biopsych

• The two roles of the human nervous system


  To collect, process and respond to information in the environment

  to co-ordinate the working of different organs and cells in the body
• the two subsystems of the nervous system


  peripheral nervous system

  central nervous system
• The divisions of the peripheral nervous system


  autonomic nervous system

  somatic nervous system
• The autonomic nervous system function


  governs all vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses

  Split into the sympathetic nervous system and the parasympathetic nervous system
• The parts of the central nervous system


  The brain: centre of all conscious awareness, the outer layer is called the cerebral cortex and is divided into two hemispheres

  The spinal cord: an extension of the brain, responsible for reflex actions
• The peripheral nervous system


  sends information to the CNS from the outside world and transmits messages from the CNS to muscles and glands
• The central nervous system


  is the origin of all complex commands and decisions
• The endocrine system


  One of the body's major information systems that instructs glands to release hormones directly into the bloodstream, these hormones are carried towards target organs in the body
• Gland


  An organ in the body that synthesises substances such as hormones
• Hormones


  chemical substances that circulate in the bloodstream and only affect target organs, they are produces in large quantities but disappear quickly
• The pituitary gland


  The main endocrine gland, often called the master gland because it controls the release of hormones from all other endocrine glands in the body
• Fight or Flight response


  1. when a stressor is perceived the hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system

  2. The ANS changes from its normal resting state (the parasympathetic state) to the physiologically aroused sympathetic state

  3. The stress hormone adrenaline is released into the bloodstream - adrenaline triggers physiological changes in the body e.g. increased heart rate, necessary for the response

  4. once the threat has passed the parasympathetic nervous system returns the body to its resting state, it acts as a break and reduces the activities of the body that were increased by the actions of the sympathetic branch, sometimes referred to as the rest and digest response
• sympathetic state


  - increases heart rate

  - increases breathing rate

  - dilates pupils

  - inhibits saliva production

  - contracts rectum
• Parasympathetic state


  - decreases heart rate

  - decreases breathing rate

  - contracts pupils

  - stimulates digestion

  - stimulates saliva production

  - relaxes rectum
• The structure of a neuron


  - Vary in size from less than a millimeter to up to a meter long

  - the cell body (or soma), dendrites, axon, myelin sheath, nodes of Ranvier and terminal buttons
• Cell body (soma) of a neuron


  includes a nucleus, which contains the genetic material of the cell
• Dendrites


  branch-like structures that protude from the neuron cell body
• Axon


  carries the impulses away from the cell body
• Myelin sheath


  fatty layer that protects the axon and speeds up chemical transmission
• Nodes of Ranvier


  where the myelin sheath is segmented to maintain the speed of chemical transmission
• Terminal buttons


  Communicate between neurons
• electric transmission - firing of a neuron


  1. when a neuron is in a resting state the inside of the cell is negatively charged compared to the outside

  2. when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur

  - this creates an electrical impulse that travels down the axon towards the end of the neuron
• types of neuron


  motor neurons, sensory neurons and relay neurons
• neural networks


  Groups of neurons communicating with each other
• The synapse


  includes the space between the neuron (called the synaptic cleft as well as the presynaptic terminal and post synaptic receptor site
• Synaptic transmission


  how signals between neurons are transmitted chemically
• what happens when the electrical impulse reaches the end of the neuron


  the end of the neuron is called the presynaptic terminal, it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles
• neurotransmitters


  chemicals that diffuse across the synapse to the next neuron in the chain, they are taken up by the postsynaptic receptor sites and are then converted back into an electrical impulse

  - each has its own specific molecular structure that fits perfectly into a post-synaptic receptor site

  - has a specialist function
• inhibition


  decreases the likelihood that the neuron will fire
• excitation


  increases the neurons positive charge and making it more likely to fire
• Localisation versus holistic theory


  - Paul Broca and Karl Wernicke discovered that specific areas of the brain are associated with particular physical and psychological functions

  - scientists believed that all parts of the brain were involved in the processing of thoughts and action
• Localisation of function in the brain


  The idea that different parts of the brain perform different tasks and are involved with different parts of the body, if a certain area of the brain becomes damaged the function associated with that area will also be affected
• hemispheres of the brain


  the brain is divided into two symmetrical halves called the left and right hemispheres

  activity on the left-hand side of the body is controlled by the right hemisphere and vice versa
• The cerebral cortex


  the outer layer of both hemispheres, about 3mm thick and is what separates us from other animals as it it more developed

  - appears grey due to the location of cell bodies
• the sub-divisions of the cortex of the brain


  named after the bones beneath which they lie; the frontal lobe, the pariental lobe, the occipital lobe and the temporal lobe
• the motor area


  located in the back of the frontal lobe, controls voluntary movement in the opposite side of the body and damage results in a loss of control over fine movements
• the somatosensory area


  located in the front of the pariental lobe, a valley separates the frontal lobe and pariental lobe called the central sulcus

  it is where sensory information is represented (from the skin)
• visual area


  located in the occipital lobe, works in opposite to the eye
• auditory area


  located in the temporal lobe, analyses speech based information, damage may produce partial hearing loss
• Broca's area


  responsible for speech production, damage causes Broca's aphasia which is characterised by speech that is slow, laborious and lacking in fluency