biopysch

• Nervous System


  A complex network of nerve cells that carries messages to and from the brain and spinal cord to different parts of the body.

  It allows different parts of the body to communicate with each other.

  It is divided into two parts: the Central NS and Peripheral NS
• Central Nervous System (CNS)

  Controls behaviour and regulates body's physiological processes.

  Divided into: Brain and Spinal Cord
• Brain


  Centre of all conscious awareness

  Divided into two hemispheres
• Spinal Cord


  Relays information between the brain and the rest of the body: this allows the brain to monitor and regulate processes such as digestion and breathing

  Also coordinates voluntary movement

  Allows you to perform simple reflexes without the direct involvement of the brain.
• Peripheral Nervous System (PNS)


  All the nerves outside the CNS

  Relays nerve impulses from CNS to the body and back again

  Divided into: Somatic NS and Autonomic NS
• Somatic Nervous System (SNS)

  Deals with our external environment.

  Consists of sensory nerves carrying information from the environment to CNS and motor nerves which carry instructions from CNS to skeletal muscles.
• Autonomic Nervous System (ANS)


  Deals with our internal environment.

  Controls activities of our internal organs and is involved in homeostatic functions (homeostasis)

  Divided into: Sympathetic and Parasympathetic
• Sympathetic Branch (SANS)

  Becomes more active when doing anything requiring the expenditure of energy.

  Involved in freeze/flight/fight mechanisms when the body is exposed to a threat.

  Series of connections from the spinal cord to major organs.
• Parasympathetic Branch (PANS)

  Active most of the time as it controls homeostatic functions and ensures we conserve energy.

  Becomes less active when SANS is activated.

  Connections between brain and organs.
• Neurons

  A nerve cell; the basic building block of the nervous system.

  Allow the NS to communicate by transmitting systems electrically and chemically.

  
• 100 Billion


  Number of neurones in the Nervous System.
• 80%


  Number of neurones in the brain
• Resting Neuron


  When the inside of a cell is negatively charged compared to the outside.
• Activated Neuron


  When the inside of a cell is positively charged when confronted with a stimulus, causing action potential to occur.

  Creates electrical impulse that travels down axon towards the end of the neuron.
• Neurotransmitter


  Chemicals that diffuse across the synapse to the next neuron in the chain.
• How do neurotransmitters work?

  Once it crosses the gap, it is taken up by the post-synaptic receptor, i.e. the dendrite of the next neuron.

  The chemical message is converted back into an electrical impulse and the process of transmission begins again.

  Each one has its own specific molecular structure that fits perfectly into a post-synaptic receptor site, like a lock and key.
• Excitatory


  A neurotransmitter that increases a neutrons positive charge

  Makes it more likely to fire and pass on an electrical impulse

  E.g. Adrenaline
• Inhibitory


  A neurotransmitter that makes a neutron more negatively charged.

  Makes it less likely to fire and pass on an electrical impulse.

  E.g. Seratonin
• Synaptic Transmission


  The process by which neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and activate the receptors on the dendrites of another neuron (the postsynaptic neuron).
• Synapse


  Gaps between neurones
• Electrically


  How signals within neurones transmit
• Chemically


  How signals between neurons transmit across the synapse
• Synaptic Vesicles


  When the electrical impulse reaches the end of the neuron (the presynaptic terminal) it triggers the release of neurotransmitters from tiny sacs called...
• Sensory Neurons


  Carry nerve impulses from PNS to CNS (sensory receptors to spinal cord and brain)

  Converts info from sensory receptors into neural impulses

  Some of these neurons only take information to the spinal cord - this is part of a reflex action.
• Relay Neurons


  Transfer impulses from the sensory neurons to the motor neurons.

  These neurons all lie within the brain or spinal cord.
• Motor Neurons


  Deliver impulses from the CNS to the PNS (all other nerves in the body)

  Form synapses within muscles to control their contractions.

  Control muscles - when excited, they contract - when inhibited, the relax.
• Cell Body (Soma)


  Contains nucleus (containing genetic material) and connects dendrites (which bring info to the neuron)
• Dendrites


  Receive and carry nerve impulses from neighboring neurons towards the cell body.
• Axon


  Carry impulses away from cell body

  As action potential jumps from node to node, speed of transmission increases
• Myelin Sheath


  Fatty layer protecting the axon and speeding up electrical transmission of the impulse
• Nodes of Ranvier


  Speed up the transmission of an impulse by forcing it to jump across gaps of an axon
• Terminal Buttons


  Communicate with the next neurons in the chain across a gap known as the synapse
• Endocrine System


  Collection of glands that produce hormone through the bloodstream

  Regulates metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood

  Affects almost every organ and cell in the body.
• Pituitary Gland


  Gland which regulates many of the body's functions

  Made of two parts: Anterior and Posterior - they produce a number of different hormones which act on different target cells.
• Posterior Pituitary


  Hormones created here:

  
  

  - Antidiuretic Hormone (ADH)

  - Oxytocin
• Adrenal Gland


  Gland which sits on top of the kidneys and releases hormones to deal with stress.

  Influences the way your body uses energy and releases adrenaline.

  Made of two parts: Cortex and Medulla - they produce a number of different hormones which act on different target cells.
• Adrenal Medulla


  Hormones created here:

  
  

  - Adrenaline

  - Noradrenaline
• Cortisol (in Adrenal Cortex)


  Often called 'stress hormone'

  Influences, regulates and coordinates many of the changes that occur in the body in response to stress
• Adrenaline (in Adrenal Medulla)

  Equips you to respond to stress (and fight or flight response) through:

  - increasing heart rate

  - increasing blood flow to vital organs (e.g. heart)

  - rapid breathing

  - secretion of sweat

  - releasing glucose
• Reproductive Organs


  A system of sex organs which work together for the purpose of sexual reproduction.