Term
| What are the functions of the nervous system? |
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Definition
1. Sense changes in environment
2. Interpret changes
3. Respond to changes in environment
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Term
What are the 2 divisions of the nervous system?
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Definition
I. Central Nervous System (CNS)
II. Peripheral Nervous System (PNS)
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Term
Central Nervous System (CNS)
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Definition
control center composed of brain and spinal cord
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Term
Peripheral Nervous System (PNS)
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Definition
cranial nerves from brain
and spinal nerves from spinal cord
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Term
| Structure of Peripherial Nervous System |
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Definition
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Term
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Definition
(sensory) takes impulses to CNS
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Term
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Definition
(motor) takes impulses away from CNS
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Term
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Definition
goes to voluntary muscles
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Term
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Definition
goes to involuntary muscles and glands
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Term
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Definition
a. Sympathetic
b. Parasympathetic
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Term
NERVOUS SYSTEM COMPOSED OF TWO TYPES OF CELLS
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Definition
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Term
Functions of Neuroglia cells
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Definition
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Term
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Definition
Schwann cell
Oligodendrocytes
Microglia
Astrocytes
Ependyma cells
Satellite cells
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Term
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Definition
basic structural and functional units of nervous system.
Can not divide mitotically, but some can regenerate a severed portion.
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Term
Three Principal Components of Neurons
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Definition
Cell body or perikaryon
Dendrites
Axon
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Term
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Definition
enlarged portion of neuron that contains nucleus and nucleolus surrounded by cytoplasm.
Cytoplasm characterized by Nissl bodies and neurofibrils
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Term
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Definition
branched processes that extend from cytoplasm of cell body.
Receive stimulus and conduct impulse to cell body
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Term
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Definition
Single, relatively long, highly branched process that conducts impulses away from cell body.
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Term
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Definition
originates from the cell body is axon hillock. Conical region where it |
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Term
| What is the length of an Axon? |
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Definition
| axons vary from a few millimeters to over a meter |
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Term
| What does the cytoplasm of the axon consist of? |
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Definition
| many mitochondria, microtubules and neurofibrils |
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Term
| What is not in the cytoplasm? |
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Definition
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Term
| what are the Special Structures? |
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Definition
Axon colaterals
axoplasm
axolemma
telodendria
synaptic end bulbs |
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Term
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Definition
| side branches that extend short distance from axon |
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Term
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Definition
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Definition
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Term
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Definition
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Term
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Definition
| sac-like structures at the end of teledendria that contain transmitter substance |
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Term
| Peripheral nerve fibers may be surrounded by? |
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Definition
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Term
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Definition
| axons containing a myelin sheath |
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Term
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Definition
| axons not containing a myelin sheath |
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Term
| What does Schwann cells produced? |
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Definition
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Term
| What is Neurilemma or Sheath of Schwann made of ? |
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Definition
| cytoplasm, a nucleus, and cell membrane |
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Term
| Neurilemma or Sheath of Schwann may assist in |
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Definition
| regeneration of injured axons |
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Term
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Definition
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Term
| smallest axons are enclosed by what? |
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Definition
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Term
| the smallest axons are not wrapped around the axon; |
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Definition
| therefore no myelin sheaths |
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Term
| Myelin in the CNS is produced by? |
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Definition
| oligodendrocytes rather than Schwann cells |
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Term
| A single oligodendrocyte may provide myelin myelin for up to |
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Definition
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Term
| what is the white matter? |
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Definition
| groups of myelinated fibers appear white and are responsible for white matter in the brain and spinal chord |
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Term
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Definition
| A damaged axon may regenerate |
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Term
| Steps for Regeneration of injured axon |
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Definition
1. distal portion degenerated
2. proximal end of injured nerve sprouts and regenerates into tube of sheath cells
3. sheath cells proliferate and axon grows 3 to 4 mm per day |
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Term
Structural classification of neuron
classified by number of processes |
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Definition
1. multipolar
2. bipolar
3. unipolar |
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Term
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Definition
several dendrites and 1 axon.
Brain and spinal cord |
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Term
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Definition
1 dendrite and 1 axon
Brain and spinal cord |
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Term
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Definition
1 process which divides to form branches that function as axon and dendrite
dorsal root ganglia |
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Term
| Functional classification |
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Definition
| classified according to direction impulse flows |
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Term
| Functional Classification |
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Definition
1. afferent or sensory - impulse travels toward CNS.
2. efferent or motor - impulse travels away from CNS.
3. association - connections from sensory to motor.
