The document provides information about coordination and response in humans. It discusses the nervous system and endocrine system. The nervous system uses electrical signals and neurons to trigger fast responses. The endocrine system uses hormones to trigger slower responses. Key hormones like insulin, adrenaline, testosterone and estrogen are discussed. Their roles, effects and sources are outlined. The differences between the nervous and endocrine systems are compared.

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INTERNATIONAL
GCSE
Biology (9-1)
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2. Co-ordination and response (Humans)
Learning objectives:
Be able to describe the differences between the hormonal and nervous responses.
Be able to understand the role of neurotransmitters at synapses.
Be able to describe the structure and functioning of a simple reflex arc.
Be able to describe the structure and function of the eye.
Be able to describe the role of the skin in temperature regulation.
Be able to understand the sources, roles and effects of the following hormones:
adrenaline, insulin, testosterone, progesterone, oestrogen, ADH, FSH and LH.
Starter:
1. Define the term homeostasis?
2. Describe how an organism responds to changes in the environment?
3. Explain how Auxin causes a plant to move towards a light source?

3. From the specification
Humans
2.86 describe how nervous and hormonal communication control responses and
understand the differences between the two systems
2.87 understand that the central nervous system consists of the brain and
spinal cord and is linked to sense organs by nerves
2.88 understand that stimulation of receptors in the sense organs sends
electrical impulses along nerves into and out of the central nervous system,
resulting in rapid responses
2.89 understand the role of neurotransmitters at synapses
2.90 describe the structure and functioning of a simple reflex arc illustrated by
the withdrawal of a finger from a hot object
2.91 describe the structure and function of the eye as a receptor
2.92 understand the function of the eye in focusing on near and distant objects,
and in responding to changes in light intensity
2.93 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.94 understand the sources, roles and effects of the following hormones:
adrenaline, insulin, testosterone, progesterone and oestrogen
2.95B understand the sources, roles and effects of the following
hormones: ADH, FSH and LH

4. The nervous system structure
Nervous system
Central nervous system Peripheral nervous system
Brain
Spinal
cord
Motor
neurons
Sensory
neurons

5. What do you think is the job of our
nervous system?
Enables humans to react to their surroundings and to
coordinate their behaviour.
Q-Can you give examples of
how humans may respond
to their surroundings?
Hint look at the picture.
A- Put on clothes when it is cold.

6. How is the nervous system is adapted to
carry out its function?
Information needs to be sent quickly and so your nervous system is
adapted to send information as electrical impulses via neurons.
Sensory neurons
Motor neurons
1) Use your textbook or the internet to label your
sensory and motor neuron.
2) State how they are different in their job and structure
Relay neurons

7. Axon
Fatty sheath/myelin sheath
Cell body
Axon terminal
Dendrites

8. 1) Electrical impulse travels down the axon.
2) When the electrical impulse reaches the axon terminal, neurotransmitters (chemicals involved in passing
nerve impulses from one neuron to the next) are released.
3) Neurotransmitters diffuse across the gap between neurons called a synapse where they bind to receptors
on the second neuron.
4) The receptor molecules on the second neuron can only bind to the specific neurotransmitters released from
the first neuron.
5) Once the neurotransmitters bind to the second neuron this triggers an electrical impulse in the second
Neuron.
Electrical impulse
Electrical impulse
Synapse
First neuron Second neuron

9. 6) Enzymes in the synaptic cleft quickly destroy
the neurotransmitter or the neurotransmitters are
taken up by re-uptake channels on the first
neuron. So its action are short lived.
First neuron Second neuron

10. Stimulus Receptor
Coordination
centre
Effector Response
A change
in the environment.
Detects the stimulus.
Includes the brain, spinal cord
and pancreas which receive and
processes information from
receptors.
Effectors include muscles and glands
That bring about responses.
Responding to changes in environment
Sensory neuron
Motor neuron

11. What is a reflex?
Are automatic and rapid; they do
not involve the conscious part of the
brain.
Q- Can you think of any examples?
Pupil reflex
Knee-jerk reflex

12. Stimulus Receptor
Coordination
centre
Effector Response
A change
in the environment.
Detects the stimulus.
Effectors include muscles and glands
That bring about responses.
Reflex
Sensory neuron
Motor neuron
Relay neuron
Message is
sent to the
brain but
bypasses the
conscious part
of the brain.

