Neuroglia Flashcards
The soma contains cellular organelles, what are the typical characteristics of a neural cell?
- Multiple mitochondria for energy production
- Rough ER and golgi for protein synthesis
- Nissl granulation (rough ER can be stained)
An axon arises from what?
A hillock
Does the axon have fought ER? Mitochondria?
Yes mitochondria, no ER
Do axons branch?
Nah
Do dentrites branch?
They can
What are multipolar neurons?
Multiple dendrites with one axon
-motor neurons
What are pseudounipolar neurons?
One axon with common stem and then two sending branches
-sensory
What are bipolar neurons?
-one dendrite and one axon
What kind of neurons can be somatic and visceral?
Motor and sensory
Where are neuroendocrine neurons found? What do they do?
- mostly in hypothalamus
- secrete peptide hormones into the blood
What kind of neurons are sensory neurons typically?
Psuedounipolar or bipolar
What is transduction?
The process of converting sensory input into a form interpretable by the nervous system
-all sensory neurons do this
Motor neurons often end in fine branches called what?
Terminal arbors
What forms the synapse between nerve cells?
Terminal boutons
What is. Synapse?
The site at which an axon terminal communicate with a second neuron or effector tissue
What is axodendritic? Is it excitatory or inhibitory?
- presynaptic axon connects with post synaptic dendrite
- can be excitatory or inhibitory
What is axosomatic? Excitatory or inhibitory?
- presynaptic axon to post synaptic soma
- either
What is axoaxonic?
- acts to increase or decrease NT release by post synaptic terminal
- axon to axon
Where are NT produces and where do they secrete?
- NT made in the soma
- go to the synapse
What are the five steps in transmission?
- Synthesis
- Storage
- Transport
- Release
- Reuptake/destruction
NT are transported along what?
Along microtubules of the axons
Anterograde transport takes things in what direction? What proteins does it use?
- away from cell body
- kinesins
Retrograde transport moves things in what direction? What proteins does it use?
- towards cell body
- dyneins
What do kinesins use for transport?
-use ATP-are to crawl along the microtubules
What is fast transport?
- uninterrupted transport using kinesins
- carries synaptic vesicles, NT, and mitochondria
What is slow transport?
- transport using Kinesins, with stops though
- transport cytosolic proteins, cytoskeletal proteins
Which transport is faster, fast or slow transport?
Slow transport is faster, but they pause frequently
What does retrograde axonal transport allow?
- allows the neuron to respond to growth factors
- recycles components of the axon terminal and damaged mitochondria
Viruses and toxins use what kind of transport?
Retrograde axonal transport
Are cell bodies grey or white?
Grey! Lack myelin!
What is a group of cell bodies within the CNS?
Nucleus
What are tracts?
Bundles of nuclei in the CNS
What is a group of tracts called?
Funiculus
What is fasciculus? Lemniscus?
- bundle of nuclei in the CNS
- ribbon of nuclei in the CNS
What is a group of cell bodies in the PNS called?
Ganglia
A group of ganglia in the PNS are called what?
Nerves
What are oligodendrocytes?
-provide myelin sheath to neurons in the CNS
What provides myelination in the PNS?
Schwann cells
What do microglia do?
-immune and inflammatory functions
What are ependimal cells?
Neuroepithelium
What kind of astrocytes are in grey matter? White matter?
Grey: protoplasmic astrocytes
White: fibrous astrocytes
What kind of shape are astrocytes?
-they are highly branched with multiple processes that give them a star like appearance
What are the functions of astrocytes?
- maintain constant pH
- secrete growth factors and cytokines
- remove glutamate from synapses
- store glycogen to help neuronal metabolism
What part of the cell can astrocytes communicate with?
Every part!
When does an astrocytic scar form?
-when injury to the CNS results in destruction of neurons and the space si filled with proliferation of astrocytes
Why are the majority of CNS tumors of astrocytic origin?
-they can proliferate in the mature brain
What is the purpose of the astrocytes end feet?
-they join together and isolate the CNS from other tissues
What are the two barriers astrocytes make?
- Glial limiting membrane: surface of the brain and spinal cord adjacent to the pia mater is covered with end feet (glial limitans)
- Blood Brain Barrier: capillaries in CNS are covered with end feet that separate them from the brain tissue
What does the term neurovascular unit describe?
All of the components of the blood brain barrier
What are the cellular components that make up the physical barrier of the neurovascular unit?
- endothelial cells and their basement membranes (tight junctions)
- preicytes on surface of capillaries
- astrocytes
- perivascular macrophages
What makes up the functional barrier of the blood brain barrier?
-a single, non-fenestrated, continuous endothelial layer
What are the aspects that make the brain immune privileged?
- tight junctions
- endothelial cells have low rates of transcytosis (creates a barrier to hydrophilic molecules)
- endothelial cells express low levels of leukocyte adhesion molecules, which limits the CNS immune serveillance
What is saltatory conduction?
Action potentials jump between nodes of ranvier
What are the smallest cells of the neural tissue?
Microglia
Microglia are normally what in their normal state?
-inactivated/ quiescent
Do we want microglia activated? Why or why not?
- no
- they get rid of debris without inflammation, but they stimulate the secretion of cytokines which release WBC
How does rabies spread?
- transported in retrograde fashion and proliferate in the cell body and spread to adjacent cells
- spread to salivary glands
- there is a treatment once the individual is effected
How does tetanus spread?
In retrograde fashion, but then it kills the neuron
-no treatment
What are two viruses that lay in sensory ganglia and can re activate?
- varicella/chicken pox
- herpes simplex
What are the two diseases that disrupt axonal transport?
Alzheimer’s and Huntington
What is bacterial meningitis?
- infection of the meninges
- group B strep can weaken BBB by suppressing tight junction protein expression
What is MS?
- activated immune Th1 cells can sneak through BBB and induce autoimmune response
- Th1 lymphocytes trigger inflammatory response and increase permeability of BBB
What kind of tumor is commonly seen in AIDS?
CNS lymphoma
What kind of legion does CNS lymphoma present?
-ring enhancing lesions
What is the most common brain malignancy?
Metastasis
What kind of legion would you see with metastasis?
Bright and dense
