MICROANATOMY Flashcards
What is the central part of the neuron?
Cell Body (Soma)
What is a long, slender projection of the neuron?
Axon
What are the shorter, branched projections of the neuron?
Dendrites
How can neurons be classified based on the total number of projections?
By the number of projections (or neurites)
How are neurons with multiple dendrites and a single axon classified?
Multipolar
How are neurons with multiple axons classified?
Bipolar
What are the two categories of dendritic structure used for classification?
Stellate and Pyramidal
How can neurons be classified based on the length of their axons?
Neurons can be classified into Golgi type I and Golgi type II based on axon length.
Describe the axon length of Golgi type I neurons.
Golgi type I neurons have long axons that can extend considerable distances.
Describe the axon length of Golgi type II neurons.
Golgi type II neurons have shorter axons compared to Golgi type I neurons.
How can neurons be classified based on their connections in the nervous system?
Neurons can be classified as sensory neurons, motor neurons, or interneurons based on their connections.
What do sensory neurons do?
Sensory neurons transmit signals from sensory organs to the central nervous system.
What do motor neurons do?
Motor neurons transmit signals from the central nervous system to muscles and glands.
What do interneurons do?
Interneurons facilitate communication between other neurons.
How can neurons be classified based on gene expression?
Neurons can be classified based on the neurotransmitters they produce, which is influenced by gene expression.
What are the “support cells” within the nervous system?
Glial cells
How many categories can glial cells be classified into?
Four
Name the categories of glial cells.
- OLIGODENDROCYTES/SCHWANN CELLS - ASTROCYTES - MICROGLIA - EPENDYMAL CELLS
What is the function of astrocytes?
They regulate the extracellular environment of the brain.
What is the most numerous type of glial cell within the human brain?
Astrocytes
What are the functions of microglia?
- Phagocytosis of neuronal and glial debris - Synaptic connection remodeling - Directing neuronal migration during brain development
What type of glial cell are microglia?
Phagocytes
Where are ependymal cells found?
They provide the lining of the ventricular system of both the brain and spinal cord.
What are the functions of ependymal cells?
- Osmotic regulation of cerebrospinal fluid - Flow of cerebrospinal fluid - Directing cell migration during brain development
What neurological condition is linked with deficits in ependymal cell function?
Hydrocephalus
What do oligodendrocytes and Schwann cells provide to neurons?
Myelin - a membranous sheath around axons
How many axons does one oligodendrocyte contribute myelin to?
Several
How many axons does one Schwann cell myelinate?
Only a single axon
Where are oligodendrocytes situated?
In the central nervous system (CNS)
Where are Schwann cells situated?
In the peripheral nervous system (PNS)
What are the components of a prototypical neuron?
I. CELL BODY (SOMA), II. AXON, III. DENDRITES
What organelles are found in the cell body (soma) of a neuron?
- Nucleus - Rough endoplasmic reticulum (RER) - Smooth endoplasmic reticulum (SER) - Golgi apparatus - Mitochondrion
What is the neuronal cytoskeleton composed of?
Microtubules, microfilaments, and neurofilaments
What is the function of microtubules in neurons?
They are important in axoplasmic transport
What is the function of microfilaments in neurons?
They are particularly abundant in axons and dendrites
What is the function of neurofilaments in neurons?
They are important in regulating axonal shape and are a promising biomarker for neurodegenerative disorders
What are the regions of axons?
Axon hillock, Axon ‘proper’, Axon terminal
What is myelin?
A membranous sheath that wraps around and insulates axons
What are Nodes of Ranvier?
Gaps in the myelin sheath that are highly enriched in voltage-gated Na+ ion channels
What are dendrites responsible for?
Receiving synaptic inputs from other neurons
What are dendritic spines?
Small sacs of membrane that protrude from dendrites to receive synaptic input
What is the sensitivity of dendritic spine structure related to?
Type and amount of synaptic activity
What conditions have been associated with abnormal dendritic spine number?
Alzheimer’s disease, schizophrenia
