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Transcript Powerpoint

2009 6

IJSO BIOLOGY Responding Part 1

Notes to Teachers:

Learning Objectives: 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, all-or 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) 2

Learning Outcomes

After studying this topic students should be able to: 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 3

Learning Outcomes (cont’d)

After studying this topic students should be able to: 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 sliding-filament hypothesis to explain muscle contraction investigate how fast our muscles react 4

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 5

Case study: A boy is reading ….

.

@#$^*??

Some terms 1. Stimuli 2. Responses 3. Receptors 4. Sense organs 5. Effectors 6. Coordination

A. The process of coordination

Stimuli  receptors nervous system effectors ->

response

endocrine system 8

Sense, stimulus, receptor and sense organ

Sense Stimulus Energy Receptor Sense organ Electromagnetic 1.sight

Light Photoreceptor Eye Mechanoreceptor Ear 2 .Hearing

3.Taste

4.Touch

Sound Touch, pain..

Mechanical deformation Chemical in food Chemical Mechanical deformation 5.Smell

Chemical in air chemical Chemoreceptor Mechanoreceptor, chemoreceptor Taste bud Skin chemoreceptor nose

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

Rods and cones in retina Wikipedia file 13

photochemical reaction

Light Rhodopsin Scotopsin + retinene (colourless) (purple) Dark Nerve impulse Under light, retinene undergoes isomeric change, rhodopsin breaks down to scotopsin and retinene (both colourless)  

Bleaching of visual pigments nerve impulse

Differences between rods and cones

Rods Cones Periphery of retina Concentrated at centre High visual sensitivity Low visual acuity Large number in yellow spot Low High -detect dim light -night vision

cannot detect colour

only detect strong light

day vision

detect colour

Wikipedia file

Each cone synapses with only one bipolar neurone



sensitivity / tightly packed



high visual acuity low visual Many rod synapses with one bipolar neurone sensitivity / less tightly packed

 

high visual low visual acuity

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  yellow green and red cones -Colour blindness -Red-green colour blindness 17

Ishihara test charts

Wikipedia file 18

Accommodation – n

ear / distant objects

Wikipedia file 19

Pupil reflex

Wikipedia file 20

Short sight and its correction

Wikipedia file 21

Long sight and its correction

Wikipedia file 22

Ear

Wikipedia file 23

Organ of corti – sensory hair cell

Wikipedia file 24

Wikipedia file 25

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.

taste buds - chemoreceptors

Wikipedia file 28

Chemoreceptors in nose

Wikipedia file 29

Distribution of taste buds sensitive to different tastes

1 . Bitter 2. Sour 3. Salty 4. Sweet Wikipedia file 30

6 IJSO BIOLOGY PART 1.2

Nerves Function of nervous system

Chasing by a dog

Wikipedia file Stimulus Light Receptor Photoreceptors Coordinating system ??

Effector ??

Response Skeletal muscles contract  Running 32

Human nervous system

Wikipedia file 33

Mammalian nervous system

Wikipedia file 34

Mammalian nervous system

Central nervous system

Peripheral nervous system Autonomic nervous system

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 38

Myelinated VS unmyelinated nerve fibre Wikipedia file 39

3 types of neurones

Motor neurone 40

Sensory neurone – olfactory sensory neurone

Wikipedia file 41

Nerves – sensory/motor/mixed

Wikipedia file 42

Nerve

Wikipedia file 43

Spinal cord

Wikipedia file 44

Wikipedia file 45

Wikipedia file 46

Wikipedia file 47

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 2-way 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.

Brain

Wikipedia file 49

Wikipedia file 50

White matter and grey matter

Wikipedia file 51

Function of brain

forebrain, midbrain / brain stem (

腦幹

) and hindbrain forebrain

cerebrum , thalamus (

丘腦

) and hypothalamus (

下丘腦

)

Cerebrum (

大腦

)

cerebral cortex

and occipital lobe – frontal, parietal, temporal Grey matter on outer surface, white matter inner surface

Cerebral cortex is highly folded

increase the surface area for holding more neurones for more complicated coordination.

Functional area of cerebrum

Functions Functional area

Sensory centre Association 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.

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.

Hypothalamus -

osmoregulation

temperature regulation, lactation

and

controlling the activities of other endocrine glands

Midbrain – controls cranial reflexes ( 腦反射 ) e.g. pupil reflex 55

Hindbrain – cerebellum (

小腦

)

(1) It receives impulses - from semi-circular canals , utriculus and sacculus about the position of head.

- from the proprioceptors (stretch receptors) tendons and joints about the in muscles, 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.

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 blood pressure - controls vasomotor function e.g. (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 body.

of the

Brain damage

What body functions would be affected if brain damage occurred in: (i) the occipital lobe (ii) the cerebellum (iii) the medulla oblongata?

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 59

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.

Withdraw reflex

Pain receptor in skin  interneurone   sensory neurone motor neurone  biceps contracts, withdraw the hand 61

(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?

(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.

Knee jerk reflex

Wikipedia file stretch receptor in patellar tendon neurone  motor neurone  muscle contracts, leg jerk forward  sensory extensor 64

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 66