The Nervous System Part 1- Neurons and Supporting Cells Flashcards
(41 cards)
What is the basic structural and functional unit of the nervous system?
Neurons
What are Supporting cells?
Supporting cells, also called glial cells and neuroglia cells, help aid the function of neurons. Unlike neurons glial cells can divide by mitosis.
Brain tumors in adults are usually composed of what type of cells?
Glial cells, because unlike neurons glial cells can divide via mitosis.
Where is the nutritional center of a neuron?
The cell body, it is where macromolecules are produced.
Where are Nissl bodies found in neurons?
Cell body and larger dendrites.
What are Nissl Bodies?
Nissl bodies are composed of large stacks of rough endoplasmic reticulum that are needed for the synthesis of membrane proteins. Seen as dark staining granules under the microscope.
Cell bodies within the CNS are frequently clustered into groups called what?
Nuclei
Cell bodies within the PNS are frequently clustered into groups called what?
Ganglia
Dendrites provide a receptive area that transmit graded electrochemical impulses where?
Towards the cell body.
Axons conduct impulses called what? and where?
Conduct action potentials away from the cell body.
Axon Hillock
The origin of the axon near the cell body, it is an expanded region.
What is the region called where the first action potentials are generated? What is it by?
Axon Initial Segment, it is adjacent to the Axon hillock.
Towards the ends of axons they can produce up to 200 or more branches that are called..?
Axon Collaterals. This allows a single CNS axon to synapse with as many as 30,000-60,000 other neurons.
Two ways neurons can be classified is by their ___ or ___.
Function or Structure.
Functional classification of neurons is based on the direction in which they conduct impulses, what are the three types?
Sensory (Afferent) Neurons: Conduct impulses from sensory receptors INTO the CNS.
Motor (Efferent) Neurons: Conduct impulses OUT of the CNS to effector organs (muscles or glands).
Association Neurons (Interneurons): Located entirely within in the CNS, serve as the associative, or integrative, functions of the nervous system.
What are the subdivisions of Efferent Neurons?
Somatic- Reflexes and voluntary control of skeletal muscles.
Autonomic- Involuntary control of smooth muscle, cardiac muscle, and glands.
Autonomic can further be divided into Sympathetic (typically speeds things up) and Parasympathetic (typically slows things down)
What are the structural classifications of neurons?
Pseudounipolar
Bipolar
MultiPolar
See pg 32 in Notes for examples.
What neurons are pseudounipolar? Anatomically how are pseudounipolar neurons described, functionally?
Sensory neurons are pseudounipolar.
Anatomically- process conducting impulses toward the cell body can be considered a dendrite and the part that conducts impulses away from the cell body can be considered an axon.
Functionally- the branched process behave as a single long axon that continuously conducts action potentials. Only the small projections at the receptive end of the process function as typical dendrites, conducting electrical impulses rather than action potentials.
What do Dendrites conduct?
Electrical Impulses (like EPSPs and IPSPs)
What do axons conduct?
Action Potentials
Where are bipolar neurons found?
Bipolar Neurons are found in the retina of the eye.
What neuron structurally is the most common? What is an example of this type?
Multipolar Neurons are most common, motor neurons are a good example of multipolar structure.
What is a bundle of axons in the PNS called?
A Nerve
What is a bundle of axons in the CNS called?
A Tract