Central Nervous System Overview

Central Nervous System (CNS)

• Brain

  • Divided into four main lobes:
    • Frontal: executive functions, decision-making, motor control.
    • Parietal: sensory perception, spatial awareness.
    • Temporal: auditory processing, memory, language.
    • Occipital: vision processing.
  • Cerebellum: coordination, balance, fine motor skills.
  • Brainstem: regulates vital functions (heart rate, breathing); connects brain to spinal cord.

• Spinal Cord

  • Transmits signals between the brain and the body.
  • Composed of segments (cervical, thoracic, lumbar, sacral).
  • Contains gray matter (neurons) and white matter (myelinated axons).

Peripheral Nervous System (PNS)

• Somatic Nervous System: controls voluntary movements and sensory information.
• Autonomic Nervous System: regulates involuntary functions.
  • Divided into:
    • Sympathetic: "fight or flight" response.
    • Parasympathetic: "rest and digest" response.

Neurons

• Basic unit of the nervous system.
• Composed of:
  • Cell Body: contains nucleus and organelles.
  • Dendrites: receive signals from other neurons.
  • Axon: transmits signals away from the cell body.
  • Myelin Sheath: insulates axon, speeds up signal transmission.
  • Synapse: junction between neurons where neurotransmitter release occurs.

Glial Cells

• Supportive cells in the nervous system.
• Types include:
  • Astrocytes: maintain blood-brain barrier, regulate blood flow.
  • Oligodendrocytes: produce myelin in CNS.
  • Schwann Cells: produce myelin in PNS.
  • Microglia: immune defense in the CNS.

Blood Supply

• Circle of Willis: arterial circle at the base of the brain, ensures collateral circulation.
• Major arteries: carotid arteries, vertebral arteries.

Functional Areas

• Motor Cortex: voluntary movement control.
• Sensory Cortex: processes sensory input.
• Association Areas: integrate information from different modalities.

Neurotransmitters

• Chemical messengers facilitating communication between neurons.
• Key neurotransmitters include:
  • Dopamine: movement, reward.
  • Serotonin: mood regulation.
  • Acetylcholine: muscle activation, memory.

Meninges

• Protective membranes covering the brain and spinal cord.
• Layers include:
  • Dura Mater: tough outer layer.
  • Arachnoid Mater: middle layer with cerebrospinal fluid (CSF).
  • Pia Mater: delicate inner layer adhering to the brain.

Cerebrospinal Fluid (CSF)

• Cushions and protects the brain and spinal cord.
• Circulates in the subarachnoid space and ventricles of the brain.

Anatomical Terms

• Anterior (Ventral): front.
• Posterior (Dorsal): back.
• Medial: toward the midline.
• Lateral: away from the midline.
• Proximal: closer to the trunk.
• Distal: further from the trunk.

Central Nervous System (CNS)

• Brain Structure: Comprises four main lobes:
  • Frontal Lobe: Responsible for executive functions, decision-making, and motor control.
  • Parietal Lobe: Involved in sensory perception and spatial awareness.
  • Temporal Lobe: Handles auditory processing, memory, and language.
  • Occipital Lobe: Dedicated to vision processing.
• Cerebellum: Coordinates movements, balance, and fine motor skills.
• Brainstem: Maintains vital functions like heart rate and breathing; acts as the connection between the brain and spinal cord.
• Spinal Cord: Facilitates signal transmission between the brain and body, with segments named cervical, thoracic, lumbar, and sacral; comprises gray matter (neurons) and white matter (myelinated axons).

Peripheral Nervous System (PNS)

• Somatic Nervous System: Governs voluntary movements and sensory information processing.
• Autonomic Nervous System: Manages involuntary bodily functions, further divided into:
  • Sympathetic Division: Prepares the body for "fight or flight" reactions.
  • Parasympathetic Division: Promotes "rest and digest" activities.

Neurons

• Fundamental units of the nervous system designed for signal transmission.
• Cell Body: Contains the nucleus and essential organelles for neuron function.
• Dendrites: Receive incoming signals from other neurons.
• Axon: Sends signals away from the cell body to other neurons or muscles.
• Myelin Sheath: Envelops axons, enhancing signal transmission speed.
• Synapse: Connection point where neurotransmitters are released between neurons.

Glial Cells

• Supporting cells that ensure the proper functioning of the nervous system.
• Astrocytes: Protect the blood-brain barrier and regulate cerebral blood flow.
• Oligodendrocytes: Responsible for the formation of myelin in the CNS.
• Schwann Cells: Myelinate axons in the PNS.
• Microglia: Serve as the immune defense in the CNS.

Blood Supply

• Circle of Willis: An arterial circle at the brain's base that provides collateral circulation.
• Major arteries supplying the brain include the carotid arteries and vertebral arteries.

Functional Areas

• Motor Cortex: Area controlling voluntary movements.
• Sensory Cortex: Processes and interprets sensory information.
• Association Areas: Integrate information from various sensory modalities, aiding in complex functions.

Neurotransmitters

• Bioactive chemicals that enable neuron communication.
• Dopamine: Involved in movement regulation and reward pathways.
• Serotonin: Influences mood and emotional regulation.
• Acetylcholine: Key player in muscle activation and memory processes.

Meninges

• Three protective membranes that encase the brain and spinal cord:
  • Dura Mater: Tough, protective outer layer.
  • Arachnoid Mater: Middle layer harboring cerebrospinal fluid (CSF).
  • Pia Mater: Thin, delicate inner layer closely adhering to the brain's surface.

Cerebrospinal Fluid (CSF)

• Provides cushioning and protection for the brain and spinal cord, circulating within the subarachnoid space and the brain's ventricles.

Anatomical Terms

• Anterior (Ventral): Referring to the front of the body.
• Posterior (Dorsal): Pertaining to the back of the body.
• Medial: Toward the midline of the body.
• Lateral: Away from the midline.
• Proximal: Closer to the trunk or point of origin.
• Distal: Further from the trunk or point of origin.