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130 Cards in this Set
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What are the three types of primary muscle tissue type? |
Skeletal, Cardiac & Smooth |
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Skeletal muscles are attached to? |
Skeletal system |
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Skeletal muscles do what? |
Allow us to move |
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What are the structures of skeletal muscles? |
Muscle tissue (muscle cells or fibers), connective tissues, nerves (voluntary muscles controlled by nerves of the CNS), blood vessels (supply large amounts of oxygen & nutrients & carry away wastes). |
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What are the 5 functions of muscles? |
1) Produce skeletal movement 2) Maintain body position 3) Support soft tissues 4) Guard body openings 5) Maintain body temperature |
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What are the 5 types of movement in skeletal muscles? |
1) origin = nonmoving 2) insertion = moving 3) attach via tendons 4) muscles oppose each other - antagonistic 5) muscles that cause the same action - synergists |
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Muscles attach to bone to allow ? |
Movement (contraction/movement) |
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What are the 7 parts of muscle structure? |
Muscle, muscle fascicle, muscle fibers=cell, myofibris, thick and thin myofilaments, myosin and actin. |
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What are the three layers of connective tissue organization? |
Epimysium, Perimysium, and Endomysium |
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Define/describe the Epimysium! |
* exterior collagen layer * connected to deep fascia * separates muscle from surrounding tissues |
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Define/Describe the Perimysium! |
* surrounds muscle fiber bundles. (fascicles) * contains blood vessel and nerve supply to fascicles |
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Define/Describe the Endomysium! |
* surrounds individual muscle cells. (Muscle fibers) * contains capillaries and nerve fibers contacting muscle cells * contains satellite cells (stem cells) that repair damage. |
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The Endomysium, Perimysium, and epimysium come together where? |
At ends of muscles, to form connective tissue attachment to bone matrix... i.e. tendon (bundle) or aponeurosis (sheet) |
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What are the six parts of the organization of skeletal muscle fibers? |
Sarcolemma, transverse tubules (T tubules), Myofibrils SR (Sarcoplasmic Reticulum) Triad Cisternae |
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What is the sarcolemma? |
* The cell membrane of a muscle cell, * surrounds the sarcoplasm. (cytoplasm of muscle fiber) * a change in transmembrane potential begins contractions |
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What are the transverse tubules (T tubules)? |
* transmit action potential through cell * allow entire muscle fiber to contract- simultaneously * have same properties as sarcolemma |
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What are myofibrils? |
Lengthwise subdivisions within muscle fiber, made up of bundles of protein filaments (myofilaments). |
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What are myofilaments responsible for? |
Muscle contraction |
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What are sarcomeres? |
Structural units of Myofibrils. Form A bands and I bands. |
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Define the sarcoplasmic reticulum. |
Membranous structure surrounding each myofibril, Help transmit action potential to myofibril, similar structure to SER, and forms chambers (terminal cisternae) attached to T tubules. |
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Define Triad. |
Formed by 1 T tubule & 2 terminal cisternae. |
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Define Cisternae. |
They concentrate Ca2+ (via ion pumps), release Ca2+ into sarcomeres to begin muscle contraction. |
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What triggers muscle contraction? |
Free calcium in the sarcoplasm. |
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Define F actin. |
2 twisted rows of globular G actin & the active sites on G actin strands bind to myosin. |
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Name 4 thin filament proteins. |
F actin, Nebulin, Tropomyosin and Troponin. |
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What does nebulin do? |
Holds F actin strands together. |
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What is tropomyosin? |
A double strand that prevents actin - myosin interaction. |
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What is troponin? |
A globular protein that binds tropomyosin to G actin and is controlled by calcium, Ca2+. |
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Describe the process of initiating contraction! |
Ca2+ binds to receptor on troponin molecule, troponin - tropomyosin complex changes and exposes active site of F actin. |
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Thick filaments contain what? |
Twisted myosin subunits and titin strands that recoil after stretching. |
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Describe the myosin molecule. |
The tail binds to other myosin molecules, the head is made of 2 globular protein subunits & reaches the nearest thin filament. |
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What is myosin action during contraction? |
During contraction, myosin heads interact with actin filaments, forming cross - bridges. Pivot, producing motion. |
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In skeletal muscle contraction, describe the sliding filament theory! |
*Thin filaments of sarcomere slide toward M line, shorten. *Between thick filaments *The width of A band stays the same. *Z lines move closer together. |
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Describe the process of neural control of skeletal muscle contraction! |
Neural stimulation of sarcolemma: @ neuromuscular junction NMJ Causes excitation-contraction coupling Cisternae of SR release Ca2+ which triggers interaction of thick and thin filaments consuming ATP and producing tension |
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Define Ach. |
