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2009 6 th IJSO BIOLOGY
Responding Part 1
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Notes to Teachers:
The five senses the meaning of the terms stimuli and respond (0.25 hr) The eye mechanism of vision: function of rods and cones, color vision (0.5 hr) The ear the structure of the ear, the mechanism of hearing: the role of the organ of Corti, investigation on senses (0.75 hr) The sensory functions of skin (0.5 hr) The structure and functions of different types of neurone (0.5 hr) Nerve impulse generation and transmission of nerve impulse, the role of sodium and potassium ions, production of resting and action potentials, allor nothing nature of the action potential, concept of threshold (1.5 hrs) Central nervous system the organization of the nervous system into the central and the peripheral nervous system, structure and functions of human brain, spinal cord, and medulla (2 hrs) Autonomic nervous systems the control of involuntary activities by the sympathetic and parasympathetic nervous systems with reference to their antagonistic actions (1 hr) Reflex action and voluntary actions (0.25 hr) How muscles move (0.25 hr)
Learning Objectives:
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Learning Outcomes
describe the various senses in our body define the terms stimulus and respond explain the roles of various parts of eyes in detecting light state and compare the functions of rods and cones explain the roles of various parts of ear in hearing perform investigation on senses e.g. sensitivity of skin of different body parts, hearing range of different ages explain the sensory functions of skin state the structure and functions of the neurons state the nature of nerve impulse describe the mechanism of generation and conduction of nerve impulse. describe the mechanism of synaptic transmission aware the complex organization of the nervous system
After studying this topic students should be able to:
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Learning Outcomes (cont’d)
identify the various parts of the human brain and spinal cord state the functions of various parts of the central nervous system state the role of the autonomous nervous system explain the functioning of a spinal reflex and the types of neurons involved state the significance of reflexes cite examples of reflex action, conditional reflex and voluntary action and outline their importance in everyday life describe the role of joints and muscles in locomotion use the slidingfilament hypothesis to explain muscle contraction investigate how fast our muscles react
After studying this topic students should be able to:
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Responding Contents Understanding of how our bodies’ senses help us respond to our environment Describe the various senses in our body Define the terms stimulus and respond and how they relate Describe how nerves carry messages Explain how muscles move arms and legs Investigate the senses Investigate how fast our muscles react
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Case study: A boy is reading …..
@#$^*??
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Some terms 1. Stimuli 2. Responses 3. Receptors 4. Sense organs 5. Effectors 6. Coordination
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A. The process of coordination
Stimuli à receptors nervous system effectors > response
endocrine system
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Sense, stimulus, receptor and sense organ
Sense Stimulus Energy Receptor Sense organ
1.sight Light Electromagnetic Photoreceptor Eye
2.Hearing Sound Mechanical deformation
Mechanoreceptor Ear
3.Taste Chemical in food
Chemical Chemoreceptor Taste bud
4.Touch Touch, pain..
