CommunicationBiology Communication By Ryan Fraser 1. Humans, and other animals, are able to detect a range of stimuli from the external environment, some of which are useful for communication. Identify the role of receptors in detecting stimuli Receptors Detect a stimulus. Are specialised cells that convert information from the environment into electrochemical signals for translation in the brain Detect any changes in the environment i.e. predator around. Explain that the response to a stimulus involves Reaction of an organism to a stimulus is called a response Stimulus a change in the environment Receptors part of the nervous system that detects a stimulus Effectors muscles or glands that are capable of producing responses to stimuli Response a change brought about by a stimulus Identify data sources, gather and process information from secondary sources to identify the range of sense involved in communication Sight (vision) – facial expression and posture in humans communicate aggression or affection Smell (olfaction) – predators such as tigers and lions use smell to locate their prey Hearing – humans use speech to communicate complex ideas Touch – humans use tactile information to communicate afftion or aggression Taste – catfish have taste receptors on their whiskers 1 -1- Lens – a transparent protein disc – focuses light onto the retina. Visual communication involves the eye registering changes in the immediate environment. Only a small range of wavelengths humans can detect. Optic nerve – the nerve connecting the eye and the brain – carries information from the eye to the brain. Ciliary body – contains the ciliary muscles and suspensory ligaments that hold the lens in position – alters the shape of the lens. Choroid – a dark pigment layer inside the sclera containing blood vessels – absorbs and prevents light scattering. Iris – contains two sets of muscles to adjust the opening of the pupil – controls the size of the pupil.Communication 2. Use available evidence to suggest reasons for the differences in range of electromagnetic radiation detected by humans and other animals Humans – 380 to 750 nm – active during the day. Infra-red are outside human range but pit vipers can see heat for their prey. Describe the anatomy and function of the human eye Conjunctiva – mucous membrane that covers the eye – protects and keeps the eye moist. Retina – the inner layer of the eye containing photoreceptors and blind spot – changes light into nerve impulses. colour vision is important to distinguish food Pit Viper – 400 to 850 nm – relies on infra-red to locate prey in dark burrows Deep sea fish – 450 to 500 nm – little light penetrates to the depth at which they live Honeybee – 300 to 650 nm – some flowers have ultra violet markings on them 2 -2- . Aqueous humour – watery liquid found between the cornea and the lens – refracts light and gives the eyeball shape. Visible spectrum – 380 to 750 (different wavelengths appear as different colours). Identify the limited range of wavelengths of the electromagnetic spectrum detected by humans and compare this range with those of other vertebrates and invertebrates Energy from the sun reaches earth as waves of electromagnetic radiation. Sclera – the tough white outer coating of the eye – protects the eye. Vitreous humour – is a jelly-like substance that fills the area around the retina – refracts light and gives the eyeball shape. Cornea – transparent front part of the eye – refracts light through to the retina. Identify the conditions under which refraction of light occurs Occurs when light moves from one medium to another medium of a different density Is the bending of light rays Identify the cornea. The clarity of the signal transferred can affect interpretation of the intended visual communication.Communication 3. aqueous humor. lens and vitreous humor as refractive media The cornea causes most refraction The aqueous humour The lens Vitreous humour Identify accommodation as the focusing on objects at different distances. describe its achievement through the change in curvature of the lens and explain its importance Accommodation Is the changing of the shape of the lens when focusing Without accommodation the eye would have a fixed focus and would not be able to change focus from distant to close objects Compare the change in the refractive power of the lens from the rest to maximum accommodation The lens in the eye changes shape to focus the image from objects At rest the lens in flattened and thin. ciliary muscles contract and the suspensory ligaments are relaxed The focal length is shorter and close objects are in focus Distinguish between myopia and hyperopia and outline how technologies can be used to correct these conditions Myopia Can see close objects clearly but distant objects are out of focus The eye cannot correctly refract the light rays entering the eye and are focused in front of the retina Curvature of the lens is too great Hyperopia Can see objects in the distance but close objects are out of focus The image is focused behind the retina because the eyeball is too short for the focal length or the curvature of the lens is not enough Technology Concave or convex lenses can be used (either glasses or contacts) Myopia is corrected using glasses in concave shape Can both be corrected using refractive surgery Explain how the production of two different images of a view can result in depth perception 3 -3- . ciliary muscles relaxed and suspensory ligaments are taunt The focus is in the distance and focal length long (refractive power low) At maximum accommodation the lens becomes more rounded. which requires two sources of vision – called binocular vision Two separate perspectives of each eye overlap