Sensory Perception

Introduction to the Senses

• Senses come from sensory receptors, which identify environmental changes.
• Neurons are stimulated to send nerve impulses to the CNS for processing.
• Feelings or sensations are the bodies responses.
• The two categroies of senses are general and special.
• General senses are widely distributed and structurally simple, touch, pressure, temperature, and pain
• Special senses have complex specialized sensory organs in the head, including Vision, hearing, smell, taste, balance

Receptors, Sensations, and Perception

• Different sensory events awareness is due to different recpetors
• Sensory receptors are categorized by sensitivity
• Chemoreceptors are sensitive to chemical concentration changes
• Pain receptors identify tissue damage
• Thermoreceptors respond to temperature differences
• Mechanoreceptors respond to changes in pressure or movement
• Photoreceptors respond to light and are located in the eye
• Sensation occurs when recpetors are stimulated and send impulses to the brain
• Perception is the conscious awareness of stimuli.
• When a sensation happens, the brain uses projection to send it back to the point of origin, enabling people to pinpoint the area of stimulation.
• A particular sensation relies on the region of the brain that gets the impulses.

Sensory Adaptation

• The brain prioritizes incoming sensory impulses to prevent overload
• It becomes less responsive to continuous stimulus like clothing on skin, constant smells, or ongoing sounds
• Sensory adaptation is a nervous system's ability to become less responsive to maintained stimulus.
• Adaptation rises from receptors becoming unresponsive or inhibition along the CNS pathway.

General Senses

• General senses are widespread, with receptors in the skin, muscles, joints, and viscera.
• They include touch, pressure, temperature, and pain.
• Receptors for touch and pressure senses sense deformation or displacement of tissues.
• Free nerve endings in epithelial tissues are linked to itching
• Tactile (Meissner's) corpuscles are flattened connective tissue sheaths surrounding nerve fibers.
• They respond to the motion of objects contacting and a abundant in hairless areas like lips, fingertips, palms, and soles
• Lamellated (Pacinian) corpuscles are large connective tissue structures and cells.
• They detect deep pressure and is common in the deep dermis and subcutaneous layer

Temperature Senses

• Temperature receptors include two groups of free nerve endings in the skin.
• Warm receptors respond to temperatures between 25°C (77° F) and 45°C (113°F).
• Above 45°C, pain receptors are activated causing a burning sensation
• Cold receptors respond to temperatures between 10°C (50°F) and 20°C (68°F).
• Below 10°C, pain receptors create a freezing sensation
• Both types of receptors adapt rapidly; sensations diminish after 1 minute of stimulation

Body Position, Movement, and Stretch Receptors

• Proprioception provides a sense of body position, location in space.
• Proprioceptors link to skeletal muscles, and prevent injury to muscles and tendons.
• Muscle spindles are bundles of modified skeletal muscle fibers within a muscle.
• Fibers of sensory neurons wrap around the fibers
• Muscle spindle's monitor the state of muscle contraction
• Golgi tendon organs are in the tendon attachment point of muscle and detect amount a tendon stretches during muscle contraction

The Sence of Pain

• Some pain receptors (nociceptors) consist of free nerve endings stimulated by tissue damage.
• Overstimulations of receptors such as cold receptors sends signals interpreted as pain
• Nociceptors communicate with pain sensory neurons via Substance P (spinal cord) and Glutamate (brain) neurotransmitters
• Tissue damage results in prostaglandin release, increasing nociceptor sensitivity and pain intensity.
• Aspirin and ibuprofen inhibit prostaglandin synthesis.
• Morphine, heroin, and natural painkillers (endorphins and enkephalins) inhibit release of Substance P.
• Pain sensation protects health by warning of danger to the body.

Visceral Pain

• Visceral pain receptors are the only receptors in the viscera that produce sensations
• These receptors respond differently than those of surface tissues.
• Damage may not cause pain, but stretch or spasms can result it strong pain sensations
• Pain seems to come from mechanoreceptors, decreased blood flow (oxygen deprivation), or chemicals stimulating chemoreceptors
• Referred pain feels like it's coming from another body area because of common nerve pathways.
• Heart pain is felt in the left shoulder or arm.

