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55 Cards in this Set
- Front
- Back
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What is the master controlling and communication system in the body?
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The Nervous System
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What are the 4 things that the nervous system controls?
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sensations, actions/movement, thoughts/thinking, and emotions
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What is main characterization of the nervous system?
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rapid communication by electrical signals that come or go and usually cause immediate responses
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What are the 3 overlapping functions of the nervous system?
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sensory input:gathered information from inside or outside of body, Integration: processes and interprets information or decisions made (without it we wouldn't know what anything is) and motor output: is response to sensory input after sense is made of it (integration)-by effector organs.
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What 2 parts make up the highly integrated and organized nervous system?
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CNS:Central nervous system:brain & spinal cord-is the integrative control or command center-interprets, makes decisions(reflexes) & dictates motor response. PNS: outside of CNS, consists of 12 prs. cranial nerves (carry mess. to and from brain) & 31 prs spinal nerves (carry mess. to & from spinal cord, like telephone wires. Peripheral nerves link all parts of body to the CNS.
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What 2 types of nerves are in the PNS?
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Sensory:afferent(somatic & visceral)-carrying impulses toward Central Nervous system;
Motor: efferent-transmits impulses away from CNS to effector organs(muscles and glands), leaves CNS to extremitites. |
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Describe the Sensory-afferent nerves found in the peripheral nervous system, PNS?
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2 types of sensory nerves in PNS:
Somatic: bring impulses from skeleton, skin, & joints to CNS; Visceral: bring impulses from organs, blood vessels..everything else to CNS. Sensory division keeps CNS constantly informed of events going on in & out of body. |
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Describe the types of Motor efferent nerves found in the PNS
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2 divisions: Motor somatic: voluntarily telling skeletal muscles what to do; Motor autonomic: invol. visceral motor, impulses from CNS to cardiac, smooth musc. & glands, has 2 subdivisions: sympathetic-turning things on, & parasympathetic-turning things off
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What are the sympathetic and parasympathetic divisions in the PNS?
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Sympathethetic (turns things on) and Parasympathetic (turning things off), are part of the Autonomic nervous system (involuntary) of the Motor efferent division (sending impulses out).
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What are neuralgia?
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They are glial cells (called nerve glue) that support and take care of neurons.
There are 6 types: 4 in CNS, & 2 in PNS. |
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What are the names of the 4 types of glial cells found in the Central Nervous System?
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Astrocytes
Microglials Ependymal Cells Oligodendrocytes |
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Describe astrocytes
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1 of 4 types of glial cells in the CNS.
Connects neurons to nutrients, recaptures & recyles released neurotransmitters, builds barriers between blood vessels/ vein, protects the brain, prevents brain cells from generating after damage to the brain |
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Describe Microglia
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2nd type of glial cell in the CNS, transforms into Phagocytic-destroy neurons that are defective, or non-self, thorny processes, Important because immune system is not in contact w/CNS & we need them to protect from bacteria coming to brain.
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Describe Ependymal Cells
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3rd type of glial cell in CNS, ciliated, 4 cavities or ventricles, line central cavities of brain & S.C., form a permeable lyr between cerbrospinal fluid & fluid that bathes the cells of CNS.
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Describe Oligodendrocytes
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4th type of glial cell in CNS. put a lipid coat on neurons, insulated w/myelin sheath to wrap around axon, covers many neurons w/ no space between
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What are the names of the 2 types of neuralgia or Glial cells in the PNS?
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Satellite cells
Schwann cells |
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Describe satellite glial cells of the PNS
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One of 2 types of glial cells in the PNS. Satellite glial cells surround neruon cell bodies in the PNS and nuture the neuron
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Describe Schwann cell.
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the 2nd type of glial cell in the PNS.
Wraps around larger nerve fibers (axon) with myelin sheath, like jellyroll becoming tighter. Inner portion wrapped very tight, w/no cytoplasm called myelin sheath w/ many layers. Outer layer not wrapped tight-has nucleus, cytoplasm called neurolemma w/other organelles, but unlike oligo. the sheath has spaces in between on the axon. It is 1 neuron covered by multiple protective myelinated schwann cells. |
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What is another name for for nerve cell and what is its main function?
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Neuron- the structural units of the nervous system. Highly specialized workhorse with only job as transmission of nerve impulses from 1 part of body to the other.
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What are the 2 locations that nerve cells are found?
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Most are found In the Central Nervous System (brain and skull protection, cannot regenerate)-called nuclei; and in the Peripheral Nervous System (anywhere that is not brain and spine)-called ganglia (knots on a string)
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What are the two types of nerve processes or projections called?
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Dendrites: main receptive/input regions, found on motor neurons, are short,tapering, diffusely branching, 100's cluster close to cell body, convey incoming messages toward the cell body, have graded potentials; Axons: Each neuron has a single axon, initial region shaped like a hill is called axon hillock, some axons are short, some long (called nerve fibers), have axon terminal branches with knobs called terminal bouttons, involves voltage-gated channels transmitting action potentials
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What is the function of the Axon Hillock?
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The little hill, cone-shaped area found on the cell body triggers or activates the action potential.
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What is the point where impulse from a neuron is transmitted or communicated to the next nerve or muscle called?
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The synapse
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In the brain, what is the gray area and what is the white area?
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The gray areas are the nuclei or cell bodies, and the axon boutton or terminals. The white areas are myellin-sheaths for fiber tracks.
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Functional Classification groups neurons according to?
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Direction of travel of the nerve impulse in relation to the Central Nervous System. There are sensory, motor, and interneurons
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What are interneurons?