Acetylcholine is a neurotransmitter. |
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Define "action potential" |
Electrical signal that travels along nerve axon and ends at synaptic terminal. |
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What does the synaptic terminal do? |
Releases neurotransmitter (acetylcholine or ACh) into the synaptic cleft. |
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Define synaptic cleft! |
The gap between synaptic terminal and motor end plate. |
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Define excitation-contraction coupling! |
Action potential reaches a triad releasing calcium and triggering contraction, requires myosin heads to be in cocked position, loaded by ATP energy. |
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What action does acetycholine play in skeletal muscle innervation, contraction? |
Acetylcholine travels across the synaptic cleft, binds to membrane receptors on sarcolemma, causes sodium - ion rush into sarcoplasm, is quickly broken down by enzyme acetylcholinesterase or AChE. |
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Define "motor end plate." |
The particular synapse made between a spinal motor neuron and skeletal muscle cell - the synapse at the neuromuscular junction. |
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What are the 5 steps of the contraction cycle? |
1. Exposure of active sites of F actin of thin filament. 2. Formation of cross-bridges due to interaction of actin filaments w/ myosin heads forming cross-bridges that pivot, producing motion. 3. Pivoting of myosin heads 4. Detachment of cross-bridges 5. Reactivation of myosin |
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Contraction duration depends on what? |
Duration of neural stimulus, number of free calcium ions in sarcoplasm and availability of ATP. |
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What occurs during relaxation? |
Ca2+ concentrations fall, Ca2+ detaches from troponin, active sites are recovered by tropomyosin and sarcomeres remain contracted. |
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Contraction is what kind of process? |
Active process |
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Relaxation and return to resting length is a ? |
Passive process |
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Define Rigor Mortis. |
A fixed muscular contraction after death caused when ion pumps cease to function & calcium builds up in the sarcoplasm. |
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What are the 2 types of skeletal muscle tension? |
Isotonic contraction and isometric contraction. |
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Describe isotonic contraction. |
Skeletal muscle changes length resulting in motion. Muscle tension > resistance : the muscle shortens (concentric contraction) Muscle tension < resistance : the muscle lengthens (eccentric contraction) |
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What is isometric contraction? |
Skeletal muscle develops tension, but is prevented from changing length. |
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What are the 3 ways that, after contraction, a muscle fiber can return to its resting length by? |
1. Elastic forces - the pull of tendons and ligaments. 2. Opposing muscle contractions 3. Gravity |
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Define fatigue. |
When muscles can no longer perform a required activity. |
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What are the results of muscle fatigue? |
1. Depletion of metabolic reserves 2. Damage to sarcolemma and SR 3. Low pH (lactic acid) 4. Muscle exhaustion and pain |
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What is the Cori Cycle? |
The removal and recycling of lactic acid by the liver. The liver converts lactic acid to pyruvic acid. Glucose is released to recharge muscle glycogen reserves. |
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What are the three types of skeletal muscle fibers? |
Fast fibers, slow fibers and intermediate fibers. |
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Describe fast fibers... |
Contract very quickly. Have a large diameter, large glycogen reserves, few mitochondria. Have strong contractions, fatigue quickly. |
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Describe slow fibers... |
Are slow to contract, slow to fatigue. Have a small diameter, more mitochondria, high oxygen supply and contains myoglobin (red pigment, binds oxygen) |
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Describe intermediate fibers. |
They are mid-sized, have low myoglobin, have more capillaries than fast fiber, slower to fatigue. |
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What are some anaerobic exercises and their characteristics? |
50 meter dash and weightlifting. Uses fast fibers, fatigue quickly with strenuous activity. Improved by frequent, brief, intensive workouts. |
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What are some Aerobic exercises and their characteristics? |
Yoga... supported by mitochondria, require oxygen and nutrients. Improved by repetitive training & cardiovascular training. Endurance. |
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What are 7 characteristics of Cardiocytes? (Cardiac muscle cells) |
1. Are small 2. Have a single nucleus 3. Have short, wide T tubules 4. Have no triads 5. Have SR with no terminal cisternae 6. Are aerobic (high in myoglobin, mitochondria) 7. Have intercalated discs |
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What are intercalated discs? |
Specialized contact points between Cardiocytes. |
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What are the functions of intercalated discs? |
Maintain structure, enhance molecular and electrical connections, and conduct action potentials. |
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What are the 4 functions of cardiac tissue? |
1. Automaticity (contraction without neural simulation) (controlled by pacemaker cells) 2. Variable contraction tension (controlled by nervous system) 3. Extended contraction time 4. Prevention of wave summation and tetanic contractions by cell membranes |
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Smooth muscle can be found where? |
1. Forms around other tissues 2. In blood vessels: regulates blood pressure and flow 3. In reproductive and glandular systems: produces movements 4. In digestive and urinary systems: forms sphincters and produces contractions 5. In integumentary system: arrector pili muscles cause goose bumps. |
