Hallucinations- side effect of abusing methamphetamine. Davids
prolonged crystal meth habit had altered his normal functioning
of some chemicals in his brain, distorting his perception of
Betty had a stroke that damaged an area on the right side of the
brain. It was a rare disorder called prosopagnosia., which is the
inability to recognise familiar faces as a result of the brain
damage caused by her stroke.
Neurons: Cells in the nervous system that communicate with
one another to perform information-processing tasks.
Santiago Ramon y Cajal- Spanish physician, learned about a new
technique for staining neurons in the brain the stain highlighted
the appearance of entire cells, revealing that they came in
different shapes and sizes.
Neurons have three basic parts” the cell body, dendrites and the
axon. Neurons have two types of specialized extensions of the
cell membrane that allow them to communicate: dendrites and
The cell body: it is also known as a soma. It is the largest
component of the neuron that coordinates the information-
processing tasks and keeps the cell alive. Functions include;
protein synthesis, energy production and metabolism. The
cellbody contains the nucleus; this structure houses
chromosomes that contain DNA. It is surrounded by a porous cell
membrane that allows molecules to flow into and out of the cell.
Dendrites: they receive information from other neurons and
relay it to the cell body. It comes from the greek work for “tree”
as they look like tree branches.
Axon: it transmits information to other neurons, muscles, or
glands. Each neuron has a single axon that sometimes can be
very long, even stretching up to a meter from the base of the
Myelin Sheath: This covers the axon. It is an insulating layer of
fatty material. It is composed of glial cells, which are support
cells found in the nervous system. Some glial cells digest parts of
the dead neurons, others provide physical and nutritional support
for neurons and other form myelin sheath to help the axon
transmit information more efficiently. Demyelinating diseases,
such an multiple sclerosis, the myelin sheath deteriorates, slowing the transmission of information from one neuron to the
other. This leads to loss of feeling in limbs, partial blindness and
difficulties in coordinated movement and cognition.
There is a small gap between the axon of a neuron and the
dendrites or the cell body of another. This gap is known as
synapse: the junction or region betweem the axon of oen neuron
and the dendrites or cell body of another.
Sensory Neurons: it receves information from the external
world and convey this information to the brain via the spinal
cord. They have specialized endings on their dendrites that
receives signals for light, sound, touch, taste and smell. In our
eyes, our sensory neurons ending are sensitive to light
Motor Neurons: it carry signals from the spinal cord to the
muscles to produce movement. These neurons oftwn have long
axons that can stretch to muscles at our extremists.
Interneurons: Most of the nervous system consists of this.
They connect sensory neurons, morotr neurons or other
interneurons. Some carry information from sensory neurons unto
the nervous system, while other carry information from the
nervous system to motor neurons and still other perform a
variety of information-processins functions within the nervous
system. They work together in small circuits to perform simple
tasks, such as identifying the location of a sensory signal and
recognizing a familiar face.
Purkinje Cells: carries information from the cerebellum to the
rest of the brain and spinal cord. They have dense elaborate
dendrites that resemble bushes.
Pyramidal Cells: found in the cerebral cortex, have a triangular
cell body and a single, long dendrite among many smaller
Bipolar cells: found in the retinas of the ye, have a single axon
and a single sendrite. The brian processes types of information
so a substantial amount of specialization at the cellular level has
evolved to handle these tasks.
Conduction : conduction of an electric signal over relatively long
distances within neurons, from the dendrites, to the cell body,
then throughout the axon. Transmission: transmission of chemical signals between neurons
over the synapse.
Conduction and transmission together is knowsn as
electrochemical action of neurons.
Neurons cell membrane is porous. They have a natural electric
charge called the resting potential.
Resting potential: the difference in electric charge between the
inside and outside of a neurons cell membrane.
Action Potential: electric signal that is conducted along the
length of a neurons axon of the synapse.
Axon ends in terminal buttons, which are knoblike structres that
branch out from an axon. A terminal button is filled with tiny
vesicles that contain neurotransmitters, chemicals that transmit
information acorss the synapse to a receiving neuron’s dendrites.
The dendrites of the receving neuron contain receptors, parts of
the cell membrane that receive neurotransmitters and either
initiate or prevent a new electrical signal.
Acetylcholine: A neuro transmitter involved in a number of
functions, including voluntary motor control, was one of the first
neurotransmitters to be discovered. Found in the brain and in the
synapses where axons connect to muscles and body organs.
They activate muscles to initiate motor behaviour. Alzheimars
desease and memory condition with severe memory impairments
is associated with the deteroration of Acetylcholine.
Dopamine: is a neurotransmitter that regulayes motor
behaviour, motivation, pleasure and emotional arousal. High
levels of dopamine is linked with schizophrenia, while low levels
are linked with Parkinson’s disease. Plays a role in drug
Glutamate: is a major excitatory neurotransmitter involved in
information transmission throughout the brain. It enhances the
transmission of information. Too much of it can overstimulate
the brain and cause seizures.
GABA- gamma-aminobutyric acid- is the primary inhibitory
neurotransmitter in the brain. They stop firing the neurons. Too
little GABA can cause neurons to become overactive. Norepinephrine: a neurotransmitter that influences mood and
arousal. Is particularly involved in states of vigilance.low levels
result in mood disorder.
Serotonin: involved in regulation of sleep and wakefulness,
eating and aggressive behaviour. Low levels result in mood
Endorphines: are chemicals that act within the pain pathways
and emotion centres of the brain. Calming and pleasurable
Agonists: drugs that increase the action of a neurotransmitter.
Antagonists: drugs that block the function of the
Methamphetamine: afeects pathways for dopamine, serotonin
and norepinephrine at the neurons synapses, making it difficult
to interpret exactly how it works. The combination of its agonist
and antagonist effects alters the fucntions f neurotransmitters
that help us perceive and interpret visual images.
Amphetamine: popular drug that stimulates the release of
norepinephrines and dopamine. In addition, both amphetamine
and cocaine prevent the reuptake of norepinephrine and
Prozac: a drug commonly used to treat depression. Is a
neurotransmitter agonist. Blocks the reuptake of the
neurotransmitter serotonin, making it part of a category of drugs
called selective serotonin reuptake inhibitors.
The nervous system is an interacting network of neurons that
conveys electrochemical information throughout the body.
The central nervous system is composed of the brain and the
spinal cord. It received sensory information from the external
world, processes and coordinates this information and sends