Book: chapter 12
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Book: chapter 12
chapter 12 bio120
The whole nerve is covered by a tough fibrous sheath called ______.
Groups of axons are bound into bundles called ___a___ and wrapped by a CT called the ___b___.
a) nerve fascicles
within a nerve, each axon is surrounded by schwann cells, and covering those schwann cells is a layer of loose CT called this ____.
This is a cablelike organ in the PNS
In two regions of the brain, there is an additional layer of gray matter located superficially
within the white matter, axons traveling to similiar destinations form axon bundles called this.
This color matter contains no neuron cell bodies but millions of axons and neuroglia
What is the site where neuron cell bodies are clustered and where synapses occur?
This zone in the CNS surrounds the hallow central cavity. In the spinal cord it is butter-fly shaped
this type of myeline sheath wraps has processes that wrap several different axons, and are widely spaced throughout the axon. Is it found in the PNS or CNS?
Axons that lack a myelin sheathe are called this. They can wrap 15 or more of these type of axons.
these gaps increase seed impulse conduction along the axon
myelin sheath gaps
what are the 3 functions of the myelin sheath?
1. prevent leakage from axons
2. increase speed of impulse conduction
3. makes impulse proagation more energy-efficient
myelin sheaths are produced from ___a___ in the CNS and from ___b___ in the PNS.
b) schwann cells
This type of neuroglia in the PNS surround all axons in the PNS and form myelin sheaths
This tye of neuroglia in the PNS surround neuron cell bodies within ganglia
What are the 2 types of neuroglia in the PNS?
1. satellite cells
2. schwann cells
This glial cell, ___a___, line up groupps and wrap their cell processes around the thicker axons in the CNS, producing insulating coverings called ___b___
b) myelin sheaths
This cell functions to pprovide a permeable layer between the cerebrospinal fluid that fills up the cavity and tissue fluid that bathes the cells of the CNS
Like other macrohages of the body, microglial cells are derived from blood cells called this.
this neuroglia are the phagocytes and macrophages of the CNS, engulfing injured or dead neurons
This type of glial cell is the smallest and least abundant of the CNS
this type of glial cell helps synapses form by develoing neural tissue, produces molecules for neural growth, and propagate calcium signals for memory
What are the 3 functions of astrocytes?
1. regulates neurotransmitter levels
2. signals increased blood flow in active regions of the brain.
3. controlling he ionic environment around neurons
This type of glial cell is the most abundant. Its radiating processes cling to either neurons or capillaries.
T or F: glial cells cannot divide
This cell type outnumber neurons in the CNS 10 to 1 and make up half the mass of the brain
this non-nervous suoprting cell covers parts of the neurons, insulating them to help eletrical activities interfering with adjacent neurons (2 names)
neuroglia or glial cells
This class makes up 99.98% of neurons in the body. They are all in the CNS and lie between the other 2 classes of neurons
this tye of neurons are multipolar, and their cell body are located in the CNS. they form junctions with effector cells that stimulate muscle contraction
the efferent neurons make up the _____ division of the PNS.
Most of these types of neurons are pseudounipolar and their cell bodies are in ganglia outside the CNS
afferent neurons make up the ____ division of the PNS
what are the 3 functional classifications of neurons
T or F: unipolar neurons do not contain dendrites
: both peripheral and central processes are considered axons
T or F: the peripheral process of the unipolar neuron is considered the axon
: the central process is an axon because it carries a nerve impulse AWAY from the cell body
In unipolar neurons, the process that runs into the CNS is the (a) and the other that extends to the receptors is called the (b)
a) central process
b) peripheral process
this class of neuron can be found in the sensory ganglia in the PNS, where they function as sensory neurons
This neuroon starts out as a bipolar neuron whose 2 processes fuse together (2 names)
unipolar neuron or pseudounipolar neuron
this class of neuron is very rare; occuring in some special sensory organs (inner ear, retina of eye) where they mostly serve as sensory neurons. They have 2 processes
which class of neuron contain 99% of neurons in the body
This class of neuron has numerous dendrites, a single axon (sometimes none), and have more than 2 processes
what are the 3 structural classifications of neurons?
