The Nervous System and Brain
The Nervous System and Brain
of the Human Nervous System
Contents
?Introduction
?Nervous System
?Neuron Function
?Brain Stem
?
?
?
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??'k?mp?s]
Introduction
thoughts, and memories. To them, the brain was nothing but a giant glob of mucus that passed snot down to the nose. [1] For hundreds or even thousands of years, the
the 20th and 21st century, and sciences. We are getting closer and closer to understanding each and every part of the
their brain waves. [2]
which we now comprehend our brain and nervous system is impressive
the least.
Nervous System
sent to the brain through the nervous system. Likewise
The nervous system is an intricate mostly of nerve cells (or
over 50 variations to the requirements the central nervous system and the peripheral nervous system.
Central Nervous System (CNS)
the backbone called the meninges
also acts as protection for the CNS. All of these
protective factors are vital for our survival
lead to serious injury or death.
Peripheral Nervous System(PNS)
The peripheral nervous system is comprised of the branches of nerves that extend from the central nervous system to the rest of our body. [6] These nerve fibers are not
to damage. There are a number of different kinds of nerve cells that are part of ?Afferent Neurons - Nerves in the peripheral nervous system that carry
nerves). [4] Afferent neurons communicate with interneurons that
legs or arms, are sent along afferent neurons to the brain where the pain can be registered.
?Efferent Neurons - Also known as motor neurons, efferent neurons (or nerves) body. [7] Efferent neurons, for example, keep our hearts beating, our lungs
breathing, and also allow us to move our bodies.
Interneurons - These are mostly found in the spine and brain. Interneurons connect nerves to other nerves and therefore do not connect to any muscles or other sensory cells. They can connect afferent neurons to efferent neurons. There are about 100 billion interneurons in the human body. [8]
- Keeping all of the nerves protected and in place are the glial cells. There are around ten times as many glial cells as there are other neurons in the brain. [9] They surround neurons and 'glue' our neural networks together. They also
and help
control neurotransmission.
Neuron Function
The nervous system is extremely complex and has around 100 billion neurons that
action
potential
through the membrane in the cell
Neurons react to neurotransmitters
norepinephrine
axons
Dendrites - These are branch projections stemming out of a neuron that bring
potentials and integrating synapses. [10] They reach out to surrounding neurons detected an electrical signal it will send it down into the cell body it is branched out from. There can be many dendrite branches on one neuron.
Axons - Also known as nerve fibers, these are projections which take information away from the cell. [11] Much like dendrites, they branch away from the cell body and have electrical impulses coursing through them, only this time they are heading away from the cell body. There can be only one axon on each neuron.
?- Axons are insulated with a myelin sheath that
ultimately
gaps called Nodes of
Ranvier
saltatory conduction and then continue on into myelin. This keeps the Synapses
ions, is able to pass. Synapses are very tiny gaps that allow signals to diffuse from
parts: a presynaptic ending, and synaptic cleft. [12]
?Presynaptic
cell organelles
?Postsynaptic site for neurotransmitters.
?Synaptic Cleft- A space between the presynaptic and postsynaptic dendrites.
Axoaxonic vesicles
terminals receive will determine whether or not the cell will decrease the strength of the signal. The electrical impulses received in the cell are called action potentials. Action potentials continually repeat as the brain and its neurons do their job.
Brain Stem
two and is called the brain stem (reptilian brain). The brain stem goes from the entire nervous system. [13] There are three parts that make up the brain stem.
?Medulla Oblongata
blood pressure, and digestion. It also relays nerve signals between the brain
?Pons- Above the medulla oblongata is the pons. The pons helps the
information that helps us with our movement, arousal
?Midbrain
the body's sensory and motor functions.
The Cerebellum
The cerebellum sits behind the brain stem at the base of the entire brain. Though the cerebellum is about one tenth of the entire brain's volume it houses almost half the
running across it and is therefore more compact than the rest of the brain. The
cerebellum has two hemispheres and was one of the first parts of the brain to ever evolve. [15] It is one of the most important parts of the brain for its ability to integrate
movement, as well as deciphering information from the ears and eyes. Some scientists also believe that the cerebellum helps us process language and music and gives us our ability to pay attention, among other things. [14] The cerebellum sends information into the brain stem which is then delivered to the rest of the brain.
The Diencephalon
Between the cerebral hemispheres and above the midbrain there is a region of the brain called the Diencephalon. It contains two very important substructures.
?Thalamus - A dual-lobed structure made of grey matter, the thalamus receives and deciphers sensory information. [16] Once it has processed sensory
information the thalamus chooses whether or not that information should be
relayed to the cortex. The thalamus receives information from parts of the
brain and body that have to do with movement and sensory information.
Signals from the cerebellum and cerebral cortex are sent to the thalamus and
the thalamus sends signals out into the cortex.
?Hypothalamus - The hypothalamus is in charge of making sure that we stay motivated. It sits beneath the thalamus and is connected to most everything in
the brain. The hypothalamus causes us to seek pleasurable activities like
hormones
behave. [17] The hypothalamus also manages the circadian rhythm
body temperature, and instinctual
Limbic System
The limbic system is comprised of a group of brain structures that are important in the processing of information and the formation of memories and emotions. There are three key areas in the limbic system.
The Basal Ganglia
The basal ganglia is connected to the thalamus and cortex. It is comprised of a group of structures that sit inside of the brain and look like two curving tubes. The basal ganglia receives most of its information from the cortex and is critical to our ability to move. [18] When the basal ganglia is damaged it severely impairs someone's ability to control their body, as can be seen in those with Hutchinson's Disease or Parkinson's Disease.
Amygdala
and well-being
part in causing arousal
amygdala. [19]
Hippocampus
shaped somewhat like a seahorse. The hippocampus is key in creating new memories by forging new neural pathways in our minds. [20] The hippocampus also helps us with spatial orientation and sleep patterns.
The Cerebral Cortex
The cerebral cortex is the largest, most apparent part of the brain. It is the outer layer of the brain that is the main source of human intelligence. The cerebral cortex is
folded
has six different layers with many neural networks. Beneath these layers is white matter and when all of these are put together we are given a huge number of connections that facilitate our ability to think, feel, and reason.
The cerebral cortex has two hemispheres and each hemisphere helps to manage different things and perform various tasks. Both the hemispheres can communicate with one another, and can be divided into four different lobes.
?Frontal Lobe- The frontal lobe is behind and beneath the forehead. It gives humans their higher level thinking skills, such as the ability to plan, pay attention, use language, and move. [21] It is able to control much of the other areas of the brain. The frontal lobe can also help us to form memories. It gives us the ability to decide how we want to act based on the information we
?Parietal Lobe
sensory input and give us perception
linked to visual systems, the parietal lobes help us to do things like button our shirts or throw footballs. [22]
?Occipital Lobe- The occipital lobes make up the main visual processing
ourselves with the external world. Without the
?Temporal Lobe- The temporal lobe spans across the brain and is below processing auditory information. [24] This auditory processing center helps us
makes it important in the formation and retrieval
Corpus Callosum
The corpus callosum connects the brain's two hemispheres together. It is a huge
brain. [25] The corpus callosum allows for optimal performance from the brain.
Some epilepsy
how the corpus callosum affects
consciousness
Conclusion
summed up all of the major
on to try and unravel the secrets of the brain and nervous system. We know a lot understand these parts of our bodies, the better we can understand humans and their societies as a whole.
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