Cell Organization - Support cells

Question 1

Support cells/ types of glial cells

Answer 1

AMOS: astrocytes, microglia, Oligodendrocytes, Schwann cells

Question 2

Glia

Answer 2

• neurons have high rate of metabolism but cannot store energy
• they must, therefore, be supplied by glial cells with a constant source of nutrients (glucose) and oxygen and will die within minutes if this is interrupted

Question 3

Astrocytes

Answer 3

• One astrocyte cell will have connections with many neurons; provide structure or matrix that holds neurons in place; surround synapses so NT are not dispersed beyond synapse; digests dead neurons (phagocytosis); forms scar tissue in area left from phagocytosis; produce some chemicals needed by neurons; absorb and release substances to keep concentration levels around neuron at critical levels; break down glucose received from capillaries into lactate used by neuron for energy

Question 4

Oligodendrocytes

Answer 4

Form myelin sheath CNS

Ranvier

A single oligo will provide myelin for multiple axons

Question 5

Microglia

Answer 5

• Phagocytosis
• Immune function for brain
• Inflammatory response to damage

Question 6

Schwann cells

Answer 6

• myelin in PNS. Wraps around one axon

      page 38, figure 2.11 shows difference between oligo and Schwann

• after axon is severed, SC digest dead axon, then form series of cylinders or tube. Axon end grows many sprouts. If one sprout finds cylinder it will regrow and reconnect with intact axon if close enough. Other sprouts die.
• severed axons grow sprouts in CNS but are blocked by scar tissue

Question 7

Blood-brain barrier

Answer 7

1. Capillaries in body have permeable walls allowing for free movement of most substances between plasma and extra cellular fluid
2. In CNS capillary walls are not permeable for most part and substances are actively transported between capillary and neuron
3. BBB allows for control of delicate balance of substances in neuron extra cellular fluid necessary for brain to function normally and exclude toxins or chemicals that would interfere with neuron function
4. BBB not as strong throughout brain e.g. in area that controls vomiting