Sistema Nervoso: Visão Geral

General Overview

• The nervous system is a complex network of specialized cells, neurons, that transmit information throughout the body.
• It's responsible for coordinating actions, processing sensory information, and regulating bodily functions.
• Two major divisions: the central nervous system (CNS) and the peripheral nervous system (PNS).

Central Nervous System (CNS)

• Composed of the brain and spinal cord.
• The brain serves as the control center for thoughts, emotions, memory, and voluntary actions.
  • Subdivisions include cerebrum, cerebellum, and brainstem.
• The spinal cord transmits information between the brain and the rest of the body.
  • Acts as a pathway for reflexes and other involuntary responses.
• Protected by the skull and vertebrae.

Peripheral Nervous System (PNS)

• Connects the CNS to the rest of the body.
• Composed of nerves that extend from the brain and spinal cord to various organs and tissues.
• Divided into the somatic and autonomic nervous systems.

Somatic Nervous System

• Controls voluntary movements of skeletal muscles.
• Sensory neurons transmit information about touch, temperature, and pain to the CNS.
• Motor neurons carry signals from the CNS to the muscles, initiating movement.

Autonomic Nervous System

• Controls involuntary functions, such as heart rate, digestion, and breathing.
• Further divided into sympathetic and parasympathetic divisions.

Sympathetic Nervous System

• Activated during stress or excitement.
• "Fight-or-flight" response.
• Increases heart rate, blood pressure, and breathing rate.
• Dilates pupils.

Parasympathetic Nervous System

• Activated during relaxation or rest.
• "Rest-and-digest" response.
• Decreases heart rate, blood pressure, and breathing rate.
• Constricts pupils.

Neurons

• Basic functional units of the nervous system.
• Contain a cell body, dendrites, and an axon.
• Dendrites receive signals, axons transmit signals.
• Communicate with each other through synapses, releasing neurotransmitters.

Neurotransmitters

• Chemical messengers that transmit signals across synapses.
• Examples include dopamine, serotonin, acetylcholine, and norepinephrine.
• Different neurotransmitters have different effects on the body.

Sensory Receptors

• Specialized cells that detect stimuli from the environment or within the body.
• Different types of receptors exist for different sensations, such as touch, light, sound, and taste.

Glial Cells

• Supporting cells of the nervous system.
• Provide support, insulation, and nourishment for neurons.
• Outnumber neurons in the brain.

Spinal Cord

• Important for relaying messages between the brain and the rest of the body.
• Contains tracts of nerve fibers that transmit sensory and motor information.
• Involved in simple reflexes.

Brain Structure

• Different regions of the brain perform specialized functions.
• Cerebrum is responsible for higher cognitive functions, like thinking, learning, and memory.
• Cerebellum coordinates movement and balance.

Brain Function

• The brain integrates information from various sources, leading to thoughts, emotions, and actions.
• Different regions are responsible for different processes across brain functions.

Development

• The nervous system develops from an early embryonic structure.
• Neurons develop and migrate to their designated locations.
• Connections between neurons form throughout life and are modified by experience.

Disorders

• Various neurological disorders can affect the nervous system.
• Examples include Parkinson's disease, Alzheimer's disease, multiple sclerosis, and stroke.