Who is this weird looking guy?
How? The components – Nervous System
What is this? Why is it important? What’s special about it?
Intro to the Nervous System activities
• There are several small experiments to do on the
nervous system on GC – do one, all or none
• Then, make a start on the Google doc - The Nervous
System
Conclusion
Reflexes are involuntary responses (reflexes
are a type of involuntary response) involving
nerves and the brain
These types of responses are not under
conscious control – they happen
automatically to keep you alive
Many homeostasis responses are reflex
responses or involuntary responses
Conclusion
Reflexes are involuntary responses involving
nerves and the brain
These types of responses are not under
conscious control – they happen
automatically to keep you alive
Many homeostatic responses are reflex
responses or involuntary responses
The Nervous System
How? The components and mechanisms
Homeostasis works using complex stimulus-response pathways in the body
This additional
step happens in
homeostasis
responses
How nerve impulses work
Neurons that aren’t transmitting nerve messages
are said to be resting
The resting membrane potential of a
neuron (average value is ~ -70mV) is due
to an electrical charge difference caused
by the membrane separating positively
and negatively charged ions
This difference in charge is caused by (Na+ and K+) ions
being actively pumped into and out of the neurons
There are also organic anions and Cl- ions inside
and outside the cell…
The net result is that the inside
of a neuron is more negative
than the outside
This sets up a charge or an
electrical potential difference of
~ -70mV
Nerve impulses travel along neurons as action potentials
The charge difference
swaps – it momentarily
becomes more positive
inside than negative
This moves down the axon
until it reaches the
terminal end of the axon
Transmission between neurons changes from electrical to
chemical
Neurotransmitters are chemicals that
cross the gap (synapse) between
neurons (or between a neuron and a
cell eg a muscle cell)
They pass the electrical signal on and
are then broken down and recycled
Note: for E you can find out exactly
how these nerve impulses work
Most are made
from amino
acids =
• You get
them from
your food
• They are
affected by
temperature
and pH too
To do now…Google classroom
•Google doc – the Nervous
System
•Use the embedded
resources to learn about
the components of the
nervous system
The nervous system and endocrine system work
together to maintain homeostasis