Essentials of Human Anatomy & Physiology Elaine N. Marieb Seventh Edition Chapter 8 Special Senses Slides 8.1 8.19 Lecture Slides in PowerPoint by Jerry L. Cook
Special Senses Title Somatosensation Essential Question Describe the structures and functions of somatosensation.
Description Somatosensation receives impulses from the body s somatosensory receptors Location in the Brain Body Regions with the Most Sensory Receptors: Lips and fingertips Found in the postcentral gyrus of the parietal lobe Posterior to the central sulcus, and anterior portion of the parietal lobe.
Sensory and Motor Areas of the Cerebral Cortex Figure 7.14 Slide 7.31
Sensory pathways are crossed The left side of the sensory cortex receives impulses from the right side of the body, and vice versa. pathways. Right Hand
Pathways for Sensory System Pain DRG (dorsal root ganglion) spinal cord thalamus SS cortex
DRG Dorsal Root Ganglion
Pathways for Sensory System Touch/Temp DRG spinal cord medulla thalamus SS cortex
What is a Penfield Homunculus? little man is a drawing that indicates the density of neurons in the somatosensory cortex The more dense the neurons are, the greater the volume that is taken up in the brain.
Special Senses Title Vision Essential Question Describe the structures and functions of vision.
Meibomian Glands
Accessory Structures of the Eye Meibomian glands modified sebaceous glands produce an oily secretion to lubricate the eye Slide 8.3b
Accessory Structures of the Eye Ciliary glands (no label) modified sweat glands between the eyelashes Figure 8.1b Slide 8.3c
Conjunctiva
Accessory Structures of the Eye Conjunctiva Membrane that lines the eyelids Connects to the surface of the eye Secretes mucus to lubricate the eye
Lacrimal Apparatus Function Protects, moistens, and lubricates the eye by producing lacrimal fluid (tears) Slide 8.5
Lacrimal Apparatus Structures Lacrimal Gland Lacrimal Canal Lacrimal Sac Nasolacrimal Duct Slide 8.5
Flow of Tears
Structure of the Eye Sclera The wall is composed of three tunics Cornea Fibrous tunic outside layer Choroid middle layer Sensory tunic inside layer Figure 8.3a Slide 8.7
The Fibrous Tunic Sclera White connective tissue layer Slide 8.8
The Fibrous Tunic Cornea Allows for light to pass through Repairs itself easily The only human tissue that can be transplanted without fear of rejection YouTube - Cornea Transplant
Structure of the Eye Ciliary Body The wall is composed of three tunics Pupil Lens Iris Fibrous tunic outside layer Choroid middle layer Sensory tunic inside layer Figure 8.3a Slide 8.7
Choroid Layer Ciliary body smooth muscle that attaches to and controls the lens Slide 8.9
Choroid Layer Lens Biconvex crystal-like structure Can change shape to allow light to properly focus on the retina Slide 8.9
Choroid Layer Iris Pigmented layer that gives the eye color Prevents light from scattering Slide 8.9
Choroid Layer Pupil Rounded opening of the iris that controls the amount of light to pass through Slide 8.9
Structure of the Eye The wall is composed of three tunics Retina Fibrous tunic outside layer Choroid middle layer Sensory tunic inside layer Optic Disc Fovea Centralis Optic Nerve Figure 8.3a Slide 8.7
Sensory Tunic Retina Contains millions of receptor cells, the rods and cones Slide 8.10
Neurons of the Retina Figure 8.4 Slide 8.11
Sensory Tunic Optic Nerve Receives information from the retina and sends it to the brain Slide 8.10
Sensory Tunic Optic Disc The site where the optic nerve leaves the eyeball The blind-spot Slide 8.10
Sensory Tunic Fovea Centralis Portion of the retina that contains only cones Area of greatest visual acuity (sharpest vision) Slide 8.10
Structure of the Eye The wall is composed of three tunics Aqueous Humor Fibrous tunic outside layer Choroid middle layer Sensory tunic inside layer Canal of Schlemm Vitreous Humor Figure 8.3a Slide 8.7
Internal Eye Chamber Fluids Aqueous humor Watery fluid found in chamber between the lens and cornea Helps maintain intraocular pressure Provides nutrients for the lens and cornea Slide 8.15a
Internal Eye Chamber Fluids Canal of Schlem Located at the junction of the sclera and cornea Reabsorbs aqueous humor into the venous blood Slide 8.15a
Aqueous humor
Internal Eye Chamber Fluids Vitreous humor Gel-like substance behind the lens Keeps the eye from collapsing Lasts a lifetime and is not replaced Slide 8.15b
Aqueous & Vitreous humor
Neurons of the Retina and Vision Rods Allow dim light vision and peripheral vision Perception is all in gray tones Slide 8.12a
Neurons of the Retina and Vision Cones Allow for detailed color vision Function in bright light to help with discriminatory vision Slide 8.12b
Image formation on the Retina The image formed on the retina as a result of the light-bending activity of the lens is a real image that is, it is reversed from left to right, upside down, and smaller than the object Figure 8.9 Slide 8.16
Eye Reflexes Convergence Reflex Moving both eyes to view close up objects Controlled by extrinsic eye muscles Slide 8.19
Eye Reflexes Pupillary Reflexes Pupils constrict due to viewing close objects or exposure to bright light Controlled by internal eye muscles and the autonomic nervous system Prevents excessively bright light from damaging the photoreceptors Slide 8.19
Visual Pathway to the optic cortex Photoreceptors of the retina Optic nerve Optic nerve crosses at the optic chiasma Optic tracts Thalamus (axons form optic radiation) Visual cortex of the occipital lobe Figure 8.11 Slide 8.18a
Special Senses Title Audition Essential Question Describe the structures and functions of hearing.