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Association neurons-conduct impulses w/in CNS, integrate sensory input or motor input, may connect sensory & motor neurons, or part of a chain of CNS neurons. Note: most multipolar neurons are interneurons.
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T/F The action potential is always the same, regardless of the stimulus?
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True. It underlies all functional activities of the nervous system.
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In reference to sodium and potassium, when sodium is 10x the amount outiside, than inside, and likewise potassium is 10x the amount inside, than outside,(although there is passive leakage), -70 mV this happens during what part of the nerve cycle?
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The resting period of a resting neuron.
Also called the resting membrane potential. Membrane is said to be polarized in this state. |
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Everytime the sodium pump goes through a cycle, what is the ratio of sodium going in to the potassium going out?
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sodium 3/ potassium 2
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What does it mean to generate a membrane potential?
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Taking a resting membrane potential and depolarizing it causes generation. This is also called a reduction of the membrane potential. The inside becomes less negative, and the outside becomes less positive. Sodium is pumped in with gradient, while postassium is pumped out, (more leaks out)
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What helps balance the sodium and postassium cations?
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The negatively charged proteins.
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What is passive leakage?
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Postassium ions leaking in and out.
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What is the whole reason behind generating a membrane potential?
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The generate a nerve impulse that is communicated in receiving, integrating or sending information.
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A change in membrane potential is dictated by 2 things:
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1)Anything that changes membrane permeability to any ion or 2) anything that alters ion concentrations on the 2 sides of the membrane.
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What are the 2 types of signals that are produced by a change in membrane potential?
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Graded potentials: incoming signals operating over short distances; Action potentials: long distance signals of axons.
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What increases the probability of generating a nerve impulse?
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Depolarization-the reduction of membrane potential, but an increase in generation of nerve impulse.
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What decreases the chances of generating a nerve impulse?
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Hyperpolarization: when potassium keeps leaking (passive leakage), but sodium is not moving; an increase in membrane potential, but a decreased chance of generating a nerve impulse.
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Describe the Graded Potential
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Chemically gated, Short lived, travels short distances, amplitude is increasing at a decreasing rate because of passive leakage,influx of sodium triggers a graded potential, chem-gated because of neurotransmitter (ACh) from another nerve, ionic musical chairs: positives are attracted to negatives knocking each other out, anterro- grade, occurs in dendrites & cell body-unmylenated parts until arrival at axon hillock or trigger zone
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Describe an Action potential
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Involves multiple Voltage-gated ion channels starting at the axon hillock, change of -70mV to +30mV, lasts ms, do not decrease in strength w/distance, only in axons, when it reaches -55mV action potential will self-initiate.
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What ensures the propagation of the action potential?
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When the sodium levels reach -55mV threshold the action potential will self-initiate. All will fire or none depending on -55mV.
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T/F The strength of the action potential is variable.
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False. The strength of the action potential is always the same, but the frequency decides whether the impulses are weak or strong. (If you can feel it then it's reaching -55.
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What is another kind of graded potential and in what type of neurons does it occur?
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Another kind is the generator potential that fires not from a neurotransmitter (chemical), but energy waves from light or sound that open ion channels. They are bipolar neurons involving special sensory nerves in eyes and ears.
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What is the refractory period definition and what are the 2 types of refractory?
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A time when a neuron will not respond to another action potential. Absolute: is during depolarization, cannot be restimulated or get anymore sodium in than there is already. Relative Refractory: following absolute, most Na+ has returned to resting state, repolarization is occuring, only an exceptionally strong stimulus can reopen the Na+ channels and allow another action potential to be initiated causing more frequency. Can even happen in hyperpolarization.
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When Dr. Mehm refers to refractory period on exam his referring to which refractory period?
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Absolute Refractory Period
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What is a conduction velocity?
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How fast an impulse moves down the axon. Neurons that are fast go to skeletal muscles, and neurons that go slow go to visceral.
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Axons with large diameters, (fatter), will conduct impulses faster or slower?
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Faster because of the thickness of the myelin sheeth.
Axons with smaller will conduct slower . |
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What are the 2 types of conduction?
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Continuous conduction: happens in unmylenated axons making a slow impulse, slow waiting for domino effect, examples are found in the brain, or in some visceral organs. Saltatory conduction: in mylenated axons, sheath prevents passive leakage helping in initiation of depolarization, called leap frog as it only happens in schwann cells.
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What is a node of ranvier?
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The space or gap, a neurofibril node, between schwann cells where voltage gated channels occur,
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What does non-dissapatory mean?
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The place in the schwann cell that is heavily mylenated, preventing potassium leakage that involves a graded potential.
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How are nerve fibers are classified?
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According to their diameter. Group A, Group B, Group C
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Describe Group A fibers.
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Group A: Thickest in mylenation, largest in nerve fiber diameter, somatic sensory for joints, muscles & skin, perpetuating a saltatory conduction of 300mph.
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Describe Group B fibers.
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Group B: Intermeidate nerve fiber diameter, lightly mylenated, oligodendrytes, goes to visceral organs at 30mph, instructing gut to digest.
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Describe Group C fibers
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Group C: Smallest in nerve fiber diameter, unmylenated, travels 3 mph, in visceral organs, continuous conduction type.
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What is a pre-synaptic neuron?
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The neuron the precedes the next which is called the post-synaptic neuron.
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When are calcium channels opened in the neurons?
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They are opened at the axon terminal that induces neurotransmitters to be released across the synaptic cleft and onto the next nerve.
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