Chapter 9: Sensory Systems (Biology of Humans) PDF

PPT CH 9 BIOLOGY of Humans: Concepts, Applications and Issues. Sixth Edition Lecture Presentation Chapter 9 Sensory...

PPT CH 9 BIOLOGY of Humans: Concepts, Applications and Issues. Sixth Edition Lecture Presentation Chapter 9 Sensory Systems Judith GOODENOUGH Betty McGUIRE Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Sensory Systems Outline: Sensory Receptors Classes of Receptors The General Senses Vision Hearing Balance and the Vestibular Apparatus of the Inner Ear Smell and Taste Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.1 Sensory Receptors (1 of 3) Structures that are specialized to detect and respond to changes in the external or internal environment They respond by generating electrochemical messages Loading… If a stimulus is strong enough, then action potentials are conducted to the brain Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.1 Sensory Receptors (2 of 3) Sensation is awareness of a stimulus How a sensation is experienced (e.g., as sight or sound) depends on which part of the brain receives the impulses Perception is the conscious awareness of sensations Understanding the stimulus occurs when the cerebral cortex integrates sensory input Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.1 Loading… Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.1 Sensory Receptors (3 of 3) Sensory adaptation Sensory receptors stop responding when continuously stimulated, leading to a decrease in the awareness of the stimulus- why you don’t the sound of the air conditioner or refrigerator Varies among receptors ▪Pressure and touch receptors adapt quickly ▪Receptors in muscles and joints that report on body position never adapt Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.2 Classes of Receptors (1 of 3) The body contains many specialized receptors: Mechanoreceptors Pressure/touch-skin organs · , Thermoreceptors temprature Photoreceptors light-vision Chemoreceptors Chemicals- - O2 , CO2 , gas Pain receptors pain - Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.2 Classes of Receptors (2 of 3) I 2 3 General senses: touch, pressure, vibration, temperature, body and limb position, pain Y S Y Receptors located in skin, muscles, bones, joints, and internal organs We are not usually aware of the general senses, but they are still important Provide information about body position Help keep internal body conditions within optimal limits Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved  9.2 Classes of Receptors (3 of 3) E Special senses Vision i Hearing Equilibrium s Smell Taste We rely on the special senses to perceive the world Receptors for the special senses are located in the head, often within specific structures Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (1 of 6) Receptors rely on either free nerve endings or encapsulated nerve endings Free nerve endings are the tips of dendrites of sensory neurons Encapsulated nerve endings are those in which a connective tissue capsule encloses and protects the tips of dendrites of sensory neurons Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.2 Loading… Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (2 of 6) Touch, pressure, and vibration rely on mechanoreceptors that respond to stimuli that stretch, compress, or twist their membrane Different mechanoreceptors occur in the skin: Mechanoreceptors that detect touch ▪Merkel disks: free nerve endings that end on Merkel cells, detecting light touch ▪Meissner’s corpuscles: encapsulated nerve endings, tell us where we have been touched Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (3 of 6) Different mechanoreceptors occur in the skin Mechanoreceptors that detect pressure ▪Pacinian corpuscles: layers of tissue surrounding a nerve ending, sense first pressure or vibration ▪Ruffini corpuscles: encapsulated nerve endings, respond to continuous pressure Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (4 of 6) Thermoreceptors respond to temperature changes Specialized free nerve endings located just below the surface of the skin One type responds to warmth; another type responds to cold Adapt rapidly –Hot tub ex Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (5 of 6) Body and limb position are continuously monitored by the brain Muscle spindles ▪Specialized muscle fibers wrapped in sensory nerve endings ▪Monitor length of skeletal muscles Tendon organs ▪Highly branched nerve fibers in tendons ▪Measure muscle tension Information from the inner ear Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.3 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.3 The General Senses (6 of 6) PAIN Free nerve endings found in all tissues of the body Damaged tissue releases chemicals that alert free - nerve endings ▪Aspirin and ibuprofen interfere with the production of - released chemicals - Churts Referred pain Heart attack in in arm) Woman , Pancreatic damage hurts in Pain felt somewhere besides the site of the injury Common with damage to internal organs Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.4 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (1 of 15) The wall of the eyeball has three layers Outermost layer—sclera and cornea Middle layer—choroid, ciliary body, and iris Innermost layer—retina Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (2 of 15) The outer layer is tough and fibrous Sclera The white of the eye Protects and shapes the eye Serves as attachment site for muscles Cornea Transparent area at the