Unit a

• Rapid movement of otoliths


  Causes dizziness
• Sensorineural hearing loss


  Treated by cochlear implants
• Vibration in cochlea


  Caused by obliteration of basilar membrane of organ of Corti
• Very dim light


  Fewer rods in fovea centralis
• Light is not refracted by pupil
• Astigmatism


  Vision distortion caused by irregularities in the cornea
• Sound waves are converted into nerve impulses

  In the organ of Corti
• Hearing aids will not improve hearing loss due to nerve damage
• Neurons


  the functional units of the nervous system that respond to physical and chemical stimuli
• glial cells


  the cells that support and nourish the neurons (also known as schwaan cells)
• Sensory neurons


  relay information about the environment to the CNS (five senses)
• Interneurons


  link sensory neurons and motor neurons in the body
• Motor neurons


  carry nerve impulses from CNS to the effectors (muscles and glands)(movement)
• cell body


  contains the nucleus and where all the metabolic reactions occur within the cell
• Dendrites


  branching terminals that carry information to the cell body (both sensory and motor)
• Axon


  extension of the cytoplasm that carries nerve impulses from the dendrites to the effectors
• Myelin sheath


  A layer of fatty tissue that covers the axon and protects it from losing charged ions formed by schwonn cells
• Nodes of Ranvier


  the gaps in between the myelin sheath
• true or false: unmyelinated nerve fibres transmit nerve fibres faster because of salitory conduction

  false
• white matter


  myelinated neurons
• grey matter


  unmyelinated neuron cell bodies and short, unmyelinated axons
• How is a electrochemical signal formed?

  unequal concentration of positive ions across a membrane
• electrical current


  a faster current that diminishes near the end and uses external source to generate energy
• Nerve impulse


  a slower process that remains strong at the end and uses cellular energy(ATP) to move ions across a cell membrane
• membrane potential


  when one is more positive than the other
• resting membrane potential


  -70mV
• Polarization


  The process where the inside of the membrane is negative and the outside is positive. Occurring due to a sodium potassium pump that moves potassium to the inside and the sodium to the outside
• Action potential


  the all or non electrical signal that has a domino effect across the membrane in the axon
• threshold potential


  -55mV
• Depolarization


  the process where the sodium channels open up and the sodium ions flood into the inside of the membrane turning the inside of the membrane positive and the outside negative
• repolarization


  the process where the potassium channels open up again and the potassium ions move from high to low and go to the outside of the axon
• hyperpolarization


  where the potential dips too low and both the sodium and potassium channels are opened and the process of polarization occurs again
• refractory period


  the recovery time before a neuron can produce another action potential
• synapse


  the connection between two neurons (also synaptic cleft)
• Neuromuscular junction


  synapse between a motor neuron and muscle cell(not in direct contact)
• Synaptic terminal


  where one impulse will travel from one end to the opposite end
• synaptic cleft


  the space between synaptic terminals
• neurotransmitters


  chemicals that move from one neuron to the next that carry signals
• acetylcholine


  most common neurotransmitter that causes depolarization
• presynaptic neuron


  the neuron that releases the neurotransmitters