animals respond to a stimulus in order to keep themselves in favourable conditions
the stimulus is co-ordinated by the central nervous system
CNS = brain and spinal cord
receptors respond to the stimulus and send impulses along the sensory neuron to the CNS
the CNS co-ordinates the information and sends impulses along motor
neurons to the effectors, which bring about a response
the peripheral nervous system consists of motor and sensory neurons that take
information from the receptor to the CNS, as well as the instructions from the CNS
to the effectors
neurons
neurons carry signals from one place to another
when neurons are stimulated they transmit an electrical impulse
two neurons do not make direct contact, when they meet there is
a small gap between them called a synapse
the signal needs to cross this gap, so it's turned into a chemical which diffuses across the synapse
the receptor molecules on the second neuron only bind to
specific chemicals released from the first neuron
this stimulates the second neuron to transmit
the electrical impulse
reflexes
a reflex is an automatic response to a stimulus
simple reflexes
produce rapid, involuntary responses
this ensures that an animal responds
in the way most likely to result in its
survival
examples include - moving towards and finding
food, moving away from predators and finding a
mate
reflex arc
reflex reactions in humans are controlled by the reflex arc
a reflex arc is the nerve pathway which makes rapid automatic responses possible
newborn reflexes
grasping reflex
startle reflex
step reflex
learning
human brain consists of millions of neurons, these
neurons are connected to form billions of pathways
whenever we experience something new, a new pathway in the brain is used
each new experience changes out behaviour, this is learning
if the experience is repeated, or the stimulus is strong, more nerve
impulses are sent along the new pathway
this reinforces the learning process, and shows us how repetition aids the learning process
learning is an important part of human survival
some skills can only be learnt at a certain age
if a child has no human
contact from birth, they
become feral
feral children can't talk or walk like a
human because they didn't learn the
skill when they needed to
the brain and memory
the cerebral cortex is the part of the brain that is responsible
for intelligence, language, memory and conscienceness
scientists use different
methods to find out which
part of the cerebral cortex do
what job
brain damage patients
electrical stimulation
MRI scans
two types of memory
long-term
and
short-term
drugs
drugs affect the impulses that
pass from one neuron to
another across the synapse
some drugs stop the impulse from passing across the synapse
others stimulate the synapse so once one impulse has
crossed the gap, its repeated
serotonin is a chemical that is released in our brains, an increase in
serotonin levels makes us feel happier
serotonin is usually absorbed by the receptor molecules on the
other side
the drug ecstasy blocks the receptor sites in the synapses in
the brain, this means serotonin levels increase and the user
gets a prolonged feeling of wellbeing