Mechanical deformation
Mechanoreceptor, chemoreceptor
Skin
5.Smell Chemical in air
chemical chemoreceptor nose 9
Skin – touch receptor, thermoreceptor (heat, cold receptor), pain receptor, pressure receptor
Epidermis B. Dermis C. Subcutis/Hypodermis D. Blood and Lymph Vessels E. Stratum Germinativum
1.Hair Shaft 2.Stratum Corneum 3.Pigment Layer 4.Stratum Spinosum 5.Stratum Basale 6.Arrector Pili Muscle 7.Sebaceous Gland 8.Hair Follicle 9.Papilla of Hair 10.Nerve Fiber 11.Sweat Gland 12.Pacinian Corpuscle 13.Artery 14.Vein 15.Sensory Nerve ending (for touch) 16.Dermal Papillary 17.Sweat Pore 18.Acidic Fluids/> Wikipedia file 10
Eye
pupil
iris
Wikipedia file 11
Eye
Wikipedia file 12
Wikipedia file
Rods and cones in retina
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photochemical reaction
Under light, retinene undergoes isomeric change, rhodopsin breaks down to scotopsin and retinene (both colourless)
à Bleaching of visual pigments à nerve impulse
Light
Rhodopsin Scotopsin + retinene (colourless)
(purple) Dark
Nerve impulse
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Differences between rods and cones Rods Cones Periphery of retina Concentrated at centre
Large number in yellow spot
High visual sensitivity
Low
Low visual acuity High detect dim light night vision cannot detect colour
only detect strong light day vision detect colour
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Each cone synapses with only one bipolar neurone à low visual sensitivity / tightly packedà high visual acuity
Many rod synapses with one bipolar neurone à high visual sensitivity / less tightly packedà low visual acuity
Wikipedia file
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trichromatic theory of colour vision Sensation of any given colour is determined by the relative frequency of impulses reaching the brain from each type of cone stimulate both green and red cones à yellow
Colour blindness Redgreen colour blindness
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Ishihara test charts
Wikipedia file
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Accommodation – near / distant objects
Wikipedia file
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Pupil reflex
Wikipedia file
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Short sight and its correction
Wikipedia file
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Long sight and its correction
Wikipedia file 22
Ear
Wikipedia file
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Organ of corti – sensory hair cell
Wikipedia file
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Wikipedia file
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Mechanism of hearing
Wikipedia file 26
Mechanism of hearing pinna collects sound waves eardrum is set into vibrations ear ossicles amplify the vibration vibrations of oval window set the fluid in inner ear into motion pressure waves in fluid set the basilar membrane into vibrations. hairs of sensory hair cells in the Organ of Corti to brush against the tectorial membrane hairs bend and this shearing force causes the excitation of sensory hair cells excites the auditory nerve (the auditory part of VIII th cranial nerve) and initiates action potential. The auditory nerve conducts the action potential to auditory cortex of cerebrum where the pitch, quality and loudness of the sound are detected. 27
taste buds chemoreceptors
Wikipedia file
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Chemoreceptors in nose
Wikipedia file
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Distribution of taste buds sensitive to different tastes
1 . Bitter 2. Sour 3. Salty 4. Sweet
Wikipedia file
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6 th IJSO BIOLOGY PART 1.2 Nerves Function of nervous system
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Chasing by a dog
Stimulus Light
Receptor Photoreceptors
Coordinating system ??
Effector ??
Response Skeletal muscles contract àRunning
Wikipedia file
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Human nervous system
Wikipedia file
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Mammalian nervous system
Wikipedia file
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Mammalian nervous system
Central nervous system Peripheral nervous system Autonomic nervous system
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Neuron(e)神經元
Wikipedia file 36
Neuron(e)神經元
Wikipedia file 37
Structure of a neurone
1.Cell body – controls cellular activities found in grey matter (灰質) 2.Nerve fibre – in white matter(白質) dendrons 樹突 axon軸突 myelin sheath surrounded by Schwann cell plasma membrane, for insulation and increase the rate of conduction of nerve impulse
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Myelinated VS unmyelinated nerve fibre
Wikipedia file
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3 types of neurones Motor neurone
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Sensory neurone – olfactory sensory neurone
Wikipedia file
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Nerves – sensory/motor/mixed
Wikipedia file
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Nerve
Wikipedia file
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Spinal cord
Wikipedia file
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Wikipedia file
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Wikipedia file
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Wikipedia file
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Functions of spinal cord
1. relays these sensory impulses to the brain 2. relay the motor impulses from the brain to the limb muscles (e.g. leg muscles) via the spinal nerves to effect coordinated movement and to keep body in equilibrium posture. 3. a passage for nerve fibres to allow the 2way conduction of nerve impulses to and
from the brain and the limb muscles (e.g. leg muscles). 4. The spinal cord is the site for control of somatic reflexes (e.g. withdrawal reflex) which are involuntary actions.