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What are the 8 characteristics of smooth muscle? |
1. Long, slender, and spindle shaped. 2. Have a single central nucleus. 3. Have no T tubules, Myofibrils, or sarcomeres. 4. Have no tendons or aponeuroses 5. Have scattered myosin fibers 6. Myosin fibers have more heads per thick filament. 7. Have thin filaments attached to dense bodies. 8. Dense bodies transmit contractions from cell to cell. |
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What are the 4 functional characteristics of smooth muscle? |
1. Excitation-contraction coupling 2. Length-Tension Relationships 3. Control of contractions 4. Smooth muscle tone |
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Explain excitation-contraction coupling. |
-Free Ca2+ in cytoplasm triggers contraction -Ca2+ binds with calmodulin: in the sarcoplasm, activates myosin light chain kinase -Enzyme breaks down ATP, initiates contraction |
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Explain "Length-Tension Relationships" |
-Thick and thin filaments are scattered -Resting length not related to tension development -Functions over a wide range of lengths (plasticity) |
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Explain the control of contractions. |
-multiunit smooth muscle cells: connected to motor neurons. -visceral smooth muscle cells: not connected to motor neurons -rhythmic cycles of activity controlled by pacesetter cells |
Subdivisions |
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Explain "smooth muscle tone" |
-maintains normal levels of activity -modified by neural, hormonal, or chemical factors |
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What are the 4 patterns of fascicle organization? |
1. Parallel 2. Convergent 3. Pennate 4. Circular |
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Describe the Parallel pattern of fascicle organization. |
Fibers are parallel to the long axis of muscle. Example: biceps brachii The center or body of the muscle thickens when parallel muscle contracts. |
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Describe the Convergent pattern of fascicle organization. |
A broad area converges on attachment site. Muscle fibers pull in different directions, depending on stimulation. Example: Pectoralis muscles |
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Describe the Pennate pattern of fascicle organization. |
Unipennate: fibers on 1 side of tendon e.g., extensor digitorum Bipennate: fibers on both sides of tendon e.g., rectus femoris Multipennate: tendon branches within muscle. e.g., deltoid |
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Describe the Pennate pattern of fascicles in general. |
Form angle with tendon Don't move as far as parallel muscles. Contain more Myofibrils than parallel muscles Develop more tension than parallel muscles. |
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Describe the Circular pattern of fascicle organization. |
Also called sphincters Open and close to guard entrances of body. e.g., obicularis oris. |
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Name the three lever types and give examples. |
First-class lever - e.g., Seesaw Second-class lever - e.g Wheelbarrow - (lifting heel up of floor) Third-class lever - Most common type - e.g deltoid |
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Define origin. |
1 fixed point of attachment. Muscles originate or insert on the skeleton. Origin is usually proximal to insertion. |
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Define insertion. |
1 moving point of attachment. |
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Define "action". |
Movements produced by muscle contraction. Body movements (flexion, extension, adduction, etc.) |
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Define Agonist. |
(Prime mover) produces a particular movement. |
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Define antagonist. |
Opposes movement of a particular agonist. Agonists and antagonists work in pairs: when 1 contracts, the other stretches. i.e., flexors-extensors, abductors-adductors, etc. |
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Define synergist. |
A smaller muscle that assists a larger agonist and helps start motion or stabilize origin of agonist (fixator). |
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What are the 9 names for muscle size? |
Longus = long Longissimus = longest Teres = long and round Brevis = short Magnus = large Major = larger Maximus = largest Minor = small Minimus = smallest |
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What 4 effects does aging have on the muscular system? |
1. Skeletal muscle fibers become smaller in diameter. 2. Skeletal muscles become less elastic. 3. Decreased tolerance for exercise. 4. Decreased ability to recover from muscular injuries. |
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Define neurons. |
Cells that send and receive signals. |
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Define neuroglia. |
(Glial cells) cells that support and protect neurons. |
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Central nervous system consists of what and what are its functions? |
Spinal cord and brain. Processes and coordinates sensory data, motor commands and higher functions. |
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Define sensory data. |
Data from inside and outside the body. |
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The PNS (peripheral nervous system) includes what and what are its functions? |
Includes all neural tissue outside the CNS. Its functions are to deliver sensory information to the CNS and carry motor commands to peripheral tissues and systems. |
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Define/describe Afferent division. |
Carries sensory information from PNS sensory receptors to CNS. |
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Define/describe Efferent division. |
Carries motor commands from CNS to PNS muscles and glands. Also includes the Somatic nervous system (SNS) and the Autonomic nervous system (ANS). |
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What does the SNS (Somatic nervous system) do? |
Controls skeletal muscle contractions: voluntary and involuntary (reflexes) muscle contractions. |
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What does the ANS (Autonomic nervous system) do? |
