Term
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Definition
| Neurons transmit nerve impulses along nerve fibers to other neurons |
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Term
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| Nerves are made up of bundles of nerve fibers. |
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Term
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Definition
| Neuroglia carry out a variety of functions to aid and protect components of the nervous system. |
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Term
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Definition
| the central nervous system (CNS), made up of the brain and spinal cord |
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Definition
and the peripheral nervous system (PNS), made up of peripheral nerves that connect the CNS to the rest of the body.
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Term
| What does the nervous system provide? |
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Definition
| The nervous system provides sensory, integrative, and motor functions to the body. |
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| what are motor functions divided into? |
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Definition
| Motor functions can be divided into the consciously controlled somatic nervous system and the unconscious autonomic system. |
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| peripheral nervous system |
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Definition
A) cranial nerves arising from the brain
1. somatic fibers connecting to skina nd skeletal muscles
2. autonomic fibers connecting it ciscera
B) spinal nerves arising from the spinal cord
1. somatic fibers connecting to skin and skeletal muscles
2) autonomic fibers connecting to viscera |
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Term
| Functions of the nervous system (3) |
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Definition
A. Sensory receptors at the ends of peripheral nerves gather information and convert it into nerve impulses. Impulses sent to brain.
B. When sensory impulses are integrated in the brain as perceptions, this is the integrative function of the nervous system.
C. Conscious or subconscious decisions follow, leading to motor functions via effectors.
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Term
| what do neuroglial cells do? |
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Definition
| Neuroglial cells fill spaces, support neurons, provide structural frameworks, produce myelin, and carry on phagocytosis. Four are in the CNS and the last in the PNS |
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Term
| What are miccroglial cells? |
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Definition
| Microglial cells are small cells that phagocytize bacterial cells and cellular debris. |
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Term
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Definition
| Oligodendrocytes form myelin in the brain and spinal cord. |
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Term
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Definition
| Astrocytes are near blood vessels and support structures, aid in metabolism, and respond to brain injury by filling in spaces. |
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Term
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Definition
| Ependyma cover the inside of ventricles and form choroid plexuses within the ventricles. |
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Term
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Definition
| Schwann cells are the myelin- producing neuroglia of the peripheral nervous system. |
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Term
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Definition
| A neuron has a cell body with mitochondria, lysosomes, a Golgi apparatus, chromatophilic substance (Nissl bodies) containing rough endoplasmic reticulum, and neurofibrils. |
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Term
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Definition
| Nerve fibers include a solitary axon and numerous dendrites |
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Term
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Definition
| Branching dendrites carry impulses from other neurons (or from receptors) toward the cell body. |
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Term
| The axon transmits the impulse where? |
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Definition
| The axon transmits the impulse away from the axonal hillock of the cell body and may give off side branches. |
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Term
| Larger axons are enclosed by what? |
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Definition
| Larger axons are enclosed by sheaths of myelin provided by Schwann cells and are myelinated fibers. |
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Term
| The outer layer of Myelin is surrounded by what? |
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Definition
| The outer layer of myelin is surrounded by a neurilemma (neurilemmal sheath) made up of the cytoplasm and nuclei of the Schwann cell. |
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Term
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Definition
| Narrow gaps in the myelin sheath between Schwann cells are called nodes of Ranvier. |
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| What do the smallest axons lack? |
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Definition
| The smallest axons lack a myelin sheath and are unmyelinated fibers |
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Term
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Definition
| White matter in the CNS is due to myelin sheaths in this area. |
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Term
| unmyelinated nerve tissue |
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Definition
| Unmyelinated nerve tissue in the CNS appears gray. |
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Term
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Definition
| Peripheral neurons are able to regenerate because of the neurilemma but the CNS axons are myelinated by oligodendrocytes thus lacking neurilemma and usually do not regenerate. |
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Term
| how can nuerons be grouped |
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Definition
| Neurons can be grouped in two ways: on the basis of structural differences (bipolar, unipolar, and multipolar neurons), and by functional differences (sensory neurons, interneurons, and motor neurons). |
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Term
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Definition
| Bipolar neurons are found in the eyes, nose, and ears, and have a single axon and a single dendrite extending from opposite sides of the cell body. |
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Definition
Unipolar neurons are found in ganglia outside the CNS and have an axon and a dendrite arising from a single short fiber extending from the cell body.
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Multipolar neurons have many
nerve fibers arising from their cell bodies and are commonly found in the brain and spinal cord.
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Term
| Sensory neurons (afferent neurons) |
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Definition
| Sensory neurons (afferent neurons) conduct impulses from peripheral receptors to the CNS and are usually unipolar, although some are bipolar neurons |
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Term
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Definition
| Interneurons are multipolar neurons lying within the CNS that form links between other neurons. |
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Definition
| Motor neurons are multipolar neurons that conduct impulses from the CNS to effectors. |
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Term
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Definition
| A cell membrane is usually polarized, with an excess of negative charges on the inside of the membrane; polarization is important to the conduction of nerve impulses. |
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Term
| A distribution of ions is determined by: |
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Definition
| The distribution of ions is determined by the membrane channel proteins that are selective for certain ions. |
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Term
| Potassium ions more readily... |
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Definition
Potassium ions pass through the membrane more readily than do sodium ions, making potassium ions a major contributor to membrane polarization.
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Term
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Definition
1. Due to active transport, the cell maintains a greater concentration of sodium ions outside and a greater concentration of potassium ions inside the membrane.
2. The inside of the membrane has excess negative charges, while the outside has more positive charges.
3. This separation of charge, or potential difference, is called the resting potential.
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Term
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Definition
D. Potential Changes
1. Stimulation of a membrane can locally affect its resting potential.
2. When the membrane potential becomes less negative, the membrane is depolarized.
3. If sufficiently strong depolarization occurs, a threshold potential is achieved as ion channels open.
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