AP1 - Chapter 11 - Nervous System

• Central Nervous System


  (CNS) Consists of the brain and spinal cord

  
• Peripheral Nervous System


  (PNS) Consists of all nerves and receptors that are not part of the brain or spinal cord.

  
• What are the four major parts of the brain?

  Cerebrum, Cerebellum, Brain Stem, and Diencephalon

  
• What are the three functions of the nervous system?

  Sensory Function (Afferent), Integrative Function, and Motor Function (Efferent)

  
• What is a Sensory Function (Afferent)?

  It carries information from the PNS to the CNS.
• What is an Integrative Function?


  When the brain is processing the information.
• What is a Motor Function (Efferent)?


  It carries the motor commands from the CNS to the PNS.
• What are the two types of cells in the nervous system?

  Neurons and Neuroglia (glial cells).
• Neurons


  It transmits the nerve impulse. Does not replicate nor replace themselves when injured.

  
• Neuroglia (glial cells)


  They are the most abundant nerve cell that supports and nourishes the neurons.

  
• Parts of a Neuron

  Dendrites, Cell body, Ganglion (ganglia), Axon, Axon terminals (synaptic knobs), Myelin sheath (myelin), Schwann cells, and Nodes of Ranvier.

  
• Dendrites


  Branchlike part of the neuron that transmits the nerve impulse toward the cell body.

  
• Cell body


  Located in the CNS and contains DNA.

  
• Ganglion (ganglia)


  Group of cell bodies in the PNS.
• Axon


  Carries impulses away from cell body to the target organ.

  
• Axon terminals (synaptic knobs)


  Ends of the axon that stores neurotransmitters.

  
• Myelin sheath (myelin)


  White fatty material that insulates the axon and speeds up nerve impulses.

  
• What is the difference between Myelinated axon and Unmyelinated axon?

  Myelinated axons have myelin and unmyelinated axons do not contain myelin.

  
• White matter


  Myelinated axons

  
• Gray matter


  Unmyelinated axons

  
• Interneurons


  Transmit nerve impulses from one neuron to another.

  
• What are the four types of cells in the CNS?

  Astrocytes, Oligodendrocytes, Ependymal cells, Microglia

  
• Astrocytes


  Help maintain our blood brain barrier.

  
• Oligodendrocytes


  Produces myelin in the CNS, can produce enough myelin for 70 different axons

  
• Ependymal cells


  Line the cavities within the brain and contain cilia to keep the cerebral spinal fluid moving.

  
• Microglia


  Cleans up the debris in the CNS.

  
• Satellite cells


  Surround neuron cell bodies in the ganglia of the PNS. Help regulate the chemical environment of the neurons.

  
• Schwann cells


  Produce myelin in the PNS.

  
• Nodes of Ranvier


  Gaps between the myelin and is the only place that a nerve impulse can happen.

  
• Blood brain barrier


  Made up of tight junctions which prevent toxic substances from entering the blood stream in our brain.
• Nerve impulses


  Electrical signal from a neuron to another structure.
• Action potential


  Nerve impulse.

  
• Potassium (K+)


  We have a lot of potassium on the inside of our cells, which can leak out.
• Sodium (Na+)


  A lot of sodium is on the outside of our cells.
• Polarization


  The resting state of a neuron, the inside of the cell is more negative than the outside of the cell.

  
• Depolarization


  Sodium ions are flooding into the cell.

  
• Repolarization


  Potassium is leaving the cell but leaves slowly.

  
• Refractory period


  An action potential cannot take place because the axon is busy and directs the action potential to continue down the axon.

  
• All-or-nothing manner


  Action potential does not lose strength with distance.
• Saltatory conduction


  When the action jumps from one Node of Ranvier to the next.