HW ch11 part1
Terms in this set (69)
What is meant by "intergration," and does it primarily occur in the CNS or the PNS?
Integration involves processing and interpreting sensory information, and making a decision about motor output. Integration occurs primarily in the CNS.
Which type of neuroglia controls the extracellular fluid environment around neuron cell bodies in the CNS? in the PNS?
Astrocytes control the extracellular environment around neuron cell bodies in the CNS, whereas satellite cells perform this function in the PNS.
Which two types of neuroglia form insulating coverings called myelin sheaths?
Oligodendrocytes and Schwann cells form myelin sheaths in the CNS and PNS, respectively.
How does a nucleus within the brain differ from a nucleus within a neuron?
A nucleus within the brain is a cluster of cell bodies, whereas the nucleus within each neuron is a large organelle that acts as the control center of the cell.
How is a myelin sheath in the CNS, and what is its function?
In the CNS, a myelin sheath is formed by oligodendrocytes that wrap their plasma membranes around the axon. The myelin sheath protects and electrically insulates axons and increases the speed of transmission of nerve impulses.
Which structural and functional type of neuron is activated first when you burn your finger? Which type is activated last to moved your finger away from the source if heat?
Burning a finger will first activate unipolar (pseudounipolar) neurons that are sensory (afferent) neurons. The impulse to move your finger away from the heat will be carried by multipolar neurons that are motor (efferent) neurons.
For an open channel, what factors determine in which direction ions will move through that channel?
The concentration gradient and the electrical gradient—together called the electrochemical gradient—determine the direction in which ions flow through an open membrane channel.
For which cation are there the largest number of leakage channels in the plasma membrane?
There are more leakage channels for K+ than for any other cation.
What determines the size of a grade potential?
The size of a graded potential is determined by the strength of a stimulus.
Which is bigger, a graded potential or an action potential? Which travels further? Which initiates the other?
Action potentials are larger than graded potentials and travel further. Graded potentials generally initiate action potentials.
An action potential does not get smaller as it propagates along an axon. Why not?
An action potential is regenerated anew at each membrane patch.
Is NOT part of the central nervous system..
Part of the central nervous system.
The brain, the spinal cord, and the tract.
Helps regulate the ionic composition of CNS extracellular fluid.
Lines brain cavities
Myelinates nerve fibers in the CNS
Myelinates nerve fibers in the PNS
What type of current flows through the axolemma during the steep phase of repolarization?
Chiefly a potassium current
Assume that an EPSP is being generated on the dendritic membrane. Which will occur?
A single type of channel will open, permitting simultaneous flow of Na+ and K+
The velocity of nerve impulse conduction is greatest in
Heavily myelinaated large-diameter fibers.
Is NOT a Chemical synapses
Ions flowing through protein channels from the presynaptic to the postsynaptic neuron.
Chemical synapses are characterized by ...
-The release of neurotransmitter by the presynaptic membranes.
-Postsynaptic membranes bearing receptors that bind neurotransmitter.
-A fluid-filled gap separating the neurons.
NOT correct about neurons.
The number of adult neurons is the same as the number formed during the embryonic period.
The peripheral nervous system _
consists of cranial and spinal nerves carrying impulses to and from the brain and spinal cord
Bodily functions that follow "a law unto itself" are controlled by the involuntary nervous system. This system is also termed ___ and functions to ____.
the autonomic nervous system (ANS); conduct impulses from the CNS to cardiac muscle, smooth muscle, and glands
The voluntary nervous system is to the involuntary nervous system as _
the somatic nervous system is to the autonomic nervous system
Based on your understanding of this cell's function, you might expect this cell to be active in neurodegenerative disorders like Alzheimers where this cell removes damaged neurons. Additionally, this cell is active in preventing encephalitis and meningitis due to its ability to phagocytize microorganisms
What is the primary difference between the somatic nervous system and the autonomic nervous system?
The somatic nervous system allows us to consciously control our skeletal muscles, and the autonomic nervous system controls activity that humans cannot consciously control, such as the pumping of the heart and the movement of food through the digestive tract.
In the figure above, which letter(s) correspond to the peripheral nervous system?
Both A and C represent portions of the peripheral nervous system (PNS).
The central nervous system _
consists of the brain and spinal cord
Based on your understanding of this cell's function, diseases that affect the myelin sheath of neurons, like multiple sclerosis, likely affects which of the cells in the figure?
Oligodendroctye, which is depicted
Which of the following line the central cavities of the brain and spinal cord and provide a fairly permeable barrier between the CSF and nervous tissue?
