The nervous system

• Nervous system: collection of organs that controls and coordinates functions throughout the body that responds to internal and external stimuli.
• Specialized cells carry messages from one cell to another
• Cells that transmit these impulses are called neuron
• 3 types of neurons: sensory, motor, interneurons
• Sensory: carry impulses from sense organs to spinal cord and brain
• Motor: carry impulses from the brain to spinal cord to muscles and glands
• Interneurons: connect sensory and motor neurons
• Cell body (soma): largest part; contains nucleus and most cytoplasm. Most metabolic activities occur here
• Dendrites: short and branched extensions, carry impulses from environment toward cell body
• Nucleus: contains genetic material (chromosomes) including information for cell development
• Myelin sheath: insulating membrane surrounding axon
• Axon: long fiber which carries impulses away from cell body, neurons only have one axon
• Schwann cells: keeping the neuron alive and covered with myelin sheath
• Nerve ending: send messages to you brain when you feel sensations
• Synapse: space between neurons, where neurons can transfer an impulse to another cell
• Human nervous system: central nervous system & peripheral nervous system
• Brain: made of 50-100 billion neurons. Has 4 lobes and regions
• Frontal lobe: memory and judgement
• Temporal lobe: long term memory
• Occipital lobe: vision processing
• Parietal lobe: sensory processing, spatial awareness, language, memory, and consciousness
• Spinal cord: connects the brain to nerves throughout the body
• Spinal cord: main communication link between brain and body
• Reflex is a quick automatic response to a stimulus
• Peripheral nervous system: A network of nerves that connects the brain to the rest of the body.
• Sensory division: transmits impulses from sense organs to the cns
• Motor division : transmits impulses from cns to muscles and glands
• Under motor division:

  1. Somatic nervous system - regulates conscious controlled activities
  2. Autonomic nervous system - regulates activites that are automatic
• Autonomic nervous system subdivisions

  1. sympathetic - responsible for increasing activity in most systems
  2. Parasympathetic - responsible in slowing down activities