At the synapse, the plasma membranes of the two neurons are seperated by this.
T or F: mitochondria are not abundant in terminal boutons
These are membrane-bound sacs filled with neurotransmitters contained in the terminal bouton.
This synapse occurs between axons and neuron cell bodies
This is where most synapses occur: between the terminal boutons of one neuron and the denrites of another neuron
this neuron transmits signals AWAY from the synapse
This neuuron conducts signals TOWARDS the synapse
some CNS transmit signals electrically through this
What is the site at which neurons communicate
the ends of the terminal arborization branches are called
This is at the end of an axon where it starts to branch profusely
Branches of axons are called this
T or F: the bigger diameter of an axon, the slower the impulses are
F: the faster the impulses are
A long axon is called
a nerve fiber
The movement of substances along axons is through this
by definition, these are impulse generators and conductors that transmit nerve impulses away from their cell body
This is where the axon attaches to the cone-shaped region of the cell body
what are the two types of processes in the neuron?
dendrites and axons
Where do the clusters of ganglia lie along
the nerves in the PNS
These are bundles of intermediate filaments that keep the cell from being pulled apart from tensile forces
these organelles continuilly renew the membranes of the neural cell and protein components of the cytosol
this is a large cluster of rER and free ribosomes in the cell body
in all cell bodies, what do they all have in common?
all consist of a single nucleus surrounded by cytoplast
these have a high metabolic rate and cannot survive for more than a few mins without oxygen
T or F: neurons have an extreme longevity and can live for over 100 years
Neurons conduct 2 electrical signals called these:
nerve impulses and action potentials
these are highly specialized cells that conduct electrical signals from one part of the body to another
neurons and nerogliaboth develo from these two embryonic tissue
neural tube and neural crest
What are the 2 main types of cells in a nervous tissue?
: the excitable nerve cell
: the nonexcitable supporting cell that wraps around the neurons
what is another name for the ANS
involuntary nervous system
the visceral motor makes up this and ontrols the function of the visceral organs
autonomic nervous system (ANS)
This part of the PNS regulates the contraction of smooth and cardia muscle and secretion by the body's many glands
this is often called the voluntary nervous system. this part of the PNS stimulate scontraction of skeletal muscles
This sense, forms taste and smell
special visceral senses
These series are felt widelyin the digestive and urinary tracts, reproductive organs, etc. sensations such as hunger and nausea are also felt here.
general visceral senses
these senses are confined to relatively small areas, which are mostly confined in the head for hearing, balance, or equilibium and vision
special somatic senses
this sense informs you of the position and movement of ur body and space, giving u a "body sense"
These are the senses whose receptors are sppread widely throughout the outer tube of the body. primarily the senses on the skin for touch, painj, pressure, vibration, and temperature
general somatic senses
what is another name for the visceral motor?
autonomic nervous system (ANS)
What are the 4 subdivisions of the PNS
1. somatic sensory
2. somatic motor
3. visceral sensory
4. visceral motor
this body region consists of structures external to the ventral body cavity, or structures of the outer tube (skin, bones)
somatic body region
this has 2 names and they are signals picked up by a sensory receptors and are carried by nerve fibers of the PNS -> CNS
sensory or afferent signals
this is included in the PNS, which are areas where the cell bodies of neurons are clustered
this consists mainly of the nerves that extend from the brain and spinal cord and is part of the nervous syste outside the CNS
peripheral nervous syste (PNS)
this consists of the brain and spinal cord. it receives incoming sensory signals, interprets it, and dictates motor responses based on past experiences, reflexes and current condition
The nervous system dictates a response by activating our muscle or glands, which are called (a), through a process called (b)
a) effector organs
b) motor output
the nervous system processes and interprets the sensory input and makes decisions about what should be done at each moment, in this process
the gathered information of a stimulus is called this
sensory recetrs monitors changes in and outside the body. these changes are called this ____.