Based on your understanding of the different types of glial cells, the cell depicted by the arrow is most likely a _
oligodendrocyte or a Schwann cell
Which type of glial cells line the central cavities of the brain and spinal cord, where they help to circulate the cerebrospinal fluid
Which type of glial cells are the most abundant and versatile and aid in making exchanges between capillaries and neurons?
Divisions of the nervous system is also known as the involuntary nervous system
The autonomic nervous system
The somatic nervous system _
conducts impulses from CNS to skeletal muscles
Which statement is true of the glial cell pictured above?
Glial cell processes touch nearby neurons, monitoring their health, and when they sense that certain neurons are injured or in other trouble, the microglial cells migrate toward them.
Which neuroglia is most responsible for helping determine capillary permeability in nervous tissue?
Based on your understanding of this cell's function, these cells influence neuronal function by "mopping up" leak potassium and by recapturing and recycling released neurotransmitters. These cells also participate in information processing in the brain.
Astrocyte, which is depicted
This part of the neuron is predominant in the area of the brain known as white matter.
From where can collaterals emerge on a myelinated nerve?
From the nodes of Ranvier
Considering the direction of axonal transport, which type of transport allows certain viruses to circumvent the barrier created by astrocytes to enter into the CNS?
The somatic sensory (afferent) fibers of the peripheral nervous system transmits information from the _____ to the CNS.
Thinking of the structure and function of the neuron, as well as the structure of the PNS, which portion of the neuron is predominately found only in the PNS?
The PNS consists chiefly of neuron processes which include both axons (C) and dendrites (A).
Match the fiber with the type of information it carries: Somatic motor fibers carry __
CNS to skeletal muscles
This part of the neuron is the predominant component of gray matter in the brain.
is not a characteristic of neurons
Neurons are relatively small, simple-structured cells.
characteristic of neurons
-Neurons can function optimally for over 100 years.
-In general, neurons cannot be replaced if destroyed.
-Neurons require continuous and abundant supplies of oxygen, and cannot survive for more than a few minutes without it.
What is the difference between nerves and tracts?
Bundles of neuron processes are called tracts in the CNS and nerves in the PNS.
Visceral afferent fibers carry _
organs in the ventral body cavity to the CNS
Another term for this area is the secretory region.
Reflexes are _
rapid automatic responses to a stimulus in which the particular stimulus always produces the same motor response
is not true of efferent neurons
Efferent neurons are bipolar.
True of efferent neurons
Efferent neurons carry impulses away from the CNS to the effector organs.
The cell bodies of most efferent neurons are located in the CNS.
Impulses from efferent neurons cause activity in skeletal muscles and glands.
Because axons are often very long, the task of moving molecules along their length might appear difficult. However, through the cooperative efforts of motor proteins and cytoskeletal elements (microtubules and actin filaments), substances travel continuously along the axon in both directions. Movement away from the cell body is anterograde movement, and that in the opposite direction is retrograde movement.
Considering the function of the soma, what structures are likely carried by anterograde movement?
Mitochondria, cytoskeletal elements, membrane components used to renew the axon plasma membrane, and enzymes needed to synthesize certain neurotransmitters
Considering the function of the soma, what structures are likely carried by retrograde movement?
Messages on the condition of axon terminals and worn out organelles
If we consider neurons to be carrying on conversations, which portion of the neuron "listens?
provides an enormous surface area for receiving signals from other neurons.
In many brain areas, these structures are highly specialized for collecting information.
short-distance signals called graded potentials.
Organelles for degradation or recycling are moved through the axon by _
characteristics Is not associated with a myelinated nerve fiber
Slow conduction of nerve impulses
characteristics associated with a myelinated nerve fiber
Rapid conduction of nerve impulses.
The presence of nodes of Ranvier.
It is always associated with an axon.
In the peripheral nervous system, it is formed by Schwann cells.
Which disease is directly related to demyelination?
Multiple sclerosis is
the autoimmune disease that leads to destruction of the myelin sheaths in the CNS
In considering the types of neurons and their predominant function, efferent is to multipolar as
afferent is to unipolar
The Nissl bodies seen in the neuron cell body represents which cellular organelle?
Rough endoplasmic reticulum
If we consider the process where neurons receive signals from and send signals to score of other neurons a "conversation," which type of neuron seems to have the most to "listen and say?
Somatic afferent fibers carry
skin, skeletal muscles, and joints to the CNS
Neurons can be classified structurally by the number of processes extending from their cell bodies. Which of the following is the most common neuron type in humans?