The is a complex network that controls our body's functions. It's made up of the brain, spinal cord, and nerves, working together to process information and coordinate responses. This system is crucial for everything we do, from breathing to thinking.
Communication in the happens through electrical and chemical signals. transmit messages, while carry information between cells. This intricate system helps maintain balance in our body, responding to changes and keeping us functioning properly.
Overview of the Nervous System
Structure and function of nervous system
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Complex network of cells and tissues transmits signals throughout the body
Composed of brain, spinal cord, and vast network of nerves
Primary function receives, processes, and transmits information to coordinate and regulate bodily functions
Sensory input receives and interprets sensory information from internal and external stimuli (touch, sight, sound)
Integration processes and analyzes sensory information in brain and spinal cord
Motor output sends signals to muscles, glands, and organs to initiate appropriate responses (muscle contraction, hormone release)
Nervous system cells
Neurons specialized cells transmit electrical and chemical signals
Cell body (soma) contains nucleus and organelles
Dendrites branched extensions receive signals from other neurons
Axon long, thin extension transmits signals to other neurons or effector cells (muscles, glands)
non-neuronal cells support and protect neurons
provide structural support, regulate neurotransmitter levels, and maintain
(CNS) and Schwann cells (PNS) form myelin sheath around axons for insulation and faster signal transmission
immune cells protect against infection and clear cellular debris
Nervous system communication for homeostasis
Communication within nervous system occurs through electrical and chemical signaling
Electrical signaling involves changes in membrane potential of neurons
Resting potential stable, negative membrane potential of neuron when not actively transmitting signals (around -70 mV)
rapid, transient change in membrane potential propagates along axon when threshold reached
Chemical signaling involves release of neurotransmitters at between neurons
Neurotransmitters chemical messengers released by presynaptic neurons bind to receptors on postsynaptic neurons or effector cells (, , )
process by which neurotransmitters are released, cross synaptic cleft, and bind to receptors, causing excitation or inhibition of postsynaptic cell
Nervous system maintains homeostasis by constantly monitoring and adjusting bodily functions
mechanisms allow nervous system to detect changes in body and initiate corrective actions
Negative feedback detects deviations from set point and initiates responses to return system to normal state (thermoregulation, blood pressure control)
Positive feedback amplifies change in body to achieve specific outcome (oxytocin release during childbirth)
regulates involuntary functions such as heart rate, digestion, and respiration
prepares body for "fight or flight" responses by increasing heart rate, blood pressure, and glucose release
promotes "rest and digest" functions by slowing heart rate, increasing digestion, and promoting relaxation
Nervous System Adaptability and Protection
: The brain's ability to reorganize and form new neural connections throughout life
Allows for learning, memory formation, and recovery from brain injuries
: The process of communication between neurons through chemical signals
Enables rapid and precise information transfer throughout the nervous system
Blood-brain barrier: A selective barrier that protects the brain from potentially harmful substances in the bloodstream
Regulates the passage of molecules between the blood and the
Divisions of the Nervous System
Central vs peripheral nervous systems
Nervous system divided into two main components: and
Central Nervous System (CNS)
Consists of brain and spinal cord
Role integrates and processes information, makes decisions, and coordinates bodily functions
Brain control center of nervous system
Cerebrum responsible for higher cognitive functions, sensory processing, and voluntary movement
Cerebellum coordinates balance, posture, and fine motor control
Brainstem regulates vital functions such as respiration, heart rate, and consciousness
Spinal cord bundle of nerves extends from brainstem and serves as conduit for signals between brain and body
Ascending tracts carry sensory information from body to brain
Descending tracts carry motor commands from brain to body
Spinal reflexes rapid, involuntary responses to stimuli occur without input from brain (knee-jerk reflex)
(PNS)
Consists of nerves and ganglia outside brain and spinal cord
Role connects CNS to rest of body, transmitting sensory information and motor commands
Sensory (afferent) division carries sensory information from receptors in body to CNS
Somatic sensory detects touch, pressure, temperature, pain, and proprioception
Visceral sensory monitors internal organs and glands
Motor (efferent) division carries motor commands from CNS to muscles and glands
Somatic nervous system controls voluntary movements of skeletal muscles
Autonomic nervous system regulates involuntary functions of smooth muscles, cardiac muscle, and glands