does that make sense (1)

Download Does that make sense (1)

Post on 27-Jul-2015




0 download

Embed Size (px)


1. Structure(5) Christmas editionFree nerve ending: simplest, most common sensory receptors located on the surface of the body known as exteroceptors and in internal organs known as visce receptors. Nociceptor are slen- der sensory fibers that are responsible for pain. Brain tissue lack Its beginning to look a lot like free sensory nerve endings and are incapable of sensing painful Christmas, everywhere you go stimuli. Nerve endings are also responsible for sensation and (page 6) touch and also sensations of heat cold.Well tell you howRoot hair plexuses: delicate, web-like arrangements of freeto spot some nerve endings that surround hair follicles that can detect any great deals with type of hair movement. the help of yourMerkel disks: disc-shaped or flattened and are responsible for vision! (Page 2-3) mediating sensations of light or discriminative touch that is lo- The minty smell of cated on the surface of the skin. (21) that peppermintMeissner Corpuscle: when deformed by a mechanical type of candle ah, its the stimulus, this type of receptor, sometimes called a tactile corpus- smell of Christmas. cle, mediates sensations of discriminative touch and low- (page 7-8) frequency vibration. (especially numerous in hairless skin areas, such as the nipples, fingertips, and lips)Pacinian Corpuscles: large mechanoreceptors, which when sec- We all love the tioned, show thick laminated connective tissue capsules. (foundcinnamon taste of in deep dermis of the skin-especially in the hands and feet-andsnickerdoodle are also numerous in joint capsules throughout the body).cookies! (page 10-Muscle Spindles- the most important stretch receptors are asso-11) ciated with muscles and tendons and are classified as proprio- ceptors. Two types of stretch receptors, called muscle spindles and golgi tendon receptors, operate to provide the body with information concerning muscle length and the strength of mus-How are we able to see all the cle contraction. (the result of stimulation is a stretch reflex that Remember to keep your bright Christmas lights? Well shortens a muscle or muscle group, thus aiding in the mainte-balance while hanging tell you how! (page 4-5) nance of posture or the positioning of the body or one of its ex-up your Christmas tremities in a way that may be opposed by the force of gravity). lights! (page 9)Golgi tendon Organs- like muscle spindles, are proprioceptors. They are located at the point of junction between muscle tissue Also in this issue... and tendon. These receptors act in a way opposite that of mus- Locations of 12 cle spindles. Stimulus 13 14 2. HOW TO SPOT KILLER DEALSStimulus Detected (5)With the help of your vision Page 2Page 13 (25) Mechanoreceptors: are activated by mechanical stimuli that insome way deform or change the position of the receptor, re-sulting in the generation of a receptor potential. Examples of thisis pressure applied to the skin or to blood vessels, or cause bystretch or pressure in the muscle, tendon, or lung tissue. Chemoreceptors: activated by either the amount or the changingconcentration of certain chemicals. Examples are our senses oftaste and smell depend on these. Thermoreceptors: activated by change in temperature. Examplesare when the outside temperature is colder than your body; yourbrain tells your body to warm up.Your vision plays an important part when spotting some Nociceptors: the relatively unspecialized nerve cell endings thatgood deals. There are 3 layers of tissue that compose the eyeball:initiate the sensation of pain are called Nociceptors. They trans-the sclera (a tough outer coat), the cornea (the transparent anteri-duce a variety of stimuli into receptor potentials, which in turnor portion that lies over the iris), and the canal of schlemm (a ring-trigger afferent action potentials. They arise from cell bodies inshaped venous sinus found deep within the anterior portion of the dorsal root ganglia that send one axonal process to the peripherysclera).and the other into the spinal cord or brainstem.(20)The choroid is the middle coat of the eye and it contains Photoreceptors: the retina is the back part of the eye that con-many blood vessels and a large amount of pigment . The ciliarytains the cells that respond to light. These specialized cells arebody , suspensory ligament, and the iris are all part of this layer:called photoreceptors. There are two types of photoreceptors Ciliary body the thickening of choroid, fits between anterior(rods and cones) in the retina. (9) margin of retina and posterior margin of iris. Suspensory ligament attached to the ciliary processes and blends with the elastic capsule of the lens to hold it in. Iris colored part of the eye.The retina is the incomplete innermost coat of the eyeball.Three layers of neurons make up the sensory retina. Photoreceptorneurons are the visual receptors, highly specialized for stimulationby light rays. Bipolar neurons are the second layer and ganglionneurons are the third layer. All axons of these neurons extend backto the optic disc; part of the sclera, which contains perforationsthrough which the fibers emerge from the eyeball as the opticnerve.