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Term
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Definition
| bundles of affarent and efferent processes and can be grouped |
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Term
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Definition
1. General somatic afferent fibers
2. General somatic efferent fibers
3. General visceral afferent fibers
4. General visceral efferent fibers |
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Term
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Definition
| Cell membrane is electrically charged or polarized so that the outside is positively charged with respect to the inside |
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Term
| What is the distribution of ions determined by? |
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Definition
| the presence of pores or channels in the membrane. some channels are always open, while others open or close like gates. |
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Term
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Definition
| nerve cell is not conducting impulses |
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Term
| There is a greater concentration of what on the outside of the cell? |
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Definition
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Term
| There is a greater concentration of what on the inside of the cell? |
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Definition
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Term
The ouside of the membrane is __________
charged and the inside is ____________ charged |
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Definition
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Term
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Definition
| difference in the electrical charge between the measured in volts. |
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Term
| The resting potential is ______ mv |
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Definition
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Term
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Definition
| membrane becomes less negative |
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Term
| What affects the neurons in a localized region of the membrane? |
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Definition
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Term
| What happens during depolarization? |
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Definition
| sodium channels open and Na passes in |
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Term
| The amount of change in potential is directly related to ? |
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Definition
Intensity of Stimulation
such changes are graded |
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Term
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Definition
| if another stimulus of the same type is received before the effect of the first stimulus subsides, the change in the local membrane is greater |
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Term
| What is the additive effect called? |
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Definition
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Term
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Definition
| the very least amount of stimulus necessary to start an action potential |
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Term
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Definition
| any condition capable of altering membrane potential |
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Term
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Definition
| sequence of electrical changes occuring when nerve cell membrane is exposed to stimulus that exceeds its threshold |
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Term
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Definition
| Channels open at almost the same time as Na channels to allow K to pass out and membrane becomes negatively charged again. |
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Term
| What is the time it takes for the action potential of repolarization to take place? |
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Definition
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Term
| What happens when too may ions pass through the membrane? |
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Definition
| the action potential ceases and active transport mechanism returns membrane to the resting period |
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Term
| What causes the ions to flow from adjacent portions of the membrane? |
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Definition
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Term
| This stimulates membrane to the threshold level and a __________________ |
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Definition
| wave of action potentials pass through |
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Term
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Definition
| propagation of action potential along nerve |
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Term
| Events leading to nerve impulse conduction: |
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Definition
1. Nerve fiber membrane developes resting potential
2. threshold stimulus received
3. Na channels open
4. Na diffuses toward
5. K channels in membrane open
6. K diffuses outward
7. Ion channels close and membrane becomes less permeable to Na and K
8. wave of action potential travels length of nerve fiber as nerve impulse |
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Term
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Definition
| time following stimulation during which neuron will NOT respond |
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Term
| Absolute Refractory Period |
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Definition
| membrane changing in Na permeability and cannot be stimulated |
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Term
| Maximum rate of nerve impulse conduction |
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Definition
| 1 impulse per millisecond |
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Term
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Definition
| if nerve resonds at all, it responds completely |
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Term
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Definition
a. unmyelinated fiber
b. myelinated fiber |
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Term
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Definition
| conducts impulse over entire membrane |
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Term
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Definition
| nerve impulse jumps from node to node. |
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Term
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Definition
| nerve impulse jumps from node to node |
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Term
| Why do the nerve impulses jump from node to node? |
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Definition
| the myelin is composed of largely of lipids which act as an insulator |
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Term
| Speed of the nerve impulse is related to what? |
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Definition
diameter of the fiber
the greater the diameter, the faster the impulse. |
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Term
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Definition
1. size of fiber
2. type of fiber
3. physiological conditions |
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Term
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Definition
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Term
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Definition
| 130 m/sec greatest diameter, myelinated, saltatory, conduction, connects with sensors detecting danger. |
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Term
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Definition
| 10 m/sec - longer refractory period, myelinated. Visceral efferent fibers |
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Term
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Definition
| slowest. .5 m/sec. thin, longest refractory period, no saltatory conduction. Impulses for pain form skin, and all motor from ganglion to smooth muscle and visceral organs |
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Term
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Definition
| junction between 2 neurons or neuron and muscle |
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Term
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Definition
| neuron located before synapse |
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Term
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Definition
| neuron located after synapse |
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Term
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Definition
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Term
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Definition
| located in synaptic end bulb and release transmitter substance substance. Causes one-way impulse conduction |
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Term
| The body produces over 30 transmitter substances which are made from what? |
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Definition
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Term
| what are examples of the transmitter substances made from amino acids? |
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Definition
| acetylcholine, norephinephrine, dopamine, glycine, glutamic acid, histamine and serotonin |
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Term
| Where is the transmitter substance produced? |
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Definition
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Term
| Where is the transmitter substance stored? |
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Definition
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Term
| What causes the release of Ca from the knob and stimulates the vesicles to release the contents into the synaptic cleft? |
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Definition
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Term
| What is destroyed by enzymes |
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Definition
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Term
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Definition
synaptic knobs from a single presynaptic neuron synapse with several post-synaptic neurons
spread out |
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Term
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Definition
several presynaptic neurons synapse with a single post-synaptic neuron
comes together |
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Term
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Definition
| excitatory transmitter receptor interaction lowers post synaptic neuron's membrane potential |
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Term
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Definition
| form myelin sheaths around axons in CNS |
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Term
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Definition
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Term
| Excitatory postsynaptic potential (EPSP) is always ________ _________ than the resting potential but ______ ________ than the threshold. |
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Definition
less negative
more negative |
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Term
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Definition
| the effect of lower the membrane potential by using sub-threshold stimuli |
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Term
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Definition
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Term
| What increases the odds that the next stimulus will reach the threshold? |
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Definition
| Facilitation - the effect of lowering the membrane potential by using sub-threshold stimuli |
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Term
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Definition
Spatial summation
Temporal summation |
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Term
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Definition
| summation is result of accumulating transmitter substance from several presynaptic knobs. |
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Term
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Definition
summation from one neuron firing several times
additive effect from acetylcholine |
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Term
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Definition
| inhibitory transmitter receptor interaction raises post synaptic neuron's membrane potential. This causes hyperpolarization of the post-synaptic membrane |
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Term
| What synapse with many presynaptic neurons, some excitatory and some inhibitory |
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Definition
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Term
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Definition
1. Facilitation
2. Initiation of impulse
3. inhibition of impuse |
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Term
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Definition
| usually excitatory, but inhibitory with respect to the heart |
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Definition
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Definition
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