Lab 7 - Nervous tissue histology Flashcards
Why do wholemounts of complete cells look different to thin histological sections
Histological section is a section through a piece of tissue – thin snapshot of a 3D environment. Whole one – thick section of tissue – lots of cells – stain entire things – more likely to see whole cell – entirety. E.g. mesentery – whole tissue, monkey gut – thin tissue
What are the size of somas ( in micrometres)
10um
What are the stringy bits you can see
Dendrites and axons ( neurites )
What are CNS grey and white matter
Cell body - where you find soma = grey matter - also contain dendrites
Axons = white matter
It appears white because of myelination - lipids wrapped around each of those - lighter
• What cell types provides the myelin sheath of axons in the PNS and CNS respectively?
PNS: Schwann Ceell
CNS: Oligodendrocytes
• How does the myelination provided by these 2 cell types differ? (i.e. how many axons does each cell type supply with myelin and how many cells contribute to the myelination of any one axon)
Schwaan cell: 1 s.cell provides myelin for only one axon, however one axon receives myelination from several s.cells.
Oligodendrocytes: 1 oligo…. Can provide myelination for several axons.
What glia cell type helps maintain blood brain barrier
Astrocytes ( CNS ) Satellite cells ( PNS )
Which glial cells line the cerebral ventricles and why
Ependymal cells
• Line the ventricles of the brain and central canal of spinal cord
• Secrete and regulate CSF – Cerebral Spinal Fluid into the ventricles
• Functions:
Filtrates blood
Provides the brain and spinal cord with nutrients
Eliminating waste products.
What is function of microglia
- Immune system - initiate immune response
- Phagocytosis - phagocytose debris and pathogens
- Release cytokines to attract other immune cells e.g. lymphocytes ( wbcs )
- CNS injury/inflammation
- Hoover of brain - eat and digest things that need to be destroyed
Difference between axons and their myelin
- Axons that are myelinated have a faster speed of action potential.
- It provides saltatory conduction, (action potential jump from node to node, making process quicker and preventing it from having to travel across the whole length of the axon)
- No myelin – nervous system slows down/ lose control = doesn’t conduct electrical activity
- Myelin acts as an insulator – makes sure electrical signal can be transported along whole axon
Identify the various connective tissue elements that, for example divide the axons into fascicles, and also surround the nerves. What are these called?
- Individual neurons are separated by a connective tissue sheath - ENDONEURIUM
- PERINEURIUM splits nerves into fascicles -onnective tissue between fasicle
- EPINEURIUM - forms outer coat of nerve - encloses whole nerve
Quantify the range of axon diameters. What are the functional consequences of this variation in diameter?
Small diameters - slower action potential - little ones - send info slower
- Larger diameters - faster action potential as there is less resistance to current spread therefore easier for ions to travel across
Most of the space within the nerve is taken up by axons and their associated myelin, but there are also some cell bodies (stained a darker purple) scattered between. What are these?
Along axons of some neurones = cell bodies = belong to Schwann Cells
Nucleus in there - from Schwann Cell
Little axon - purple nucleus - Schwann Cell
What is function of microglia
- Immune system - initiate immune response
- Phagocytosis - phagocytose debris and pathogens
- Release cytokines to attract other immune cells e.g. lymphocytes ( wbcs )
- CNS injury/inflammation
- Hoover of brain - eat and digest things that need to be destroyed
Difference between axons and their myelin
- Axons that are myelinated have a faster speed of action potential.
- It provides saltatory conduction, (action potential jump from node to node, making process quicker and preventing it from having to travel across the whole length of the axon)
- No myelin – nervous system slows down/ lose control = doesn’t conduct electrical activity
- Myelin acts as an insulator – makes sure electrical signal can be transported along whole axon
