9.5 Option - Communication

1. Humans, and other animals, are able to detect a range of stimuli from the external environment, some of which are useful for communication

Students learn to:

Identify the role of receptors in detecting stimuli: - A stimuli is any change in the internal and external environment of an organism- This stimuli is picked by the organisms receptors- In the most simple form a receptor in organisms consists of single cells scattered around the body- In many organisms receptors have become more concentrated in particular areas to from sensory organs, which

contain non-sensory tissue and sensory cells. E.g. The eye

Explain that the response to a stimulus involves: - Stimulus: Any change in the internal or external environment of an organism- Receptor: The receptor detects this change, and sends messages to the brain or CNS by impulses in the nerve- Messenger: These impulses then trigger the CNS or brain to process the information and trigger new impulses- Effectors: These new impulses are transmitted to the effectors for it to produce a response- Response: A response is produced in response to the stimulus

Students:

Identify data sources, gather and process information from secondary sources to identify the range of senses involved in communication: - Sight: Sight is a common form of communication, many animals have dangerous looking colours so as to detour

predators - Sound: This is a common form of communication, many animals use different sounds for different situations, such

as danger- Touch: Touch can be used as communication in such forms as comforting gestures. For example humans hug to

comfort or show affection - Taste: Chameleons use taste to identify if a territory is occupied. As chameleons rub their cloaca on branches to

mark there territory. Chameleons have a very poor sense of smell- Smell: Young babies are known to be capable of identifying their mother, by their smell

2. Visual communication involves the eye registering changes in the immediate environment

Students learn to:

Describe the anatomy and function of the human eye, including the:- Conjunctiva: Thin transparent membrane that is there to protect the exposed areas of the eye- Cornea: Transparent, and allows light to enter as well as helping bend or refract it. Has many nerves and is

sensitive to touch and pain- Sclera: Outermost layer of the eye at the back, opaque in colour forming the ‘white’. Tough non-elastic tissue

protecting the delicate inner layers, helps maintain shape as well as allowing a place for the attachment of muscles for movement

- Choroid: Middle of the eye containing most of the blood vessels. Posterior black to reduce scattering and reflecting of light within the eye. Anterior continues to form the ciliary body and lens

- Retina: Lines the posterior two thirds of the eye and is thin and delicate. Contains several layers of nerve cells. Contains photoreceptors, rods and cones.

- Iris: Consists of connective tissue and smooth muscles. These muscles are arranged circular and radially and control the size of the pupil

- Lens: Refracts light rays and directs them onto the retina. It is highly elastic allowing it to change shape to accommodate to different distances

- Aqueous Humor: Watery fluid in the anterior section of the eye, between the cornea and lens. It has a composition similar to blood plasma and provides nutrients for the lens and cornea

- Vitreous Humor: Jelly like material filing the remainder of the eye, behind the lens and enclosed by the retina. Contains dissolved nutrients, refracts light and helps maintain the shape of the eye

- Ciliary body: Produces aqueous humor, as well as this it controls the ciliary muscle which changes the shape of the lens by controlling the suspensory ligaments

- Optic nerve: Carries information from the eye to the brain changing light energy into nerve impulses

Identify the limited range of wavelengths of the electromagnetic spectrum detected by humans and compare this range with those of other vertebrates and invertebrates:- Humans: Detect range lengths of 380nm to 760nm- Invertebrates: Many insects (honeybees) can detect wavelengths in the ultraviolet UV range of the spectrum. Their

light sensitive cells can detect shorter wavelengths present in the UV range. They are unable to detect some of the longer wavelengths in the red part of the spectrum, they see red as black. Therefore bees do not have a wider spectrum, but rather a different range

- Vertebrates: Many birds are able to detect light in to the UV range of the spectrum. In addition to this birds tend to be able to detect light most efficiently in the red. Therefore they have a wider range of detection

Students:

Plan, choose equipment or resources and perform a first-hand investigation of a mammalian eye to gather first-hand data to relate structures to functions: - After removing the fatty tissue from the eye- Made an incision behind the cornea, and in front of the lens- Aqueous humor escapes, then studied the anterior section of the eye. Observing the pupil and the iris - Removed the lens and the vitreous humor and examined the lens- Observed print through the lens, whilst squeezing it to observe what happens- Examined the retina

Use available evidence to suggest reasons for the differences in range of electromagnetic radiation detected by humans and other animals: - Different animals require vision in different areas of the spectrum. This allows them to live appropriately in their

habitats- For example; Honey bees are able to detect light into the UV range. This is beneficial as many flowers have UV

patterns, this helps direct bees to the pollen and nectar in the centre of the flower

3. The clarity of the signal transferred can affect interpretation of the intended visual communication

Students learn to:

Identify the conditions under which refraction of light occurs:- As light moves through a medium of a different density, the speed at which its travelling changes- Because of the light slowing down or speeding up, the light rays are bent or refracted- When light is passed through a biconvex lens, the rays are refracted towards a central point, known as the focal

point

Identify the cornea, aqueous humor, lens and vitreous humor as refractive media: - The density of the cornea, aqueous humor, lens and vitreous humor are close to that of water- They all refract light- The greatest amount of refraction occurs when light hits the cornea, as the density between the air before it and

the cornea are of extreme differences

Identify accommodation as the focusing on objects at different distances, describe its achievement through the curvature of the lens and explain its importance:

- This is the ability of the eye to focus on objects of varying distances- The grater the distance, the smaller the curvature of the lens. This is done by:

. The cilliary muscles relax, and pull back

. As this happens they tighten the suspensory ligaments

. This stretches and elongates the lens, allowing for a slighter curve- The closer the distance the greater the curve of the lens must be to allow for quicker diffraction. This is done by:

. The cilliary muscles contract and stretch out

. This causes the suspensory ligaments to slacken

. The lens becomes more rounded allowing for greater curve of the lens

Compare the change in the refractive power of the lens from the rest to maximum accommodation: - The thinner the lens, or less curvature, that is when at rest, the less refractive power- When at maximum accommodation, the refractive power of the lens increases- Therefore, the refractive power of the lens from rest to maximum accommodation is of a greater refractive power

Distinguish between myopia and hyperopia and outline how technologies can be used to correct these conditions: - Myopia is the eyes inability to focus on distant objects, as the focal length is to short meaning the image falls short

of the retina- Myopia is caused by: Eyeball too elongated in shape, refractive power of the cornea is inadequate or the lens may

not become flat enough- Hyperopia is the eyes inability to focus on short distances, as the focal length is too long and the image does not

converge quick enough for the retina- Hyperopia is caused by: Eyeball to rounded or short, lens is to flat and cannot change enough- Both hyperopia and myopia are easily corrected through the use of spectacles, and in more recent time’s contact

lenses. As well as this there are now permanent corrections through the use of laser eye surgery- Spectacles for myopia are concave, and hyperopia are convex

Explain how the production of two different images of a view can result in depth perception: - This is the ability to accurately judge the distance of an object- Human eyes are spaced apart, they therefore take in the same image at two slightly different angles- The two images are directed to the brain where they are put together and any missing information is filled in.

Allowing you to see the image in 3D- This is called binocular or stereoscopic vision

Students:

Plan and choose equipment or resources and perform a first-hand investigation to model the process of accommodation by passing rays of light through convex lenses of different focal lengths:- Aim: To model accommodation by passing rays of light through convex lenses of different densities, to observe the

focal length - Ray box, multiple slit slides, biconvex lenses of different densities and power pack- Placing the first convex lens 6 cm from the ray box, and measured the focal length of the light that passes through

the lens. Then did so for the second lens- Results showed that the greater the density of an object, and the greater the curvature, the greater the refractive

power and therefore shorter focal length

Analyse information from secondary sources to describe changes in the shape of the eye’s lens when focusing on near and far objects:- Far objects: Lens elongates (becomes longer and thinner) The ciliary muscles relax, causing the suspensory

ligaments to tighten. Refractive power decreases- Near objects: Lens becomes thicker and curvature increases. The ciliary muscles contract, causing the suspensory

ligaments to shorten and slacken. Refractive power increases

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:- Cloudy opaque film build up over the lens of the eye- Decreases visual clarity, reduces light availability to the eye- Opaque covering can eventually lead to blindness, even with capable photoreceptors- Cure: Surgical removal of the lens by making an incision on the eye ball. This lens is then replaced with a plastic

intraocular lens (IOL)- This has major implications on society, as half of the worlds blind population is bind due to cataracts. Many of

whom are from third world countries

4. The light signal reaching the retina is transformed into an electrical impulse

Students learn to:

Identify photoreceptors as those containing light sensitive pigments and explain that these cells convert light images into electrochemical signals that the brain can interpret:

Describe the differences in distribution, structure and function of the photoreceptor cells in the human eye:

Photoreceptor Structure Distribution Number Function (pigment)Cone Cone shaped,

broader than rodsContain idopsins

Distributed in groups throughout the retina, concentrated in macula. There are fewer around the periphery

6 to 7 million cones

Work better in bright light cones distinguish colourOne cone for blue, one for green, one for red. The idopsin for each colour is different

Rod Rods are long and narrowContain Rhodospin

Evenly distributed across the retina. Absent from the fovea

125 million rods

Work better in dim light Higher sensitivity than cones

Outline the role of rhodopsin in rods:

- Rhodopsin is made up of two parts, a retinal molecule that is derived from vitamin A and a protein called opsin- Light strikes the rhodopsin pigment, and it changes from a resting state to an excited state. This is due to the

activation of the retinal- When the retinal becomes activated, the rhodopsin splits into an opsin part and a free retinal part. Rhodopsin is

said to be bleached- The activated pigment causes a change in electrical charges of the membrane of the cone- This starts an electrical impulse triggering the release of neurotransmitter - The neurotransmitter then stimulates the bipolar cell, triggering an impulse (electrochemical signal)- The bipolar cell transmits the electrochemical signal to the ganglion cells which in turn carry it to the brain- Rhodopsin is then regenerated to be used again

Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or green light:- Cones allow us to see in colours. This is due to the cone cells containing one of three different pigments- This makes each more sensitive to light in one of three wavelengths:

1. Short wavelengths of ‘blue light’ 455nm2. Medium wavelengths of ‘green light’ 530nm3. Long wavelengths of ‘red light’ 625 nm

- The sensitivity of cones also allows it to detect light to some extent of either side of their peak sensitivities. This allows for an overlap in some colours, and therefore allows for the cones to detect a range of colours from the spectrum

Explain that colour blindness in humans results from the lack of one or more of the colour-sensitive pigments in the cones:- The cones have three different types of pigment, to detect different colours- If a particular pigment is missing then the cones are unable to detect that colour- Subsequently the person is said to be ‘colour blind’ therefore human colour blindness is caused by the absence of

one or more pigments

Students:

Process and analyse information from secondary sources to compare and describe the nature and functioning of photoreceptor cells in mammals, insects and in one other animal: - Planarians (free-living aquatic flatworms): Have a basic cup-shaped structure lined with pigment cells- This pigment cup may contain fluid, being the only refractive part of the eye- Each eye has fewer photoreceptors resulting in very poor visual acuity. The simple image that forms is unclear and

not inverted. The role is therefore to detects light in the environment and where it comes from- Insects: Have more compelxe structures called compound eyes- They detect light, movement and colour- Made up of 8000 units called Ommatidia, which sees only part of an object- When put together a mosaic type picture is formed. Ommatidia are larger than rods and cones and as a result

there are fewer. This results in a blurred image by human standards- However the time taken for one ommatidium to receive a light stimulus, generate and impulse and then

regenerate is far quicker than the mammalian eye. This results in a far more efficient flicker vision. This makes the insect far more efficient at detecting movement

Process and analyse information from secondary sources to describe and analyse the use of colour for communication in animals and relate this to the occurrence of colour vision in animals: - Colour can be used as an essential form of communication in breeding. E.g. The male satin bowerbird (Aus) builds a

bower of grass twigs and decorates it with brightly coloured objects. This attracts the female, he then performs a dance. If the female suitably impressed, they copulate and the female then flies off to build a nest and lay eggs

- Visual displays can also be used as warning mechanisms, the peacock displays its colourful feathers when they are threatened

- Food recognition, colouration of flowers is linked to attracting pollination by birds and bees. They are also visited at night, suggesting flowers may have ultraviolet markings on them, attracting birds and bees

- Colour is the most important form of communication with birds. Birds are therefore capable of seeing both well into the ultraviolet range and the normal, red, green and blue ranges.

- Bees however rely on UV, and are sensitive to UV, green and blue-

5. Sound is also a very important communication medium for humans and other animals

Students learn to:

Explain why sound is a useful and versatile form of communication: - Sound bends around objects, and travels around corners. It moves through all substances, solids, liquids and gases- An animals reliance on sound is therefore always supported by its environment- Animals to don’t have to be in visual or direct contact to communicate, like other senses. When the other senses

are impaired or absent, sound can be used as the primary from of communication- Sounds may be varying pitch, loudness and tone. A complete message can be conveyed in a short space of time.

Sound will travel 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 is produced by a vibrating object that forms a compression wave in a medium- The frequency of the sound produced is the same as the frequency of the vibration of the source of the sound

Outline the structure of the human larynx and the associated structures that assists the production of sound: - Larynx is a hollow box, housing the vocal cords. It consists of a framework of nine cartilages, joined by membranes

and ligaments. These form a box, the voice box, in which sound can be produced and resonate. - Sound is produced by: The lunges produce air; this air must be strong enough to push open the vocal cords. This

achieved by the relaxing of the diaphragm to form a dome shape, and the internal intercostals muscles so that the pressure inside the chest cavity is higher than the outside of the body. This means air is forced out in attempt to equalise the air pressure.

Students:

Plan and perform a first-hand investigation to gather data and identify the relationship between wavelength, frequency and pitch of a sound:- Used an audio generator and a CRO- Selected a frequency of 20Hz and recorded the sound waves. Then did so at 200Hz and - Results showed that as frequency is increased, there is an increase in pitch, and a decrease in wave lengths

Gather and process information from secondary sources to outline and compare some of the structures used by animals other than humans to produce sound:- Grass hopers produce sound by rubbing one part of their body along another. The scrape a row of pegs on their

back legs, along the hard edges of their front legs

- Catfish, when alarmed or travelling in a shoal, vibrate a bone against their swim bladder producing a noise similar to a giant aerator

- Birds produce sound through syrinx. Elastic membranes of connective tissue inside the syrinx open and close as the bird exhales. The pressure of their air entering the syrinx, the size of the syrinx, and elasticity of the folds determine how the sound is produced

6. Animals that produce vibrations also have organs to detect vibrations

Students learn to: Outline and compare the detection of vibrations by insects, fish and mammals

Feature Fish Mammal InsectName of structure that detects vibrations

Lateral line Ear Tympanum

Type of vibration detected Pressure waves soundwaves Soundwaves

How it works Mechanoreceptors with hair cells in capula, detect changes in water pressureThis causes and impulse to the brain

Outer, middle and inner ear. Tympanic membrane between the outer ad middle ears converts the soundwave into mechanical vibrations. Inner ear has the cochlea which has hair cells which generate an impulse. The impulse is sent to the brain

Tympanum is an internal air chamber enclosed by tympanic membraneSoundwaves cause the tympanic membrane to vibrate and attached nerve fibres are generated and travel to the brain

Similarity Receptors detect vibrations. Nerve fibres send the info to the brain

Receptors detect vibrations. Nerve fibres send the info to the brain

Receptors detect vibrations. Nerve fibres send the info to the brain

Difference Lateral line provides fish with info about changes in the direction and speed of water

Ear provides info about changes in direction and pitch. Has cochlea and opens to outside

Tympanum provides information about changes in direction of sounds and detects certain pitch. No cochlea. Has tympanic membrane

Describe the anatomy and function of the human ear, including: Part of ear Anatomy FunctionPinna Forms outer ear

Composed of cartilageHelps collect and localise sound wavesProduces ear wax, to prevent dirt entering the ear and making it water repellent

Tympanic membrane Taut membrane consisting of three layers, outer layer continuous with outer layer of auditory canal

Transmits sound through vibrations in the membrane, the pars tensa provides the active vibrating area in response to sound

Ear ossicles:-Hammer-Anvil-Stirrup

BonesHammer lies towards the side of the headAnvil is attached to the hammer and the long process is attached to the stirrup The footplate of the stirrup rests on the oval window

The hammer vibrates with the tympanic membrane passing the vibrations to the anvilAnvil gives the sound a small boost of 2.5dBStirrup gives the sound a boost of 20dB

Oval window Membrane between the middle ear and inner ear.