between the fields of view Analyse information from secondary sources to describe changes in the shape of the eye’s lens when focusing on near and far objects At rest – les is flattened – suspensory ligaments taut – ciliary muscles relaxed – focus on far objects – focal length long – refractive power low Full accommodation – lens is rounded – suspensory ligaments relaxed – ciliary muscles contracted – focus on near objects – focal length short and refractive power high Process and analyse information from secondary sources to describe cataracts and the technology that can be used to prevent blindness from cataracts and discuss the implications of this technology for society Cataracts cause the cornea to become cloudy A surgical operation can be performed to replace the cloudy lens called an intraocular lens It is cheap and simple and can restore sight 4 -4- .Communication Depth Perception Is the ability to judge the distance between objects Requires three-dimensional vision. structure and function of the photoreceptor cells in the human eye Rod Cells 125 million Are found in the retina mostly in periphery (except the fovea) Contain a form of rhodopsin called visual purple Important in night vision. green cones and blue cones Cone cells react when a particular wavelength of light hits them and send and impulse to the brain Different combinations of cones cells that react are interpreted by the brain as different colours Explain that colour blindness in humans result from the lack of one or more of the colour-sensitive pigments in the cones Full colour vision depends on all three colour sensitive pigments being present in the cone cells If one type is missing then a condition known as colour blindness 5 -5- . Identify photoreceptor cells as those containing light sensitive pigments and explain that these cells convert light images into electrochemical signals that the brain can interpret Photoreceptor cells Are located in the retina They convert light energy into electrochemical signals that the brain can interpret They contain photo-pigments which change their structure when they absorb energy which produces a nerve impulse Sent via the optic nerve to the brain Describe the difference in distribution.Communication 4. red or green light Humans have three types of cone cells which means they can detect the full spectrum red cones. work in dim light and do not detect colour Important for detecting movement and shape but the images lack detail and they are monochromatic Cone Cells 7 million of them Responsible for colour vision and are important for visual acuity Found mostly in the fovea Densely packed and each cell has individual nerve ending Are less sensitive than rod cells and require bright light Have three different forms for colour vision Outline the role of rhodopsin in rods Rhodopsin Is a light sensitive pigment (works in the dark) When hit by light it splits into two parts – retinal and opsin This produces an electrochemical signal that travels to the brain via the optic nerve Identify that there are three types of cones. The light signal reaching the retina is transformed into an electrical impulse. each containing a separate pigment sensitive to either blue. able to detect motion accurately Hawk – signal lens eye forming image – four types of cone cells with rhodopsin – colour vision 6 -6- . insects and in one other animal Human – can see by single lens eye forming an image – photo pigment of rhodopsin (three types) and has colour vision Bee – have colour and ultraviolet vision – photo pigment of rhodopsin.Communication When either the red or green cone cells are damage red-green colour blindness occurs Process and analyse information from secondary sources to compare and describe the nature and functioning of photoreceptor cells in mammals. Plan and perform a first-hand investigation to gather data to identify the relationship between wavelength. Sound is also a very important communication medium for humans and other animals. Explain why sound is a useful and versatile form of communication A variety of sounds can be made by an individual Sound travels well in both air and water The sender does not have to be visible to the receiver – useful at night an in dark environments Works over long distances Explain that sound is produced by vibrating objects and that the frequency of the sound is the same as the frequency of the vibration of the source of the sound Sound energy travels in waves and requires a medium to pass through Sound energy is formed when an object vibrates causing other molecules to vibrate Outline the structure of the human larynx and the associated structures that assist the production of sound The larynx is located below the tongue and soft palate in front of the neck It has rings of cartilage surrounding the two vocal cords Sound is produced by the vocal cords vibrating The vocal cords are muscular and can alter volume Movement of the lips.Communication 5. tongue. frequency and pitch Pitch and frequency are closely related as frequency of waves increase pitch increases Gather and process information from secondary sources to outline and compare some of the structures used by animals other than humans to produce Grasshoppers – rub little pegs on their back legs against ridges on their forewings Fish – insert a muscle into their swim bladder which causes vibrations when contracted 7 -7- . soft palate and jaw all result in changes to sound. middle and inner ear and identify the energy transformation that occur Sound travels as a pressure wave 8 -8- . Grasshoppers have a tympanic organ with a membrane over an air sac located on a leg or abdomen Fish Lateral system which is a line of cells which run along the body