(5) 3. Locations of receptors (24)VISION CONT.Page 12Page 3 Cavities & Humors The eyeball has a large interior space divided into two cavities. The anterior cavity lies in front of the lens and has two subdivisions: Exteroceptors: are near the surface of the body. The extero- The anterior chamber the space anterior to the iris and posteriorceptors located in the skin provide the sensations of pain, to the cornea.touch, temperature, and pressure. The posterior chamber the small space posterior to the iris and Visceroceptors: located in the blood vessels and viscera. anterior to the lens. Proprioceptors: receptors located in muscles, tendons, The posterior cavity is larger than the anterior cavity and it occupiesjoints, and the external ear. the entire space posterior to the lens, suspensory ligament, and ciliary body. Muscles There are two types of eye muscles. The extrinsic eye muscle is the skeletal muscles that attach to the outside of the eyeball and to the bones of the orbit, and its named according to their position on the eyeball. The muscles are superior, inferior, medial, and lateral rectus muscles and the superior and inferior oblique muscles.(5) Accessory StructuresEyebrows and eyelashes give some protection against foreign objectsentering the eye. Eyelids consist of voluntary muscle and skin with atarsal plate, lined with conjunctiva, a mucous membrane, and a pal-pebral fissure where the upper and lower eyelids join together. Lacri-mal glands are about the size and shape of an almond, and are locat-ed at the upper, outer margin of each orbit. Approximately a dozensmall ducts lead from each gland anddrain tears onto the conjunctiva.Lacrimal canals are small channelsthat empty into lacrimal sacs.Lacrimal sacs are located in a groovein the lacrimal bone. Nasolacrimalducts are small tubes that extendfrom the lacrimal sac into the inferiormeatus of the nose.(5) 4. Take a gander at the Christmaslights Process of seeing Taste cont. (23) Page 4 Page 11 The cornea, pupil, iris, and lens work together to The Neural Pathway refract light rays so that the rays from the Christmas lights focus directly on the retina. The Taste Pathway Light rays first touch the cornea. The cornea hasTransduction occurs when different taste substances cause a 2 purposes: 1) it bends light rays as they pass through it change in the flow of ions across the membrane of a taste cell. in order to focus them through the lens and towards theDifferent substances affect the membrane in different ways: back of the eye. 2) its smooth, reflective surface serves Bitter and sweet substances bind into receptor sites which to protect the eye from external damage.release other substances into the cell. Once light passes the cornea, it hits the aqueous Sour substances contain H+ ions that block channels in the humor, a clear watery fluid. The purpose of the aqueous membrane. humor is to keep a constant pressure within the eye. Salty substances break up into Na+ ions which flow through Behind the aqueous humor are the iris and the pupil.the membrane directly into the cell. They both work together to control the amount of light Electrical signals generated in the taste cells are transmitted in 3 that enters the eye. The iris consists of two muscles on pathways: either side of the pupil that can dilate or constrict to ad- The chorda tympani nerve conducts signals from the front and just the size of the pupil. Behind the iris and the pupil issides of the tongue. the lens, and elastic structure that becomes thinner to The glosso-pharyngeal nerve conducts signals from the back of focus on distant objects and thick to focus on nearby the tongue. The vagus nerve conducts taste signals from the mouth and objects. the larynx. All these parts of the eye work together to allowThese three nerves make connections in the brain stem in the nu- you to see all the Christmas lights.cleus of the solitary tract (NST) before going on to the thalamusand then to two regions of the frontal lobe (the insula and the (19)frontal operculum cortex).Why dont deer see hunters who arewearing bright orange?Deer have under-developed cones. They have nored-sensitive cones in their eyes, which prohibitthem from distinguishing red or orange fromgreen and brown. 5. All the tasty treats...yum!(23)PROCESS OF SEEING CONT. Page 10 Page 5 Describe the role of Photopigments Both rods and cones contain photopigments, or light sensitive pig- ments compounds that are found in the distal area of both types of photoreceptors near the pigments retina. A derivative called reti- nal acts as the light-absorbing portion of all photopigments. Rods the single photopigment found in rods is rhodopsin. Rhodopsin is highly light sensitive that a dim light can cause a rapid bre