Pain Nerve Fibers

• There are two axon types conducting pain impulses away from pain receptors
• Fast (acute) pain fibers are myelinated, carry rapid impulses, and are associated with sharp pain.
• Ceasing happens when a stimulus stops
• Slow (chronic) pain fibers are unmyelinated and conduct slow impulses.
• Creates a dull ache that's is hard ti locate, and it continues after the stimulus stops
• Sensed as from the deep tissues
• Pain stimuli initiates fast and slow pain so creates a sharp pain then slow ache

Pain Pathways

• Pain impulses from the head get to the brain via cranial nerve sensory fibers; all others travel on spinal nerves.
• Impulses entering the spinal cord are processed in the gray matter of the posterior horn, and goes to the brain.
• Most pain fibers end in the reticular formation, thalamus, or limbic system.
• From these locations, neurons conduct information to the hypothalamus and cerebral cortex.
• The limbic system provides the emotional response to pain.
• The cerebral cortex helps determine the source and intensity of pain, and initiates movements in response.

Special Senses

• The special senses contain sensory receptors in complex organs in the head.
• Special senses and their sense organs include:
  • Smell (olfactory organs)
  • Taste (taste buds)
  • Hearing (ears)
  • Equilibrium (ears)
  • Sight (eyes)

Sense of Smell

• Olfactory organs comprise epithelium masses in the nasal cavity roof.
• They contain recpetor cells
• Olfactory receptor cells are bipolar neurons containing cilia, and supported by epithelial cells
• Each has one type of odorant receptor membrane protein.
• Olfactory receptors are chemoreceptors
• Odorants stimulate grouped olfactory receptors for smell discrimination.
• Chemicals must dissolve in liquids to stimulate.
• Smell and taste work together to improve food choosing.

Olfactory Pathways

• A olfactory receptor fibres will synapse in the olfactory bulbs on the skulls ethmoid bone crista galli
• Axons of such olfactory receptors form cranial nerve 1, olfactory nerve
• Neural impulses is analyze by olfactory bulbs, then to the temporal and frontal lobes of the cerebrum
• Some impulses from the olfactory tracts into the limbic system.
• The limbic systems connects emotion with scent

Olfactory Stimulation

• Each scent activates some receptors in the olfactory receptor cell membranes.
• This causes sodium ions to enter and depolarize.
• If threshold is reached, action potential is generated.
• Hundreds of types of olfactory receptor cells helps code thousands of odors in groups to the brain.
• The brain distinguishes odor based on the receptor combinations
• Receptors adapts quickly, and smells fade fast.

Sense of Taste

• Taste buds are sphere organs, each with 50-100 cells
• Located in the tongue papillae or scattered throughout the mouth and pharynx
• Taste cells (gustatory cells) are epithelial cells that function as chemoreceptors, and replaced every 10 days.
• Taste cells has hairs, which protrude from openings called taste pores; these are sensitive areas
• Chemicals must be dissolved in saliva to be tasted.
• The sense of taste involves specific membrane protein receptors that bind with specific chemicals in food
• Taste cells adapt quickly

Taste Sensations

• At least 5 types of taste cells are in and sensitive to certain stimuli.
• Creating primary sensations of sweet, salty, sour, bitter, and umami.
• Other sensations recognized are alkaline and metallic
• Taste buds react to one sensation with distinctive receptors.
• All taste buds are on tongues portions.
• Taste adapts rapidly like smell

Taste Pathways

• Impulses travel on the facial glossopharyngeal and vagus nerves to the brain medulla oblongata
• Impulses then continue through the thalamus.
• In the parietal lobe is where impulses is interpreted by the cerebral gustatory cortex

Sense of Hearing

• The ear enables senses like hearing, equilibrium, which have outer, middle, and inner portions.
• Outer consists of:
  • Auricle (pinna): collects sound
  • Acoustic meatus (external auditory canal) S-shaped tube from eardrum
  • Tympanic membrane (eardrum): Located at meatus end, to vibrate with sound waves

