"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."
This topic covers the structure and function of the nervous system, including neurons, neurotransmitters, and the different parts of the brain and spinal cord.
Neurons: The basic building blocks of the nervous system.
Nerve cells: The cells that transmit information through electrical and chemical signals.
Central nervous system (CNS): The brain and spinal cord that receive, store, and process information.
Peripheral nervous system (PNS): The branches of nerves throughout the body that deliver information to and from the CNS.
Sensory neurons: The cells that detect and respond to changes in the environment.
Motor neurons: The cells that activate muscles and glands in response to changes in the environment.
Autonomic nervous system (ANS): The part of the PNS that regulates involuntary body functions.
Sympathetic nervous system: The ANS branch responsible for emergency response “fight or flight”.
Parasympathetic nervous system: The ANS branch responsible for rest and relaxation.
Somatic nervous system: Part of the PNS that controls voluntary movements and reflexes.
Spinal cord: The cable-like structure of nerves that runs through the center of the spine and connects the brain to the rest of the body.
Brainstem: The lower part of the brain that connects to the spinal cord and controls basic life functions such as breathing and heart rate.
Cerebellum: The part of the brain responsible for coordination and balance.
Limbic system: The part of the brain that controls emotions, memory, and motivation.
Cortex: The outer layer of the brain responsible for advanced functions such as consciousness, reasoning, and language.
Neurotransmitters: Chemicals that transmit signals between neurons.
Hormones: Chemicals that are released by glands or neurons and influence the functions of the body or other organs.
Synapses: The spaces between neurons where neurotransmitters are released to send signals.
Neuroplasticity: The ability of the brain to adapt and change in response to new experiences or injury.
Diseases and disorders of the nervous system: Examples include Alzheimer's, Parkinson's, epilepsy, multiple sclerosis, and spinal cord injuries.
Central Nervous System (CNS): This is composed of the brain and the spinal cord. It processes and coordinates all incoming sensory information and outgoing motor commands.
Peripheral Nervous System (PNS): This is composed of all the nerves outside the CNS, including cranial nerves, spinal nerves, and their branches. It connects the CNS to the rest of the body, allowing for sensory reception, movement, and communication between organs.
Autonomic Nervous System (ANS): This regulates internal body functions, including breathing, heart rate, digestion, and secretion of hormones. It's further divided into the sympathetic and parasympathetic nervous systems, which work together to maintain homeostasis.
Somatic Nervous System (SNS): This controls voluntary motor movements and sensory function. It's responsible for sending information from the senses to the CNS and for sending motor commands from the brain and CNS to the muscles.
Enteric Nervous System (ENS): This is a complex network of neurons and glial cells that controls the gastrointestinal tract's function. It's often referred to as the "second brain.".
Cranial Nerves: These are the 12 pairs of nerves that originate from the brain and control movement and sensation in the head and neck.
Spinal Nerves: These are the 31 pairs of nerves that originate from the spinal cord and control movement and sensation in the rest of the body.
Afferent Nervous System: This transmits sensory information from the periphery to the CNS.
Efferent Nervous System: This transmits signals from the CNS to the muscles, glands, and organs.
Sensory Nervous System: This receives and transmits sensory information from the environment.
Motor Nervous System: This controls voluntary and involuntary movement through the PNS.
Sympathetic Nervous System: This triggers the "fight or flight" response, including increased heart rate, dilation of the pupils, and increased blood pressure.
Parasympathetic Nervous System: This promotes "rest and digest" functions, such as digestion, relaxation, and sleep.
Motor Neurons: These are specialized neurons that control movement.
Sensory Neurons: These are specialized neurons that detect sensory stimuli.
Interneurons: These are specialized neurons that transmit signals between other neurons.
Glia: These are specialized cells that support and protect neurons, and play a critical role in CNS function.
"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."