front of the eye Allows light to enter Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (3 of 15) The middle layer is vascular Choroid Contains blood vessels that supply eye tissue with nutrients and oxygen Contains melanin, which absorbs light reflected from the retina Ciliary body Ring of tissue, primarily muscle, that encircles the lens Holds lens in place and changes its shape Iris colored part Muscular part of the choroid in front of the ciliary body Regulates pupil size Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (4 of 15) Pupil An opening in the center of the iris Allows light to enter the eye and reach the retina Dilates in dim light Constricts in bright light Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (5 of 15) Retina The innermost layer of the eye, it contains photoreceptors that respond to light by generating electrical signals ▪Types of photoreceptors Rods –black and white Cones- color Fovea ▪Region of the retina with the greatest concentration of cones ▪Objects are focused here for sharp vision Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (6 of 15) Carries visual information from the eye to the brain for interpretation Blind spot Region where the optic nerve leaves the retina The retina lacks photoreceptors here An image that strikes the blind spot cannot be seen Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (7 of 15) Posterior chamber (Back) Located between the lens and the retina Contains vitreous humor; a jelly-like fluid that is never replaced Anterior chamber (front) Located between the cornea and the lens Contains aqueous humor; a watery fluid that is continuously replaced ucans eye Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.5 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 9.1 (1 of 2) Table 9.1 A Review of the Structures of the Eye and their Functions Structure Description Function blank blank Outer layer Sclera Outer layer of the eye Protects the eyeball Cornea Transparent dome of tissue forming the outer layer at Refracts light, focusing it on the retina the front of the eye blank blank Middle layer Choroid Pigmented layer containing blood vessels Absorbs stray light; delivers nutrients and oxygen to tissues of eye Ciliary body Encircles lens; contains the ciliary muscles Controls shape of lens; secretes aqueous humor Iris Colored part of the eye Regulates the amount of light entering the eye through the pupil Pupil Opening at the center of the iris opening for incoming light blank blank Inner layer Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 9.1 (2 of 2) Structure Description Function Retina Layer of tissue that contains the photoreceptors (rods Receives light and generates neural and cones); also contains bipolar and ganglion cells messages involved in retinal processing Rods Photoreceptor Responsible for black-and-white vision and vision in dim light Cones Photoreceptor Responsible for color vision and visual acuity Fovea Small pit in the retina that has a high concentration Provides detailed color vision of cones blank blank Other structures of the eye Lens Transparent, semispherical body of tissue behind the Fine focusing of light onto retina iris and pupil Aqueous Clear fluid found between the cornea and the lens Refracts light and helps maintain shape humor of the eyeball Vitreous Gelatinous substance found within the chamber Refracts light and helps maintain shape humor behind the lens of the eyeball Optic nerve Group of axons from the eye to the brain Transmits impulses from the retina to the brain Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (8 of 15) Glaucoma Second leading cause of blindness Results when drainage of the aqueous humor is blocked Loading… ▪Pressure within the eye reaches dangerous levels ▪Blood vessels supplying the optic nerve and retina collapse and cells die Progressive and painless Marijuana (Treatment ( · PillS Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (9 of 15) Sharp vision requires that light be focused on the retina Light is bent (refracted) at four points when it enters the eye Cornea Aqueous humor Lens Vitreous humor Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (10 of 15) Lens Elastic and can change shape Ciliary muscle controls changes in shape Accommodation to see clearly both far - near Changing the shape of the lens to change the bending of light Cataract A lens that has become cloudy, usually due to aging Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.6 short- fat Longer + Skinnier up close Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.7 -Cateract Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved  9.4 Vision (11 of 15) Focusing problems Farsightedness see far, Not near lenses Not far Nearsightedness genetic he near, , ing Astigmatism blurry vision Causes include discrepancies in the thickness or curvature of the lens or the shape of the eyeball Normal vision can be restored with corrective lenses or laser-assisted surgeries (e.g., LASIK and LASEK) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 9.2 Table 9.2 Focusing Problems of the Eye Problem Description Cause Correction Farsightedness See distant Eyeball too short or Convex lens; objects more lens too thin; lens increases corneal clearly cannot become curvature round enough Nearsightedness See nearby Eyeball too long or Concave lens; objects more lens too thick; lens decreases corneal clearly than cannot flatten curvature distant objects enough Astigmatism Visual image is Irregularities in Lenses that