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Terms in this set (47)
What are the three main functions of a nervous system?
Sensory Input, Integration, Motor Output
What structures complete the Central Nervous System (CNS)?
Brain and spinal nerve cord in vertebrates
Motor output is the conduction of signals from the _____, to the _____.
CNS; effector cells such as muscles
Signals are conducted by _____, which are bundles of _____ wrapped in connective tissue.
Sensory and motor neurons are collectively called the _____.
Peripheral Nervous System (PNS)
The structural and functional unit of the nervous system is the _____.
What are the four main parts of a neuron?
Cell body; dendrites; axon; synaptic terminals
The site of contact between a synaptic terminal of a neuron and a target, such as another neuron, a muscle cell, or a gland, is called a _____.
What are the cells called that lie on each side of a synapse?
pre-synaptic cell and post-synaptic cell
The simplest type of nerve circuit is termed a _____.
What is the minimum number of neurons that can make up a "reflex arc", and what would these neurons be?
2; there must be at least one sensory neuron and at least one motor neuron
What are "interneurons"?
these are neurons within the CNS
Interneurons are constantly _____. What does this active provide the context for?
active; for interpreting sensory input and directing an appropriate response
Ganglia and nuclei are collections of _____. How do they differ from one another?
cell bodies of neurons; Ganglia are found in the PNS while nuclei are found within the brain
Supporting cells, called _____ or _____ are _____.
glia; glial cells; essential for the structural integrity of the nervous system and for the normal functioning of the neurons
Which glial cells provide structural and metabolic support for neurons?
What do these glial cells also form?
the blood-brain barrier
What cells form the insulating sheaths around axons? Where are these cells found?
Schwann cells-outside the CNS; Oligodendrocytes-within the CNS
All cells have an electrical charge difference across their plasma membrane called the _____.
The membrane potential exists because _____.
the different concentration of certain ions across the cell membrane
The membrane potential of an unstimulated neuron is called the _____.
resting membrane potential
What makes invertebrates like squid and lobsters such good animals for the study of nerve impulses?
they are large in diameter
What is the principal + charged ion outside of a cell?
What is the principal + charged ion inside of a cell?
How do these ions move across the cell membrane?
They must either be pumped by membrane proteins or by simple diffusion through ion channels
All cells have a membrane potential; however, only certain cells such as _____ and _____ have the ability to generate large changes in their membrane potential. These cells are called _____.
neurons; muscle cells; excitable
What types of ion channels are present in the cell membrane? How are these channels opened?
ungated channels and gated channels; ungated channels are always open while gated channels are opened either by chemicals or by a threshold voltage
What are the two different types of "graded potentials"?
hyperpolarization and depolarization
Define each type of "graded potential". Tell which ion channels is involved in each type of "graded potential".
hyperpolarization:a change in membrane potential so that the membrane potential becomes more negative compared to resting membrane potential--K+ ion channel
depolarization:a change in membrane potential so that the membrane potential becomes less negative compared to resting membrane potential--Na+ ion channel
Why are these voltage changes called "graded potentials"?
because the amount of hyperpolarization or depolarization depends upon the strength of the stimulus
If a sufficiently strong stimulus causes depolarization to reach "threshold potential" it triggers a different type of response called an _____.
In a neuron, an action potential can only be generated in the _____.
The action potential is a non-graded, all or non event; meaning _____.
magnitude of the action potential is independent of the strength of the depolarizing stimulus that produced it, providing the stimulus reached threshold depolarization level
The action potential arises because the plasma membrane has _____ ion channels.
Which two types of voltage-gated ion channels contribute to the action potential?
Na+ and K+
Which voltage-gated ion channel opens first and which one opens second in an action potential?
1st- Na+, 2nd- K+
The _____, not their amplitude codes for stimulus intensity in the nervous system.
number of action potentials per second
What two factors affect the speed at which an action potential travels down an axon?
the diameter of the axon, the larger the diameter the faster the action potential. The presence of myelin around the axon, myelin insulates the axon and allows the action potential to travel by "salutatory conduction"
What is a synapse?
Synapses are unique cell junctions that control communication between a neuron and another cell
Name the two general two types of synapses.
Electrical Synapses and Chemical Synapses
One important function of the chemical synapse is to allow _____.
nerve impulses to travel in only one direction through the nervous system
The "motor division" of the PNS is divided into two functional divisions, called the _____ and _____ nervous systems.
The somatic nervous system carries signals to _____.
The autonomic nervous system carries signals to _____.
cardiac muscle, smooth muscle, and glands
The autonomic nervous system consists of two divisions that act on body organs with _____.
The Sympathetic Division correlates with _____.
an activation of the fight of flight response
The Parasympathetic Division causes _____.
a calming effect and a return to an emphasis on self-maintenance functions
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