brain cells

• neurons


  ~80 billion in adult human 

  • Can generate a series of electrical impulses that allow them to send information throughout the brain 
  • Typical neuron consists of: soma, dendrites and axons 
• What is the average size of a soma?

  ~20 micrometers
• What is the primary function of the soma in a neuron?

  It is the metabolic center of the neuron
• What does the cytoplasm include?

  Everything within the cell membrane, excluding the nucleus
• Where does protein synthesis occur in the neuron?

  In the cytoplasm
• What is cytosol?

  Intracellular fluid inside the cell
• What does the nucleus contain?

  DNA
• How do organelles in a neuron compare to those in a eukaryotic animal cell?

  They are the same as in a eukaryotic animal cell
• What is the role of mRNA in protein synthesis?

  It carries the genetic message to the sites of protein synthesis
• What is the process of creating mRNA called?

  Transcription
• What happens at the promoter region during transcription?

  RNA polymerase joins nucleotides to form pre-mRNA
• When does RNA polymerase stop joining nucleotides?

  When it recognizes the terminator region/end triplet code
• What occurs after the pre-mRNA is formed?

  It is spliced to remove the introns
• What is the next step after splicing pre-mRNA?

  Protein is created via translation
• How does mRNA exit the nucleus?

  Via nuclear pores into the cytoplasm
• What happens to amino acids in the cytoplasm?

  They are linked together into a chain, forming proteins
• What is the primary function of mitochondria in a neuron?

  Generates ATP
• What are the two types of endoplasmic reticulum mentioned?

  Rough and smooth endoplasmic reticulum
• Why is the neuronal membrane critical?


  It is critical for the function of the neuron
• What is the role of the cytoskeleton in a neuron?

  It provides shape, positioning, and tracks transportation
• axon


  Only found in neurons

  • Specialised for information transfer over distances 
  • No RER and hardly any ribosomes 
  • Axon hillock - where axon originates 
  • Neurofilaments cluster together as fascicles 
  • Axon terminal - where axon contacts other neurons 
  • Terminal abour - branches at end of axon 
  • Mitochondria
  • Synaptic vesicles 
  • Synapse 
• dendrites


  Unipolar 

  • Dendritic spines
  • Increases synaptic contact
  • Important for plasticity and learning
  • On post synaptic = full of receptors 
• types of neurites


  Neurites (axon and dendrite)

  • Unipolar
  • 1 neurite is attached to a soma
  • No dendrites at soma
  • Bipolar 
  • 1 dendrite and 1 axon are attached to soma 
  • Multipolar 
  • Many neurites attached to soma 
  • Many dendrites and 1 axon
• How many glial cells are there approximately in adult humans?

  ~85 billion
• What is the primary role of glial cells?

  They act as 'glue', supporting neurons
• Why are glial cells important for brain signaling?

  They enhance electrical signaling of neurons
• What do glial cells do with debris left by dead neurons?

  They remove it
• How do glial cells regulate the chemical environment?

  They control the extracellular concentration of several substances
• What type of glial cells are most abundant in the brain?

  Astrocytes
• What is the role of astrocytes in relation to neurons?

  They fill most of the spaces between neurons
• How do astrocytes influence neurite growth?

  They probably influence whether a neurite can grow or retract
• What special proteins do astrocytes have in their membrane?

  Proteins that actively remove many neurotransmitters from the synaptic cleft
• What do microglia function as?

  Phagocytes to remove debris left by dead or degenerating neurons and glia
• What can astrocytes trigger through their neurotransmitter receptors?

  Electrical and biochemical events
• What is the primary function of oligodendroglial and Schwann cells?

  • Provide layers of membrane that insulate axons
• Where are oligodendroglial cells found?

  Only in the CNS
• Where are Schwann cells located?

  Only in the PNS
• What are the differences between oligodendroglial and Schwann cells?

  • Oligodendroglial cells: found in CNS
  • Schwann cells: found in PNS
• Who introduced a stain that selectively colors parts of the cell in brain tissue?

  Franz Nissl
• What did Nissl's stain show about the nuclei of cells?

  It could stain the nuclei of all cells and clumps of material surrounding the nuclei of neurons