science chapter 2 form 4

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BODY COORDINATION
Process by which different parts of the body work together to bring about the correct
response

2. EXAMPLE :
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Detect the stimulus Carry out the response
Changes detected are called
STIMULI
Eg : light , heat , sound , pressure , touch
, chemicals

3. Body coordination is important because:
(a) It enables our body to respond to changes in our surroundings.
(b) It regulates appropriate responses to these changes.
(c) It protects our body from injuries.
ACTIVITY 
Q1 : Figure 2.3 shows a boy accidentally hammering his
hand
(a) What is the stimulus in this reaction?
(b) What is the response?
(c) Which part of the body coordinates this action?
Q2 : Figure 2.4 shows a boy being chased by a dog.
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4. (a) What is the stimulus in the diagram given above ?
(b) What is the response?
(c) Which part of the body coordinates this action?
Q3 : Walking is an activity that all of us carry out everyday.
(a) Name the systems that control and regulate this activity.
(b) Explain how the systems you named in 3(a) help to control and regulate this
activity.
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HUMAN NERVOUS SYSTEM

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6. MIND MAP : HUMAN NERVOUS SYSTEM
MIND MAP : NEURONE
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7. COMPARISON BETWEEN THE DIFFERENT TYPES OF NEURONES
ACTIVITY 
Q1 . (a) Name the components of the central nervous system.
(b) Name the components of the peripheral nervous system.
(c) To which system do the spinal nerves and the cranial nerves belong to?
Q2. (a) What is the smallest functional unit in the nervous system?
(b) Draw a labelled diagram of that functional unit.
Q3. (a) Name the three types of neurones present in our nervous system.
(b) What is the function of each type of neurone named in 3(a)?
Aspect Sensory neurone Relay neurone Motor neurone
Axon Short Short Long
Dendron Long Short Short
Cell body In the middle of the
neurone, in the dorsal
ganglion
In the middle of the
neurone
At one end of the neurone,
in the grey matter of the
spinal cord
Function To transmit impulses from
the receptors to the central
nervous system
To transmit impulses from
the sensory neurones to
motor neurones
To transmit impulses from
the central nervous system
to the effectors
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8. REFLEX ACTION
• An automatic and rapid response to a stimulus that does not involve the brain
• Controlled by the spinal cord
• Function : To avoid or protect us from serious injuries
Example of reflex action
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9. Activity
Q1.
Which of the following is the correct pathway of body coordination?
A Skin  Stimulus  Brain  Response  Muscle
B Skin  Stimulus  Response  Brain -> Muscle
C Stimulus  Skin  Brain  Muscle  Response
D Stimulus  Brain  Skin  Muscle  Response
Q2.
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10. Q3 (a) What is a receptor?
(b) Give two examples of receptors.
Q4 (a) What is an effector?
(b) Give two examples of effectors.
Q5 Draw a diagram to show the path taken by an impulse in a reflex arc.
Q6 (a) What is a reflex action?
(b) Give two examples of reflex actions.
PROPRIOCEPTORS - sensors that provide information about joint
angle, muscle length, and muscle tension
• Receptors that are connected to sensory neurons
• Respond to stimuli that related to position and movement of the body
• Found in : muscles , tendons , ligaments and joints
• Function : Help to coordinate muscular activites and maintain body balance and posture
• Examples : buttoning shirt , climbing a ladder , tying shoe lace, locking the door
( without looking )
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12. ACTIVITY
Q1 (a) What are proprioceptors?
(b) Name two places in the body where they can be found.
Q2 Explain how impulses from the proprioceptors are transmitted.
Q3 (a) What is the importance of proprioceptors?
(b) Name two occasions when it is very important for a person to keep his balance
The human brain
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13. Differences between voluntary and involuntary actions
Aspect Voluntary Involuntary
Awareness We are aware of the actions We are not aware of the actions
Control Action can be controlled Action cannot be controlled
Controlled by Controlled by the somatic nervous system
Controlled by the autonomic nervous
system
Stimuli
Receives stimuli from the external
environment through the sensory organs
Receives stimuli from the internal
organs
Examples • Writing
• Dancing
• Constriction of the pupil
• Beating of the heart
ACTIVITY
Q1 The diagram shows a human brain.
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14. Name the parts labelled X, Y and Z and list their functions.
Q2 (a) What is an involuntary action?
(b) Give one example of an involuntary action.
(c) State three differences between involuntary and voluntary actions.
Q3 Name five possible effects due to injury to the brain.
Endocrine system
• Consists of endocrine gland
• gland without ducts which secrete hormones directly into the bloodstream
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15. Endocrine system
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17. COMPARISON BETWEEN THE NERVOUS SYSTEM AND ENDOCRINE SYSTEM
Hormones
Functions of hormones
Effects of excessive
hormones
Effects of deficiency of
hormones
Growth hormone
(from the
Pituitary gland
• Controls the qrowth of muscles and
bones
• Stimulates the activities of other
endocrine qlands
• Controls the reabsorption of water
• Gigantism in
childhood
• Acromegaly in
adults
• Dwarfism
Thyroxin (from
the thyroid gland)
• Controls the metabolism of the body
• Ensure normal physical and mental
development
• Goitre – swelling
the thyroid gland
• cretinism: Stunted
physical and mental
development
Insulin (from the
pancreas)
• Controls the level of qlucose in the
blood
• hypoglycaemia
-Low blood glucose
level
• Diabetes mellitus
-High blood glucose
level
Adrenaline (from
the adrenal
glands)
• Prepares the body for action in an
emerqency
• Extreme tiredness -
Oestrogen (from
the ovaries)
• Stimulates the development of
female secondary sexual
characteristics
• Excessive female
characteristics and
early puberty
• Deters the
development of female
secondary sexual
characteristics
Progesterone
(from the ovaries)
• Controls the menstrual cycle • Failure in delivery at
the correct time
Menstrual problems
Abortion of embryo
Testosterone
(from the testis
glands)
• Controls the development of
male sex orqans
• Produces sperms
• Stimulates the development of
male secondary sexual
characteristics
• Excessive male
characteristics and
early puberty
• Deters the
development of male
secondary sexual
characteristics
• Reduced sperm
production
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NERVOUS
SYSTEM
ENDOCRINE
SYSTEM
SIMILARITIES
• Control and coordinate activites in body
• Perform appropriate reactions when being stimulated
DIFFERENCES
COMPONENTCOMPONENT

