Nervous System Overview

Nervous System Overview

• The nervous system controls and coordinates bodily functions and responses to environmental changes.
• It transmits messages via electrical signals.
• Neurons transmit electrical signals, triggering the release of neurotransmitters, which cause responses (e.g., muscle contraction, hormone release).
• The nervous system consists of the brain, spinal cord, and peripheral nerves.

Brain Structure and Protection

• The brain sits atop the body, protected by the skull.
• It's encased in cerebrospinal fluid (CSF) and meninges, providing a protective cushion.
• CSF and the meninges also protect the spinal cord.

Spinal Cord

• The spinal cord is a nerve bundle connecting the brain to the body.
• It relays information between the brain and the rest of the body.
• Spinal nerves emerge from the spinal cord and are part of the peripheral nervous system.
• The cauda equina, resembling a horse's tail, is a collection of nerves at the spinal cord's end, carrying information to and from pelvic organs and lower limbs.

Divisions of the Nervous System

• The nervous system has two major divisions: central nervous system (CNS) and peripheral nervous system (PNS).
• The CNS includes the brain and spinal cord. Its function is to relay, process, and analyze information.
• The PNS contains all other nerves. It receives sensory input and relays commands from the CNS to the body.

Peripheral Nervous System (PNS)

• The PNS is divided into the sensory and motor divisions.
• The sensory division transmits signals from sensory organs to the CNS.
• The motor division carries signals from the CNS to muscles or glands.
  • The motor division has two subdivisions: the somatic and autonomic nervous systems.
    • The somatic nervous system controls voluntary, conscious movements of skeletal muscles.
    • The autonomic nervous system controls involuntary functions. It regulates heart rate, sweating, digestion, salivation, and urination; responds to changes in body temperature; and controls the "fight or flight" response.

Autonomic Nervous System (ANS)

• The ANS is further subdivided into the sympathetic and parasympathetic nervous systems.
• The sympathetic nervous system generally increases body functions like heart rate, breathing rate, sweating, and the "fight or flight" response.
• The parasympathetic nervous system generally decreases bodily functions, like heart rate, breathing rate, sweating, and stimulates digestion, salivation, and urination.