13. Sensory neuron
Motor neuron
Stimulus
Relay neuron
Effector muscle
Receptor
Message is sent to the brain but
by passes the conscious part of the brain Reflex arc

14. The effector muscle carries out a
response. In this case, its
movement away from the stimulus.

15. Exam-style question
Look at the picture describe how information is passed
from the sensory neuron to the relay neuron? (3 marks)
Sensory neuron
Relay neuron
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16. Exam-style question
Look at the picture describe how information is passed
from the sensory neuron to the relay neuron? (3 marks)
Sensory neuron
Relay neuron
Release of chemical from sensory neuron
chemical crosses synapse
Attaches to receptors on the relay neuron triggering
an electrical signal.

17. In addition to the nervous
system, we have a second
control system known as
the endocrine system, which
helps coordinate changes in our
body.
This system is made up
of glands/organs which
secrete chemical messengers
called hormones that carry out
their effects.

18. Hormone Transport
Hormones travel in the blood to
their target organ to produce
their effects.
Target organ contains receptors
on their cell membrane, where
the hormones bind to.
Note- Steroid hormones don’t work by binding to
membrane receptors.

19. Features of the endocrine system
• Slow acting
• Uses chemical messengers
called hormones
• Effects of the endocrine
system are long lasting
• Hormones travel in the blood
Q) Produce a table to compare the endocrine
system to the nervous system.

20. • Slow acting
• Uses chemical messengers called
hormones
• Effects of the endocrine system are
long lasting
• Hormones travel in the blood
• Fast acting
• Uses electrical signals/impulses
• Effects of the nervous system are
short lasting
• Electrical signals/impulses travel
via neurons
Endocrine system Nervous system

21. Key hormones to learn
Below is a list of key hormones, you need to remember where they
are produced, what are their effects and what is their role:
1) Adrenaline
2) Insulin
3) Testosterone
4) Progesterone
5) Oestrogen
6) ADH
7) FSH
8) LH
Paper 2 only

22. Adrenaline
Source: Adrenal gland
Role: Preparation for 'fight or flight' instinct.
Effects: Increases breathing rate, heart rate, flow of
blood to muscles, conversion of glycogen to glucose.

23. Insulin
Source: Pancreas
Role: Controlling blood glucose levels.
Effect: Increases conversion of glucose into
glycogen for storage.

24. Testosterone
Source: Testes
Role: Male
reproductive
hormone.
Effect:
Development of the
secondary sexual
characteristics.
Voice breaks
Testes start to
produce sperm
cells
Body becomes
more muscular
Underarm
hair grows
Pubic hair grows

25. Progesterone
Source: Ovaries
Role: Menstrual cycle
Effects: Stops FSH being produced (so that only
one egg matures in a cycle). Repairs, thickens and
maintains the uterus lining. Stimulates the pituitary
gland to release LH.

26. Oestrogen
Source: Ovaries
Role: Female reproductive
hormone.
Effects: Development of
the female secondary
sexual characteristic and
has a role ovulation.
Hips get wider
Breasts develop
Ovaries start to
release egg
cells -
menstruation
starts
Underarm
hair grows
Pubic hair
grows

27. Antidiuretic hormone (ADH)
Source: Pituitary gland
Role: Controlling the water content of the blood.
Effect: Increases reabsorption of water by the
collecting ducts.

28. Follicle stimulating hormone (FSH)
Source: Pituitary gland
Role: Menstrual cycle
Effects: Causes an egg to mature in an ovary.
Stimulates the ovaries to release oestrogen.

29. Luteinising hormone (LH)
Source: Pituitary gland
Role: Menstrual cycle
Effect: Triggers ovulation (the release of a mature
egg).

