Sense Organs Flashcards
What are the 2 groups sense organs are divided into?
general sense and special sense
What do general senses include?
touch, pressure, pain, temperature (heat and cold), proprioception, visceral sensations
What do special senses include?
eye (vision), ear (hearing), equilibrium (balance and head position), smell (odors), taste, electromagnetic/light, mechanical, chemical
What is a sensory receptor?
a specialized cell or cell processes
What are the simplest sensory receptors?
free nerve endings (branching tips of dendrites)
What is receptor function?
receptor specificity
development of receptor potentials
translates a stimulus into an action potential that can be quickly conducted to the CNS (transduction)
the intensity of the stimulus is indicated by the frequency and pattern of action potentials
What is the classification of general sense receptors?
nociceptors, thermoreceptors, chemoreceptors
What do nociceptors recieve?
pain and local anesthetics
What do thermoreceptors recieve?
temperature
What are the three types of mechanoreceptors?
tactile receptors (touch, pressure, and vibration), baroreceptors (pressure in blood vessels), proprioceptors (positions of joints and muscle)
What do chemoreceptors recieve?
chemical concentration
What is smell provided by?
paired olfactory organs
Where is olfaction located?
in the nasal cavity on either side of the nasal septum
What are the two parts of olfaction called?
vomeronasal organ and olfactory mucose/bulb
What are the steps of olfactory reception?
odorants –> bind to odorant binding proteins –> opens sodium channels –> graded potentials –> action potentials
What are the steps of the olfactory pathways?
receptor potential –> olfactory nerves (cranial nerve I) in the olfactory bulb –> olfactory tract –> thalamus –> olfactory centers (temporal lobe) of the brain
What is the olfactory organ made up of?
olfactory epithelium and lamina propria
What are olfactory receptor cells and where are they located?
they are olfactory cilia that contain receptor proteins sensitive to chemicals dissolved in overlying mucus in the olfactory epithelium
What kind of cells are in olfactory epithelium
supporting cells
What are the surfaces of the olfactory epithelium coated with>
secretions of the olfactory glands
What is the lamina propria
an underlying layer of areolar tissue that contains olfactory glands
What is in gustation?
taste (gustatory) receptors are clustered in taste buds
What are taste buds associated with?
taste buds are associated with epithelial projections (lingual papillae) on dorsal surface of tongue
What does each taste bud contain?
gustatory cells, which extend taste hairs through a narrow taste pore
What are the steps to the gustatory pathway?
receptor potential in the gustatory cells –> facial nerve and glossopharyngeal nerve –> medulla oblongata –> thalamus –> gustatory area of the cerebral cortex in the parietal lobe of the brain
What are the three layers of the eye?
fibrous tunic, vascular tunic (uvea), neural tunic (retina)
What is included in the fibrous tunic?
outer layer, sclera, cornea, limbus
What is included in the vascular tunic (uvea)?
middle layer, iris, ciliary body, choroid
What is the neural tunic?
inner layer
What does the pigment part of the neural tunic include?
a thin outer layer that absorbs light that passes through the neural part
What does the neural part of the neural tunic include?
a thick inner layer that contains light receptors and associated neurons
What is included in the neural part of the retina
photoreceptor neurons, visual receptors (rods, cones, bipolar cells, ganglionic neurons)
What do the rods in the eye do?
the do not discriminate colors and are every light sensitive
What do the cones of the eye do?
they provide color vision and include macula lutea and fovea *highest concentration of cones; provides sharpest vision
What is the optic disc?
a blind spot (a circular region)
What is the function of the lens of the eye?
to focus a visual image on the photoreceptors by changing its shapes
When is light refracted?
light is refracted (bent) when it passes through the cornea and lens, precisely forming a miniature image
What is accommodation?
focusing images on the retina by changing the shape of the les, the lens becomes rounder to focus on the image of a nearby object
What are the steps of the visual pathway?
axons from all ganglion cells converge on the optic disc –> optic nerves –> optic chiasm –> optic tracts –> optic radiations –> visual cortex of occipital lobe in another side
What typically shows little convergence?
cones
What is convergence?
information processing and integration
What is the fluid inside the inner ear?
endolymph
What protects and surrounds the membranous labyrinth?
The bony labyrinth
What is the inner ear subdivided into?
vestibule
three semicircular canals
cochlea
What does the vestibule receptors provide?
receptors provide sensations of gravity and linear acceleration
What do semicircular canals receptors provide?
receptors provide sensations of rotation
What do cochlear receptors provide?
receptors provide the sense of hearing
What is the basic receptor of the inner ear?
hair cell
How does a hair cell release chemical transmitters?
distortion of the stereocilia and kinocilium makes the cell release chemical transmitters
What do stereocilia and kinocilium provide?
provide information about the direction and strength of the mechanical stimuli
What is the pathway for equilibrium sensations?
hair cells of the vestibule and semicircular ducts –> sensory neurons –> vestibular branch of the vestibulocochlear nerve –> vestibular nuclei at the boundary between the pons and the medulla oblongata –> cerebellum and parietal lobe
What is the auditory pathway?
the sensory neuron afferent fibers forms the cochlear branch of the vestibulocochlear nerve –> cochlear nucleus in the medulla oblongata –> temporal lobe of the opposite side of the brain
