The brain and nervous system

• The nervous system has 3 main functions: 

  1. Receive information 
  2. Process information 
  3. Coordinate a response to information 
• The nervous system can receive information:

  • Externally (vision, sound, etc)
  • Internally (muscles, joints, etc) 
• The nervous system - 2 parts:

  1. Central Nervous System (CNS)
  2. Peripheral Nervous System (PNS)
• The Central Nervous System - 2 parts:

  1. Brain
  2. Spinal cord
• Peripheral Nervous System - 2 parts: 

  1. Autonomic Nervous System 
  2. Somatic Nervous System 
• Autonomic Nervous System - 2 parts:

  1. Sympathetic Nervous System
  2. Parasympathetic Nervous System 
• CNS:

  • Processes information received through the sensory systems and other parts of the body. 
  • Activates appropriate actions. 
• The brain:

  • Intricate network of cells.
  • Processes information from the body’s external and internal environments. 
  • Overseas everything we see, think, and do. 
• Functions of nervous system

  -> Receive information: the vibrating air molecules are received at the ear and sent to the brain via the auditory nerve

  -> Process information: the brain processes the auditory information and interprets the sound as your mobile phone's ring tone

  -> Coordinate a response to information: the brain sends messages along nerve pathways to activate muscles to pick up the phone, check who's calling, and speak
• Spinal cord

  -> Receives sensory information from the body (via the PNS) and send these messages to the brain for processing

  -> Receives motor information from the brain and send it to relevant parts of the body (via the PNS) to control muscles, glands, and internal organs so appropriate actions can be taken

  -> Damage to spinal cord results in paralysis below the damage
• Spinal reflex

  -> Responses are involuntary and occur automatically in response to certain stimuli e.g. when touching something hot

  -> Purpose is to prevent damage/increase chances of survival
• PNS


  -> Peripheral nervous system

  -> Network of nerves outside the CNS that transmits information to and from the CNS
• SNS

  -> Somatic/skeletal nervous system

  -> Network of nerves that carry information to the CNS and motor information from the CNS

  -> This system is under complete voluntary control
• ANS

  -> Autonomic nervous system

  -> Network of nerves that carries messages between the CNS and the heart, lungs, and other internal organs and glands

  -> Regulates and controls the functioning of internal organs automatically (without having to think about it), and functions fairly independently of the CNS in maintaining the body's internal states and processes
• Sympathetic nervous system

  -> Arouses the body when we experience an extreme emotion, feel threatened, or suddenly experience stress

  -> It can very easily prepare the body for an immediate response in an emergency by releasing adrenalin, leading to higher energy supplies, alertness, and heart rate

  -> Uses the fight-flight-freeze response
• Parasympathetic nervous system

  -> In the absence of threat the parasympathetic nervous system helps to maintain the internal body environment in a steady, balanced state

  -> Counterbalances the activities of the sympathetic nervous system and restores the body to a state of calm once the need for the sympathetic nervous system activation has passed
• Sympathetic nervous system effects

  -> Pupils dilate (enhances vision by allowing more light)

  -> Digestive activity lowers (allows blood to momentarily flow to other areas)

  -> Bronchi relaxes (increases breathing, more O2)

  -> Heart rate accelerates (more blood and O2)

  -> Bladder relaxes
• Parasympathetic nervous system effects

  -> Constricts pupils

  -> Digestive activity continues

  -> Bronchi goes back to normal (steady breathing)

  -> Heart rate inhibits

  -> Bladder constricts
• Neuron

  -> Individual nerve cell that receives, processes, and transmits messages to other cells in the form of neural impulses (or action potential)

  -> They are called the 'building blocks' or 'primary functions' of the nervous system
• Dendrites

  Branch like extensions at the front end of the neuron that receive neurotransmitters from other neurons
• Cell body/soma

  Control center of a neuron, containing its nucleus and DNA
• Axon

  A cable like extension from the cell body of a neuron that sends messages to other neurons
• Axon terminal

  Branch like extensions of the axon at the end of a neuron that release neurotransmitters across the synapse to be received by other neurons
• Myelin sheath

  Fatty white tissue that surrounds the axons of neurons
• Synaptic gap

  Gap between the axon terminal and dendrites of two different neurons
• Synapse

  Made up of:

  1. Axon terminal of presynaptic neuron

  2. Synaptic gap

  3. Dendrites of postsynaptic neuron
• Neurotransmitters

  Chemical messengers that allow communication to occur between neurons
• Glutamate

  -> Plays a role in memory and learning and is the most common type of neurotransmitter in the CNS

  -> An excitatory neurotransmitter which increases the activity of a neuron when it is received

  -> Too much can lead to high pain sensitivity, too little can lead to inhibited memory
• Neurohormones

  -> Specific neurotransmitters that can be produced in the brain as well as in the body which are able to act both as neurotransmitters and hormones

  -> Have a long lasting effect and travel between the synaptic gap
• Endorphins

  -> Produced by the pituitary gland in the brain and in other parts of the body

  -> Natural painkillers that are released when we experience pain or stress to improve your mood and sense of well-being
• Cerebral cortex

  -> Main functions include sensory areas (receive/process sensory info), motor areas (initiate voluntary movement), and association areas (more complex functions that require integration of inputs of information- HOTS)
• Cerebral hemispheres


  -> Two almost symmetrical brain areas running from the front to the back of the brain (left and right hemispheres)
• Hemispheric specialisations


  -> Where one hemisphere has greater control over a particular function

  -> Damage to the left hemisphere often results in difficulties with language related activities such as understanding speech (Wernicke's area) and talking fluently (Broca's area)

  -> Damage to the right hemisphere often results in difficulties with tasks that involve visual and spatial abilities such as using a map to navigate an unknown location
• Left hemisphere specialisations

  -> Specialises in verbal and analytical functions

  -> Verbal functions involve the use or recognition of words such as in reading, writing, speaking, and the understanding of speech

  -> Analytical functions involve breaking a task down into its key parts and approaching it in a sequential step-by-step way

  -> E.g. applying a formula to solve a maths problem

  -> Controls voluntary movement of right-hand side of body
• Right hemisphere specialisations

  -> Specialises in non-verbal functions

  -> This includes visual and spatial thinking, recognising faces patterns and tunes, creative thinking, daydreaming, recognising emotions from facial cues

  -> E.g. raised eyebrow, trembling lips

  -> Controls voluntary movements of the left-hand side of body
• Prefrontal cortex

  -> Is located just behind the forehead

  -> Involved with sophisticated mental abilities (HOTS) e.g. reasoning, planning, problem solving, decision making, and symbolic thinking

  -> It is also involved with attention, regulation and expression of emotions, and personality
• Frontal lobe

  Responsible for planning and initiating voluntary body movements
• Primary motor cortex

  -> A strip of neural tissue located at the rear of each frontal lobe and roughly running across the top of your head

  -> Initiates and controls voluntary movements through its control of skeletal muscles

  -> A different area along the primary motor cortex is involved with the movement of each specific body part

  -> There is contralateral control and 'top-down' organisation
• Broca's area

  -> Specific area of cortex located next to the primary motor cortex in the left hemisphere of the frontal lobe

  -> Required for speech and supplies info to the appropriate motor cortex areas

  -> If damaged you would still know what you want to say but would find it difficult to produce the words
• Parietal lobe

  -> Processes and receives bodily or 'somatosensory' information including touch, temperature (from the skin), and information about muscle movement and the body's position (from muscles, tendons, and joints)

  -> It is also involved with attention and spatial reasoning