30. Exam-style question
What is a hormone? (1 mark)
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31. Exam-style question
What is a hormone? (1 mark)
- Chemical messenger
- Substance transported to / acting on a target organs

32. Exam-style question
How are hormones transported to their target organs?
(1 mark)
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33. Exam-style question
How are hormones transported to their target organs?
(1 mark)
- Bloodstream/ in the blood

34. Exam-style question
Describe how insulin changes blood glucose levels? (2
marks)
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35. Exam-style question
Describe how insulin changes blood glucose levels? (2
marks)
- Lowers blood glucose levels
- By allowing glucose to move (from blood) into (liver) cells
- Convert into glycogen

36. Exam-style question
Describe how the hormones FSH, oestrogen and LH are
involved in the control of the menstrual cycle? (3 marks)
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37. Exam-style question
Describe how the hormones FSH, oestrogen and LH are
involved in the control of the menstrual cycle? (3 marks)
- FSH stimulates oestrogen (production) / egg maturation
- Oestrogen inhibits FSH
- LH stimulates egg / ovulation

38. Cornea – refracts light, bending it
as it enters the eye.
Iris - controls the amount of light
that enters the eye.
Lens - focuses light onto the retina.
Retina – contain light receptors
which detect light.
Optic nerve - carries impulses from
the eye to the brain.
Sclera - tough and strong so the eye
ball is not damaged.

39. Journey of light
Light will pass through the eyeball
on its journey to the retina.
The cornea and the lens help bend
light so that it can be brought into
focus onto the retina.
This part of your eye is known as the blind spot, you don’t
know it’s there because your brain fills the gap. It’s called the
blind spot as there are no light receptors.

40. Activity 1 – Finding your blind
spot
1. To find your blind spot, take a piece of paper and
draw a small X on the right side.
2. Now, take your ruler and measure about 10 cm to
the left of the X.
3. Draw a dot there about the size of a penny.
4. Hold the paper in front of you and close your right
eye. Look at the X. Even though you're looking at
the X you should be able to see the dot out of the
corner of your eye.
5. Slowly move the paper in front of you. Try moving
it left and right or closer and farther away.
Remember to keep looking at the X. At a certain
point, the dot will seem to disappear out of the
corner of your eye.

41. Accommodation
Accommodation describes
the process by which the
lens changes shape to
focus on distant and close
objects.

42. Distant objects:
- Ciliary muscle relax;
- Suspensory ligaments pulled tight;
- Lens pulled flat.
Close objects:
- Ciliary muscle contract;
- Suspensory ligaments relax;
- Lens becomes thicker.
Ciliary muscleSuspensory ligaments
Lens

43. The pupil reflex
This reflex controls the amount of light entering the
eye; this is controlled by the radial and circular muscles
of the eye.
Dim light Bright light
Radial
muscles
contract
Circular muscles
relax
Pupil dilates
Radial
muscles
contract
Circular
muscles
contract
Pupil contract

44. Temperature regulation
Skin surface
When your body temperature is above the normal range, this is detected by the thermoregulatory
centre in the brain. As a result, blood flow is increased in the capillaries close to the surface of the
skin, causing them to become wider due to the increased pressure. This is known as vasodilation;
heat can escape the blood through the skin by radiation. Temperature receptors in the skin can
also send impulses to the thermoregulatory centre in the brain, giving information about skin
temperature.
Heat escaping
by radiation.
Capillaries

45. Temperature regulation
Skin surface
When your body temperature is below the normal range, this is detected by the
thermoregulatory centre in the brain. As a result, blood flow is decreased in the capillaries
close to the surface of the skin, causing them to become narrow due to the decreased
pressure. This is known as vasoconstriction; heat escaping the blood through the skin by
radiation is reduced.
Capillaries

46. Temperature regulation
When you are hot, your
sweat glands in the skin
release more sweat. The
sweat absorbs heat energy
so when the sweat
evaporates, heat is lost
from the skin thus cooling
you down.

47. Temperature regulation
Skin hair
When you are cold, your skin
hairs can stand on end. This
action traps a layer of air above
the skin which helps
to insulate the skin against heat
loss.
When you are hot, your skin
hairs lay flat thus allowing
more heat to be lost through
radiation.

48. Exam-style question
The human body temperature is kept at 37OC, describe
how your body keeps the body temperature constant?
(6 marks)
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49. Exam-style question
The human body temperature is kept at 37OC, describe
how your body keeps the body temperature constant?
(6 marks)
Too high
- Thermoregulatory centre in the brain detects increase
- More blood flow in blood vessels close to the skin
- Leads to vasodilation
- Sweat glands release more sweat to cool the body
- By evaporation
- Skin hair lay flat
Too low
- Reduced blood flow in blood vessels close to the skin
- Leads to vasoconstriction
- Skin hair stand on end trapping air