SENSES Sensory Receptors - detect environmental changes and trigger nerve impulses   - somatic senses (touch, pressure, temp, pain) - special senses (smell, taste, vision, equilibrium, hearing)

Receptors 1. Chemoreceptors = chemical 2. Pain receptors = pain 3. Thermoreceptors = heat 4. Mechanoreceptors = pressure, location 5. Photoreceptors = light

Sensations What do you think is going on in this picture? Sensation = feeling that occurs when a brain interprets a sensory impulse Projection = process where the cerebral cortex causes a feeling to stem from a source (eyes, ears) Sensory adaptation = sensory receptors stop sending signals when they are repeatedly stimulated   What do you think is going on in this picture? Sensory Deprivation is a technique initially used by neuro-psychiatrists designed to deliberately reduce or completely remove stimuli from one or all of the senses.

Somatic Senses Temperature Senses (warm and cold receptors) 1. Sensory Nerve Fibers - epithelial tissue, pain and pressure 2. Meissner's corpuscles - hairless areas of skin (lips, fingertips) 3. Pacinian corpuscles - deep pressure (tendons, joints) Temperature Senses (warm and cold receptors)

Sense of Pain Visceral Pain - occurs in visceral tissues such as heart, lungs, intestine Referred pain - feels as though it is coming from a different part (heart pain may be felt as pain in arm or shoulder) Acute Pain - originates from skin, usually stops when stimulus stops (needle prick) Chronic Pain - dull aching sensation

Rank the pain from least to worst. Stubbed toe Burn from stove Slamming finger in a door Paper cut Sprained ankle Sore throat Sore muscles

Regulation of Pain Inhibitors of Pain (natural brain chemicals can be mimicked by drugs such as morphine) Enkephalins Serotonin Endorphins

The Rising Tide of Prescription Abuse 2.6 million people nationwide now regularly use prescription pain pills for recreational purposes. Taken in small doses, painkillers produce feelings of euphoria with no hangover.  

Where do most people obtain prescription drugs? What regulations can be imposed to stop prescription drug abuse?

Special Senses Olfactory (smell) Gustatory (taste) Hearing & Equilibrium Sight

Sense of Smell (Olfactory) Odor --> Receptor Cell  -->  Olfactory bulb --> Olfactory Tract  --> LIMBIC SYSTEM Why do cells trigger memories?

Sense of Taste (Gustatory) Papillae = taste buds

Sense of Taste (Gustatory) Sweet Sour Bitter Salty Umami? Imagine the taste of: Strawberries Cheetos Banana French Fries Chocolate

Umami - a savory taste, is one of the five basic tastes, together with sweet, sour, bitter and salty. A loanword from the Japanese umami can be translated "pleasant savory taste". Bacon, cheddar and beef all have umami, and together they “synergize the umami effect.” Toss in sautéed mushrooms and you’ve struck an umami mother lode. Umami, he says, “alters our perception of other tastes, making salt, saltier, sweet sweeter, and bitter and sour less biting.” It is a taste that can’t be duplicated with any of the other four tastes.

What did the right eye say to the left eye? Between you and me, something smells!

Sense of Hearing External Ear Auricle (pinna) - outer ear External Auditory Meatus - opening to the eardrum

Middle Ear (tympanic cavity) Eardrum (tympanum) Auditory Ossicles - malleus, incus, stapes - transmit vibrations and amplify the signal Auditory Tube (eustachian tube) - connects the middle ear to the throat - helps maintain air pressure

Inner Ear Labyrinth - communicating chambers and tubes Osseous Labyrinth and Membranous Labyrinth Perilymph and Endolymph (fluids within the labyrinth) Semicircular Canals - sense of equilibrium  Cochlea - sense or hearing Organ of Corti - contains hearing receptors, hair cells detect vibrations

Why do children get tubes put in their ears?

