1.1 neuro - neurohistology Flashcards
How are neurons classified?
By their structure and function, including types such as pseudo-unipolar, bipolar, and multipolar.
What are the important characteristics of neurons?
Excitable (generate and propogate action potentials), postmitotic (do not divide), and highly variable.
What are the parts of a neuron that should be sketched and labeled?
Cell body (soma), nucleus, dendrites, axon, myeline sheath
What is the function of an axon?
To send information and carry nerve impulses to other neurons, muscle fibers, or glands.
What is the function of a dendrite?
Cellular extensions that receive information.
What are the 3 types of neurons in vertebrates?
- Pseudo-unipolar (1 process exits the soma and splits into a central -to CNS- and peripheral -to environment- process)
- Bipolar (1 axon and 1 dendrite)
- Multipolar (1 axon, many dendrites)
What are the components of a synapse?
- Presynaptic neuron
- Synaptic vesicles
- Presynaptic membrane
- Neurotransmitters
- Synaptic cleft
- Postsynaptic membrane
- Receptors
- Postsynaptic neuron
What is the primary function of neuroglia?
Support, nourish, and protect neurons. Form the blood-brain barrier
What is the difference between neurons and neuroglia?
Neurons are excitable and postmitotic, while neuroglia outnumber neurons, do not propagate impulses, and can divide.
What are the types of glia found in the central nervous system?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
What are the types of glia found in the peripheral nervous system?
- Schwann cells
- Satellite cells
What cells are responsible for myelination in the CNS?
Oligodendrocytes.
What cells are responsible for myelination in the PNS?
Schwann cells.
Which cell type lines the ventricles?
Ependymal cells.
Which cells migrate into the CNS and are not derived from the neural crest or neural tube?
Microglia.
What cell types form the blood-brain barrier?
- Astrocytes
- Endothelial cells of capillaries
What is the main component of gray matter?
Neurons and their proximal dendrites.
What is the main component of white matter?
Myelinated axons.
What is the function of astrocytes?
To maintain the blood-brain barrier and support neuronal function.
True or False: Microglia originate from the neural tube.
False.
Fill in the blank: The _______ consists of tight junctions between the endothelial cells of brain capillaries and the foot processes of astrocytes
Blood-Brain Barrier
What are Nissl bodies responsible for?
High levels of protein synthesis.
What is the role of ependymal cells?
- Line the ventricles of the brain and central canal of the spinal cord
- Form the choroid plexus
- Form the cerebrospinal fluid barrier
How do oligodendrocytes contribute to white matter?
By myelinating multiple axons.
What substances cross the blood-brain barrier freely?
Lipid-soluble substances
- Oxygen
- Carbon dioxide
- Alcohol
- Most anesthetic agents
What substances cross the blood-brain barrier very slowly?
Water-soluble substances
- glucose
- creatine
- urea
- most ions
What is the difference between myelinated and unmyelinated axons?
Myelinated axons are covered by a myelin sheath (multilayered lipid and protein covering), while unmyelinated axons are not.
What two types of cells comprise nervous tissue?
Neurons and neuroglia
What is the purpose of the cell body of a neuron?
Contains nucleus and other organelles
What are nissl bodies
Large stacks of rough endoplasmic reticulum in neurons
What do axon terminals do?
Participate in synapses of neurons
What is a synpase?
Site of communication between two neurons
Presynaptic neuron
Neuron carrying an impulse toward a synapse (axon)
Postsynaptic neuron
Neuron carrying an impulse away from the synapse (dendrite)
What is a synapse between a neuron and a muscle fiber?
Neuromuscular junction
Presynaptic membrane
Site of neurotransmitter release
Synaptic cleft
Small space between teh pre and post synaptic sites, contains enzymes that break down neurotransmitters
Postsynaptic membrane
Site of neurotransmitter reception
Where are neurotransmitters located in synapses
In synaptic vesicles in the presynaptic neuron
Do glia generate or propogate impulses? Do glia divide?
No; Yes
What is the function of the blood-brain barrier
Protect brain cells from harmful substances and pathogens
What types of substances can not cross the BBB?
Proteins and most antibiotic drugs
What cells surround the bodies of neurons of PNS ganglia?
Satellite cells
Function of microglia?
Resident macrophages; Remove cellular debris, microbes, and damaged nervous tissue
What do schwann cells do?
Myelinate cells of the PNS
What do satellite cells do?
Surround the bodies of neurons of PNS ganglia
