SCIENCE : The Nervous System

• Neuron


  A cell that transmits electric impulses-typical neuron consists of a cell body, a long axon and shorter branching structures called dendrites
• Axon


  The part of a neuron that carries impulses to other neurons-thread-like structures that range in length from less than 1mm to about 1m
• Myelin sheath


  A fatty layer around neurons which increases the speed of impulses-insulates the axon, allowing signals to be passed quickly around the body
• Dendrites


  Part of a neuron that receives messages from other neurons-branch out to receive messages from multiple neurons and send impulses to the cell body for processing
• Cell body


  Part of a neuron that contains the nucleus-to control all of the functions of the neuron
• Parasympathetic nervous system


  Predominates in quiet "rest and digest" conditions-slows and relaxes-reduce activities-help controls body's response during rest
• Sympathetic nervous system


  Controls "fight-or-flight" responses-prepares the body for tough physical activity-increases heart rate, blood pressure-responding to dangerous and stressful situations
• Temporal Lobe


  Emotions, memories, language, parts of visual perception
• Axon terminal


  The ends of axons which transmit messages to other cells via use of neurotransmitters at synapses
• Brain


  Centre of the nervous system, sensory information and direct motor responses control all body function, made up of billions of nerve cells
• Central nervous system


  The brain and the spinal cord, receives information from the sense organs and organizes the body's response
• Peripheral nervous system


  All of the nerves extending from the brain and the spinal cord-relays messages between the sense organs, central nervous system and the muscles and glands
• Motor neuron


  A cell that sends messages from the central nervous system to an effector-pass impulses from the brain and or spinal to a muscle or gland, causing it to act
• Sensory neuron


  A cell that sends messages from receptors to the central nervous system-pass a signal to the brain or spinal cord, allowing us to feel a sensation
• Interneuron


  A cell that sends messages within the central nervous system-relay messages from sensory neurons to motor neuron, for example knee-jerk
• Parietal lobe


  Processing the sense of touch, heat, pressure and pain, spatial coordination (space between things)
• Voluntary


  Executed consciously under the control of the brain-example like running and dancing
• Neurotransmitter


  Chemical compounds which transmit messages across synaptic gaps/clefts from one neuron to another, controlled by the nervous system
• Hemispheres


  The cerebrum is divided into two halves, the right and the left, each hemisphere controls the opposite side of the body, the left controls speech, comprehension, arithmetic and writing, the right controls creativity, spatial ability, artistic and musical skills
• Frontal lobe


  Thinking, reasoning, decision making, personality
• Cerebellum


  Balance, motor movement and muscle memory
• Cerebrum


  Largest part of the brain, 90% brain volume, responsible for complex thoughts, divided two halves called the cerebral hemispheres
• Medulla


  The bottom-most part of your brain, where your brain and spinal cord connect-key conduit for nerve signal-help control heartbeat, breathing and blood pressure
• Spinal cord


  The conduit between the brain and the rest of the body-carries nerve signals
• Occipital lobe


  Visual perception of colour, form and motion
• Involuntary


  Movement that happen without thinking-example for breathing
• Effector


  An organ that acts in response to a stimulus-muscles and glands are types of effectors
• Stimulus


  Something an organism's nervous system can detect in the environment include smells, sounds, light or pain
• Receptor


  Cell that detects stimuli of specific type-organisms have different receptors to detect stimuli including light, colour, heat and sound
• Homeostasis


  The process of keeping the body running smoothly with stable internal environment
• Sensory organ


  A part of the body that detects stimuli-nose, tongue and eyes are examples of human sense organs
• Somatic


  A subdivision of your peripheral nervous system stretches to nearly every part of your body-deliver information from your senses to your brain-carry commands from your brain to your muscles so you can move around-voluntary movements
• Autonomic


  A component of the peripheral nervous system-regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion and sexual arousal-three anatomically distinct divisions-sympathetic, parasympathetic and enteric