Anatomy of the Ear The ear is divided into three areas Outer (external) ear Middle ear Inner ear Figure 8.12 Slide 8.21
The External Ear Pinna (auricle) collects, funnels, and amplifies sound Figure 8.12 Slide 8.22
The External Ear External auditory canal Narrow chamber in the temporal bone Has Ceruminous (wax) glands Slide 8.23
The External Ear Tympanic Membrane Separates the outer and middle ear Vibrates when hit by sound waves Slide 8.24a
Tympanic Membrane
Bones of the Tympanic Cavity
Middle Ear Ossicles Vibrations from eardrum move the malleus These bones transfer sound to the inner ear Figure 8.12 Slide 8.25b
Middle Ear Oval Window Opening at the head of the cochlea Sound vibrations from the stapes is transmitted to inner ear Figure 8.12 Slide 8.25b
The Middle Ear or Tympanic Cavity Auditory Tube connects the middle ear with the throat Allows for equalizing pressure during yawning or swallowing Slide 8.24b
Auditory Tube
http://www.entsurgery.net Auditory Tube
Inner Ear or Bony Labyrinth Cochlea Contains the organ of Corti where the hearing receptors are found Figure 8.12 Slide 8.26a
Inner Ear or Bony Labyrinth Vestibule Contains muculae which are involved in static equilibrium Reports on the position of the head Figure 8.12 Slide 8.26a
Inner Ear or Bony Labyrinth Semicircular Canals Involved in dynamic equilibrium Responds to angular or rotary movements of the head Figure 8.12 Slide 8.26a
Pathways for Sensory System Audition Receptors: Mechanoreceptors Stimulus Energy: Sound Pathway Ear: hair cells Ear: vestibulochochlear nerve medulla midbrain thalamus auditory cortex (temporal lobe)
Organs of Hearing Organ of Corti Contains the hearing receptors or the hair cells. Slide 8.27a
Organs of Hearing The receptors are positioned on the basilar membrane, and the hairs are embedded in the tectorial membrane Slide 8.27a
Organs of Hearing When the tectorial membrane is disturbed, this stimulates the hair cells which send information to the cochlear nerve. Slide 8.27a
Sensorineural Deafness Deafness that is caused by damage to neural structures (cochlear nerve or auditory cortex cells) Can be caused by stroke or trauma Slide 8.27a
Conduction Deafness Deafness that is caused by any interference with the conduction of vibrations from the outer to the inner ear Can be caused by wax accumulations, otitis media, fusion of the ossicles, or pressure imbalance between the middle and outer ear Slide 8.27a
Organs of Equilibrium Receptor cells are in two structures Vestibule Semicircular canals Figure 8.16a, b Slide 8.30a
Static Equilibrium The vestibule helps us with static equilibrium or the position of the head with respect to the pull of gravity when the body is not moving. Slide 8.31
Static Equilibrium Figure 8.15 Slide 8.32
Dynamic Equilibrium The semicircular canal helps with dynamic equilibrium, which responds to angular or rotary movements of the head, rather than straight-line movements. Slide 8.33a
Dynamic Equilibrium Figure 8.16c Slide 8.33a
OLFACTION
http://www.entsurgery.net OLFACTION
Olfactory Epithelium Figure 8.17 Slide 8.36
Olfaction The Sense of Smell Olfactory Bulb Contains the receptors for the sense of smell Slide 8.35
Olfaction The Sense of Smell Cribiform Plate Portion of the ethmoid bone where the olfactory bulb sits Slide 8.35
Olfaction The Sense of Smell Olfactory Tract The neural pathway from the olfactory bulb to the olfactory cortex in the brain Slide 8.35
Olfaction The Sense of Smell receptors are in the roof of the nasal cavity Neurons with long cilia Chemicals must be dissolved in mucus for detection Slide 8.35
Pathways for Sensory System Olfaction Receptors: Chemoreceptors Stimulus Energy: Chemical Pathway Olfactory sensory neurons Olfactory bulb neurons olfactory cortex (in temporal lobe)
Anatomy of the Tongue Figure 8.18 Slide 8.40
Taste Buds house the receptor organs Location Tongue Soft palate Cheeks Figure 8.18a, b Slide 8.37
Anatomy of the Tongue Figure 8.18 Slide 8.40
The Tongue and Taste Papillae Small peglike projections that house the taste buds Slide 8.38
Anatomy of the Tongue Figure 8.18 Slide 8.40
Structure of Taste Buds Gustatory cells Specific epithelial cells that respond to chemicals dissolved in saliva Slide 8.39a
Anatomy of the Tongue Figure 8.18 Slide 8.40
Structure of Taste Buds Gustatory Hairs Taste receptors that emerge from the taste pores Slide 8.39b
Gustation
Pathways for Sensory System Gustation Receptors: Chemoreceptors Stimulus Energy: chemical (sweet, sour, bitter, salty) Pathway Taste bud Facial nerve (VII) or glossopharyngeal nerve (IX) or vagus nerve (X) medulla thalamus cortex (parietal lobe)
Taste Sensations Sweet receptors Sugars Saccharine Some amino acids Sour receptors Acids Slide 8.41
Taste Sensations Bitter receptors Alkaloids Salty receptors Metal ions Slide 8.41
Factors that affect Taste Sensations Stimulation of our olfactory aromas Temperature and texture of food Spicy foods can excite pain receptors in our mouth Slide 8.41