18. ACTIVITY
Q1 Identify the following hormones:
(a) The hormone that prepares the body for emergency
(b) The hormone that reduces the amount of glucose in the blood
(c) The hormone that controls the metabolic rate of the body
(d) The hormone that controls the formation of male secondary sexual characteristics
(e) The hormone that controls the menstrual cycle
Q2 State the function of a hormone produced by:
(a) The thyroid gland
(b) The ovary
(c) The pancreas
Q3 Name the diseases caused by:
(a) Insufficient insulin
(b) Excessive thyroxine
(c) Insufficient growth hormones
COORDINATION BETWEEN THE NERVOUS SYSTEM AND THE ENDOCRINE SYSTEM
IN EMERGENCY SITUATIONS
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FORM OF IMPULSEFORM OF IMPULSE
TARGET AREATARGET AREA
SPEED OF IMPULSESPEED OF IMPULSE
EFFECTIVE PERIODEFFECTIVE PERIOD

19. EFFECT PF DRUG ABUSE ON BODY COORDINATION
Drug abuse : Taking of drugs in high or excessive dosage for non-medical purposes
Groups of drugs Examples
The effects on body coordination and the nervous
system
Stimulants
• Caffeine
• Cocaine
• Nicotine
• Amphetamines
• Increase the rate of metabolism
• Activate the nervous system
• Make an individual more active
• Cause the same effect as adrenaline
Depressants • Heroin
• Cannabis Barbiturates
• Alcohol
• Reduce stress
• Calm the mind
• Slow down the flow of nerve impulses
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20. • Slow down responses to stimuli
• Make an individual feel sleepy and less
anxious
Anti-
depressants
• Morphine
• Opium
• Relieve pain
• Ease mental stress
• Induce sleep
Hallucinogens
• Cannabis
• Ecstasy
• Diethylamide lysergic acid (LSD)
• Cause imaginations
• Change the pathways of impulses in the brain
• Cause unpredictable behaviour
Inhalants • Petroleum
• Organic solvents
• chloroform
• Cause hallucinations
• blackouts
• Unconsciousness
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