Download Nerves and the brain

Nerves and the brain
Nerve
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A nerve is a bundle of axons or neuronal fibres
bound together like wires in a cable.
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Neurons or nerve cells are the functional units of the
nervous system. They are specialized cells that
transmit signals from one location in the body to
another location by electrochemical changes in their
membranes.
Nerve
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Neurone consists of three main parts:
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Cell body - contains the nucleus and other cell organelles.
High level of cellular activity - means there is a large
amount of endoplasmic reticulum - secretes protein visible
in cytoplasm
Dendrites - pick up messages using their extensive
branches to increase the surface area of the ‘receiving end’
of the nerve cell
Axon - conducts messages away from the cell body. The
axon has many vertebrates surrounded by schwann cells
(supporting cell that forms insulating layer of myelin sheath)
Areas of the cerebrum involved in the perception and interpretation of
light and sound
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Refer to the diagram of the cerebrum
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Parietal lobe - at the top of the head towards the back - this area
is important for interpreting sensory signals including sight and
sound
Occipital lobe - located at the back of the head - concerned with
vision as well as perception such as touch, pressure temperature
and pain - site of visual cortex
Temporal lobe - located at the side of the head above the ears interprets the impulses from the ears and give meaning to
information - important region for the sense of hearing.
Using specific examples, the importance of correct interpretation of
sensory signals by the brain for the coordination of animal behaviour
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The environment in which an organism lives is constantly
changing. Sense organs such as the ear and the eye detect
these changes and send information to the brain. The brain then
interprets the information and sends an impulse to an effector
organ such as a muscle. It is essential that the brain interpret
signals from the sense organs correctly.
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The cerebral cortex is the most important association centre of
the brain. Information comes to this area from our senses and
the brain sorts it out in the light of past experiences. As a result,
motor impulses are sent along the nerves to cause an
appropriate action to take place.
Using specific examples, the importance of correct interpretation of
sensory signals by the brain for the coordination of animal behaviour
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For example, the eyes and ears, receptors in muscles and tendons,
pressure sensors on the feet all provide signals about the position of the
body in space. The cerebrum of the brain interprets all of these signals
and sends messages to various effectors to balance the body in space.
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Walking involves several receptors, including the eyes, gravity receptors
in the ears, pressure sensors in the feet and position receptors in the
joints. These receptors are connected to the brain by neurones and the
brain interprets the signals it receives. The brain sends messages to the
muscles and other effectors to coordinate the process of walking.
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The importance of the brain in the coordination of animal behaviour is
highlighted when parts of it are damaged. The paralysis that follows a
stroke, or the shaking movements of people with Parkinson’s disease, are
signs of damage to the brain. In people with these conditions, muscular
contractions are no longer coordinated by the brain