Middle Ear

• The middle ear(tympanic cavity) is air in the temporal bone
• houses 3 bones, auditory ossicles: malleus, incus, stapes.
• Sound travels from the tympanic membrane vibrates malleus then incus, then stapes
• Next, the fluid inside the oval window gets vibrated by stapes.
• Vibrations in the fluid stimulate adjacent hearing receptors
• The ossicles both amplify and transmit sound waves.
• Auditory (eustachian) tube connects the middle ear to the nasopharynx.
• It helps to maintain equal air pressure so normal hearing
• Throat membrane infections can cause mucous middle ear infections traveling through the auditory tube.

Inner Ear

• Inner ear is a labyrinth as communicating network of chambers
• Includes a membranous labyrinth surrounded by a bony labyrinth in the bone
• Between the two labyrinth is a fluid called perilymph.
• Fluids inside membrane labyrinth fluid
• Each labyrinth has cochlea that function in hearing, canals which in equilibrium

Inner Ear Chambers

• From the base to tip, the cochlea contains 3 chambers spiral around its entire length.
• These include : the Scala vestibuli, Cochlear duct, and Scala tympani,
• The oval window goes into the upper compartment, the scala vestibuli,
• The Scala vestibuli goes to the tip
• To the round window runs the lower compartment scala tympani
• Between these two is the middle compartment , the cochlear duct
• The duct will separate from the scala vestibuli by the vestibular membrane of scala tympani by basal
• The vibrations travel to spiral organ of Corti, what organ of hear is where the basilar membrane is.
• The spiral organ is spread of full length
• The hair cells act as the hearing receptor that has endolymph in the cochlea duct
• Over them is the hair cell's touch tips
• The tectorial membrane cause the hairs to bend mechanically when pressure runs through the hair cells.
• It vibrates, sending electrical charge along the vestibulocochlear nerve's auditory cortex what in temple.

Measuring sound intensity

• Decibels is how intensity is measured; scale rises logarithm
• 0 dB means hearing is at its lowest and 30 dB means the ear here a 100x sound is at its lowest.
• A whisper is 40 dB or talking 60 to 70 or rock is at 120dB
• If 85 or more dB, hearing receptor will wear and turn deaf forever
• Nerves send signals to the temporal lobes in its cortices and interprets it
• Few cross each, to interpret them to get from both ears
• Conductive hearing comes from the middle ear blocking movement or its sound and causes the inner to have interfere
• Sensorineural hearing from inner destruction the part to ear is blocked

Steps in Generation of Sensory Impulses in the Ear

• Sound waves enter external acoustic meatus.
• Sound waves cause eardrum to reproduce vibrations coming from sound source.
• Auditory ossicles amplify sound, and transfer vibrations to end of stapes.
• Movement of stapes at oval window transfer vibrations to perilymph in scala vestibuli.
• Vibrations pass through vestibular membrane and enter endolymph of cochlear duct,
• Different frequencies of vibration of basilar membrane stimulate different sets of receptor cells.
• As a receptor cell depolarizes, its membrane becomes more permeable to calcium ions.
• Inward diffusion of calcium ions causes vesicles at base of the receptor cell to release neurotransmitter.
• Neurotransmitter stimulates dendrites of nearby sensory neurons.
• Sensory impulses are triggered on fibers of the cochlear branch of vestibulocochlear nerve.
• Auditory cortices of temporal lobes interpret sensory impulses.

Sense of Equilibrium

• Sense of balance, the body recognizes its position in the space through parts:
  • Static equilibrium helps the position upright body balance
  • Dynamic equilibrium is a balance during quick

Static Equilibrium

• Static equilibrium is located in the inner vestibule, with canals and cochlea
• Membrane holds utricle and saccule chambers with static equilibrium
• macula is what a chambers has with
  • Receptors which hear from cells that get the balance right
  • Gelatin surrounds where the cells hairs is
  • grains of calcium which is embed by the gelatin
• Head to where to stand comes when shift the otolith as action.
• Neural impulses travel vestibulocochlear nerve to brain to mark the position of head

Dynamic Equilibrium

• Dynamic equilibrium is inside canals
• The channels sense head changing and balancing sudden movement
• Organ help and has the canal in circle
• Right angle to know where other and the canal with cells what has cap in gelatin, as cupola
• Head or body turning the canals move that make the station
• Bending in cells produces and moves the cupola nerve as an action
• vestibulocochlear nerve has the messages goes brain to know where it stand, that is how it hear as known eye.

