There are three types of
neurons that carry neural
information around the body
Sensory Neurons - unipolar neurons (they
only transmit messages) that process
information taken from one of the 5
senses to find out the current state of the
body both inside and out
Relay Neurons - these multipolar neurons (transmit
and receive information) are only located in the
brain and spinal cord; they transport messages
around the CNS, connecting sensory and moto
neurons
Motor Neurons - also multipolar, motor neurons form synapses with
muscles located in the CNS , to carry signals from the CNS to the glands
and muscles to inform them of the required function
Synapse transmission:
Each neuron is
seperated by a gap
known as a synapse
Signals between neurons
are transferred chemically
via neurotransmitters
When an electric signal
reaches the presynaptic
terminal, it triggers the
release of a neurotransmitter
from the synaptic vesicle
The neurotransmitter
diffuses across the
synapse to the
postsynaptic receptor
site of the next neuron
Excitation vs Inhibition
Excitation - increases the positive
charge of the postsynaptic neuron,
increasing the chance the signal with
be continued e.g. adrenaline
Inhibition - increases the negative charge of the
postsynaptic neuron, decreasing the chance of the signal
being continued e.g. serotonin
Gland types:
Pituitary - controlled by the hypothalamus, it
regulates the endocrine system by releasing a
hormone that signals to other glands which
hormones need releasing
Adrenal - facilitates the release of
adrenaline as part of the flight or fight
response
Testes - facilitates the release of testosterone,
responsible for male well being + development; Women
have a small amount of it
Ovaries - facilitates the release of oestrogen and progesterone,
the female hormones responsible for ovulation and the
menstrual cycle
The fight or flight response
The hypothalamus
percieves the situation as
being stressful
The ANS changes from the
parasympathetic (resting) state to the
sympathetic (physiologically aroused)
state
A hormone called ACTH is released from the pituitary gland
This hormone causes the adrenal gland to release adrenaline, which causes:
Increased alertness
Increased respiratory rate
Increased blood flow to muscles
Dilated pupils
Increased heart rate
Raised blood pressure
Reduced activity
in digestive
system to
conserve energy