Human Nervous System Quiz

The Nervous System

• The nervous system is widely distributed in the body and involves most organs.
• It collects stimuli from the environment, transforms them into nerve impulses, and passes them to a large, highly organized reception and correlation area where they are interpreted.

Functions of the Nervous System

• Three principal functions: sensory input, integration, and motor output.
• All actions, thoughts, and emotions can be boiled down into these three functions.

Sensory Input

• Special senses:
  • Eyes: sight
  • Nose: smell
  • Tongue: taste
  • Ear: hearing
  • Skin: touch
• Nociception: pain receptor
• Temperature
• Stretch receptor (bladder)

Integration

• The nervous system processes sensory input and decides what to do about it.
• "Fight or flight" response.

Motor Output

• The response that occurs when the nervous system activates certain parts of the body.

Types of Nervous System

• Two main categories:
  • Central Nervous System (CNS): brain and spinal cord
  • Peripheral Nervous System (PNS): nerves

Divisions of Peripheral Nervous System

• Sensory Division (Afferent): picks up sensory stimuli
• Motor Division (Efferent): sends signals from the CNS to the rest of the body
  • Somatic: voluntary
  • Autonomic: involuntary
    • Sympathetic: fight or flight
    • Parasympathetic: heart beat, peristalsis (movement of intestine muscles)

Cells of the Nervous System

• Two main cells:
  • Neurons: receive stimuli and send signals
  • Glial cells: protect, nourish, insulate, and help neurons send signals

Types of Glial Cells

• Central Nervous System:
  • Astrocytes
  • Microglial cells
  • Ependymal cells
  • Oligodendrocytes
• Peripheral Nervous System:
  • Satellite cells
  • Schwann cells

Glial Cell Functions

• Astrocytes:
  • Most abundant glial cells
  • Anchor neurons to blood supply (capillaries)
  • Allow exchange of ions between neurons and capillaries
• Microglial cells:
  • Provide immune defense against invading microorganisms in the brain and spinal cord
• Ependymal cells:
  • Create, secrete, and circulate Cerebrospinal fluid (CSF)
• Oligodendrocytes:
  • Produce an insulating barrier called myelin sheath
• Satellite cells:
  • Surround and support neuron cell bodies
• Schwann cells:
  • Wrap around axons and produce an insulating barrier called myelin sheath

Neuron Characteristics

• Longest lived cells
• Irreplaceable (amitotic)
• Huge appetite: consume 25% of daily calories

Neuron Structure

• Soma (cell body):
  • Life support
  • Contains organelles (nucleus, mitochondria)
• Dendrites:
  • Pick up signals and convey them to the soma
• Axon:
  • Long extension
  • Transmit electrical impulses away from the cell body to other cells

Types of Neurons

• Based on processes:
  • Multipolar neuron: majority, three or more processes from the soma (axon and several dendrites)
  • Bipolar neuron: two processes from the soma (axon and one dendrite), found in retina of the eye
  • Unipolar neuron: one process, usually seen in sensory receptors
• Based on function:
  • Sensory (afferent) neurons: pick up sensory stimuli and send them towards the CNS
  • Interneurons (association neurons): transmit signals between sensory and motor neurons, live within the CNS
  • Motor (efferent) neurons: send signals from the CNS to the rest of the body (muscles or glands), mostly multipolar

Test your knowledge of the human nervous system, including its functions, components, and processes. Learn about sensory integration and motor output!