15.1 Irritability 15.2 The five senses 15.3 The eye 15.4 Structure and functions of the eye 15.5 The control of the amount of light entering the eye 15.6 The accommodation of the eye Mind Map 15 Detecting environmental conditions

15.1 Irritability Irritability

15.1 Irritability Irritability Ability senses our surroundings responds to surroundings

Body Lion is coming Part A Part B Running Part C 15.1 Irritability

Body Lion is coming Part A Stimulus Receptor Part B Central Nervous System (CNS) Running Response Nerve impulse Nerve Nerve impulse Part C Effector 15.1 Irritability

Stimuli Receptor CNS Effector Response

15.1 Irritability Receptor CNS Effector Nerve Response Stimuli

15.1 Irritability Stimuli Pressure, touch, pain, movement of air, heat, cold, light, sound, chemicals substances Blood pressure, water potential and CO 2 conc. in blood, tension in muscles A change in External environment Internal environment

15.1 Irritability Stimuli Receptor CNS Effector Nerve Response

produces Receptor Central Nervous System (CNS) Stimulus Nerve nerve impulses 1 2 Interpret as sensation stimulates Receptors 15.1 Irritability

Receptors Detect stimuli produce nerve impulses Irritability Stimulus

15.1 Irritability StimulusSensation LightSightSoundHearingChemicals in airSmellChemicals in foodTaste Change in temp. Touch Pressure Pain Heat or cold Texture Pressure Pain

15.1 Irritability Stimuli Receptor CNS Effector Nerve Response

15.1 Irritability Effector Response Muscle 1 Gland 2 Muscle contraction Secretion

Innate 15.1 Irritability Behaviour Lower animals Same stimulus with different responses Modified by learning Higher animals

15.2 The five senses Five senses

15.2 The five senses Hearing Smell Sight Touch Taste Touch

15.2 The five senses Touch Skin What kinds of receptor are found in the skin? Pain receptor Touch receptor Cold receptor Heat receptor Pressure receptor

Touch Skin 15.2 The five senses Distribution of receptors Uneven Even

15.2 The five senses Hearing Smell Sight Touch Taste

15.2 The five senses Taste Tongue Taste bud

Taste Epithelium Soluble chemicals in food Gives the sensation of taste 15.2 The five senses Brain

15.2 The five senses Four basic taste sensations Sourness Saltiness Sweetness Bitterness Taste

15.2 The five senses Hearing Smell Sight Touch Taste Smell

15.2 The five senses Smell Nose Nasal cavityUpper epithelium

15.2 The five senses Nasal cavityUpper epithelium Mucus Smell

15.2 The five senses Smell Air Soluble chemicals in gas Smell receptor Gives sensation of smell Brain Mucus

15.2 The five senses Detects soluble chemicals Nose Tongue Stimulates appetite 1 Detects harmful substances 2 Initiates secretion of digestive juices 3 Sense Smell Taste Flavour of food

15.2 The five senses Hearing Smell Sight Touch Taste Hearing

15.2 The five senses Ear Hearing Outer Ear Middle Ear Inner Ear

15.2 The five senses Pinna Auditory canal Eardrum Air vibration Pinna collects the sound wave Passes along auditory canal Strikes on the eardrum Result Eardrum vibrates Hearing

15.2 The five senses Eardrum Ear bones Oval window Vibration of ear bones Transmittion of vibration Oval window Hearing

15.2 The five senses Oval window Cochlea Auditory nerve Vibration of fluid in cochlea Sensory hair cells are stimulated Nerve impulses are produced Auditory nerve transmits impulses Hearing

15.3 The eye The Eye

15.3 The eye Eye muscles Skull Optic nerve Tear gland Eye ball

Skull For protection 15.3 The eye

the eye can be rotated Contract or relax 15.3 The eye Eye muscles

15.3 The eye Transmits impulses to the brain Optic nerve

15.3 The eye Tear gland Keep the eyes moist Kill germs Tears

15.4 Structure and functions of the eye Structure & functions of

15.4 Structure and functions of the eye Wall of eyeball

15.4 Structure and functions of the eye ScleraChoroidRetina Three layers in the wall of eyeball

15.4 Structure and functions of the eye Sclera For muscle attachment 3 Tough Protection Keeping the shape of eyeball 1 2

15.4 Structure and functions of the eye Choroid Internal reflection of light

15.4 Structure and functions of the eye Internal reflection of light Black pigmentAbsorbs lightChoroid

15.4 Structure and functions of the eye Contains blood vessels Choroid Supply nutrients and oxygen to the eyeball

15.4 Structure and functions of the eye Walls of eyeball

15.4 Structure and functions of the eye Cornea Conjunctiva protects

15.4 Structure and functions of the eye Light Cornea Allows light to pass transparent 1 Refraction of light curved 2

15.4 Structure and functions of the eye

Cornea is continuous with Sclera

15.4 Structure and functions of the eye Lens Suspensory ligament Ciliary muscle

15.4 Structure and functions of the eye Lens For focusing

15.4 Structure and functions of the eye Ciliary muscle Contracts Or Relaxes Change the tension of suspensory ligaments Change the thickness of the lens For focusing

15.4 Structure and functions of the eye Controls the size of pupil Controls the amount of light entering the eye Pupil Iris