Controls subconscious actions: contractions of smooth muscle and cardiac muscle, glandular secretions and divisions; sympathetic division-has a stimulating effect and parasympathetic division- has a relaxing effect. |
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Describe the 3 major parts that make up a neuron. |
Cell body (soma), short branched dendrites and long single axon. |
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What is perikaryon? |
Cytoplasm |
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What are the major organelles of the cell body? |
Large nucleus and nucleolus, cytoplasm, mitochondria, RER and ribosomes and cytoskeleton (neurofilaments and neurotubules and neurofibrils), nissl bodies, dendrites, and axon. |
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Define synapse. |
Area where a neuron communicates with another cell. |
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Define synaptic cleft. |
Small gap that separates the presynaptic membrane and the postsynaptic membrane. |
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Define synaptic knob. |
Expanded area of axon. Contains synaptic vesicles of neurotransmitters. |
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Define neurotransmitters. |
They are chemical messengers -are released at presynaptic membrane. -affect receptors of postsynaptic membrane. -are broken down by enzymes -are reassembled at synaptic knob. |
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What are the 4 structural classifications of neurons? |
1. Anaxonic neurons: found in brain and sense organs 2. Bipolar neurons: found in special sensory organs. 3. Unipolar neurons: found in sensory neurons of PNS. 4. Multipolar neurons: common in the CNS. |
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What are the 3 functional classifications of neurons? |
1. Sensory neurons 2. Motor neurons 3. Interneurons |
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What are the 4 types of CNS neuroglia? |
1. Ependymal cells 2. Astrocytes 3. Oligodendrocytes 4. Microglia |
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What are the 2 types of Neuroglia of the PNS? |
1. Satellite cells: regulate environment around neuron 2. Schwann cells: forms myelin sheath around axon |
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What is the resting potential for a neuron? |
70mV |
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Define Internodes. |
Myelinated segments of axon. |
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Define Nodes. |
Also called "nodes of Ranvier" - gaps between Internodes |
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Define myelinated. |
A nerve that has a myelin sheath. (A soft white material of lipid and protein that is secreted by Oligodendrocytes and Schwann cells). White matter |
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Define unmyelinated. |
Without a myelin sheath. (Gray matter) |
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What is membrane potential? |
Nerve impulses=electrical signal 2 poles (+,-) = voltage or potential difference. The potential inside a cell membrane measured relative to the fluid just outside. It is negative under resting conditions and becomes positive during an action potential.
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What are 3 factors that generate membrane potential? |
1. Action of sodium/potassium pumps. 2. Permeability differences between 2 different ions. 3. Presence of fixed anions (-) unable to leave the cell. |
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What is the Na/K pump? |
A protein complex that continually pumps 3 Na ions out of cells while drawing 2 K ions into cell- helps to maintain the electrical gradient. |
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Define resting potential. |
Refers to the state of the neuron prior to the sending of a nerve impulse. |
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Define hyperpolarizaton. |
Refers to increasing the polarization or the difference between the electrical charge of two places. |
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Define depolarization. |
Refers to decreasing the polarization towards zero. |
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Define the "threshold of excitement." |
Refers to any stimulation beyond a certain level and results in a massive depolarization. |
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Define action potential. |
A rapid depolarization of the neuron. |
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What is the "All-or-None Law?" |
Either a stimulus produces Action Potential or it doesn't. |
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What are voltage-activated (gated) channels? |
They are membrane channels whose permeability depends upon the voltage difference across the membrane. (Sodium channels are voltage activated channels). |
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What is a refractory period? |
This period occurs after an action potential, during this time the neuron resists another action potential. |
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Define absolute refractory period. |
The first part of the period in which the membrane can not produce an action potential. |
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Define relative refractory period. |
The second part in which it takes a stronger than usual stimulus to trigger an action potential. |
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What is "propagation of the action potential?" |
The term used to describe the transmission of the action potential down the axon. |
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Define Saltatory Conduction. |
Term used to describe the "jumping" of the action potential from node to node. |
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Define Saltatory Conduction. |
Term used to describe the "jumping" of the action potential from node to node. |
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What are "local neurons?" |
They have short axons Exchange information with only close neighbors Do not produce action potentials |
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What are graded potentials? |
Membrane potentials that vary in magnitude and do not follow the All-or-None Law. |
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Define synapse. |
The specialized gap that exists between neurons. |
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