Slide 1

Somatic and Special Senses Chapter 10 Mr. Wright, 2011

Slide 2

INTRODUCTION Section 10.1

Slide 3

Sensory Receptors Sensory receptors detect environmental changes and trigger nerve impulses. The CNS then processes and interprets the impulse. Finally, the body reacts to the sensory impulse.

Slide 4

Sensory Receptors 2 main categories: Somatic Senses touch, temperature, and pain Special Senses performed by complex sensory organs; things like taste, smell, sight, etc.

Slide 5

RECEPTORS AND SENSATIONS Section 10.2

Slide 6

Types of Receptors Chemoreceptors stimulated by changes in chemical concentration Pain receptors stimulated by tissue damage Thermoreceptors stimulated by changes in temperature Mechanoreceptors stimulated by changes in pressure or movement Photoreceptors stimulated by light

Slide 7

Sensations Sensation a feeling that occurs when the brain interprets a sensory impulse What you feel is based on which region of the brain receives the impulse. Projection your brains analysis of where the feeling comes from

Slide 8

Sensory Adaptation When receptors are continuously stimulated many of them undergo sensory adaptation. Receptors will stop sending impulses to stop sensation. Examples: You dont feel your clothes you are wearing Garbagemen dont notice the smell anymore Water feels hot when you get into a hot tub, but only for a little while.

Slide 9

SOMATIC SENSES Section 10.3

Slide 10

Somatic Senses Somatic senses - touch, pressure, temperature, and pain.

Slide 11

Touch and Pressure 3 kinds of receptors: Sensory Nerve Fibers free nerves between epithelial cells Meissners Corpuscles found in hairless portions of skin, respond to motion and light touch. Made of CT. Pacinian Corpuscles found deep in skin and in muscles and joints, sense heavy deep pressure. Made of CT.

Slide 12

Temperature Two types of receptors: warm and cold. Warm are most sensitive from 77 -113 degrees F. Cold are most sensitive from 50 68 degrees F. Once you go below 50 or above 113, pain receptors are triggered. Sensory adaptation does take place!

Slide 13

Pain Pain receptors are stimulated by tissue damage. Have little to no sensory adaptation. A pain receptor may send several impulses so pain can persist. How exactly pain receptors are stimulated is poorly understood. Chemical?

Slide 14

Visceral Pain Viscera your guts Pain receptors in the viscera are the only receptors that produce sensation. You dont feel temperature or pressure, but you sure as heck feel pain.

Slide 15

Visceral Pain Visceral pain may be referred pain. Referred pain felt in a different part of the body than the place of stimulation. For example, people having heart attacks generally feel a sharp pain in their left shoulder. Caused by common nerve pathways and mistakes by the cerebral cortex.

Slide 16

Types of Pain Fibers Acute conduct nerve impulses rapidly, you feel a sharp pain. Chronic conduct impulses slowly, you feel a dull, aching pain. An event that stimulates pain receptors usually stimulates both first you feel a sharp pain, followed by a dull ache.

Slide 17

SENSE OF SMELL Section 10.5

Slide 18

Olfactory Receptors Olfactory smell Olfactory receptors are chemoreceptors. Very closely associated with taste.

Slide 19

Olfactory Organs Olfactory Organs yellowish-brown masses in the upper nasal cavity. Dendrites from nerve cells stick out of epithelium and are covered with cilia. Odors dissolve into liquids in the nose and bind to these receptors.

Slide 20

Olfactory Nerve Pathways Stimulated olfactory receptors send impulse to the brain olfactory bulbs

Slide 21

Olfactory Stimulation There are many, many different olfactory receptors. The combination of which receptors are stimulated determines what you smell. For example: 3, 4, and 8 together might smell like chicken, while 1, 5, and 10 together might smell like chocolate.

Slide 22

Olfaction Lab Get Ya Stank On, Yo Create a table like the following on a piece of paper: You will pick five different objects from around the room (you may use items of your own if you have something). Smell them and fill out the table: Name of item what are you sampling? Describe the smell what does it smell like? Is it strong? Weak? Does it burn? Sensory imprinting - sometimes, a smell is tied closely to a certain though or memory. Does the smell bring anything to mind? Does it make you taste something in your mouth? Sensory Adaptation Give yourself a minute or so to forget the smell. Then, start smelling it again, but this time keep breathing it in. Time how long it takes before you no longer notice the smell. NameDescriptionImprinting?Adaptation?

Slide 23

SENSE OF TASTE Section 10.6

Slide 24

Sense of Taste Taste Buds special organs of taste Located on the tongue on tiny elevations called papillae. Also found on the roof and walls of the mouth.

Slide 25

Taste Receptors Each taste bud contains 50 150 taste cells, and each cell is replace every 3 days. These cells are found within a taste pore, and have small taste hairs that stick out. Taste hairs are stimulated by liquids in the mouth and send impulse to the brain.

Slide 26

Taste Sensations 4 primary tastes: Sweet Sour Salty Bitter The combination of these tastes that a food brings about is what causes its unique taste. Pain receptors can also be stimulated.

