Special Senses 15-01 PDF Lecture Slides

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Special Senses Part A 15 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pears...

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Special Senses Part A 15 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Chemical Senses ▪ Chemical senses – gustation (taste) and olfaction (smell) ▪ Their chemoreceptors respond to chemicals in aqueous solution ▪ Taste – to substances dissolved in saliva ▪ Smell – to substances dissolved in fluids of the nasal membranes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Taste Buds ▪ Most of the 10,000 or so taste buds are found on the tongue ▪ Taste buds are found in papillae of the tongue mucosa ▪ Papillae come in three types: filiform, fungiform, and circumvallate ▪ Fungiform and circumvallate papillae contain taste buds Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Taste Buds Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.1  Taste Sensations ▪ There are five basic taste sensations ▪ Sweet – sugars, saccharin, alcohol, and some amino acids ▪ Salt – metal ions ▪ Sour – hydrogen ions ▪ Bitter – alkaloids such as quinine and nicotine ▪ Umami – elicited by the amino acid glutamate Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Gustatory Pathway Figure 15.2 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Influence of Other Sensations on Taste ▪ Taste is 80% smell ▪ Thermoreceptors, mechanoreceptors, nociceptors also influence tastes ▪ Temperature and texture enhance or detract from taste Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sense of Smell Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.3  Eye and Associated Structures ▪ 70% of all sensory receptors are in the eye ▪ Most of the eye is protected by a cushion of fat and the bony orbit ▪ Accessory structures include eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Conjunctiva Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Lacrimal Apparatus ▪ Consists of the lacrimal gland and associated ducts ▪ Lacrimal glands secrete tears ▪ Tears ▪ Contain mucus, antibodies, and lysozyme ▪ Drain into the nasolacrimal duct Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Lacrimal Apparatus Figure 15.6 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Extrinsic Eye Muscles ▪ Six straplike extrinsic eye muscles ▪ Enable the eye to follow moving objects ▪ Maintain the shape of the eyeball ▪ Four rectus muscles originate from the annular ring ▪ Two oblique muscles move the eye in the vertical plane Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Extrinsic Eye Muscles Figure 15.7a, b Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Summary of Cranial Nerves and Muscle Actions ▪ Names, actions, and cranial nerve innervation of the extrinsic eye muscles Figure 15.7c Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Structure of the Eyeball ▪ A slightly irregular hollow sphere with anterior and posterior poles ▪ The wall is composed of three tunics – fibrous, vascular, and sensory Tunic tissue forming a layer or covering of an organ or part, such as any of the tissue layers of a blood vessel wall. ▪ The internal cavity is filled with fluids called humors ▪ The lens separates the internal cavity into anterior and posterior segments Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Structure of the Eyeball Figure 15.8a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Fibrous Tunic ▪ Forms the outermost coat of the eye and is composed of: ▪ Opaque sclera (posteriorly) ▪ Clear cornea (anteriorly) ▪ The sclera protects the eye and anchors extrinsic muscles ▪ The cornea lets light enter the eye Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Vascular Tunic (Uvea): Choroid Region ▪ Has three regions: choroid, ciliary body, and iris ▪ Choroid region ▪ Supplies blood to all eye tunics Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Vascular Tunic: Ciliary Body ▪ A thickened ring of tissue surrounding the lens ▪ Composed of smooth muscle bundles (ciliary muscles) ▪ Anchors the suspensory ligament that holds the lens in place Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Vascular Tunic: Iris ▪ The colored part of the eye ▪ Pupil – central opening of the iris ▪ Regulates the amount of light entering the eye during: ▪ Close vision and bright light – pupils constrict ▪ Distant vision and dim light – pupils dilate Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Pupil Dilation and Constriction Figure 15.9 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sensory Tunic: Retina ▪ A delicate two-layered membrane ▪ Pigmented layer – the outer layer that absorbs light and prevents its scattering ▪ Neural layer, which contains: ▪ Photoreceptors that transduce light energy ▪ Bipolar cells and ganglion cells ▪ Amacrine and horizontal cells Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sensory Tunic: Retina Figure 15.10a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Retina: Ganglion Cells and the Optic Disc ▪ Ganglion cell axons: ▪ Run along the inner surface of the retina ▪ Leave the eye as the optic nerve ▪ The optic disc: ▪ Is the site where the optic nerve leaves the eye ▪ Lacks photoreceptors (the blind spot) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Retina: Ganglion Cells and the Optic Disc Figure 15.10b Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Retina: Photoreceptors ▪ Rods: ▪ Respond to dim light ▪ Are used for peripheral vision ▪ Cones: ▪ Respond to bright light ▪ Have high-acuity color vision ▪ Are found in the macula lutea ▪ Are concentrated in the fovea centralis Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings