Introduction to the Nervous System

• The nervous system is a complex and busy system
• The nervous system is the main control system
• The nervous system takes information and gives commands
• The nervous system enables the body to perceive, respond, and adapt to its surroundings
• The nervous system controls voluntary and involuntary body movements

Divisions of the Nervous System

• The central nervous system exists
• The peripheral nervous system exists

Central Nervous System

• The central nervous system is composed of the brain and spinal cord
• The central nervous system is the body's main control unit
• The central nervous system receives and processes sensory information
• The central nervous system responds with motor output

Brain

• The brain, the body's headquarters, has three main parts
• The brain controls automatic behaviors
• The brain controls memories and emotions
• The brain is responsible for sensory processing
• The brain is responsible for movement and coordination
• The brain is responsible for speech and language
• The brain is responsible for thought processing

Parts of the Brain

• Cerebrum, the largest part of the brain, handles conscious thoughts and actions
• Parts of the cerebrum deal with language and sensory perception
• Cerebral cortex is the cerebrum's thin outer layer
• Thalamus relays sensory information before distribution in the cerebrum
• Hypothalamus regulates body temperature, hunger, and vital functions
• Ventricles containing cerebrospinal fluid protect the brain from impact

Parts of the Brain Continued

• Hippocampus enables memory formation
• Amygdala deals with emotional processing, fear, and aggression

Brain Stem

• The brain stem connects the brain and spinal cord, with two parts: midbrain and medulla oblongata
• Midbrain relays sensory information and handles reflex control
• Medulla Oblongata controls involuntary actions like heartbeats and breathing

Parts of the Brain

• Cerebellum, the little brain, is composed of folia
• Cerebellum controls balance, coordination, and posture
• Cerebellum is involved in language, emotional processing, and attention

Spinal Cord

• The spinal cord is a cylindrical structure of gray and white matter
• The spinal cord runs from the brain up the back, protected by the spine
• The spinal cord links the brain to the body, transmitting signals via neurons

Neurons

• Neurons are the nervous system's building blocks
• Neurons are responsible for signal transmission
• Sensory, motor, and interneurons comprise the three neuron types

Parts of a Neuron

• Dendrites receive signals
• The cell body contains the nucleus
• The nucleus contains genetic material
• Axon transmits electrical impulses
• Schwann cells produce myelin sheath that gives structure to the PNS
• Myelin sheath insulates the axon for faster transmission
• Axon terminal transmits electrical and chemical signals

Types of Neurons

• Sensory neurons transmit sensory input from the body to the brain
• Sensory neurons are afferent neurons
• Motor neurons receive commands from the CNS to the body
• Motor neurons are efferent neurons
• Interneurons enable quick reflex responses, connecting sensory and motor neurons

Peripheral Nervous System

• Peripheral Nervous System sends information from body to brain
• The Peripheral Nervous System receives commands from brain
• The Peripheral Nervous System disseminates commands
• The Peripheral Nervous System senses, moves in command, and processes unconscious movements

Somatic Division

• Somatic Division enables conscious action
• Somatic Division manages sensory and motor information
• Sensory nerves control senses
• Sensory nerves transmit information to the brain then comes back as motor output

Autonomic Division

• Autonomic division governs involuntary actions
• The sympathetic division is responsible for the fight or flight response
• The sympathetic division is triggered by stress and danger
• The parasympathetic division balances the sympathetic division
• The parasympathetic division is responsible for relaxation and digestion
• The parasympathetic division follows the rest and digest or feed and breed principle