Slide 27

SENSE OF HEARING Section 10.7

Slide 28

The Ear 3 main parts: External Ear Middle Ear Inner Ear Functions in hearing and equilibrium.

Slide 29

External Ear 2 parts: Auricle the outer ear (also called the pinna) External Auditory Meatus your earhole which goes about 2 cm deep The auricle of the ear funnels sound vibrations into the meatus, inside the head.

Slide 30

Middle Ear Vibrations from the meatus hit the eardrum, causes it to vibrate. This then causes the auditory ossicles (bones) to vibrate, in order: Malleus (the hammer) Incus (the anvil) Stapes (the stirrups) The stapes is connected to a membrane called the oval window, causes it to vibrate.

Slide 31

Auditory Tube There is a small tube that connects the middle ear to the throat auditory (eustachian) tube Conducts air into the middle ear to maintain pressure necessary for vibrations. Causes ears to pop!

Slide 32

Inner Ear We are going to simplify the heck out of this, because it looks something like this and is very complex:

Slide 33

Inner Ear The Basics Vibrations hit the oval window. This causes liquid within the inner ear to start to vibrate. Vibrations travel through several canals, and will stimulate receptor cells which signal the brain.

Slide 34

Inner Ear The Basics Different receptor cells have slightly different sensitivities. Some sound frequencies will stimulate certain receptors but not others.

Slide 35

SENSE OF EQUILIBRIUM Section 10.8

Slide 36

Sense of Equilibrium 2 types of equilibrium Static balance when the head and body are still Dynamic balance when the head and body are in movement.

Slide 37

Static Equilibrium Vestibule organ of static equilibrium, found between semicircular canals and cochlea The vestibule is filled with tiny hairs called macula and crystals called otoliths. As you move your head, the otoliths roll around and press against the macula. The macula then signal the brain, informing it of the heads new position.

Slide 38

Dynamic Equilibrium Organs of dynamic equilibrium semicircular canals. Each canal corresponds to a different anatomical plane.

Slide 39

Dynamic Equilibrium As you move your head in a direction, hairs in the canals move the opposite direction as fluids pass over them. The combination of these hairs movements tells the brain how you are moving and about your position.

Slide 40

Dynamic Equilibrium Other sensory structure also aid with dynamic equilibrium: Joints in the neck transfer information about position of the body to the brain. Your eyes also detect changes in posture and signal the brain.

Slide 41

SENSE OF SIGHT VISUAL ACCESSORIES Section 10.9

Slide 42

Accessory Organs - Eyelid Each eyelid is 4 layers: Skin (thinnest in the body) Muscle Connective Tissue Conjunctiva mucus membrane that lines the inner surface of the eyelid, secretes mucus

Slide 43

Accessory Organs Lacrimal Gland Lacrimal gland secretes tears There are a series of ducts that also carry tears into the nasal cavity. This is why you might get a runny nose when you cry. Tears are ALWAYS being produced, even when youre not crying they moisten the eye and protect against infection. Antibacterial

Slide 44

Accessory Organs Tarsal Glands The eye also has structures called tarsal glands, which secrete oil to help lubricate the eye.

Slide 45

Accessory Organs - Muscles There are 6 different muscles that move the eye. They work together to move certain ways. Orbicularis Oculi controls your blinking.

Slide 46

SENSE OF SIGHT STRUCTURE OF THE EYE Section 10.9

Slide 47

Structure of the Eye The eye is a hollow sphere about 2.5cm in diameter. 3 distinct layers: Outer Tunic Middle Tunic Inner Tunic Filled with fluids.

Slide 48

Outer Tunic 2 main parts: Sclera the whites of your eyes, makes up 5/6 of the outer tunic. Protects the eye and attaches to muscles. Cornea The front 1/6 of the eye, transparent window Helps focus light into the eye

Slide 49

Middle Tunic Choroid Coat posterior 5/6 of the middle tunic, absorbs light and nourishes. Ciliary Body anterior 1/6 of the middle tunic, ligaments attach to hold the lens

Slide 50

Middle Tunic Lens Elastic (can change shape) Allows the eye to focus on an object Accommodation the ability of the lens to change shape to focus

Slide 51

Middle Tunic Iris The colored portion of the eye Divides the space between cornea and lens into two chambers (posterior and anterior) Pupil opening in the center of the eye Aqueous humor liquid that fills these two chambers

Slide 52

Inner Tunic Retina Back of the eye Contains photoreceptors Joins to the optic nerve Optic Disc Where the nerves of the eye join the optic nerve No photoreceptors = blind spot Vitreous Humor jellylike fluid filling the eye

Slide 53

SENSE OF SIGHT HOW IT WORKS Section 10.9

Slide 54

Light Refraction Light from the outside enters the eye and is refracted (bent) by the lens This focuses the light onto the retina for viewing. The image is upside down and backwards, but your brain interprets it in the right position.

Slide 55

Visual Receptors 2 Types: Rods Cones