The Nervous System

• Helps detect changes and coordinates with the other body systems to maintain homeostasis
• Coordinate fast response, including reflex responses
• Works closely with endocrine (hormones) system to detect changes in the external environment to maintain a constant internal environment
• The Nervous System is made up of the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
• Both Nervous Systems are made up of nerve cells called neurons
• The CNS is composed of the brain and spinal cord.
• The PNS is composed of the nerves that connect the CNS to the rest of the body
• The PNS relays information to and from the CNS
• The CNS has a major role in controlling the activity of other organs and cells in the body.
• Neurons receive signals or information
• Neurons integrate incoming signals to determine whether the information should be passed along
• The Cell body is also known as soma
• The Cell body also contains the nucleus
• Dendrites and Axons extend from the cell body
• Dendrites are short, branching processes extending from the cell body
• Dendrites receive and process incoming information
• Signals that the dendrites receive can either be excitatory or inhibitory.
• If the neuron fires, a nerve impulse (also known as and action potential) is conducted down the axon
• Axon is the longer process extending from the Cell body
• Dendrites deliver information to the cell body
• Axon carries information away from the cell body
• The Myelin Sheath helps speeds up the transmission of a nerve impulse down a long axon, and protect the neurons
• Myelin sheaths not found on dendrites, only on axons
• Myelin sheaths are produced by Schwann cells and act like insulation on a electrical wire
• Myelin sheaths are made of fat and protein
• The gaps between the myelin sheath are called nodes of Ranvier.
• Towards the end of a neuron, the axon splits into many branches known as the axon terminals or synaptic terminals.
• Axon terminals make connections to target cells by releasing neurotransmitters
• Axons are specialised to conduct action potentials
• The Cell body controls cell functions and produces proteins for the cell
• Neurons communicate signals to target cells, other neurons, muscles and glands