The Senses Flashcards
Special sense have receptors …..
-strategically placed in unique organs for hearing and balance,olfaction(smell), gustation(taste), and visual system
Sensory receptors are formed by…. And there function is…
terminals of afferent neurons or by specialized cells that synapse with afferent neurons
-to gather information about the external and internal environment
Sensory receptors respond to stimuli such as… by changing their…. To …..which results in a ….
-respond to stimuli such as light, heat, chemicals, mechanical stress, by changing their conductance to ions such as sodium, potassium, calcium which results in a change in membrane potential
Define sensory transduction
-conversion of stimulus to a change in membrane potential
What types of sensory receptors are formed by dendrites of an afferent neuron
-temperature and pain receptors
What types of sensory receptors are formed by a cell that synapses with an afferent neuron
-mechanoreceptors, photoreceptors and chemoreceptors
What are the 2 main types of sensory receptors?
-receptor is afferent neuron
-receptor regulates afferent neuron
What are the 5 basic types of sensory receptors
-mechanoreceptor: detect changes in body position, pressure, acceleration(auditory receptors of the ear)
-photoreceptors: detect light and are located in the eye
-chemoreceptors: detect specific molecules or conditions such as acidity(taste buds)
-thermoreceptors: temperature
-nocireceptors: detect tissue damage or noxious chemicals. Their activity leads to pain
Touch and pressure receptors in human skin can be
-free neuronal endings or encapsulated neuronal endings of sensory neurons
What does the meissne’s copuscle in the skin sense?
-touch
What does the pacinian corpuscle in the skin sense?
-pressure
Define propioception
-the sense of the relative position of the neighboring parts of the body
Propioceptive sense is composed of
-information from sensory neurons located in the inner ear (motion and orientation)
-and in the stretch receptors located in the muscles and the joint supporting ligaments(stance)
Propioceptors detect stimuli used by the
-CNS to monitor and maintain body and limb positions
-mechanoreceptors in muscles,tendons, joints detect changes in pressure/tension of body parts
Where are stretch receptors found
-in muscle and tendons (in tendons its called golgi tendon organs= nerve fiber with collagen strands that connect the muscle to the tendon; GTO detects muscle tension
Stretch receptors in the muscle:
-detect position and movement in the limbs by detecting how much and how fast a muscle is stretched
Balance involves
The vestibular system of the inner ear
The vestibular apparatus is comprised of… and perceives
-3 semicircular canals and 2 fluid filled chambers; utricle and saccule
-the position and motion of the head using mechanoreceptors
Semicircular canals in the ear detect..
-rotation motion
The ampulla of the semicircular canal
-detects rotational movement of the head body
The utricle and saccule in the ear give information about
-head position (up/down)
-changes in the rate of linear motion of the body
Summarize the concept of balance
-Gelatinous mass moves in response to gravity or movement, bending hair cells and initiating action potentials
-patterns of stimulation are translated by brain into specific information about head position of acceleration
Hearing relies on…
-sensory hair cells in the ear that respond to the vibrations of sound waves
Define sound waves
-Exist as variations of pressure in a medium such as air
- are created by the vibration of an object which cause the air surrounding it to vibrate
-the vibrating air then causes the human eardrum to vibrate, which the brain interprets as sound
Vibrations produce…. Volume or loudness is function of …… Pitch is function of
-sound waves
-function of wave amplitude
-function of wave frequency
The eardrum is also called the
-tympanic membrane
The eustachian tube leads to
-the throat
-when we swallow the tube opens, air flows in or out of the ear to equalize pressure
The Basilar membrane….
