The nervous system is classified into two primary parts:
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Central Nervous System (CNS): This includes the brain and spinal cord. The CNS is responsible for processing information and coordinating responses. It serves as the control center for the body, integrating sensory information and generating motor commands.
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Peripheral Nervous System (PNS): This encompasses all the nerves outside the CNS. The PNS connects the CNS to the limbs and organs. It is further divided into:
- Somatic Nervous System: Controls voluntary movements by innervating skeletal muscles.
- Autonomic Nervous System: Regulates involuntary bodily functions, including heart rate, digestion, and respiratory rate. It is subdivided into:
- Sympathetic Nervous System: Responsible for the body's 'fight or flight' response.
- Parasympathetic Nervous System: Promotes the 'rest and digest' functions.
Neurons
Neurons are the fundamental functional units of the nervous system. They are specialized cells responsible for transmitting information throughout the body. Here are some key points about neurons:
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Structure: A typical neuron consists of three main parts:
- Cell Body (Soma): Contains the nucleus and organelles, responsible for the overall maintenance and function of the neuron.
- Dendrites: Branch-like structures that receive signals from other neurons and transmit them towards the cell body.
- Axon: A long, thin projection that conducts electrical impulses away from the cell body toward other neurons, muscles, or glands.
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Types of Neurons:
- Sensory Neurons: Transmit sensory information (e.g., touch, pain, temperature) from sensory receptors to the CNS.
- Motor Neurons: Carry signals from the CNS to muscles and glands, facilitating movement and actions.
- Interneurons: Connect neurons within the CNS and play a critical role in reflexes and complex processes like learning and memory.
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Function: Neurons communicate through electrical impulses known as action potentials, which travel along the axon. When an action potential reaches the synaptic terminal, it triggers the release of neurotransmitters—chemical messengers that cross the synapse (the gap between neurons) and transmit signals to other neurons.
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Plasticity: Neurons exhibit plasticity, meaning they can adapt structurally and functionally in response to activity, learning, or injury. This ability is crucial for processes such as learning, memory, and recovery from neuronal damage.
In summary, neurons are vital for the transmission of signals within the nervous system, enabling the responses, interactions, and functions of the entire organism.
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