Inner Ear: Cochlea Inside the cochlea are special neurons called HAIR CELLS The stapes is attached to the OVAL WINDOW, and vibrations cause the perilymph to vibrate; the hair cells here transmit this vibration. Therefore the HAIR CELLS in this region are receptors for HEARING. As you age, hair cells become damaged (loud music can speed this process along). Older people usually can’t hear frequencies that younger people can hear. Try the hearing test!

Steps in Hearing 1. Sound waves enter external auditory meatus 2. Eardrum vibrates 3. Auditory ossicles (malleus, incus, stapes) amplify vibrations 4. Stapes hits oval window and transmits vibrations to cochlea 5. Organs of corti contain receptor cells (hair cells) that deform from vibrations 6. Impulses sent to the vestibulocochlear nerve 7. Auditory cortex of the temporal lobe interprets sensory impulses 8. Round window dissipates vibrations within the cochlea

Cochlear Implants A cochlear implant receives sound from the outside environment, processes it, and sends small electric currents near the auditory nerve.    The brain learns to recognize this signal and the person experiences this as "hearing". 8 month old reacts to coclear implant How cochlear implants work (youtube video)

Sense of Equilibrium Static Equilibrium - maintain stability and posture   Dynamic Equilibrium - balance during sudden movement Cerebellum - interprets impulses from the semicircular canals and maintains overall balance Walking on two legs is harder than you think… Robot Fails

OTOSCOPE Otolaryngology (pronounced oh/toe/lair/in/goll/oh/jee) Otolaryngologists are physicians trained in the medical and surgical management and treatment of patients with diseases and disorders of the ear, nose, throat (ENT), and related structures of the head and neck. They are commonly referred to as ENT physicians.

THE EYE The eye is in the orbit of the skull for protection. Within the orbit are 6 extrinsic eye muscles, which move the eye. There are 4 cranial nerves: Optic (II), Occulomotor (III), Trochlear (IV), and Abducens (VI). People of Asian descent have an EPICANTHIC FOLD in the upper eyelid; no functional difference.

Visual Accessory Organs Can You Guess the Celebrity Eyes? Visual Accessory Organs These are organs that do not directly contribute to your sense of sight or vision, but do play a role in the health and functionality of the eye. Choices: Miley Cyrus, Kristen Stewart, Jennifer Lawrence

Eyelid Covers and protects the eye, thin skin   Skin will not protect you from intense radiation, that’s why we use special goggles in a tanning bed

CONJUNCTIVA is a covering around the eye and under the eyelids. PINK EYE - also known as CONJUNCTIVITIS    (from bacteria, very contagious) Pink Eye Slide Show from Web MD

Figure 16.7a

Retina The retina is made up of PHOTORECEPTORS, which are sensors for light.

Rods = monochromatic (b&w) Cones  = color vision

Light Refraction Light bends around objects   Images viewed by the eye are upside down

Vitreous Humor fovea centralis Aqueous Humor

R.O.Y.G.B.I.V   Rainbows are seen after rain because light is passing through water droplets.  This separates the white light into the individual colors of the spectrum

The Eye as an Optical Device

Accomodation Lens changes shape to facilitate focusing Shape change is dependent upon the suspensory ligaments 

We have difficulty interpreting images that are upside down Which one is the real mona lisa?

PUPILS Fun Fact: -When you are looking at someone you love, your pupils dilate, and they do the same when you are looking at someone you hate.

What causes red-eye? The flash on a camera is bright enough to cause a reflection off of the retina -- what you see is the red color from the blood vessels. Many cameras have a "red eye reduction" feature. In these cameras, the flash goes off twice -- once right before the picture is taken, and then again to actually take the picture. The first flash causes people's pupils to contract, reducing "red eye" 

Problems with Vision FLOATERS are when a capillary breaks and cells break off.    Floaters don’t actually move, the eye just tries to track them.

Lasik Surgery

See a real LASIK surgery (not for the squeamish)