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Mechanics of the Nervous System

• The nervous system is a network of neurons in the brain, spinal cord, and periphery.
• The central nervous system (CNS) includes the brain and spinal cord, while the peripheral nervous system (PNS) consists of nerves and ganglia.
• The cerebrum is a part of the brain that mediates information transmission between the brain and body below the neck, while the spinal cord coordinates certain reflexes and is a conduit for sensory and motor information.
• The spinal cord is protected by vertebrae and has a core of grey matter surrounded by white matter, with dorsal and ventral roots for afferent and efferent neurons.
• The PNS connects the CNS to limbs and organs via cranial and spinal nerves, conveys information from the environment to the CNS through afferent neurons, and transmits messages from the CNS to muscles and glands via efferent neurons.
• The PNS includes 43 pairs of nerves, with 12 cranial nerve pairs and 31 spinal nerve pairs.
• The somatic nervous system controls voluntary body movement, receives sensory information, and controls spinal nerves that innervate skin, joints, and muscles.
• The autonomic nervous system controls involuntary functions and the internal environment, with afferent neurons carrying sensory information and efferent neurons controlling smooth muscle, cardiac muscle, and glands.
• The autonomic nervous system has three further subdivisions: the sympathetic nervous system, the parasympathetic nervous system, and the enteric nervous system.
• The sympathetic nervous system coordinates the fight or flight response, while the parasympathetic nervous system coordinates the rest and relax response.
• The enteric nervous system lines the gastrointestinal tract and controls digestion, including swallowing, enzyme release, and nutrient absorption.
• Understanding the structure and function of the nervous system is important for understanding the mechanics of action potential signal transmission along axons.