Holds the fluid of the cochlea. As the footplates of the stirrup vibrates the oval window vibrates, sending waves through the perilymph

Round window Membrane located in the round window niche at the base end of the lower canal of the cochlea

The round window allows the release of the hydraulic pressure of the perilymph that is caused by the vibration of the stirrup on the oval window

Cochlea Snail shaped structure containing three canals filled with fluid

Vibration wave patterns from the stirrups footplates set up a

The lowest canal contains perilymph as well as the upper canalThe middle canal contains endolymph Middle canal holds the organ of corti

vibration in the membranes and a travelling wave pattern in the perilymph and endolymph of the cochlea.This is transmitting the vibration alongMiddle canal holds the organ of corti

Organ of corti Contains inner and outer hair cellsInner hair cells have a nerve fibre attached

The hair cells convert the vibrations into electrochemical energy.

Auditory nerve A collection of nerve cells-nerve tissue. It leads from the cochlea to the brain

The transmission of neural energy from the cochlea to the brain

- The ear is responsible for: Sound transmission, balance and pressure

Outline the role of the Eustachian tube: - The Eustachian tube helps to equalise the pressure on either side of the tympanic membrane by bringing in air

from the mouth

Outline the path of a sound wave through the external, middle and inner ear and identify the energy transformations that occur:

Describe the relationship between the distribution of hair cells in the organ of Corti and the detection of sounds of different frequencies:

Inner ear:- Stapes; vibrate the oval window setting up a pressure wave in the perilypmh of the upper canal- Reissener's membrane the moves transferring energy to the endolymph of the middle canal- This vibrates the basilar membrane stimulating the hair cells of the organ of corti- The hair cells send messages along nerve fibres to the brain where they are interpreted - The pressure waves contine to the round window at the end of the lowest canal

- There are thin fibres of various lengths in the basilar membrane of the organ of corti. Each of these vibrate at different frequencies

- When the cochlea vibrates at a frequency, the vibration is detected by the fibre of the corresponding length - Hair cells run along the length of the basilar membrane and the hair cells associated with the stimulated fibres are

then bent - Thus different frequencies of sound will activate the basilar membrane at different locations and this will, in turn,

activate different sets of hair cells- Hair cells are arranged along the basilar membrane from those stimulated by low frequencies at the apex to those

stimulated by high frequencies at the base

Outline the role of the sound shadow cast by the head in the location of sound: - When sound waves are coming from directly in front or behind or above the head, both ears receive the sound

equally and the sound will be the same for both ears.- When sound is coming from one side the receptors in the ear closest to the sound will be stimulated slightly earlier

and also more intensely- The brain locates the sound as coming from one side of the head- The head is said to cast a Sonic shadow or sound shadow on the sound coming into an ear from the opposite side

of the body

Students: Gather and process and analyse information from secondary sources on the structure of a mammalian ear to relate

structures to functions:- Refer to: Describe the anatomy and function of the human ear, including.....

Process information from secondary sources to outline the range of frequencies detected by humans as sound and compare this range with two other mammals, discussing possible reasons for the differences identified: - The range of sound detected by humans is from 20 to 20000Hz (0.02 KHz to 20KHz)- The human ear is most sensitive to frequencies of 2000 to 4000 Hz which corresponds with speech

- The frequency range for dolphins is less than 1Khz to greater than 100KHz- Lower frequency sounds travel further in aquatic mediums- Because they surface they need to be capable of detecting higher frequency sounds- They require a greater range of frequencies as they have a greater reliance on sound, as opposed to other senses

such as visual which is limited in their environment. They also use these higher frequencies to detect there locations, know as echolocation

- The Kangaroo rat is a nocturnal animal. The frequency ranges from 0.03KHz to about 50KHz- Need for a greater sensitivity to sound due to visual constriction - Their predators produce low frequency sounds, by detecting these sounds they can be aware of predators around

them

Process information from secondary sources to evaluate a hearing aid and a cochlea implant in terms of:

Hearing aid Cochlea implantPosition and type of energy transfer occurring

-Battery operated hearing device, that amplifies vibrations so that they can physically stimulate the nerves of the cochleaUses the normal auditory pathway, and consists of microphone, amplifier and earphone-Positioned inside the curve of the pinna and ear canal-Sound waves are picked up and magnified by the amp, this is

-Battery operated hearing device, that electrically stimulates the nerves of the cochlea by by-passing the normal auditory pathwayConsists of implanted receiver package, electrode array, speech processer and the headset-receiver package and electron array are implanted in the ear, and headset and speech processer are

channelled to the auditory canal by the earphone, then follows the normal auditory pathway

worn externally-Sound waves are picked up by the mic, and converted into electrical code by the speech processor, code is sent by cable to head set, transmitted to the implant, which transforms the signal into electrical impulses which stimulate the cochlear nerves

