Psychology

• Neuron


  Also called nerve cells, are cells of the nervous system that communicate with each other, as well as muscle and gland cells
• Neurons


  • Responsible for receiving sensory input, processing this information, sending motor commands to our muscles, or for transforming and relaying the electrical signals at every step in between
• Features of Neurons


  • Dendrites
  • Cell body
  • Axon
  • Axon Terminals
  • Myelin Sheath
• Dendrites


  Extensions of the cell body that receive neurotransmitters from other cells and convert neurotransmitters into electrical nerve impulses and pass towards cell body
• Cell body


  Also called a soma, contains a nucleus that controls the metabolism and maintenance of the cell, responsible for the life processes of the cell
• Axon


  A long, narrow tube that carries the information (neural impulse) toward the terminal branches away from the cell body
• Axon Terminals


  The enlarged points of axon branches that store neurotransmitters and release them into the synaptic cleft
• Myelin Sheath


  Fatty covering of the axon that acts as an insulator protecting the axon from stimuli that could interfere with electrical nerve impulse transmission, increases the speed and conduction of transmission
• Types of Neurons


  • Sensory Neurons
  • Motor Neurons
  • Interneurons
• Sensory Neurons


  Process sensory information from the sense organ and carry the sensory messages to the spinal cord and brain (CNS)
• Motor Neurons


  Carry motor messages from the spinal cord and brain (CNS) to the muscles, glands and organs of the body
• Interneurons


  Act as the connection between sensory neurons and motor neurons, transfer messages from sensory neurons to motor neurons within the CNS, shorter than other neurons and often do not have a myelin sheath
• Electro-Chemical Signal


  Neurons carry an electro-chemical signal that is passed onto other neurons, an electrical nerve impulse (electrical signal) travels through a neuron and the neurotransmitters (chemical signal) travel between the synapses of connecting neurons
• Synapse


  A junction between two neurons, between the end of the axon (terminal buttons) of the presynaptic (before the synapse) neuron and the receptor site on the dendrites of a post synaptic (after the synapse) neuron
• Neurotransmitters


  Molecules found within the nervous system that act as chemical messengers, allow neurons to communicate by relaying information across the synapse and to glands and muscle cells
• Stages in Neurotransmission


  1. Electrical nerve impulses (action potential) travel to the Axon terminal in the pre-synaptic neuron

  2. The action potential causes neurotransmitters to be released from vesicles in the Axon terminals

  3. Neurotransmitters diffuse across the synaptic cleft

  4. Neurotransmitters sponge too sites on the dendrites of the post-synaptic neuron

  5. Dendrite converts neurotransmitters into electrical nerve impulses which travel to the cell body
• Direction of Transmission
• The speed of the action potential through neurons depends on the thickness of the myelin sheath that covers the Axon
• Neurotransmitters


  Chemical messages sent between neurons so they can communicate, they are triggered & released by electrical impulses arriving at the axon terminal, they diffuse and attach to receptions on the membrane of the following neurons dendrite, this causes an electrical signal to be released in the next neuron
• Common neurotransmitters and their effects

  • Dopamine - Involved in learning, attention and pleasurable sensations, Parkinson's disease
  • Serotonin - Involved in sleep and mood, Deficits are linked to depression, Drugs like Prozac increase the availability of serotonin
  • Noradrenaline - Helps the body deal with danger or threat, Important in memory retrieval, Noradrenaline dysfunction is associated with mental disorders, especially depression
  • Endorphins - Regulate our feelings and perceptions of pain – the body's natural pain-killing drugs that are released when the body's stressed, Released when you experience positive mood
• Serotonin


  The neurotransmitter typically associated with regulating and improving mood, depression is a mood disorder that is partly influenced by serotonin, instead of serotonin moving effectively from one axon terminal to the pre-synaptic neuron and binding to the receptors on the dendrite of a post-synaptic neuron, some of the serotonin moves up and is reabsorbed into the axon terminal, this means that not enough serotonin travels through the synaptic cleft
• Prozac


  A SSRI (Selective Serotonin Retake Inhibitor) that inhibit the reabsorption of serotonin in the brain which allows more of the neurotransmitter to successfully pass through
• Regular exercise has also been found to increase neural transmission of serotonin in the brain
• Biological psychology


  A discipline of psychology that studies the connections between biological processes and psychological experiences
• Biological psychology


  • To understand it, we need to understand how and why we perceive the world the way we do
  • Involves the nervous system
  • Involves brain structure and function
  • Involves brain plasticity
• Parts of the nervous system

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Central Nervous System (CNS)


  Brain and spinal cord
• Peripheral Nervous System (PNS)


  Nerves outside of the brain and spinal cord that carry sensory information to the CNS and motor messages from the brain to organs and muscles
• Divisions of the PNS

  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  Carries sensory information to the CNS and motor messages from the CNS to skeletal muscles
• Autonomic Nervous System (ANS)


  Carries motor messages from the brain to internal glands and organs and sensory messages from the glands and organs to the brain
• Divisions of the ANS


  • Sympathetic Nervous System
  • Parasympathetic Nervous System
• Sympathetic Nervous System


  Regulates glands and internal organ function to physically prepare the body for increased activity during heightened physical or emotional stress
• Parasympathetic Nervous System


  Revives bodily functioning produced by the sympathetic nervous system by calming the body and maintaining an energy level suitable for normal bodily functioning
• Sympathetic Nervous System


  Controls the 'flight or fight' response
• Parasympathetic Nervous System


  Controls the 'rest and digest' response
• Effects of Sympathetic and Parasympathetic Nervous Systems

  • Pupils of the eyes: Sympathetic - Pupils dilate, Parasympathetic - Pupils contract
  • Salivary glands: Sympathetic - Saliva production inhibited, Parasympathetic - Saliva production stimulated
  • Heart: Sympathetic - Heart rate increases, Parasympathetic - Heart rate decreases
  • Digestive tract: Sympathetic - Digestion inhibited, Parasympathetic - Digestion is stimulated
• Brain


  Adult brain is about the size of a small cauliflower and weighs around 1.4kg
• Human brain


  • Has the same basic structure as other mammal brains but is larger in relation to body size than any other brains
  • The cerebrum makes up 85% of the brain's weight
  • It contains about 86 billion nerve cells – gray matter
  • It contains billions of nerve fibres (axons and dendrites) – white matter
• Brain development in embryo

  1. First develops into 3 bulges that later develop into Hindbrain

  2. Midbrain

  3. Forebrain