correct distorted curvature of cornea for the or lens asymmetrical bending of light Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.8 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (12 of 15) Light focused on the retina causes changes in photopigment molecules within photoreceptors Photoreceptors release less inhibitory neurotransmitter The activity of cells processing visual information increases Electrical information from rods and cones is sent to bipolar cells and then to ganglion cells Electrical signals from the retina travel via the optic nerve to the thalamus and then to the visual cortex Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.9 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (13 of 15) Two types of photoreceptors, rods and cones, respond to light with a neural message sent to the brain Rods: vision in dim light More numerous than cones Responsible for black-and-white vision Contain the pigment rhodopsin, which is broken down in bright light Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (14 of 15) Cones: responsible for color vision Three types: ▪Red ▪Blue ▪Green Produce sharp images A reduced number or lack of one type of cone results in color blindness More Men be its on X unromosome Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.10 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.11 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.4 Vision (15 of 15) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (1 of 14) In order to hear, the ear collects and amplifies sound waves that are produced by vibrations The loudness of a sound is determined by the amplitude of the sound wave The pitch of a sound is determined by the frequency of the sound waves I · WLoud W & quiet high pitch mummus low Pitch Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.12 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (2 of 14) The ear has three main parts: the outer ear, the middle ear, and the inner ear Outer ear Functions as a receiver Includes the pinna and external auditory canal ▪Pinna Gathers sound and channels it to the external auditory canal Helps determine sound direction ▪External auditory canal Leads to the tympanic membrane (eardrum) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (3 of 14) Tympanic membrane cararum Separates the outer ear from the middle ear Vibrates at the same frequency as the sound waves and transfers these vibrations to the middle ear Must have nearly equal pressure on both sides to vibrate properly Auditory tube (Eustachian tube) Connects middle ear cavity with the throat; alleviates pressure differences Cause of spread of infections between ear/throat Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (4 of 14) Middle ear Functions as an amplifier Consists of an air-filled cavity within the temporal bone of the skull and the three auditory bones- ossicles Malleus (hammer) Incus (anvil) Stapes (stirrup) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (5 of 14) The middle ear bones Convey airborne sound waves from the eardrum to the oval window, a sheet of tissue at the entrance to the inner ear The force of the eardrum’s vibrations is amplified 22 times in the middle ear ▪Needed to transfer vibrations to fluid of inner ear ▪Occurs because the eardrum is larger than the oval window, so pressure is concentrated Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (6 of 14) Inner ear Functions as a transmitter to Brain ▪Generates neural messages in response to pressure waves caused by sound waves ▪Sends these messages to the brain for interpretation Contains two sensory organs ▪Cochlea (hearing) ▪Vestibular apparatus (body position and movement) - - semicircular caral Blance & Vestibule Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.13 yes drains pressure tiphanic Membrane Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 9.3 (1 of 2) Table 9.3 Review of the structures of the Ear and Their Functions Structure Description Function blank blank Outer ear Pinna Fleshy, funnel-shaped part of the Collects and directs sound waves ear protruding from the side of the head External auditory canal Canal between pinna and tympanic Directs sound to the middle ear membrane blank blank Middle ear Eardrum (tympanic Membrane spanning the end of the Vibrates in response to sound waves membrane) external auditory canal Malleus (hammer), incus Three tiny bones of the middle ear Amplify the vibrations of the tympanic (anvil), and stapes (stirrup) membrane and transmit vibrations to inner ear Auditory tube (Eustachian A tube that connects the middle ear Allows equalization of pressure in tube) with the throat middle ear with external air pressure Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 9.3 (2 of 2) Structure Description Function blank blank Inner ear Cochlea Fluid-filled, bony, snail- shaped Houses spiral organ (of Corti) and has chamber openings called oval window and round window Spiral organ (of Corti) Contains hair cells The organ of hearing Oval window Membrane between the middle and Transmits the movements of the stapes inner ear that the stapes presses to the fluid in the inner ear against Round window Membrane at the end of the lower Relieves pressure created by the canal in cochlea movements of the oval window Vestibular apparatus Fluid-filled chambers and canals Monitors position and movement of the head Vestibule (utricle and Two fluid-filled chambers Maintains static equilibrium (body and saccule) head stationary, information on