Conditions under which the technology will assist hearing

For people with a ruptured tympanic membrane or damaged ossiclesFor people with adequate residual hearing

For profoundly or totally deaf people who receiver no benefits from a conventional hearing aidDamaged hair cells in cochlea

Limitations of each technology Able to detect fewer sounds than cochlear implant

Requires surgeryPost-op side effectsExpensive and ongoing costs

7.Signals from the eye and ear are transmitted as electro-chemical changes in the membranes of the optic and auditory nerves

Students learn to:

Identify that a nerve is a bundle of neuronal fibres:- A nerve is a bundle of neuronal fibres

Identify neurones as nerve cells that are the transmitters of signals by electro-chemical changes in their membranes: - Nerve impulses are electrical in nature and chemical as it passes across the synapse- Nerve impulses transmit a signal due to the exploitation of a property all cells have, an electrochemical potential

across their membranes - This is a difference in electrochemical charge across the cell membrane- This difference is due to the concentration of ions (charged particles). That is high concentration of Na+ (sodium) in

the extracellular fluid (outside the cell) and low concentration in the cytoplasm (inside)- The potential is maintained by a Na+-K+ pump, a specialised protein in the membrane. This actively transports Na+

outwards, and keeps K+ inside, held by negatively charged biological molecules

- Therefore at resting potential there is a higher concentration of sodium ions (Na+) outside the axon membrane than inside it. This due to the membrane being impermeable to Na+ due to sodium ion channels being shut

- There is a higher number of K+ inside than outside, although a small do move out- Therefore, the inside is more negatively charged than the outside, which is more positively charged

- A nerve impulse then reaches the resting nerve fibre, caused by a neurotransmitter- This stimulates the membrane to become permeable to sodium ions- Small number of Na+ rushes in, and the resting potential is reversed- That is the inside is now positive and the outside is negative, this is an action potential- The nerve impulse is passed along the membrane, as it only occurs at the nodes of ranvier. The nerve impulse

jumps from one node to the next (except at unmyelinated fibres here it is slower)

- One node of renvier notifies the next by:- Some of the diffused Na+ diffuses down the cytoplasm inside the membrane and myelin sheath to the next node- This Na+ causes the membrane to become permeable to Na+, initiating an action potential- As the nerve impulse passes, the resting potential is quickly restored by the Na+-K+ pump actively transporting Na+

outwards and K+ inwards

- Whilst the nerve impulse is electrical down the axon it is chemical across the synapse. This happens by:

- When the nerve impulse reaches the axon branches and synaptic knobs, this causes the release of neurotransmitter molecules from small vesicles in which they are stored

- Neurotransmitters are chemicals stored in vesicles in axon branches, that can transmit a signal across the synapse, for example adrenalin (epinephrine)

- Once the neurotransmitter is released from the vesicle into the synapse, it travels across the synapse to the membrane dendrites of the next neuron. There is stimulates the membrane to become permeable to sodium (by opening the sodium ion channels) thus initiating a nerve impulse in the next neuron

- Once the neurotransmitter has acted, it is degraded by an enzyme into its component molecules and returned to the axon branch to be resynthesised and stored

Define the term ‘threshold’ and explain why not all stimuli generate an action potential: - Threshold is the amount of positive change in membrane potential which is required before an action potential is

produced- The depolarisation must reach a threshold which is at least 15mV more positive then the resting potential of -70mV- No action potential is produced if the depolarisation is below this level- This is one reason as to why not all stimuli generate an action potential

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound: Cerebrum

Sound Visual (light)

Explain, using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour:- If sensory signals are not received or properly interpreted, the bodies responses to the stimulus in the environment

can become impaired- For example: - MS; this is when the immune systems destroys the myelin sheaths. Resulting in a short circuit in nerve impulses.

This then causes muscle control problems and visual disturbances. - Alcohol; Impairs the transmission of messages. By blocking nerve impulses by reducing the plasma membranes

permeability to sodium ions, if there is no sodium entry, there is no action potential. This results poor coordination, lack of concentration, retarded reflexes and blurred vision

Students:

Performa a firsthand investigation using stained prepared slide and/or electron micrographs to gather information about the structure of neurones and nerves:

Perform a firsthand investigation to examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate regions involved in speech, sight and sound perception:

Cerebrum

Auditory Medulla oblongata Cerebellum Visual

Speech

Present information from secondary source to graphically represent a typical action potential:

Option- Communication1.2.1Receptors are used to detect changes in the ambient environment, and concert them into nervous impulses so the brain is able to detect them.

1.2.2

The response to a stimulus involves firstly there being a stimulus, which is a change in the ambient environment, which the receptor detects. This is then transported to the central nervous system through the peripheral nervous system. Once the CNS has received the message and decided how to counteract the change, it then sends this response back through the PNS to the effecter glands and muscles, which perform this response.

