Overview of the Nervous System

Overview of the Nervous System

• The nervous system is a complex network of specialized cells that transmit information throughout the body.
• Its primary function is to coordinate and control bodily activities, enabling communication between different parts of the body.
• It allows organisms to react to stimuli and maintain homeostasis.

Structure of the Nervous System

• Composed of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).

• Central Nervous System (CNS): Composed of the brain and spinal cord.

• Brain: Interprets sensory information and initiates responses.

• Spinal cord: Connects the brain to the peripheral nervous system, transmitting signals between them.

• Peripheral Nervous System (PNS): Consists of nerves that branch out from the CNS to connect it with the rest of the body.

• Sensory (afferent) neurons: Carry sensory information from the body to the CNS.

• Motor (efferent) neurons: Carry signals from the CNS to muscles and glands in the body, initiating responses.

• Somatic nervous system: Controls voluntary movements.

• Autonomic nervous system: Controls involuntary functions (e.g., heart rate, digestion). Further divided into sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) branches.

Types of Neurons

• Neurons are specialized cells in the nervous system that transmit electrochemical signals.

• They are composed of:

• Cell body (soma): Contains the nucleus and other organelles.

• Dendrites: Receive signals from other neurons.

• Axon: Transmits signals away from the cell body.

• Myelin sheath: Insulating layer that speeds up signal transmission.

• Synapses: Junctions between neurons where signals are transmitted.

Neurotransmitters

• Chemical messengers that transmit signals across synapses.
• Different types of neurotransmitters have diverse functions, influencing various bodily processes like mood, memory, and movement.
• Key neurotransmitters include dopamine, serotonin, acetylcholine, norepinephrine, and GABA.

Sensory Systems

• The nervous system receives and processes information from the environment through sensory receptors.
• Different sensory systems are specialized to detect specific stimuli, such as light, sound, touch, taste, and smell.
• Each sensory system has specialized receptors that convert stimuli into electrical signals that are transmitted to the CNS.

Brain Regions and Functions

• The brain is divided into distinct regions with specific roles.
• Cerebrum: Largest part of the brain, responsible for higher-level functions such as thought, memory, and language. Divided into left and right hemispheres.
• Cerebellum: Coordinates movement and balance.
• Brainstem: Controls basic life functions like breathing, heart rate, and sleep-wake cycle. Includes the midbrain, pons, and medulla oblongata.

Neural Pathways

• Specific circuits of neurons that transmit information within the nervous system.
• These pathways allow for complex interactions and coordination of various bodily functions.
• Information travels from sensory organs to the brain (ascending) and from the brain to the effectors (descending).

Disorders of the Nervous System

• Many conditions can affect the nervous system, impacting its structure and function.

• Some examples include:

• Stroke: Disruption of blood flow to the brain.

• Multiple sclerosis: Autoimmune disease causing damage to the myelin sheath.

• Parkinson's disease: Neurodegenerative disorder affecting movement.

• Alzheimer's disease: Neurodegenerative disease characterized by memory loss.

• Epilepsy: Chronic disorder characterized by seizures.

Nervous System Development

• The nervous system develops from a simple structure to a complex network of interconnected neurons during embryonic development.
• It involves cell proliferation, migration, differentiation and formation of neural circuits.