Nervous System

• Central Nervous System (CNS)


  Responsible for receiving and processing information on changes to your environment. Consists of the brain and spinal cord.
• Central Nervous System (CNS)

  • Contains sensory neurons which carry neural messages to the CNS
  • Contains inter neurons which carry neural messages through the CNS (in between the sensory and motor neurons)
• Peripheral Nervous System (PNS)


  Consists of all the nerves located outside the central nervous system. Divided into somatic nervous system and autonomic nervous system.
• Peripheral Nervous System (PNS)

  • Contains motor neurons which carry neural messages from the CNS to an effector (muscle, organ or gland)
• Types of Neurons


  • Sensory neuron
  • Inter neuron
  • Motor neuron
• Axon


  A single, tubelike extension that transmits neural information to other neurons
• Dendrite


  A part of the neuron that is on the inside and finger-like, transmits information to the soma (cell body)
• Myelin Sheath


  A white, fatty substance (made up of certain types of glial cells) that surrounds and insulates the axon, allowing for rapid movement of the message along the axon without being interrupted or distorted
• Axon Terminals


  Small structures like sacs that store and secrete neurotransmitter that is manufactured by the neuron and carries its chemical message to other neurons or cells
• Soma


  The body of an organism, where all the information is integrated before sent to the Axon
• Synapses


  The gap between each neuron, connecting neurons and helping transmit information from one neuron to the next
• Nodes of Ranvier


  The gaps formed between the myelin sheath where the axons are left uncovered, allowing the generation of a fast electrical impulse along the axon
• Nucleus


  An oval shaped membrane-bound structure found in the soma or body of the neuron, to guide the axon hillock that generates the impulses throughout the axon
• Terminal buttons


  Found at the end of the axon terminals, responsible for sending signals to other buttons through the synapses
• Neurotransmitters


  Found at the end of each axon terminal (at the synaptic buttons), transmitting the electrical impulse from the presynaptic neuron to the postsynaptic neuron
• How neural messages travel along each neuron

  1. Neurotransmitters move across the synapse and bind to receptors on the membrane of the dendrites of the next neuron

  2. This may result in triggering the receiving neuron to convert the message into a nervous impulse and conduct it along its axon

  3. When it reaches the axon terminal, neurotransmitters are released into the synapse to be received by the dendrites of the next neuron

  4. This continues until the message reaches a motor neuron, which then communicates the message to an effector, such as a muscle or gland
• Reflex Arc


  A quick response to a stimulus that does not involve the brain (for example, knee jerk). The message travels from receptor to sensory neuron to interneuron in the spinal cord then directly via the motor neuron to the effector.
• Reflex Arc vs Conscious Action

  A reflex arc is an automatic response to a stimulus, while a voluntary response is a conscious decision. Reflex arcs are rapid and involuntary responses to a stimulus that do not require conscious thought.
• Your nervous system involves the use of both electrical signals (nerve impulses) and chemical signals (neurotransmitters)
• Four Lobes of the Brain

  • Frontal Lobe
  • Occipital Lobe
  • Parietal Lobe
  • Temporal Lobe
• Frontal Lobe


  Enables the brain to think abstractly and creatively, solve problems, reflect upon events and make judgments. Responsible for language and creative thinking.
• Occipital Lobe


  Entirely dedicated to managing our vision, interpreting how we see things around the world.
• Parietal Lobe


  The control centre for all the body's somatosensory input, giving us our sense of touch, our ability to understand form through touch, and our recognition of stimuli from our own bodies (pain, temperature, pressure, etc). Also aids in some speech and visual functions.
• Primary Somatosensory Cortex


  Located at the top of the parietal lobe and next to the primary motor cortex, involved in the recognition of stimuli from our own bodies and the outside world (pain, temperature, pressure, etc).
• Temporal Lobe


  Primarily responsible for processing auditory information from the ears. Also houses some peripheral language and speech functions, and gives us our musical abilities.
• Cerebellum


  Coordinates fine muscle movements and regulates posture and balance. Particularly active when learning a new movement or performing a sequence of movements where the next movement cannot be predicted in advance.
• Cerebrum


  The largest part of the brain, responsible for higher-order thinking (such as problem solving and making decisions) and controlling speech, conscious thought and voluntary actions. Also involved in learning, remembering and personality.
• Brain Stem


  Regulates life support systems, such as heart rate, breathing, and blood pressure. Controls involuntary actions like breathing, heartbeat, blood pressure, coughing, vomiting, sneezing and salivating.
• Medulla


  Lowest part of the brain and a continuation of the spinal cord, connecting the brain.
• Pons


  A small bundle of neural tissue involved in sleep, dreaming and arousal from sleep, as well as helping control breathing and coordination of some muscle movements.
• The brain is divided into three parts: cerebellum, cerebrum and brain stem
• DNA


  Contains the instructions needed for an organism to develop, survive and reproduce.
• Structure of DNA


  • Phosphate group
  • Sugar group (deoxyribose)
  • Base (one of 4, adenine (A), thymine (T), guanine (G), cytosine (C))
• Phosphodiester bond


  The line connecting the Phosphate and sugar group
• Complementary base pairs


  G > C (Vice versa)

  A > T (Vice versa)
• Hydrogen bonds


  Hold the bases together in DNA
• Examples of stimuli


  • Sight
  • Smell
  • Touch
  • Sounds
  • Taste
• Examples of receptors


  • Receptors of vision
  • Receptors of balance
  • Receptors of taste
  • Receptors of smell
  • Receptors on the skin
• Examples of effectors


  • Pancreas
  • Ovary
  • Triceps
  • Biceps