1.3.1Mechanoreceptors: detect sound waves and pressure on skin

Thermoreceptors: Temperature

Photoreceptors: light, colour and movement

Chemoreceptors: detect dissolved molecules (taste) and molecules in air (touch)

2.2.1The purpose of the eye is to allow the entry of light, organize rays into a clear image, convert light signals into electrochemical impulses and prevent leakage of light within the eye. To do this, there are several components:

- Conjunctiva: The protective layer on the outside of the eye- Cornea: the outer eye which is the first change in density- Sclera: Is posterior on the outside of the eye (the white part) which is tough and elastic, maintaining the shape.- Choroid: Contains most blood vessels. Is black at the back, restricting light leakage- Retina: The retina is the point that the light hits which is the image that is interpreted to the brain. Contains

photoreceptors.- Iris: The Iris is a protective boundary which expands or contracts in to restrict the amount of light that enters the eye- Lens: is the accommodative component of the eye which changes in curvature through a refractive medium- Aqueous and vitreous humour: Are refractive mediums which maintain the shape of the eye- Ciliary body: involves muscles and ligaments which contract or loosen in order to change the curvature of the lens- Optic nerve: is the nerve which transmits the message received by the retina to the brain

2.2.2Humans are trichromatic organisms, that is, they are able to detect light from the red, green and blue ranges of the spectrum. This is due to the wavelengths of light which they are able to see, ranging from roughly 380- 780. In comparison, other organisms are able to detect light in different ranges of the spectrum. Some invertebrates such as bees are able to detect light in the ultraviolet range of the spectrum, although they are not capable of detecting light in the red range of the spectrum, while vertebrates such as wombats are able to detect light from the infrared range of the spectrum, without being able to detect ultraviolet wavelengths. Some organisms are only able to detect a dichromatic range of colours, while others are able to detect a tetrachromatic range of colours.

2.3.1We got a sheep’s eye, a scalpel, scissors, gloves and tweezers. We then cut away the fatty tissue and cut roughly along the equator of the eye, to avoid the lens. We then cut the lens out and observed that, the optic nerve, aqueous humour and several other features such as the retina.

2.3.2The reason behind differences of electromagnetic radiation which is detected among various organisms is evolutionary. Due to the variation and adaptation, organism’s behaviours require them to detect different ranges of light which cater to their needs. Natural selection states that over time, they will adapt to enable them to detect light in the required range of the spectrum.

3.2.1There must be a change in density, speed and the surface must be transparent.

3.2.2The refractive medium in the eye is the cornea, aqueous humour, lens and the vitreous humour.

3.2.3

Accommodation is the eyes ability to detect light at different distances. For far objects, the ciliary muscles loosen, causing the ligaments to contract, and hence, pull the lens taut so the thin curvature enables decreased refraction. For close objects, the muscles contract which causes the ligaments to loosen so that the curvature of the lens increases to increase the amount of refraction.

3.2.4A lens at rest refracts the light inwards, although, in comparison to a lens at maximum accommodation, the light is refracted inwards at a much steeper angle.

3.2.5Myopia is the inability to focus on distant objects as the lens suffers from an inability to flatten out; therefore the light rays focuses in front the retina. It is corrected with a concave lens in the form of contacts or glasses which refract the light outwards slightly before it reaches the eye so the light has to converge from a wider point

Hyperopia is the inability to focus on close objects as the lens is incapable of compressing, therefore, the light rays focus behind the retina. It is corrected with a convex lens in the form of glasses or contacts so that it refracts the light inwards slightly, giving it more time to converge upon reaching the eye.

3.2.6Two different images of a view enable an object to be detected from different angles. In doing this, the eye is able to see the object in 3 dimensions as the images are put together as one, filling in any missing information. This is called binocular vision.

3.3.1We gathered a ray box, and a multi light slide and two biconvex lenses of different curvatures. We then turned on the ray box and measured 10cm back from it, where we positioned one of the lenses on top of a piece of paper. By tracing the lens and the rays until the point of convergence, and then doing the same, keeping all variables consistent, we were able to compare the two results. The results were obtained by measuring the focal length.

Accuracy: used ruler and traced the beams

Validity: kept all variables constant, except for the curvature of the lens

Reliable: repeat

3.3.3Cataracts are a disease which affects the protein in the lens, causing it to become opaque. This results in blurred vision. To fix this, an operation known as phacomulsification is used, this involves the insertion of a rod which vibrates and breaks the lens. The lens is then sucked out and replaced with a plastic lens that is completely transparent and functional. This technology provides a safe and fairly easy way of allowing the elderly members of society a chance to see clearly, while maintaining a normal lifestyle.

4.2.1Photoreceptor cells are found in the retina which contains light sensitive pigments. These receptor cells detect light at the cones and rods which simulates an electrical charge that travels throughout elongated cells in the photoreceptor cells. As this electrical charge travels through the cones and rods to the foot, a chemical that exists in the synapse allows this charge to transfer over it and on to the bipolar cell layer where it continually travels through the ganglion cell layer and the optic nerve fibres to reach the brain.

4.2.2CONES RODS

STRUCTURE

- Shorter and conical shaped- Contains outer, inner and conducting

segments- Contains cell body and foot- Visual pigment is iodopsin

- Long and narrow shaped- Contains outer, inner and conducting

segments- Contains cell body and foot- Visual pigment is rhodopsin

DISRIBUTION - Fewer around he peripheral of the retina

- Most concentrated in the macula- Roughly 6-10 million

- Evenly distributed along retina- Detects movement- Many rods per bipolar layer- Are very sensitive, responding to low

intensity

- Detects black and white- Roughly 125 million

FUNCTION

- Detects bright light- Detects colour

- Detects movement - Are very sensitive, responding to low

intensity- Detects black and white

4.2.3Rhodopsin exist in a deactivated or an activated form. They are used to detect black and white shades of light which simulates the change in electrical charge. From here, electrical charges are continuous, carried over the synapse by the neurotransmitter. The rhodopsin joins back together to detect a new light source.

