Lecture 8 week 4 Flashcards
What are major cell types of the adult human central nervous system
- Neurons
- Oligodendrocytes (CNS) &
Schwann cells (PNS) - Astrocytes
- Microglia
- Ependymal cells
What is Multiple Sclerosis
- Destruction of myelin sheath
due to an autoimmune disorder - Unmyelinated axon – 0.5 to
2m/s - Myelinated axon – 6 to 120m/s
How do neurons target cells?
With a specific neurotransmitter
Where do neurons typically release one type of neurotransmitter?
At a given pre-synaptic neuron (ex. dopamine, seratonin, norepinephrine, acetylcholine, etc.)
What can inputs be?
Either excitatory or inhibitory
What is net response based on?
Based on overall effect of all inputs
What to neurons have the ability to do?
Diverge, converge and form networks.
What is synaptic divergence?
Many other nerve cells influenced by one
What is synaptic convergence?
One nerve cell influenced by many others
What happens around 10 years of age in humans, regarding the brain
Lots of remodelling is done within brain’s neural network. Brain develops new synapses and prunes away unused synapses.
What are some changes in teen/emerging adult brain?
- Growth in size 90% complete but massive reorganization & development of synapses i.e. networking
- Increased sensitivity to dopamine – does this explain why teens respond strongly to social reward?
- Large increase in myelination i.e. increase in transmission speed of neurons
- These changes should facilitate learning & social networking which are important for survival – does it also explain risky behaviour?
What do oligodendrocytes and shwann cells do?
Produce myelin
Where do oligodendrocytes span?
Oligodendrocytes span multiple axons and are found in the CNS
Where do shwann cells span?
Shwann cells do not span multiple axons and are found in the PNS
What are astrocytes?
- Stellate (starlike) morphology
- Many functions but very important
for communication - More abundant than neurons
What are ependymal cells
- Line ventricles to form a barrier
- Produces cerebrospinal fluid
What are microglia?
- Mobile, macrophage-like, immune
cells
What are 5 key functions of astrocytes?
- Coordinate overall function of the blood brain barrier (BBB) & provide nutrients to neurons
- Coordinate function of the ventricle epithelium (brain network)
- Coordinate function at the Nodes of Ranvier
- Participate in/form tripartite synapses with neurons
- Serve as “superhubs” for neural networks via syncytium formation (cytoplasm containing many nuclei & enclosed in cell membrane), &
calcium signaling via gap junctions (astrocyte clouds)
What does the blood brain barrier (BBB) do?
- Very tight control over what gets through
to the brain - Very good protection against most bacteria
& toxins
What can get through the blood brain barrier ?
- Very small lipid-soluble compounds (essential
fatty acids) - Caffeine & alcohol
- Glucose via specific glucose transporter GLUT1
(not insulin-sensitive) - An issue when targeting drugs for the brain