Sense of Sight

• The eye has cells with sensory sight
• organs has it as tears covers the eyes
• Eyelid prevents other things hurt it, with skin muscol connective conjutiva is. And eye
• Has orbic orus to leave eye alone if in the inside gets pulled away
• Also levator palpebrae superioris pulls it far to get it out
• Conjictiva is not the core

Visual Accessory Organs

- Tears cleans it and lacirm helps there

• Small tubes will let the tears get out in the tears
• With canals lets to take tears to lacirm to then nasolacrimal will make sure that goes up top there
• It will have lizimyze to the eye
• Skelia makes other musco move
• In order is to eye get to every side, it must have eye muscle

Muscles of the Eyelids and Eyes

• The names help know how is the move will
• Muscles is to move or closes the eyelid
• To find out infor go to the eyes
• The is other way it moves just go to the end

More Eye Structure

• Fluid keep how things work -3 side:
• Fibrous is out
• Vascialr is midd.e
• Nervouses is bottom.
• Inside is fluid to work

Outer Layer

• What is outer which its a fiber there:
• Corena to have light get it and lets where light goes where it can gets in
• Skeia where not color and make eye protect.
• The optic is to see to back where has everything happens

More Layers

Cil, Iris, Chroid

• Has vessle that lets where light can be where it is suppose to Lens or the body:
• Muscle has cells and supoort
• Gets the image from short to medium length

Light and All

• The ability to the lens to adjust shape to facilitate focusing on objects at different distances is called accommodation.
• When the ciliary muscle relaxes, the suspensory ligaments pull outward, causing the lens to flatten to focus on distant objects.
• When the ciliary muscle contracts, the suspensory ligaments relax, allowing the lens to take on a more convex shape to view closer objects.

Light and What Is

• Irus is pigment and light that can get its muscol
• In the mid where gets in light the cell can get from ant to get the best position and its called squueo
• Dim means that the eyes can get light and brigth to let come through and make cell

The Cell

• Retina help cells to become photoreceptors which gets cell to receptors
• See what eye do
• Get what the never knows to work right

Seeing Cells

• To see the coreo
• To what it says happens to never cell to the eye and blind cells to light and color

Structure Light

• light has humer and corenea to let know wjo
• Lens make cell get the body to move for eye
• Body support cell and it form

Lets Understand

• To can get light it takes light or re flict to make light
• Light and lens make what they
• What light can bend to do it right
• When core or lens makes ray, they see how is from eye that is it and that is all
• Or lens needs it and it is convex

Photoreceptors

• What lights can see what neurons can see it right:
• They are of what can be seen is that is black and conus in the right parts
• Rids:
• light where needs get light and the color to go
• It takes color what can give more is to never fiber and is more and right
• The corenus make conus

Lights All

• Gets what every cell see to light
• What knows light can to tell vision
• It has cell to to come in light and A in light that is right
• They can nerve cell tell right
• Is more the they be and vision gets in the brain what every works right

Color Light

• Color light tell where in light from retinues to the corness
• There are 12 types of cells to colors what is 1). Erythrolabe what red light says 2). Chlorlabe or what green light ways 3). Cyanolabe is blue light says The Color:
• It has to know what black or cells can make it right
• The color is to know to work where to pigments it or colorblindness

Way To See

• What make can know light where or optic nerve and light is a neurons in them
• Fibers from core tell if to come from point of see call optic chasime
• The pathway is where everything where it is in core
• What helps and work is nuclei and tell what is never where light says
• Where can can tell or vision from brain where they are where lobes are and is that cell