4.2.4There are different types of iodopsin, each are sensitive to different ranges of light. In the human eye, there are three different types of iodopsin which are pigment sensitive to blue, red or green light. Rhodopsin and iodopsin contain a retinal molecule and a protein called opsin. The types of opsin distinguish between what each is sensitive to.

4.2.5As there are various types of opsin which are sensitive to different ranges along the spectrum, the absence of one of these would result in the inability to detect a colour. Red green colour blindness is the absence of red and green sensitive opsin, or poorly working opsin.

4.3.1Eyes vary in structure and function over a variety of animals from complex to simple.

Simple Light Receptors: organisms such as planarians involve a cup shape of pigment cells that contain a refractive fluid. As it is so simple, the purpose of there eyes are to detect light sources rather than clear images.

Compound eyes: Insects have a collection of roughly 8000 detection units called ommatadia. Each ommatadia detects a sector of vision, which, when combined, produces a mosaic type of picture which is blurred. The purpose of this is to detect light, movement and colour, while being more beneficial over humans in the sense that they have a broader range of vision.

4.3.2Animals of varying species use colours as a form of communication. The purpose of certain animals to detect certain colours is to allow them to detect certain signals.

Humans use colours as a form of signaling in every day life. They are used in mapping, for survival such as different colours in war and as a form of display such as looking pale shows illness.

Other animals use light for many reasons such as:

- To distinguish between species, sex type, maturity and readiness- As a warning mechanism (e.g. peacocks exposing their feathers)- Food recognition (bees attracted to ultraviolet markings

5.2.1Sound can travel around bends and through all mediums, allowing it to be very versatile. It is used for communication, but also for functioning. When visual, tactile and olfactory senses are impaired or insufficient in a particular environment, sound can be used and detected. Whales emit sound and listen for the echo to detect distances of objects which is known as echolation.

5.2.2Sound originates from something which vibrates rapidly enough to organize the movement of molecules into compression waves. It must travel through particles that can be compressed, where it moves back and forwards in the same direction as the flow of energy. Frequency is determined by cycles per second, called a hertz, and distinguishes between pitches. Wavelength is the distance between two adjacent compressions which coincides with frequency (low frequency has short wavelengths). Amplitude is the displacement of a particle and determines the volume.

BASICALLY: sound is produced by a vibrating object that forms a compression wave in a medium. The frequency of the sound produced is the same as the frequency of the vibration of the source of sound.

5.2.3The larynx consists of nine cartilages joined by membranes and ligaments which form a hollow box where sound can be produced and resonates.

5.3.1We used a Cathode Ray Oscilloscope (CRO), an audio generator and a power pack. We powered up the audio generator and CRO, then selected a sine wave output of 20Hz, and identified there being 4 crests. We drew the diagram and changed it to 200Hz, then 2000Hz, where the amounts of crests increased each time. From this we concluded, the higher the frequency, the higher the pitch, the shorter the wavelength.

5.3.2ANIMAL GROUP EXAMPLE NAME OF

STRUCTUREMAIN FEATURES- STRUCTURE AND FUNCTION

Insects Grasshopper TymbalsWings

- Stridulation: rubs front of wing against rough part of another wing

- Ribbed membranes at the base of the abdomen buckle and produce a pulse sound

Fish Sea catfish Underwater microphones

Vibrate the bone against the swim bladder

Birds Storks Syrinx Elastic membranes of connective tissue inside the syrinx open and close as the bird exhales

Mammals Eastern Horse Shoe Bat

Throat Movement of the air in the trachea and nasal sacks.

6.2.1FEATURE FISH MAMMAL INSECTName of structure

Lateral line Ear Tympanum

Type of vibration detected

Pressure waves Sound waves Sound waves

How it works Mechanoreceptors with hair cells detect changes in water pressure causing an impulse to the brain. Bony fish detect vibrations through the skull to the hairs in an inner ear

Have an outer, middle and inner ear which collects and directs the sound waves from the air, converting it to vibrations, and then electrochemical energy which sends nervous impulses to the brain

The tympanum which is enclosed by a tympanic membrane (eardrum) receive vibrations from sound waves and send nerve impulses to the brain via the nerve fibres.

Similarity Receptors detect vibrationsNerve fibres send info to the brain

Differences Lateral line allows for information on changes in direction and speed of water movement Bony fish does not have a cochlea and has an internal ear

Ear provides information about changes in direction and pitch of sounds.Has an externally exposed cochlea and tympanic membrane

Tympanum provides information about changes in direction of sounds and certain pitch.Does not have a cochlea.Has an externally exposed tympanic membrane

6.2.2- Pinna (cartilage): Is external and produces earwax for the purpose of directing and collecting sound waves.- Tympanic membrane (membranous): The earwax allows it to be moist for flexibility, and the thin, solid and flexible

structure allows it to transmit sound- Ear ossicles (bone): consists of the hammer, anvil and stirrup which allow sound to be transmitted and amplified

- Oval Window (membrane): Is a covering between the middle and inner ear to transmit sound and hold fluid in the cochlea.

- Round window (membrane): Is at the base end of the lower canal of the cochlea to control pressure and transmit sound- Cochlea (membrane): Is snail shaped with three canals filled with fluid which allows for transmission, and the middle

canal contains the organ of corti.- Organ of Corti (membrane): The organ of corti converts mechanical energy (kinetic) into electrochemical energy. It does

this by its hair cells being stimulated to certain frequencies and sends the message through the nerve fiber that it is attached to.

- Auditory nerve (tissue): It is a collection of nerve cells that leads from the cochlea to the sense organ. It transmits energy to the brain.

