Human Nervous System Quiz

Study Notes

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.

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

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

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

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)

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

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

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

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

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