Bio 30 - Unit A

• What are neurons?

  • functional unit of the nervous system
• What are dendrites?

  • pick up impulses and conduct then towards the body
• What is the cell body with the nucleus?

  • control center of neuron
• What are glial cells (schwann cells)?

  • non conducting
  • important for structural support and metabolism of nerve cells
• What is the axon?

  • carries impulses away from cell body
• What are the axon terminal buds?

  • sends a signal
  • neurotransmitters
• What is the process of the sensory neuron?

  • starts a sensor
  • cell body not at receiver end
  • very long
  • have glial cells
• What are interneurons?

  • connect neurons to each other
  • very short
  • no glial cells
• What are motorneurons?

  • ends at effector
  • very long
  • have glial cells
• What do all glial cells do?

  • protection
  • waste removal
  • provide nourishment
  • help insulate
  • speed up signal transmission
• What are nodes of ranvier?

  • gaps in between glial cells
  • no nodes = no ions exchanging
• What is the myelin sheath?

  • fatty covering
  • surrounds many neurons
  • insulates axon
  • increases speed of transmissions
• Neurons with myelin appear..?

  • white (white matter)
  • outside
• Neurons without myelin appear…?

  • grey (grey matter)
  • inside
• What is the process of a normal transmission?

  • sensory neuron
  • spinal cord
  • interneuron
  • brain
  • spinal cord
  • motorneuron
• What is RSIME?

  • r = receptor
  • s = sensory neuron
  • i = interneuron in spinal cord
  • m = motor neuron
  • e = effector
• What is electrical potential?

  • charge difference across a neuron membrane
• What is the resting potential?

  • charge difference across the membrane at rest
  • neuron charge = 0 = dead
• What is action potential?

  • reversal of polarity (+,-) when a neuron sends an impulse
  • all or none signal
• What happens if the stimulus isn’t big enough?

  • charge difference doesn’t change - at rest (-70mV)
  • no response
• What happens if the stimulus is big enough?

  • charge will pass threshold point (-55mV)
  • never sends an impulse
• What are the stages of an action potential?

  • rapid depolarization (+)
  • repolarization (excess -)
  • refractory/reset period (NOT SOPI)
  • neuron can’t send signal
• When a neuron is at rest, where would you find a higher sodium concentration? Where would the K+ concentration be higher?

  • higher Na+ = outside
  • higher K+ = inside
• Is the inside of a neuron + or - compared to the outside at rest?

  • negative compared to outside
• What cellular mechanism works to establish the above conditions?

  • sodium - potassium pump
  • active transport moves ions
  • ion differences = -3Na+, 2K+
• What happens in depolarization?

  • membrane potential hits threshold (-55mV)
  • Na+ gate opens, enters the neuron
  • membrane potential rises to +40mV
  • ions inside causes axon to switch charges
• What happens in repolarization?

  • membrane potential at +40mV
  • Na+ gate closes
  • K+ gate opens, leaves neuron
  • membrane potential drops to (- 90mV) more negative
  • axon = (-)
• What happens in refractory?

  • neurons is inside, not SOPI until pump catches up
  • neuron can‘t send impulse
• What is saltatory conduction?

  • impulse ‘skipping’ speeds up transmission
• How does one neuron activate the next?

  • impulse activates transporters in presynaptic neuron
  • chemical messengers move across the space and stimulate postsynaptic neuron
• Neurotransmitter that starts depolarization is…?

  • excitatory (promotes a signal)
• Neurotransmitter that blocks depolarization or hyperpolarize the neuron is…?

  • inhibitory (blocks a signal)
• What happens when nervous signals stop?

  • cholinesterase breaks down acetylcholine
• What are fast electrochemical messenges?

  • carried by nerves
• What are slow electrochemical meesenges?

  • carried by wood
• What does the CNS do?

  • coordinating center for incoming and outgoing information
• What does the PNS do?

  • carries information between organs and CNS
• Role of brain in CNS?

  • process, store information
  • monitor homeostasis
• Role of spinal cord in CNS?

  • reflexes
  • relays sensory neurons in
  • relays motor neurons out
• What does the medulla oblongata do?

  • regulates autonomic nervous system