fired in one minute
What is a fast on, fast off firing receptor called?
Rapid or Fast Adapting
What is another term for fast adapting?
Phasic
What is a slow on and slow to turn off receptor?
Slow adapting
What is another term for slow adapting?
Tonic
Which order neuron is sensory adaptation specific to, typically?
1st order
3 somato sensory receptors?
1) Mechanoreceptors
2) Thermoreceptors
3) Nociceptors
Name 4 mechanoreceptors
1) Meissner Corpuscles
2) Merkel Discs
3) Ruffini Corpuscles
4) Pacinian Corpuscles
What 2 things do mechanoreceptors for touch sense?
1) Pressure
2) Deformation of skin
Where is Meissner corpuscle found?
Dermis
True or false: Meissner corpuscles are part of the connective tissue of dermis?
True
Which mechanosensor is NOT encapsulated?
Merkel discs
Where are a lot of Meissner corpuscles found?
Finger tips
What does Meissner Corpuscles sense?
Vertical indentations on the skin ex: Braille
Is the receptive field of the Meissner Corpuscle large or small?
Small
Are Meissner Corpuscles slow or fast adapting?
Fast
Where are Merkel discs?
Dermis
Do Merkel discs have a small or large receptive field?
Small
Are Merkel discs slow or fast adapting?
Slow
Where are Ruffini corpuscles?
Dermis and joints
What do Ruffini detect?
Stretching of skin and rotation of joints
Are Ruffini corp slow or fast adapting?
Slow
Does Ruffini have small or big receptive fields?
Big
Where are Pacinian corpuscles?
Deep dermis near SubCu
Do Pacinian corpuscles have big or small receptive fields?
Big
Are Pacinian fast or slow adapting?
Fast
What does Pacinian sense?
Vibration and movement
Name 3 proprioceptors of mechanoreceptors?
1) muscle spindle
2) golgi tendon organs
3) joint receptors
What do muscle spindles detect?
Muscle stretch
Where are muscle spindles found?
Perimysium (connective tissue)
Where is golgi tendon organ?
In tendon near muscle insertion on bone
What does Golgi tendon organ sense?
Tendon stretch and muscle force
What do joint receptors sense?
Stretch of joint capsule
What are thermoreceptors?
Sense temperature
Are thermoreceptors slow or fast adapting?
Slow
What is an ion channel that opens when temperature is sensed that triggers an action potential?
TRP Channel
What does TRP stand for?
Transient Receptor Potential
What temp activates a TRPV channel?
90-120F
What temp activates TRP-M8 channel?
50-104F
Where are TRP-V located?
Deep dermis
Where are TRP-M8?
Superficial dermis, close to epidermis
What senses temp below 50 or above 120?
Nociceptors (pain)
3 classes of nociceptors
1) thermal
2) mechanical
3) polymodal
True or false: pain threshold is the same for everyone?
True
True or false: pain tolerance varies person to person
True
How much of eye is visible on our body?
1/6
What are 3 layers of eye?
1) fibrous
2) vascular
3) neural
What are 2 parts of fibrous layer?
1) sclera
2) cornea
What part of the eye is tough, fibrous and anchoring?
Sclera
What runs through a small opening at the back of the sclera?
Optic nerve
What is the transition between the sclera and the cornea called?
Corneal limbus
What is the transparent, domed-shape portion of the eye?
Cornea
What is the cornea made of?
Stratified squamous epithelial cells
What is main function of cornea?
Helps to focus light on retina
What is the cornea considered “immune privileged”?
No blood vessels so no immune cells; makes transplant without rejection possible.
What is the vascular layer of the eye called?
Uvea
What are 4 parts of uvea?
1) iris
2) pupil
3) choroid
4) ciliary body
What are 2 muscles of the iris?
1) sphincter pupillae (circular)
2) dilator pupillae (radial)
What is the shape of the lens?
Biconvex
What does the lens do?
Focuses light on retina
What does ciliary body do?
1) connects to ligaments that hold and shape lens
2) makes fluid between cornea and iris
Where is choroid?
Behind retina
2 functions of choroid
1) provide nutrients via blood vessels
2) absorb light
What is the innermost layer of the eye?
Neural layer
Where are rods and cones?
Retina
What is responsible for night vision?
Rods
How many rods per eye?
120 million
What colors do cones “see”?
Red, green and blue
How many cones per eye?
6 million
Where are most cones located?
In the macula
What is the center part of the macula with highest concentration of cones?
Fovea
Where does optic nerve leave the retina?
Optic disc
Because the optic disc doesn’t have photo receptors, what is it known as?
Optic blind spot
What is contained in the anterior chamber of the eye?
Cornea and iris
Where is the posterior chamber of the eye?
Between iris and lens
What 2 chambers make up the anterior section of the eye?
Anterior and posterior
What fluid is in anterior section of the eye?
Aqueous humor
What fluid is in posterior section of the eye?
Vitreous humor
What produces aqueous humor?
Ciliary epithelium
What does aqueous humor do?
1) provide nutrients (lens, cornea)
2) structural support
Where does aqueous humor flow through out of the eye?
Trabecular mesh work (spongey)
What circular channel leads aqueous humor from trabecular mesh to aqueous vein?
