Coordination and
Homeostasis
B9
Learning Goals
1. Understand how stimulus and
response works in animals.
2. Describe the parts of a neuron and its
function
3. Explain the role of the central nervous
system (CNS)
4. Understand the pathway of reflex
arcs.
Coordination in Animals
One of the characteristics of all living
things is the ability to detect and respond
to changes in its environment. This is
know as sensitivity
Changes in an organism's environment
are called stimuli. And are sensed by
specialized cells called receptors.
The organism responds using effectors
Coordination in Animals
To make sure that the right effectors
respond at the right time, there needs to
be some kind of communication system
between the receptors and effectors.
The way in which receptors pick up
stimuli, and pass information on to
effectors, is called coordination.
Two methods
Nerves and Hormones.
The human nervous system
The human nervous system is made of
cells called neurons.
Neurons contain the same basic parts
as any animal cell. (Nucleus,
Cytoplasm, Cell membrane)
However, their structure is especially
adapted to be able to carry signals very
quickly.
The central nervous system
The central nervous system is made up
of brain and spinal cord.
Its role is to coordinate the information
travelling through the nervous system.
When receptors detects a stimulus, it
sends an electrical impulse to the brain
or spinal cord, then an impulse is sent
along the appropriate nerve fibres, to the
appropriate effector.
Reflex Arcs
If you touch a hot plate, this
information is detected by a sensory
receptor in your finger.
The receptor generates a nerve
impulse, which travels to the spinal
cord along the axon of a sensory
neuron.
In the spinal cord, the neuron passes
an impulse on to several other
neurons are called relay neurons.
The relay neuron also passes impulse
to the brain and onto an effector.
Reflex Arcs
The effectors are the muscles in your
arms. The impulse travels to the
muscle along the axon of a motor
neuron. Your muscle then contracts,
so that your hand is pulled away.
This kind of reaction is called a reflex
reaction, you do not need to think
about it.
Reflex Arcs
Reflex actions are examples of
involuntary actions. They are not
under conscious control.
However many of our action are
voluntary they happen because we
decided to carry them out.
Learning Goals
1. Understand how stimulus and
response works in animals.
2. Describe the parts of a neuron and its
function
3. Explain the role of the central nervous
system (CNS)
4. Understand the pathway of reflex
arcs.
Hormones
1. Endocrine glands 1. What it is?
2. Adrenaline 2. Its function in the human body
3. Cortisol 3. The benefits
4. Insulin 4. The disadvantages
5. Dopamine 5. What happens if we secrete it a
lot. diseases associated with this
6. What happens if we don't secrete
it enough. diseases associated
with this
The eye
The eye is the receptor organ.
Its function is to detect and light, and to transfer the energy in the light to electrical
energy in a nerve impulse.