containing hairs that detect vibrations. hammer. Mammals Collect sound and transfer it into the auditory canal The tympanic membrane vibrates in response to the pressure of sound The three ossicles magnify the vibrations and the signal travels into the cochlea where hair cells in the organ of Corti convert vibration into an electrochemical impulse Describe the anatomy and function of the human ear Pinna – fleshy external organ consisting of skin – collects sound and directs into the ear canal Tympanic membrane – thin membrane between the external ear and the middle ear – vibrates when sound waves reach it. Animals that produce vibrations also have organs to detect vibrations. transfers the vibration to the hammer Ear ossicles – three tiny bones located in the middle ear. Insects Mosquitoes have hairs on the antennae of males which detect the buzz made by females flying. anvil and stirrup – magnify and transfer vibrations from the tympanic membrane to the oval window on the cochlea Oval Window – flexible membrane between the middle and inner ear – transfers vibrations from the stirrup to the fluid of the cochlea Round window – flexible membrane between the middle and inner ear – bulges outwards to allow displacement of fluid when vibrations are transferred to the cochlea Cochlea – fluid filled spiral tube that contains the organ of Corti – detects different frequencies of sound Organ of Corti – consists of hair cells on the basilar membrane – hair cells translate vibrations into electrochemical signals Auditory nerve – consists of the axons of the hair cells and leads from the cochlea to the brain – transfers the impulse from hair cells to the brain Outline the role of the Eustachian tube Is part of the middle ear Connects the middle ear to the nose and throat and keeps the pressure in the middle and the outer ear equal Drain fluid from the middle ear Outline the path of a sound wave through the external. fish and mammals They all detect vibrations using different organs containing hair cells. Outline and compare the detection of vibrations by insects. Swim bladder which vibrates and are transferred to an internal ear.Communication 6. Process information from secondary sources to evaluate a hearing aid and cochlear implant Hearing Aid Sound energy to electrical then amplified sound Used for people with damage to outer or middle ear Advantages is relatively cheap and no surgery required Will not restore normal hearing and amplifies background noise Cochlear Implant Sound to electrical energy Used for people with profound deafness or damage to the inner ear or auditory nerve Advantages are provides hearing to deaf people Surgery is expressive and may have other side effects 9 -9- . discussing possible reasons for the differences identified Bats can hear very high frequencies 100000 – 120000 Hz. Humans 20000 Hz.Communication These vibrations reach the eardrum and the sound energy is converted into mechanical energy by the movement of the eardrum and ossicles in the middle ear This mechanical energy travels through fluid in the cochlea and bends hair cells in the organ of Corti The hair cells convert the mechanical energy into an electrochemical signal that is transmitted to the brain via the auditory nerve Describe the relationship between the distribution of hair cells in the organ of Corti and the detection of sounds of different frequencies Frequencies are detected in the organ of Corti It contains 15000 hairs which are distributed along the basilar membrane Sound waves cause the basilar membrane to flex and different frequencies cause movement membrane at different locations Outline the role of the sound shadow cast by the head in the location of sound The vibrations cannot pass through the head This causes a different intensity of the sound Process information from secondary sources to outline the range of frequencies detected by humans as sound and compare this range with two other mammals. the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour The brain interprets the signals arriving from the sensory organs If there is damage to the brain the signals will not be interpreted correctly For example if there is damage to the occipital lobe objects may seem larger or smaller 10 . Signals from the eye and ear are transmitted as electrochemical changes in the membranes of the optic and auditory nerves.Communication 7.10 - . using specific examples. Identify that a nerve is a bundle of neurone fibres A neurone or nerve consists of a large cell body containing a nucleus and other cell organelles with extensions from both ends called dendrites and axons A myelin sheath made up of specialised cells surrounds the axon They are specialised for transmitting signals from one part of the body to another Identify neurones as nerve cells that are the transmitters of signals by electrochemical changes in their membranes Nerve impulses travel along neurones by a combination of electrical and chemical changes An electrical impulse travels from the dendrites of a neurone to the axon where it causes the release of a neurotransmitter from the membrane This chemical diffuses to the membrane of the dendrites of the next neurone This initiates an electrical signal in the next neurone and the process is repeated Define the term ‘threshold’ and explain why not all stimuli generate an action potential Identify those areas of the cerebrum involves in the perception and interpretation of light and sound The cerebrum is the largest part of the brain Vision and colour recognition are controlled by the occipital lobes which are located towards the back of the cerebral cortex Sound is processed in two areas of the temporal lobes – Broca’s area and Wernicke’s area Explain.