6.2.3The role of the Eustachian tube is to equalize pressure on either side of the tympanic membrane by taking in air through the mouth.

6.2.4Auditory canal

SOUND TO KINETIC

Tympanic membrane (vibrations)

Hammer (vibrations)

Anvil (vibrations)

Stirrup (vibrations)

Oval window (vibrations)

Upper canal (vibrations)

Middle canal (vibrations)

Organ of corti converts MECHANICAL TO ELECTROCHEMICAL ENERGY

Lower canal (vibrations)

Round window

6.2.5In the basilar membrane are hairs of different lengths which vibrate at a different frequency. The hairs are aligned in the basilar membrane from those stimulated at high frequencies, to those stimulated at low frequencies (shortest to longest) from the base to the apex. This determines the pitch, although the volume is detected by the amplitude of the sound wave, which influences the amount of bending of the hair cells and the amount of nerve impulses generated in the neurons. There are 15500 receptor cells, where 90% of the nerve fibres service the much less numerous inner hair cells.

6.2.6The obstruction or absorption of a sound wave by an object is called a sonic or sound shadow. As humans are binaural (two ears) the head placed between it creates a sound shadow for the ear on the opposing side to the source. Because of this, sound is received less than a split second apart, creating the perception of source location. This is used by visually impaired people.

6.3.2Humans can detect frequencies from 20Hz-20000Hz, being most sensitive between roughly 2000-4000Hz which corresponds with the pitch of speech.

The kangaroo is nocturnal and therefore relies heavily on sound. It detects a higher range of frequencies, roughly between 0.03kHz to about 50kHz, which is used to detect their predators who communicate at low frequencies.

External

Middle

Inner ear

Dolphins have an even broader range. This is attributed towards the lower frequencies in water and the higher frequencies when surfacing, the decrease in visual capabilities and for echolocation.

These variations are derived from evolutionary adaptive requirements.

6.3.3HEARING AID COCHLEAR IMPLANT

Description - Artificial hearing device- Battery operated- Single component (microphone,

amplifier, earphone)- Amplifies vibrations for natural

stimulation- Uses normal auditory pathway- Detects less sound than cochlear

implant

- Artificial hearing device- Battery operated- 3 components (implant receiver,

speech processor, headset)- Electrically stimulates nerves- Bypasses normal auditory pathway- Detects more sound than hearing aid

Positioning Sits inside the pinna and ear canal Receiver package and electron array are implanted in inner earHeadset and speech processor are worn externally

Conditions Ruptured tympanic membrane or damaged ossicles

Damaged hair cells in the cochleaFor def people

Energy transfer Sound waves are picked up by the microphone, magnified by the amplifier and channeled into the regular auditory pathway

Sound waves are detected by the microphone, converted into electrical code and then is transferred into electrical impulses which stimulate the cochlea nerves. Electrochemical messages are sent to the brain

Limitations Background noise is a problemDistance is limited to less than 3 metresDoes not assist for inner ear problems

Requires potentially dangerous surgeryVisibleExpensive with ongoing costsNeeds to be adjusted for different situationsDistance is limited

Implications Allows for improved hearingIs quit easy to inputNormal life can occur

Can allow for speechAllows individuals to participate in hearing dependant eventsIs quite obstructive

7.2.1A nerve is a bundle of Neuronal fibres

7.2.2Neurones are nerve cells that consist of dendrites that lead to a cell body, then an axon which are surrounded by myelin sheath (not in interneurones) and branch out into axon branches. They are transmitters of signals by electro-chemical changes in their membranes

7.2.3Threshold is the amount of positive change in electrochemical potential change that must occur to cause an action potential. Stimuli cause a change in electrical charge through the axon. The greater the stimuli that is detected, the greater the change in electrical charge. Potassium ions exist inside the axon, with little amounts outside with sodium ions. Because of this, there is a greater positive charge outside the axon, leaving the electrochemical potential charge inside the axon at -70mV. When a stimuli is detected, active transport uses ATP to allow the membrane to become permeable to sodium ions at the node of Ranvier. This process is called depolarization, where there is a reversal in membrane potential, resulting in action potential. In order for a stimulus to generate action potential, it must reach a change in electrochemical potential of 15mV.

7.2.4

The components of the cerebrum that are involved in the perception and interpretation of light and sound are the medulla oblongata, the cerebellum the occipital lobe which contains the visual section of the cerebrum, and the temporal lobe which contains the auditory section of the cerebrum

7.2.5The correct interpretation of sensory signals by the brain for the coordination of animal behaviour is important generally to facilitate behavioural responses in survival. An example is the migration patterns that rely on detecting changes in the environment and recalling mental pictures or maps in the brain. Another example is detecting a visual signal of a predator and being able to remove itself from the danger.

7.3.1We observed slides to identify the structure of a neurone. They have a collection of dendrites that lead to a cell body which then attaches to a very thin, long axon. These axons are surrounded by myelin sheath, except for the interneurones, and branch out into axon branches.

7.3.2We used a scalpel and therefore had several safety requirements when dissecting a brain. We looked at the ventral surface and identified the cerebellum and medulla oblongata. We then identified the region at the back on the occipital lobe as the area that detects visual signals, the temporal lobe in the middle which detected auditory signals, and the area at the front and back which causes speech.

7.3.3We looked images which showed action potential, where sodium ions were represented with black dots, and potassium ions were represented with white dots. Sodium entered at the node of Ranvier.