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Neurons
chapter 7 neurons
| Question | Answer |
|---|---|
| What is anther name for neurons (neurons) | nerve cells |
| What do neurons do (neurons) | transmit messages (nerve impulses) from one part of the body to another |
| What do all neurons have (neurons) | cell body which contains the nucleus and is the metabolic center of teh cell, and one or more slender processes extending from the cell body |
| What does the cell body do (neurons) | metabolic center of the neuron. |
| What does the cell body consist of (neurons) | contains organelles except for centrioles, rough ER, call Nissl substance, and neurofibrils (important in maintaining cell shape) |
| Neuron cells processes (fibers)look like (neurons) | vary length from microscopic to 3-4 feet. The longest one in humans is from the lumbar region of the spine to the great toe. |
| What are neuron processes that convey incoming messages toward the cell body called (neurons) | dendrites |
| What are neuron processes that generate nerve impulses and conduct them away from the cell called (neurons) (neurons) | Axon |
| Neurons can will have hundreds of branching ----- (neurons) | dendrites (dendr = tree) |
| Neurons will only have one ---- (neurons) | Axon (from a cone like region of the cell body called the axon hillock) |
| axons branch profusely at their terminal end forming hundreds to thousands of ---- (neurons) | axon terminals |
| Axon terminals contain (neurons) | hundreds of tiny vesicles,or membranous sacs that contain chemicals called neurotransmitters |
| Each axon terminal is separated from the next neuron by a tiny gap called (neurons) | the synaptic cleft |
| The synaptic cleft functional juntion is called (neurons) | synapse |
| neurons never touch each other (neurons) | |
| Most long nerve fibers are covered with a whitish, fatty material, called --- (neurons) | myelin (has a waxy appearance) |
| What is the role of myelin (neurons) | protects and insulates the fibers and increases the transmission rate of nerve impulses |
| Axons outside the CNS are myelinated by --- (neurons) | Schwann Cells |
| What are Schwann cells (neurons) | specialized supporting cells that wrap themselves tightly around the axon (jelly-roll fashion)(p. 228 7.5) |
| when the Schwann cells wrap around the axon a tight coil of wrapped membranes called what encloses the axon | myelin sheath |
| Most of the Schwann cell cytoplasm ends up just beneath the outermost part of its plasma membrane. This part of the Schwann cell (external to the myelin sheath) is called --- (neurons) | neurilemma |
| Since the myelin sheath is formed by individual Schwann cells, it has gaps or indentations call--- at regular intervals (neurons) | nodes of Ranvier |
| myelinated fibers are also found in the CNS but there it is called--- that for CNS myelin sheaths | oligodendrocytes |
| People with multiple sclerosis (MS) the myelin sheaths around the fibers are gradually destroyed, converted to hardened sheaths called (neurons) | scleroses |
| For the most part cell bodies are found in the CNS in clusters called --- (neuron) | nuclei |
| neurons do not routinely undergo cell division after birth | |
| small collections of cell bodies called ganglia are found in a few sites outside the CNS in the PNS (neurons) | |
| Bundles of nerve fibers running through the CNS are called --- | tracts |
| Bundles of nerve fibers running through the PNS are called | nerves |
| White matter consist of dense collections of myelinated fibers (tracts)in the CNS | |
| Gray matter contains mostly unmyelinated fibers and cell bodies in the CNS | |
| Functional classification of neurons | sensory or afferent, motor, and association neurons |
| neurons carrying impulses from the sensory receptors (in the internal organs or skin) to the CNS are --- (neurons) | sensory or afferent (means: to go toward) neurons |
| The cell bodies of SENSORY neurons are always found in a ganglion outside the | CNS |
| SENSORY neurons keep us informed about what is happening both inside and outside the body | |
| The dendrite endings of the sensory neurons are usually associated with specialized --- that are activated by specific changes occuring nearby | receptors |
| There are special sense organs and simple sensory receptors seen in skin (cutaneous sense organs) and in the muscles and tendons (proprioceptors) | |
| the least specialized of the cutaneous receptors are the --- | pain receptors (bare dendrite endings) |
| what are the most numerous receptors | pain receptors because pain warns us that some type of body damage is occurring or is about to occur. |
| ---- detects the amount of stretch or tension in skeletal muscles, their tendons, and joints | proprioceptors |
| proprioceptors send information to the brain so proper adjustments can be made to maintain balance and normal posture | (propia means "one's own") and the proprioceptors constantly advise our brain of our won movements |
| Neurons carrying impulses from the CNS to the viscera and /or muscles and glans are | MOTOR or efferent neurons |
| The cell bodies are always located in the | CNS |
| ---- connect the motor and sensory neurons in neural pathways and like motor neurons their cell bodies are always located in the CNS | association neurons or interneurons |
| structural classifications based on the number of processes extending from the cell body | |
| if there are several process extending from the cell body the neuron is a | multipolar neuron (since all motor and association neurons are multipolar this is the most common structural type) |
| neurons with two processes - axon and dendrite | are called bipolar neurons |
| biplar neurons are rare in adults only found in some special sense organs (eye, nose) | |
| Unipolar neurons have a single process emerging from the cell body. | |
| nerve impulses | neurons have two major functional properties (irritability and conductivity |
| the nerve function of irritability is the ability to respond to stimulus and convert it into a nerve impulse | irritability |
| the ability to transmit the impulse to other neurons, muscles, or glands is called | conductivity |
| the plasma membrane of a resting or inactive neuron is | polarized (fewer positive ions sitting on the inner face of the neuron's plasma membrane then there are on its outer face in the tissue fluid that surrounds it |
| major positive ions inside the cell are potassium (k+) | |
| major positive ions outside the cell are sodium (Na+) | |
| If the inside of the cell remains more negative as compared to the outside, the neuron will stay inactive | |
| An inward rush of sodium ions changes the polarity of the neuron's membrane in event called | depolarization |
| graded potential is when | inside is now more positive and the outside is less positive |
| action potential | |
| nerve impulse |
Created by:
Hootlc2005
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