Nervous System Fundamentals Quiz

Nervous System Fundamentals

• The nervous system is the body's master control and communication system.
• It receives information from inside and outside the body, processes this information, and then responds accordingly.
• The nervous system is organized into two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS).

Central Nervous System (CNS)

• The CNS includes the brain and spinal cord.
• The CNS processes sensory information, coordinates responses, and controls higher-level functions like intelligence, memory, and behavior.
• The CNS contains neural tissue, connective tissue, and blood vessels.

Peripheral Nervous System (PNS)

• The PNS consists of all neural tissue outside the CNS, including nerves and ganglia.
• The PNS delivers sensory information to the CNS and motor commands from the CNS to muscles and glands throughout the body.
• The PNS also contains sensory receptors that detect changes in the internal and external environment.

Functional Divisions of the Nervous System

• The nervous system has an afferent (sensory) division and an efferent (motor) division
• The afferent division delivers sensory information from the PNS to the CNS.
• The efferent division carries motor commands from the CNS to muscles and glands.
• The efferent division is further categorized into somatic (voluntary) and autonomic (involuntary) nervous systems
  • The Somatic nervous system controls voluntary activities like skeletal muscle movement.
  • The Autonomic nervous system regulates involuntary activities including heart rate, digestion, and glandular secretions. The autonomic nervous system is further split into the sympathetic and parasympathetic divisions.

Nervous Tissue

• Nervous tissue consists of neurons and neuroglia (supporting cells).
• Neurons process and transmit nerve signals.
• Neuroglia nourish, support, and protect neurons.

Neuron Structure

• The typical neuron consists of a cell body, dendrites, and an axon.
  • The cell body contains the nucleus and other organelles.
  • Dendrites receive signals from other neurons.
  • The axon transmits signals away from the cell body.
• The axon often has a myelin sheath for faster signal transmission.

Neuroglia (Supporting Cells)

• Neuroglia in the CNS (central nervous system):
  • Astrocytes: Most abundant, provide support and form the blood-brain barrier (BBB).
  • Oligodendrocytes: Form myelin sheaths around axons in the CNS.
  • Microglia: Act as the immune system in the CNS, and are defensive in nature.
  • Ependymal cells: Line cerebrospinal fluid-filled cavities.
• Neuroglia in the PNS (peripheral nervous system):
  • Schwann cells: Form myelin sheaths around axons in the PNS that allow for regeneration if damaged.
  • Satellite cells: Surround neuron cell bodies in ganglia; provide support and regulate environment around the neurons.

Neural Synapse

• Neurons communicate with each other at synapses.
• Neurotransmitters are chemical messengers that transmit signals across synapses.

Classification of Neurons

• Neurons are classified by their structure and/or function.
  • Anatomical classification include Unipolar, Bipolar, Pseudounipolar, and Multipolar based on their shape.

Functional Classification

The following additional classifications are based on the directionality of the signal:

• Sensory neurons transmit messages to the central nervous system.
• Motor neurons transmit messages away from the central nervous system.
• Interneurons connect sensory and motor neurons.

Myelin Sheath

• The myelin sheath is a fatty substance that coats some axons.
• It acts as insulation and speeds up signal transmission.

Nodes of Ranvier

• Nodes of Ranvier are gaps in the myelin sheath.
• Action potentials jump between these gaps, increasing transmission speed. This is called saltatory conduction.