-forms part of the floor of the cochlear duct
-anchors the sensory hari cells in the organ of corti
-vibrates in response to the vibrations transmitted through the inner ear
Organ of corti
-region of the inner ear that contains sensory hair cells that detect the sound vibrations transmitted to the inner ear
-is the sensory organ of hearing which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea
-is the sensory epithelium, a cellular layer on the basilar membrane
In the ear, Hair cells arranged in rows of inner hair cells…. And outer hair cells…
-responsible for hearing
-regulate tension of basilar membrane
In the ear, as sterocilia bend, they open
-K+ gates (mechanically gated ion channel)
Bending steriocilia in one direction…. Bending in the opposite direction…
-depolarizes the cell and stimulates neurotransmitter release
-repolarizes the cell and stops release
Hair cells in the organ of Corti are “turned” to certain sound frequencies by way of their location in the cochlea due to the…. In the basilar membrane
-degree of stiffness
Basilar membrane is …. Near the oval window and … at the outer end of cochlear duct
-narrow and stiff
-wider
High pitched sounds vibrate the basilar membrane at its…
-narrow, stiff beginning end
What does the cornea do?
-transparent, admits and refracts light, covers the iris, pupil and anterior chamber
What does the iris do?
-eye color
-behind the cornea, around the pupil
-controls the diameter of the pupil
-regulates amount of light that strikes the lens
What is the sclera of the eye
-white outer layer of the eyeball, protective layer
What is the chriod of the eye?
-vascular layer of the eye, between the sclera and the retina
What does the lens of the eye do?
-focuses image on the retina
What is the retina
-layer of neural cells that lines the back of the eye
-has photoreceptor cells that are sensitive to light and neurons that integrate information detected by photoreceptors
What is the macula of the eye
-pigmented area in the retina, contains the fovea
-involved in high acuity vision
What is the fovea region of the eye?
-region of the macula in the retina
-has high density of cone cells (photoreceptive cell for color
-also needed for sharp vision (detail)
Where is the blind spot of the eye ?
-area where the optic nerves passes through the optic disc: has no light detecting photoreceptive cells
here a part of the field of vision is not perceived, but the brain interpolates the blind spot based on surrounding, detail, and information from the other eye so the blind spot is not normally perceived
What is the anterior chamber of the eye
-lies between the the cornea (front of the eye) and the iris (colored part of the eye)
-filled with aqueous humor
What is the posterior chamber of the eye?
-located behind the iris and in front of the lens.
- Filled with aqueous humor
What is the vitreous chamber
-located behind the lens
-filled with vitreous humor
What is aqueous humor and its function in the eye
-a thin, watery fluid found in both the anterior and posterior chambers of the eye
-maintains intraocular pressure
-supplies nutrients to avascular parts of the eye
-removes waste
What is the vitreous humor of the eye and its function
-a thick, viscous fluid (gel like substance) that helps maintain the shape of the eye and absorb shock
-occupies the space behind the lens and in front of the retina at the back of the eye
What is the cillary body in the eye?
-part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor
What is the function of the cilliary muscle?
-a ring of smooth muscle fibers that a responsible for changing the shape of the lens in the eye to achieve accommodation
What happens when the eye focuses on a distant object?
-the ciliary muscles relax, allowing the ligaments that support the lens to tighten. The tightend ligaments flatten the lens, bringing the distant object into focus on the retina
What happens when the eye focuses on a close object?
-the ciliary muscles contract, loosening the ligaments and allowing the lean to become rounder. The rounded lens focuses a near object on the retina.
What are the basic steps of vision
-to see the eye must first form a precise image on the retina
- light energy striking the retina must be converted to action potentials transmitted to the brain by the optic nerve
-several cells, especially photoreceptor cells called rods and cones are needed for the eye to process light
What are amacrine cells
Group of dopamine-secreting neurons located in the retina of the eye
They release dopamine into the extracellular medium, are specifically active during daylight hours, and become silent at night
The retinal dopamine(amacrine cells) acts to…
-enhance the activity of the cone cells in the retina while suppressing rod cells, the result is to increase sensitivity to color and contrast during bright light conditions, at the cost of reduced sensitivity when the light is dim
Rods
-specialized for detection of low-intensity light
Cones
-specialized for detecting light of different wavelengths(colors)
The photorecpetor cells of the eye (called rods and cones)…
-contain photoreceptive molecules that absorb energy of light(photon) and generate changes in membrane potential
In rods, photopigment or photoreceptive molecules is
-rhodopsin, g protein receptor
In cones, photopigment or photoreceptive molecule is
-iodopsin
-iodopsins contain the protein complexes 1,2, and 3(red,yellow, green)
Photopigments (such as rhodopsin,iodopsin) are found in the
-discs of photoreceptor cells (that is rods and cones)
-consist of retinal combined with an opsin protein
In vertebrates chemoreceptors form parts of receptor organs for
-taste(gustation) and smell (olfaction
Chemoreceptors respond to the presence of
-specific molecules in the environment
What are papillae and the different types
-specialized regions of the tongue
-types of papillae: filiform, vallate, fungiform, foliate
Which types of papillae contain tastebuds?
