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The Nervous System
The Nervous System
The nervous system controls all of the voluntary and involuntary actions in the body. This system receives and sends out signals that help detect and make changes to maintain homeostasis. The nervous system is made up of the brain, the spinal column, and the nerves throughout the body.
The brain is the control center of the body.
The brain stem links the brain and the spinal cord. It controls all of the involuntary actions of the body that keep you alive, such as your heart beat, blood pressure, and breathing.
The cerebellum is the small section at the back of the brain, just above the spinal cord, that controls balance and posture.
The cerebrum controls voluntary movement, language, and your thoughts.
The brain sends out electrical signals through the rest of the nervous system.
The brain stem leads down the spinal column (spinal cord) to carry the electrical nerve signals from the brain to the rest of the body. An injury to the spinal column causes a break in the delivery of these electrical signals and can lead to paralysis of areas of the body.
An injuryat the brain stem often results in death since the signals to control involuntary actions cannot be sent out.
The nervous system is made of specialized cells called neurons. The neuron has a branched structure and consists of a cell body, branches called dendrites, and a long extension called an axon. The branches of the neuron allow multiple signals to travel through the cell to various parts of the body.
How Do Nerves Transmit Signals?
How Do Nerves Transmit Signals?
Each individual nerve cell may have hundreds of dendrites that can detect a stimulus or impulse. This signal is carried to the cell body and travels down the axon to the end of the cell, where it communicates with other nerve cells.
Nerve cells communicate with each other at special junctions called synapses. A synapse is the point of connection between the axon of one neuron and the dendrites of another.
At a synapse, the arrival of an impulse at the end of an axon triggers the release of a chemical agent, called a neurotransmitter.
Neurotransmitters interact with receptors located in the dendrite of the next neuron to transmit the signal.
When the brain perceives a threat, a signal is sent to the hypothalamus. The hypothalamus is part of 2 interacting systems: nervous and endocrine. It regulates body functions that control temperature, digestion, blood pressure, and the release of hormones. This signals the sympathetic nervous system to prepare for action.
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