Quiz #3 Flashcards
Nervous System
communication network that enables animal to adjust to internal and external environmental changes
What do sensory components do?
detect environmental changes
What do motor components do?
provide response to processed information
What do integrative components do?
process sensory data coupled with information stored in memory
What are the two types of cells of the nervous system?
- neurons
- glial
What are neurons?
transmit nerve impulses and join with others via synapses
What are glial cells?
provide service to neurons and their environment
How many neurons do humans have? How many glial cells?
100 million neurons and 10x glial cells
What are the three components of a neuron?
- cell body
- dendrites (many)
- axon (one)
What are dendrites? What do they do? What do the look like?(3)
- conduct impulses towards cell body
- sites for receiving information from other neurons
- highly branched, large surface area for communication with axons
What does an axon do?
conduct impulses away from cell body
What is a nerve fiber composed of?
an axon and its myelin covering if present
What is a neurilemma? Where is located?
Surrounds the myelin sheath
Located in a myelinated axon
What is an axolemma?
Plasma membrane of axon, beneath the myelin sheath
What are Nodes of Ranvier? Where are they found? Function?
- regularly spaced, myelin-free
- gaps along myelinated axon
- the axolemma is directly exposed to fluid and exchanges electrolytes and nutrients
Whare is the telodendric zone located?
terminal branches of axon
What does the polarity of a neuron refer to?
the number of poles or processes that stem from cell bodies
What is a bipolar neuron? (Length, composition, location)
Short
One axon and one dendrite
Retina and olfactory region (nose)
What is a multipolar neuron? (Length, composition, location)
Typically long
Many dendrites and one axon
Most are located in the CNS
What is a nucleus?
group of nerve cell bodies within brain and spinal cord (CNS)
What is a ganglion?
group of nerve cell bodies outside of brain and spinal cord (PNS)
What is a tract/fasciculus?
bundle of parallel fibers within brain and spinal cord (CNS)
What is a nerve?
bundle of neuron fibers outside brain and spinal cord (PNS)
Synapse
continuity from one neuron to the next
What is the synaptic gap? How are impulses transmitted?
no physical contact of neurons in the space between neurons. Impulses are transmitted chemically.
What are the three characteristics of a synapse?
- one-way conduction (direction)
- facilitation (repeated impulses provide easier subsequent transmission)
- greater fatigability then neurons (repetitive impulses fade, tire faster)
A neuron’s axon terminal bud is in ___ ___ to another ____. The ___ ___ fits into the ____ of the ___ ___ cell membrane
- close
- proximity
- neuron
- terminal
- bulb
- postsynaptic
Synaptic cleft
gap between axon terminal and postsynaptic cell
Where are synaptic vesicles located? What do they contain?
- terminal bulb
- neurotransmitters
Oligodendrocytes
myelin sheath formation in PNS
Function of Schwann cells
myelin sheath formation in PNS
Astrocytes (4, location and function)
- numerous, star shaped
- provide support and blood vessel nourishment
- release excitatory neurotransmitter glutamate in response to stimulation
- CNS
Ependymal cells (location and function)
- Line ventricles of brain and central canal of spinal cord
- Unite with capillaries to form choroid plexus
Choroid Plexus (location and function)
- in the ventricles
- produces cerebrospinal fluid
Myelin (composition, function)
- White lipid substance
- forms sheath around nerve fibers and serves as electrical insulator
How are myelin sheaths formed in the CNS and the PNS
- In CNS: oligodendrocytes
- In PNS: Schwann Cells
Why are unmyelinated fibers not insulated?
they are in direct association with extracellular fluid
Myelinated means ___ conduction?
faster
Schwann cell (composition, 3)
- cytoplasm contains myelin and wraps around nerve fiber many times
- nucleus lies in the cell beneath the neurolemma
- one cell around on axon
Oligodendrocyte (composition, 3)
- cytoplasm has multiple extension and each wraps around a nerve fiber
- one cell provides sheath for multiple axon locations
- axon bulges at node and is exposed to extracellular space
Depolarization
occurs due to sodium and potassium entering the cell
Saltatory conduction
depolarizing action potential jumps from node to node, traveling along myelinated segments
PNS
outer cytoplasmic processes of adjacent neurolemmocytes (Schwann cells) overlap to restrict exposure to extracellular space
CNS
myelin formed by oligodendrocytes and nodes are broadly exposed to extracellular space
What is the CNS composed of?
brain and spinal cord
What is the PNS composed of? What are the two divisions?
- cranial and spinal nerves
- somatic (voluntary) and autonomic (involuntary)
Autonomic Nervous System (ANS) (3 divisions)
- sympathetic NS
- parasympathetic NS
- enteric NS
Sympathetic Nervous System
fight or flight
Parasympathetic Nervous System
rest and digest
