Nervous Tissue, Types & Properties of Neurons Flashcards
The nervous tissue originates from the…
…ectoderm
What are glia cells?
Glia cells serve to support neurons; they are not neurons
Approximate number of neurons in the human brain:
10E11
Two common histological procedures are:
- tissue fixation
- staining
System classification of neurones:
- Sensory neurone (detects stimuli; first neurone in the input-output path)
- CNS neurones (process signals; lie between sensory & motor neurones)
- Motor neurone (controls the output; last neurone in the input-output path)
Functional classification of neurones (always relative to a particular structure):
- Afferent neurone (first neurone in a sequence of neurones along the signal propagation pathway) - Interneurone (neurone between the entry point and the output) - Efferent neurone (output neurone)
Structural classification of neurones:
- Unipolar (has only one axon and no dendrites; this is typical for sensory neurones) - Bipolar (has one axon and one branching dendrite) - Multipolar (has one axon and many branching dendrites; majority of CNS neurones are of this type)
Morphological classification of neurones:
- Pyramidal cell
- Stellate cell
- Basket cell
- Granule cell
- Chandelier cell, etc. etc.
Do neurones reproduce?
Neurones do not reproduce (in the sense that they do not divide).
A typical neurone has…
…a cell body, dendrites, and one axon
Myelinated segments of axons are separated by…
…nodes of Ranvier
The typical resting potential of a neurone:
Cytoplasm is negatively loaded relative to the extracellular liquid (-70mV)
The resting potential is maintained by…
…the sodium-potassium pump (Na+, K+)
How does the sodium-potassium pump function?
It moves 3 Na+ out and 2 K+ in at the expense of 1 molecule of ATP
What is the threshold for creating an action potential?
-55 mV
