Neuroglia (Quiz 1) Flashcards
The Brain and Spinal Cord
Central Nervous System (CNS)
Everything outside of the CNS
Carries sensory (afferent) info from sensory receptors to the CNS
Carries motor (efferent) instructions from the CNS to the effectors
PNS
Divisions of the PNS
1) Somatic Nervous System
2) Autonomic Nervous System
3) Enteric Nervous System
Division of the PNS that controls skeletal muscle
Voluntary Control
Somatic Nervous System
Division of the PNS that controls the heart, smooth muscle in viscera, blood vessels and glands
Autonomic Nervous System
Two Divisions of the Autonomic Nervous System
1) Sympathetic Nervous System
2) Parasympathetic Nervous System
“Resting and Digestion” division of ANS
Parasympathetic Nervous System
Carries most Parasympathetic Output
The Vagus Nerve
“Fight or Flight (or Freeze)” division of ANS
Sympathetic Nervous System
Division of the PNS that controls the GI Tract
Enteric Nervous System
Refers to a structure that is long and thin
Fiber
Nerve Fibre AKA
Axon
A bundle of axons in the PNS
Nerve
A bundle of Axons in the CNS
Tract
Nerve Cell AKA
Neuron
“glue”
Protects and Supports Neurons
Neuroglia
aka Glia
Myelin-producing Cells in the PNS
Respond well to most forms of injury
Schwann Cells
Increases speed at which impulses propagate along an axon and prevents nerve signal leakage
Myelin (Myelin Layer or Myelin Sheath)
*Myelin Sheaths line up along the length of an axon, with only small gaps in between them.
Small gap between two myelin sheaths (Schwann Cells) lined up along an axon
Node of Ranvier
Myelin producing cells in the CNS
1 Cell forms segments of Myelin for about 30 Neurons
Looks like sparse branches of a tree
More fragile than Schwann Cells
Oligodendrocytes
(oligo = few) + (dendron = tree) + (cyte = cell)
A Disease that attacks Oligodendrocytes
Myelin replacement occurs but the process becomes unreliable and eventually stops
Multiple Sclerosis (MS)
“Star-shaped”
Most numerous glial cell in the CNS
Provide physical support to fragile neurons
Help to form the Blood Brain Barrier (BBB)
*Have long, highly branched processes which end on the walls of capillaries that contribute to the BBB
Astrocytes
A complex filtration system that alters (lessens) the permeability of brain capillaries
Severly limits the passage of many harmful substances from the blood to the neurons. However, it also hinders the delivery of many important therapeutic agents to the brain
Is permeable to alcohol, amphetemines and some toxic metals
Trauma, radiation, hypertension and infection can affect efficiency
Blood Brain Barrier (BBB)
*In cases where a person has suffered a traumatic brain injury there is a 10-50% chance of developing epilepsy, due to a damaged BBB
Adaptation of the brain in response to new situations in which structual changes happen within the Brain. Can result in changes to behaviour, thinking, and emotions.
Neuroplasticity (Brain Plasticity)
Astrocytes have processes which wrap around Neurons to form?
a “tripartite synapse”
*Contributes to neural plasticity
Three parts of a “Tripartite Synapse”
1) Presynaptic Neuron
2) Post Synaptic Neuron
3) Astrocyte
An unfortunate product of Neural plasticity
Chronic Pain
A disorder that causes a heightend response to painful stimulus
Hyperalgesia
A disorder that causes a painful response to a normally non painful stimulus
Allodynia
Clusters of Neuron Cell bodies in the PNS
Ganglia
Clusters of Neuron cell bodies in the CNS
Nuclei (us)
Glial cells that cover the surface of ganglia
Thought to have a similar role to astrocytes
Supply nutrients to the surrounding neurons and act as cushioning
*have been linked to Chronic pain in the PNS
Satellite Glial Cells
Immune system cells that recognize, engulf and destroy infected, damaged or dead cells
Macrophages
Resident Macrophages of the CNS
Facilitate and coordinate responses between the peripheral immune system and the brain
Microglia
Affect the behaviour of other cells
Can be Pro- or Anti- Inflammatory
Cytokines
Pro and Anti-inflammatory cytokines can be transported into the brain via 2 pathways.
1) Blood (Humoral Pathway)
2) The Vagus Nerve (Neural Pathway)
Presents as pain, heat, redness, swelling and loss of function
(Cardinal Signs)
Peripheral Inflammation
a) May resemble peripheral inflammation in situations such as meningitis, head trauma, or autoimmune disease of the CNS
b) Can be used to identify a different event driven by microglial cells, showing few if any of the cardinal signs of peripheral inflammation
Neuroinflammation
