Grey matter

• What are nerve cells called?

  Neurones
• What role do neurones play in the nervous system?

  They coordinate communication within the nervous system
• What is the main component of the neurone's cell body?

  The nucleus
• What do organelles like mitochondria provide for neurones?

  Energy in the form of ATP
• What are dendrites involved in?

  Conducting impulses towards the cell body
• What do axons do in a neurone?

  Conduct impulses away from the cell body
• How many types of neurones are there?

  Three
• What are the three types of neurones?

  Sensory, motor, and relay
• What do motor neurones transmit signals to?

  Muscles and glands in the body
• What do sensory neurones transmit impulses from?

  Receptors to the central nervous system
• Where are relay neurones located?

  Within the central nervous system
• What do relay neurones transmit impulses between?

  From sensory neurones to motor neurones
• How does the diameter of nerve cells affect impulse transmission?

  Wider diameter transmits impulses more quickly
• What is myelination?

  A layer of fatty substance around neurones
• How does myelination affect impulse speed?

  Increases speed by acting as an insulator
• What is saltatory conduction?

  Impulse jumps between nodes of Ranvier
• What is the resting state of nerve cells?

  When they are not actively transmitting impulses
• What causes the negative charge inside a nerve cell at rest?

  Imbalance between sodium and potassium ions
• What is the value of the resting potential?

  -70mV
• What happens during depolarization of a neurone?

  Sodium ions diffuse into the neurone
• What triggers the opening of sodium ion channels?

  Excitation of the neurone cell membrane
• What is the threshold potential for action potential?

  -55mV
• What occurs at the end of depolarization?

  Start of repolarization
• What causes repolarization in a neurone?

  Closing of sodium channels and opening of potassium channels
• What is hyperpolarization?

  When potential difference exceeds resting potential
• What restores the resting potential after hyperpolarization?

  Sodium-potassium pump
• What is the refractory period?

  Time when neurone cannot be excited
• How does an action potential travel along a neurone?

  As a wave of depolarization
• What are synapses?

  Junctions between two neurones
• What happens when an action potential arrives at a synapse?

  Presynaptic membrane depolarizes
• What causes calcium channels to open in the presynaptic neurone?

  Depolarization of the presynaptic membrane
• What do calcium ions cause in the presynaptic neurone?

  Fusion of synaptic vesicles with the membrane
• What neurotransmitter is commonly released at synapses?

  Acetylcholine
• What happens when neurotransmitters bind to receptors on the postsynaptic membrane?

  Opens cation channels for sodium ions
• What is an excitatory postsynaptic potential (EPSP)?

  When neurotransmitter causes depolarization
• What is an inhibitory postsynaptic potential (IPSP)?

  When chloride ions cause hyperpolarization
• What role do digestive enzymes play in the synaptic cleft?

  Break down neurotransmitters to prevent overstimulation
• What happens to neurotransmitters after they are broken down?

  They are taken up by the presynaptic membrane
• Why can action potentials only travel in one direction?

  Due to the refractory period and receptor presence
• What are cells specialized for detection of stimuli called?

  Receptors