Canal of Schlemm
What 2 functions is ear responsible for?
Hearing and balance
2 parts of outer ear
1) Pinna (auricle)
2) ear canal
Name 3 ear bones of middle ear
1) maleus
2) incus
3) stapes
Name 2 parts of inner ear
1) cochlea
2) semicircular canals
What does cochlea do?
Converts sound waves to electrical impulses
What do semicircular canals of inner ear do?
Help with balance
What is auricle (pinna) made of?
Cartilage
What is a lobule?
Ear lobe
What is the 1” tube that leads to the tympanic membrane?
External acoustic meatus (ear canal)
What produces wax in the ear?
Ceruminous glands
What is another name for tympanic membrane?
Ear drum
Where is middle ear located in skull?
Inside temporal bone
What forms the lateral wall of the middle ear?
Ear drum
What is the posterior wall of middle ear called?
Mastoid antrum
What is found in the anterior wall of middle ear that leads to nasopharynx?
Eustachian tube
Name 3 functions of eustachian tybe
1) equalizes pressure
2) protects ear from fluid reflux
3) clears mid ear secretions
Through what does vibration from stapes to inner ear travel?
Oval window
What are 2 parts of cochlea?
1) bony labyrinth
2) membranous labyrinth
What is bony labyrinth of cochlea filled with?
Perilymph
What is membranous labyrinth of cochlea filled with?
Endolymph
Is cochlea at the front or back of the head?
Front
What is cochlea responsible for?
Hearing
Where are semicircular canals found, front or back?
Back
What are semicircular canals for?
Balance
What connects the middle ear to the inner ear through the oval window?
Scala vestibula
What converts vibration to electrical impulse in the cochlea?
Organ of Corti
Where is Organ of Corti found?
Cochlear duct
What is considered the “mastermind of hearing”?
Organ of Corti
What are hearing receptors in Organ of Corti called?
Hair cells
What connects the middle ear to the inner ear through the round window?
Scala tympani
What CN receives electrical impulse?
CN 8
What are 2 parts of vestibular apparatus (inner ear)
1) semicircular canals
2) utricle and saccule
What contain fluid and balance receptors in their macula?
Utricle and Saccula
What is gustation?
Taste
What does the intrinsic muscle of the tongue do?
Helps tongue change shape
What does the extrinsic muscle of the tongue do?
Attaches and guides movement
What is the V-shaped groove across the rear of the tongue?
Sulcus terminalus
What does sulcus terminalus divide on the tongue?
Front 2/3 from back 1/3
What are bumps of lymphatic tissue on back of tongue?
Lingual papillae
What do lingual papillae do?
Fight pathogens with B & T cells
What give rough texture and helps food stick to tongue?
Anterior papillae
What is the most numerous type of papillae?
Filiform
What is the threadlike papillae that cover the anterior 2/3 of tongue?
Filiform
What are Filiform papillae for?
Touch (not taste)
Where are fungiform papillae found?
Tip if tongue
Where are foliate papillae found?
Sides of tongue
What are the large, round papillae found just in front of sulcus terminalis?
Circumvallate
What are the epithelial cells in taste buds?
Taste receptor cells
True/False: taste receptor cells can be found from the soft palate to the upper esophagus
True
How often are taste receptor cells replaced by basal layer of taste buds?
Every 2 weeks
Taste receptor cells are chemoreceptors that respond to what?
Tastants
What sticks out through taste pore on taste receptor and contacts tastants?
Gustatory hair
Cells bodies in the front of the tongue have axons that transfer taste to brain via which CN?
Facial nerve
Cells bodies in the back of the tongue and oral cavity have axons that transfer taste to brain via which CN?
Glossopharyngeal
Cells bodies in the back of throat and esophagus have axons that transfer taste to brain via which CN?
Vagus
What are 5 tastes?
Sweet
Salt
Sour
Bitter
Umami
What taste sweet/umami
Fungiform (tip of tongue)
What taste salt/sour?
Foliate (side)
What taste bitter?
Circumvallate (back)
How are salt/sour neurotransmitters released?
Depolarization
How are sweet/bitter/umami neurotransmitters released?
G-protein coupled pathway
4 factors that affect taste
1) hunger
2) adaptation
3) smell
4) age
What tastes are you more sensitive to when you’re hungry?
Sweet and salt
What is olfaction?
Smell
What 4 areas make up nasal cavity?
1) vestibule
2) respiratory region
3) olfactory region
4) lamina propria
What is the shell-like bony part of respiratory region called?
Conchae (superior, middle, inferior)
What does mucus in respiratory region do?
Trap pathogens
Moisten air
What is olfactory region lined with?
Olfactory epithelium
What does olfactory epithelium contain?
Olfactory receptor cells
What shaped cell supports olfactory receptor cells?
Columnar
What type of neurons do olfactory receptor cells have?
Bipolar
What does the cilia use to grab odorants?
G-protein receptors
How many different odors can we smell?
10,000+
How many different type of smell receptor proteins?
1000+
What are 2nd order neurons of olfactory bulb called?
Mitral cells
Which side of the olfactory tract is responsible for smell triggering emotion/memory?
Lateral
How quickly can adaptation of smell occur?
< 1 minute
What kind of cells are the gustatory hairs?
Epithelial