15.4 Structure and functions of the eye Aqueous humour Vitreous humour Help in refracting light 1 Maintain the shape of the eyeball 2 Diffusion of food and oxygen to the lens and the cornea 3

15.4 Structure and functions of the eye Retina

15.4 Structure and functions of the eye Sclera Choroid Retina

15.4 Structure and functions of the eye Light-sensitive cells Sclera Light Cone Rod Optic nerve Retina Choroid

15.4 Structure and functions of the eye Cone How do you perceive the colours? Three types of cones: blue cones red cones green cones

15.4 Structure and functions of the eye Cone How do you perceive the colours? blue cones If blue light strikes on, blue colour can be perceived. It is the same for red cones and green cones

15.4 Structure and functions of the eye How do you perceive the colours? Red cone Blue coneGreen cone - +- Blue - -+ Green + -- Red + ++ White - -- Black All colours in between are produced by stimulation of various combinations of the different types of cones

15.4 Structure and functions of the eye Rod It is sensitive to light of low intensity for dim light vision

15.4 Structure and functions of the eye Yellow spot Blind spot

15.4 Structure and functions of the eye Clearest image detection with greatest colour discrimination No rods present The density of cones is the highest in the yellow spot Yellow spot

15.4 Structure and functions of the eye No image can be detected A point that optic nerve leaves the eyeball No photoreceptors Blind spot

15.4 Structure and functions of the eye Rod contains visual purple for dim light vision Night blindness Difficult to see in the dark No visual purple formation Not enough vitamin A in diet

15.4 Structure and functions of the eye Image formation and eye accommodation

15.4 Structure and functions of the eye Light rays reflected from an object pass through cornea, aqueous humour, lens and vitreous humour

15.4 Structure and functions of the eye Image Image formed is real, upside down and smaller than the object

15.4 Structure and functions of the eye Nerve impulses are produced Image is detected by rods & cones on retina Image

15.4 Structure and functions of the eye Image cerebrum Vision is produced Impulses pass along the optic nerve to the cerebrum for interpretation

Experiment 15.1 To dissect and examine an ox’s eye 1. Obtain an ox’s eye from a butcher. 2. Examine the eye muscles and the optic nerve. 3. Remove the fat from the back of the eye Structure and functions of the eye

4. Cut through the cornea at right angles. Pick up the flaps of the cornea and examine the iris Structure and functions of the eye Experiment 15.1 To dissect and examine an ox’s eye

5. Cut through the iris and into the sclera to about half-way around the walls of the eye. Examine the inner parts of the eye Structure and functions of the eye Experiment 15.1 To dissect and examine an ox’s eye

6. Remove the lens. Place it on a piece of paper. Observe the words underneath. Then press the lens to feel its elasticity and observe the words through the lens again. What changes do you observe? 15.4 Structure and functions of the eye Experiment 15.1 To dissect and examine an ox’s eye 7. Remove the vitreous humour. Identify the blind spot.

15.5 The control of the amount of light entering the eye

Iris Pupil Radial muscles Circular muscles

15.5 The control of the amount of light entering the eye Prevents photoreceptors on retina from being over-stimulated Under bright light The size of pupil becomes smaller Circular muscles contract and radial muscles relax

15.5 The control of the amount of light entering the eye Allows more light to pass through the lens to form a clearer image Under dim light The size of pupil becomes larger Circular muscles relax and radial muscles contract

15.6 The accommodation of the eye

A B Lens Focal length Compare the two figures In figure A, * Thicker lens * Shorter focal length

15.6 The accommodation of the eye The ability of the eye to adjust the thickness of the lens for viewing near & distant objects is called accommodation

15.6 The accommodation of the eye Near object 1. Ciliary muscles contract 2. The tension of suspensory ligament is reduced 3. Lens becomes thicker

15.6 The accommodation of the eye Distant object 1. Ciliary muscles relax 2. The tension of suspensory ligament is increased 3. Lens becomes thinner

15.6 The accommodation of the eye Summary Near object Distant object Ciliary muscles Contract Relax Suspensory ligaments Tension decreases Tension increases Lens Thicker Thinner

15.6 The accommodation of the eye

Near or Far object ? Distant object because the image cannot be focused onto the retina but not clear Short sight 15.6 The accommodation of the eye

Wearing concave lens Correction Short sight 15.6 The accommodation of the eye

cannot see the near object clearly Wearing convex lens Correction Near object Long Sight 15.6 The accommodation of the eye

It is a hereditary disease Common type is red-green colour blindness certain colours may not be distinguished If a certain type of cone is missing, 15.6 The accommodation of the eye

Mind Map Detecting of environmental conditions is called change in external or internal environment is called detected by nerve impulses sent to to produce mainly by include sense organ structures include for consists of common eye defects irritability stimulus receptors brain or spinal cord effectors include muscles and glands response five senses hearingtastesightsmelltouch eartongueeyenoseskin 1. aqueous humour 2. vitreous humour 3. retina 4. optic nerve 5. sclera 6. cornea 7. choroid 8. lens 9. iris 10. pupil 1. circular muscles 2. radial muscles controlling the size of pupil 1. long sight 2. short sight 3. colour blindness examples