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Brain
Wikipedia file
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Wikipedia file
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White matter and grey matter
Wikipedia file
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Function of brain forebrain, midbrain / brain stem (腦幹) and hindbrain
forebrain cerebrum, thalamus (丘腦) and hypothalamus (下丘腦)
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Cerebrum (大腦) cerebral cortex – frontal, parietal, temporal and occipital lobe Grey matter on outer surface, white matter inner surface Cerebral cortex is highly folded to increase the surface area for holding more neurones for more complicated coordination.
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Functional area of cerebrum Functional area
Functions
Sensory centre
receives sensory impulse from various receptors of sense organs and produce sensation e.g. skin sensation (pain / pressure…), vision, audition, vestibular sensation (movement of head), taste and olfaction.
Association centre
site for other integrative functions e.g. emotion, language, learning, memory, planning, judgment, motivation, intelligence, etc.
processes impulses from the sensory cortex, medulla or cerebellum and relay them to the motor centre in the cerebral cortex.
Motor centre It sends motor impulse to the skeletal muscles of hands or legs to initiate voluntary movement and other skeletal muscles to maintain balance.
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Hypothalamus osmoregulation, temperature regulation, lactation and controlling the activities of other endocrine glands.
Midbrain – controls cranial reflexes (腦反射) e.g. pupil reflex
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Hindbrain – cerebellum (小腦) (1) It receives impulses from semicircular canals, utriculus and sacculus about the position of head.
from the proprioceptors (stretch receptors) in muscles, tendons and joints about the muscular movement
from motor centre of cerebral cortex. (2) After processing the information received, the
cerebellum coordinate the muscular activities to perform precise body movements. coordinates reflexes in the body to maintain equilibrium.
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Hindbrain – medulla oblongata (延腦) (1) cardiovascular centre controls cardiovascular function e.g. heart beat rate respiratory centre controls respiratory function e.g. ventilation rate vasomotor centre controls vasomotor function e.g. blood pressure
(2) It is also the control centre for many involuntary actions e.g. swallowing, sneezing, coughing, blinking of eyes.
(3) It helps to maintain the equilibrium state of the body.
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Brain damage What body functions would be affected if
brain damage occurred in: (i) the occipital lobe (ii) the cerebellum (iii) the medulla oblongata?
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Reflex action Quick, inborn, automatic, stereotypic Spinal cord / medulla / midbrain Significance: 1. Homeostatis 2. prevent body from damage 3. Conduct body function 4. Conditioned reflex
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Reflex VS voluntary action
Reflex actions Voluntary actions
1. Inborn / need not learn Not inborn / can be learned 2.Usually faster Usually slower 3.Stereotyped response Different responses 4.Control centre is in medulla Control centre is in cerebrum or spinal cord 5.A receptor is involved A receptor may not
be involved / may be initiated spontaneously.
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Pain receptor in skin à sensory neurone à interneurone à motor neurone à biceps contracts, withdraw the hand
Withdraw reflex
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(ii) this reflex is automatic / not involve the cerebrum until after the event.
Interneurone to brain can transmit sensory impulse to the sensory area of cerebrum where the sensation of pain is produced.
Withdrawal of the stimulated hand occurs before sensation of pain is experienced. WHY?
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(ii) this reflex is automatic / not involve the cerebrum until after the event.
Interneurone to brain can transmit sensory impulse to the sensory area of cerebrum where the sensation of pain is produced.
Withdrawal of the stimulated hand occurs before sensation of pain is experienced. WHY?
It takes a shorter time for the impulses transferred to the effector (biceps) than to the cerebrum. It is the cerebrum that gives the sensation of pain.
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stretch receptor in patellar tendonà sensory neuroneà motor neuroneà extensor muscle contracts, leg jerk forward
Knee jerk reflex
Wikipedia file
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Conditioned reflex (條件反射) Pavlov Smell of food >
(natural stimulus)
salivation (natural reflex)
Bell sound >
(conditioned stimulus)
Salivation (conditioned reflex)
Wikipedia file 65
Conditioned reflex VS voluntary actions Conditioned reflex actions Voluntary actions
1. A stimulus is necessary A stimulus may not be for producing response necessary
2.Usually faster Usually slower 3.Stereotyped different responses
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