-Vallate, Fungiform, Foliate
What is the function of the paillae filiform?
-filament-shaped
-provide a rough surface for food manipulation
What is the function the paillae vallate?
-largest, least numerous
-have taste buds
What is the function of the paillae fungiform?
-mushrooom shaped
-scattered over the surface of the tongue and look like small red dots
-have taste buds
What is the function of the paillae folliate?
-leaf-shaped, in folds on the sides of the tongue
-contain most sensitive taste buds
-decrease in number with age
Define tastebuds
-includes supporting cells surrounding taste (gustatory cells)
-are sensory structures that detect taste
-replaced every 10 days
-taste cells have microvilli extending into tastepores
Taste receptors..
-detect molecules from food or other objects that come into direct contact with the receptor
-are used primarily to identify foods
What do tastants do?
–they are dissolved in saliva and enter the taste
-by various mechanism (depending on the taste) tastants cause the taste cells to depolarize
The sour taste type
-most sensitive receptors on lateral aspects of the tongue
-H+ ion of acids cause depolarization
The salty taste type
-most sensitive receptors on tip of tongue. Shares lowest sensitivity with sweet
-anything with NA+ causes depolarization
The bitter taste type
-most sensitive receptor on posterior aspect
-highest sensitivity
-sensation produced by alkaloids which are toxic
The sweet taste type
-most sensitive receptor on tip of tongue
-shares lowest sensitivity with salty
What are the three main things that affect taste
-texture affects the perception of taste
-temperature affects taste perception
-taste is influenced by olfaction
What is the olfactory tract
-axons of afferent neurons from cells of the olfactory bulb that connect to several target regions in the brain including the amygdala
What is the olfactory bulb
-multi-layered structure that has axons from olfactory neurons organized in clusters, functions to help discriminate odors, filter out background odors to enhance sensitivity to odor detection
What are the olfactory receptive neurons
-bipolar neurons that have dendrites with cilia that protrude into the mucus covering the olfactory epithelium and axons that synapse with mitral cells in the olfactory bulb
Describe the steps of olfaction
-odorant molecules bind ot odorant receptors located on the cilia of olfactory receptor cells
-each olfactory receptor cell expresses one type of olfactory receptor that can respond to a set of different odorants
-the axons of the olfactory receptor cell that have the same type of receptor coverage and form synapses with mitral cells in structures called glomeruli(which are located in the olfactory bulb)
-multiple axons synapse with a single mitral cell
-mitral cell axons comprise the olfactory tract and transmit action potentials to various targets in the brain
Dendrites of olfactory neurons have
-enlarged ends(olfactory vesicles)
Cilia (olfactory hairs) of olfactory neuron are embedded in
-mucus
-odorants dissolve in mucus
Olfactory bulbs also connect to
-the limbic system
-signals can elicit emotional/visceral responses
Information goes to olfactory cortex of the
-frontal lobe without going through the thalamus
-only major sense that does not go through thalamus
The three regions in front lobe affect
-conscous perception of smell and interact with limbic system
The lateral olfactory area
-conscious perception of smell
Medial olfactory area
-visceral and emotional reactions to odors
Intermediate olfactory area
-effect modification of incoming information