position of head) Semicircular canals Three fluid-filled chambers oriented Maintain dynamic equilibrium (body at right angles to one another or head moving) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (7 of 14) Cochlea (Latin for “snail”) Two openings ▪Oval window—stapes fits into ▪Round window—relieves pressure Three longitudinal compartments filled with fluid ▪Central compartment Floor consists of basilar membrane, which supports the spiral organ Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (8 of 14) Spiral organ Most directly responsible for hearing Consists of hair cells and overhanging tectorial membrane Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.14 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (9 of 14) Sequence of events in the inner ear Movement of the stapes against the oval window sets up pressure waves in the fluid of the inner ear Movements of the fluid cause the basilar membrane to swing up and down The swinging presses projections on the hair cells against the overlying tectorial membrane Bending of the hair cells alters the rate of nerve impulses in the auditory nerve, which carries sound information to the brain Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (10 of 14) Loudness The louder the sound ▪The more hair cells are stimulated ▪The more each individual hair cell bends, which increases the number of impulses The brain interprets the increased number of impulses as louder sound Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (11 of 14) Pitch Sounds of different pitch activate hair cells at different places along the basilar membrane The brain interprets input from hair cells in different areas as sounds of different pitch Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (12 of 14) Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (13 of 14) 2 Deafness treatable Types of hearing loss 1. Conductive South blocking Vibration in ear Canal ▪Involves an obstruction along the route that sound follows to the inner ear Many ear infections 2 Sensorineural - ▪Caused by damage to either the hair cells or the nerve - supply of the inner ear # cause of sensory neuval deafness ↳ Loud sounds construction workers , Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.5 Hearing (14 of 14) External (outer) ear infections Infection in the external auditory canal Often caused by water trapped in the canal Favorable environment for bacteria “Swimmer’s ear” Middle ear infections cardrum + oscides Usually result when infections of the nose and throat move through the auditory tubes More common in children because their auditory tubes are horizontal, allowing easier access to bacteria- head shape bacteria like und > - - : Cut to crawl hornzontal Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.6 Balance and the Vestibular Apparatus of the Inner Ear (1 of 3) Vestibular apparatus A fluid-filled maze of chambers and canals within the inner ear Consists of Semicircular canals Help with balance when we are moving Vestibule Helps with balance when we are not moving Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.6 Balance and the Vestibular Apparatus of the Inner Ear (2 of 3) Semicircular canals Three canals in each ear Responsible for dynamic equilibrium Ampulla at base of each canal Each contains a tuft of hair cells embedded in gelatinous material, called the cupula Movement of the head causes fluid within the canals to move, which pushes the cupula and stimulates the hair cells Hair cells send messages to the brain Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.6 Balance and the Vestibular Apparatus of the Inner Ear (3 of 3) Vestibule Consists of two fluid-filled cavities Utricle—senses forward tilting of the head Saccule—senses vertical movement of the head Responsible for static equilibrium Both cavities contain hair cells overlain by gelatinous material with embedded otoliths Movement of the head causes the gelatin to move, which stimulates the hair cells Hair cells send messages to the brain Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.15 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.7 Smell and Taste (1 of 3) Olfactory receptors smees Sensory neurons with long hairs covered by mucus located in the roof of each nasal cavity One of the few types of neuron known to be replaced during life Odor molecules Dissolve in the mucus and bind to the olfactory receptor cells, stimulating them If a threshold is reached, then the message is carried to olfactory bulbs in the brain The olfactory bulbs process the information and pass it to the limbic system and cerebral cortex Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.16 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.7 Smell and Taste (2 of 3) Taste buds Located on the tongue and inner surfaces of the mouth Composed of taste cells and supporting cells Cells replaced every ten days Taste buds sense five basic tastes Sweet Salty Sour Bitter Umami Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved 9.7 Smell and Taste (3 of 3) Taste cells Have taste hairs that project into a pore at the tip of the taste bud Taste hairs have receptors for chemicals found in food When food molecules are dissolved in saliva, they enter the pore and stimulate the taste hairs Although they are not neurons, taste cells generate electrical signals that are sent to sensory neurons wrapped around them Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 9.17 Copyright © 2021, 2018, 2015 Pearson Education, Inc. All Rights Reserved