Ch 10 Flashcards
Sensory Receptors
-transduce (convert energy into a different form) different forms of energy in the “real world” into nerve impulses
- different modalities of sensations (sound, light, pressure) arise from differences in neural pathways in CNS and synaptic connections
- ->ex. optic nerve delivers an impulse: brain interprets it as light even though the impulse is the same as for hearing
What are the functional sensory receptors?
chemoreceptors
photoreceptors
thermoreceptors
mechanoreceptors
chemoreceptors
*functional sensory receptor
sense chemicals in environment (taste/smell) or blood
photoreceptors
*functional sensory receptor
sense light
thermoreceptors
*functional sensory receptor
respond to cold or heat
mechanoreceptors
*functional sensory receptor
stimulated by mechanical deformation of the receptor (touch, hearing)
What are the information sensory receptors?
proprioceptors
cutaneous
special senses
proprioceptors
- information sensory receptor
- found in muscles, tendons, and joints
- provide a sense of body position and allows find muscle control
cutaneous skin receptors
- information sensory receptor
- touch, pressure, heat, cold, and pain
special sense receptors
- information sensory receptor
- vision, hearing, taste, smell, equilibrium
What are the origin-named sensory receptors?
exteroceptors
interoceptors
exteroceptors
- origin-named sensory receptor
- respond to stimuli from OUTSIDE the body
- inclues cutaneous receptors and special senses
interoceptors
- origin-named sensory receptor
- respond to INTERNAL stimuli
- found in organs
- monitor BP, pH, and oxygen concentrations
Phasic
*fast adapting
respond w/burst of activity when stimulus is first applied, but quickly adapt to stimulus by decreasing response
-sensory adaptation - cease to pay attention to constant stimuli (becomes new normal)
-ex. smell, touch, taste
Tonic
*slow adapting
maintain a high firing rate as long as stimulus is applied
-ex. pain
What sensory pathway does not go to the thalamus first?
olfactory
Taste & Smell
Chemoreceptors
- taste (gustation) responds to chemicals dissolved in food/drink
- smell (olfaction) responds to chemical molecules from the air, olfaction increases gustation
Gustation
- receptors: taste buds
- consists of 50-100 specialized epithelial cells w/long microvilli
- each taste bud has taste cells sensitive to each taste (salty, sour, sweet, unami, bitter)
- microvilli come in contact w/chemicals
- cells behave like neurons by depolarizing and producing action potentials
- cells release neurotransmitters onto sensory neurons
Olfactory Receptors
- bipolar neurons w/ciliated dendrites projecting into nasal cavity
- proteins in cilia bind to odors
- 380 genes code for 380 different olfactory receptors (complex)
- one odorant molecule simulates one protein
Vestibular Apparatus
- provides sense of equilibrium
- located in inner ear
- consists of:
1. Otolith Organs - utricle and saccule (linear acceleration)
2. Semicircular Canals (rotational acceleration)
Inner Ear
- consists of bony labyrinth surrounding a membranous labyrinth
- between two is fluid called perilymph
- endolymph: fluid in membranous labyrinth, cilia are, high K concentration = depolarization
perilymph
fluid between bony and membranous labyrinth
-needed b/c if it was up against bone we wouldn’t have flexibility to detect subtle movements
Sensory Hair Cells
- in endolymph
- modified epithelial cells w/stereocilia and one kinocilium
- fluid/sound wave movement bends hairs
- when stereo cilia bend toward kinocilium, K channels open and K rushes in = depolarization
- cells release neurotransmitter that depolarizes sensory dendrites in vestibulocochlear nerve
Middle Ear
air-filled cavity between tympanic membrane and the cochlea
- containes three bones called ossicles: malleus, incus, stapes
- vibrations are transmitter/amplified along the bones
- stapes is attached to oval window which transfers vibrations into cochlea
Cochlea
- hearing part of inner ear
- fluid filled
- Three chambers:
1. Upper Chamber: portion of bony labyrinth called scala vesibuli (perilymph)
2. Lower Bony Chamber: called scala tympani (perilymph)
3. Cochlear Duct: contains a membranous labyrinth, called scala media (endolymph)
Hearing
- when sound waves enter scala media, the tectorial membrane vibrates, bending stereo cilia in hair cells of Organ of Corti
1. opens K channels that are facing endolymph
2. K rushes in (high on outside, backwards)
3. releases glutamate onto sensory neurons
4. K returns to perilymph at base of stereocilia
Vision
- comes from light energy transducer into nerve impulses
- only limited part of electromagnetic spectrum can excite photoreceptros
Path of Light
- Light passes through the cornea
- enters into anterior chamber of eye
- passes through pupil: can change shape to allow more/less light in
- passes through lens, can change shape to focus image
- passes through posterior chamber and vitreous body
- lastly, hits retina: photoreceptors are found and absorbed by the pigmented choroid layer
Pupil and Iris
- iris can increase/decrease the diameter of pupil
- iris also has pigmented epithelium for eye color
Pupil/Iris Constriction
contraction of circular muscles via parasympathetic stimulation
Pupil/Iris Dilation
contraction of radial muscles via sympathetic stimulation
Lens
- composed of layers of living cells that are normally completely clear
- avascular
- cell metabolism in anaerobic
- attached to muscles called ciliary bodies
- suspended from suspensory ligaments
Visual Fields
- part of the external world projected onto retina
- right side projected onto left side of retina, vice versa
Lens Accommodation
- ability of the lens to keep an object focused on the retina as the distance between the eye and object moves
- -> contraction= ciliary muscles causes lens to thicken/roundup (close vision)
- -> relaxation= ciliary muscle causes lens to thin/flatten (distant vision)
-glasses: help focus light onto retina where photoreceptor cells are
Retina
- extension of the brain, neural layers ace outward toward incoming light
- neuron axons in retina are gathered at a point called optic disc (blind spot) and exit as the optic nerve (blood vessels enter/leave here)
- photoreceptors (rods and cones) are the inner layer (toward vitreous body)
- ->these synapse on middle layer of bipolar cells, which synapse on the outer layer of ganglion cells
- ->also horizontal cells and amacrine cells within the layers
Rods
black and white vision in low light
-contain rhodopsin
Cones
color vision an acute
-contain photopsin which vary depending upon cone
Rods/Cones
outer segment: full flattened discs w/photopigment molecules
inner segment: contains the cell organelles
Vision
- dissociation of opsin closes Na channels
- photorecptors are hyper polarized and inhibition on bipolar cells is lifted
- bipolar cells activate ganglion cells that transmit action potentials to brain
