"The nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body."
An introduction to the nervous system, its structure, and functions.
Neurons: The basic building blocks of the nervous system, neurons are specialized cells that transmit information via electrochemical signals.
Neurotransmitters: Chemical messengers that transmit signals between neurons and other cells in the body.
Synapses: The junctions at which neurons communicate with one another.
Action potentials: Electrical impulses that allow neurons to transmit signals over long distances.
Glia: Non-neuronal cells that support and regulate the activity of neurons.
Central nervous system (CNS): The brain and spinal cord, which are responsible for information processing and integration.
Peripheral nervous system (PNS): The network of nerves that connect the CNS to the rest of the body.
Autonomic nervous system: The part of the PNS responsible for regulating involuntary processes, such as heart rate and digestion.
Somatic nervous system: The part of the PNS responsible for voluntary movements and sensory perception.
Cerebral cortex: The outer layer of the brain, responsible for consciousness, perception, and higher cognitive functions.
Brainstem: The neural pathway that connects the brain to the spinal cord and regulates basic life-sustaining functions.
Limbic system: A network of brain structures responsible for emotions, motivation, and memory.
Neuroplasticity: The ability of the nervous system to change and adapt in response to experience.
Neurogenesis: The process of generating new neurons in the brain.
Neurodegeneration: The progressive loss of neurons in the nervous system, leading to diseases such as Parkinson's and Alzheimer's.
Psychopharmacology: The study of how drugs affect the nervous system and behavior.
Neuroimaging: Techniques for visualizing the structure and activity of the nervous system, such as MRI and fMRI.
Electrophysiology: Techniques for measuring the electrical activity of neurons, such as EEG and patch clamping.
Cognitive neuroscience: The study of how the brain gives rise to cognitive processes such as perception, attention, and memory.
Developmental neuroscience: The study of how the nervous system develops and matures over the course of an individual's life.
Central Nervous System (CNS): The CNS consists of the brain and spinal cord. It is responsible for processing sensory input, controlling movement, and regulating vital bodily functions.
Peripheral Nervous System (PNS): The PNS consists of all the nerves outside of the CNS, and is responsible for transmitting sensory information to the CNS, and motor commands from the CNS to the muscles and organs.
Somatic Nervous System (SNS): The SNS controls voluntary movements and reflexes, and is responsible for sensory processing related to touch, pain, temperature, and body position.
Autonomic Nervous System (ANS): The ANS controls involuntary bodily functions, including heart rate, respiration, digestion, and glandular secretion. It is divided into two branches: the sympathetic nervous system and the parasympathetic nervous system.
Sympathetic Nervous System (SNS): The SNS is responsible for the "fight or flight" response, increasing heart rate, respiratory rate, and blood pressure in response to stress or danger.
Parasympathetic Nervous System (PNS): The PNS is responsible for the "rest and digest" response, slowing heart rate and promoting digestion and relaxation.
Enteric Nervous System (ENS): The ENS is a complex network of neurons located in the walls of the gastrointestinal tract, responsible for controlling digestion and other digestive system functions.
Cranial Nerves: The 12 pairs of cranial nerves are responsible for sensory and motor functions of the head and neck. They include the optic nerve, the olfactory nerve, the trigeminal nerve, and others.
Spinal Nerves: The 31 pairs of spinal nerves are responsible for sensory and motor functions of the rest of the body outside of the head and neck. They include the sciatic nerve, the ulnar nerve, and others.
Afferent Nerves: Afferent nerves carry sensory information from the peripheral nervous system to the central nervous system.
Efferent Nerves: Efferent nerves carry motor commands from the central nervous system to the muscles and organs of the body.
"Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago."
"The vertebrate nervous system consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS)."
"The central nervous system (CNS) consists of the brain and spinal cord."
"The peripheral nervous system (PNS) consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body."
"Nerves that transmit signals from the brain are called motor nerves or efferent nerves."
"The PNS is divided into three separate subsystems, the somatic, autonomic, and enteric nervous systems."
"The sympathetic nervous system is activated in cases of emergencies to mobilize energy."
"The parasympathetic nervous system is activated when organisms are in a relaxed state."
"The enteric nervous system functions to control the gastrointestinal system."
"At the cellular level, the nervous system is defined by the presence of a special type of cell, called the neuron."
"Neurons send these signals in the form of electrochemical impulses traveling along thin fibers called axons."
"The connections between neurons can form neural pathways, neural circuits, and larger networks that generate an organism's perception of the world and determine its behavior."
"Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support."
"The only multicellular animals that have no nervous system at all are sponges, placozoans, and mesozoans."
"The medical specialty of neurology studies disorders of the nervous system and looks for interventions that can prevent or treat them."
"In the peripheral nervous system, the most common problem is the failure of nerve conduction."
"Demyelinating disorders such as multiple sclerosis and amyotrophic lateral sclerosis."
"Neuroscience is the field of science that focuses on the study of the nervous system."
"The size of the nervous system ranges from a few hundred cells in the simplest worms, to around 300 billion cells in African elephants."