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203 Cards in this Set
- Front
- Back
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What are the 4 functions of muscles?
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generate heat
allow for movement control posture necessary for breathing |
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What are the 4 functional characteristics for muscles
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Excitability/irretability
contractillity extensability elasticity |
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define excitability/irretability
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ability to repond to a stimulus
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define contractillity
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the ability of a muscle to shorten
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define extensability
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the ability of a muscle to stretch when pulled
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define elasticity
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ability of a muscle to go back to its orginal shape after it was stretched. you dont want this to happen
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epimyseum
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means muscle. Its a connective tissue sheet that covers the entire muscle.
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Fasicle.
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many circular structures within the epimysium
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Paramyseum
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the CT sheath that surrounds the fasicles.
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What is inside a fasicle
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many muscle cells or fibers
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Endomyceym
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the Ct sheath that surrounds each muscle cell
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Myofibrills
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inside each muscle cell
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where is a sarcomere located
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inside myofibrils.
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Sacrolema
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Cell membrane
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Sacroplasma
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cytoplasma
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What is the smallest part of a muscle capable of contracting
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the sarcomere
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Z disc
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dense regions of cytoplam that seperate sarcomeres
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Actin
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thin protien filaments that are directly attached to the Z disc
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Myocin
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Thick protien filaments that slightly overlap actin. They are indirectly attached to the Z disc by titin
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Titin
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An elastic protien that indirectly attches the Z disc to the myosin
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Active binding sites are on
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Actin
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Tropomyosin
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A protien that covers an active binding site when the muscle is relaxed.
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descibe and locate Cross bridges
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Located on myocin and attach to the active site for the muscle to contract
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I Band
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2 located on each sarcomere. Lighter in color. only contain actin and titin, never myocin
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what gives muscles the striated look
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I bands
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A Band
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Covers myocin and the overlapping actin. ( The part of the actin that is not included in the I Band
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H Zone
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The par t of the A band that contains only myocin
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M line
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The imaginary line in the middle of the sarcomere
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Motor end Unit
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A motor nueron and the part of the muscle that it stimulates it
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motor neuron
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a nerve cell that carrys info from the front of the brain out to the effectors.
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The effetors are always going to be ______ in muscle movement
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skeletal muscles
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Axon terminal
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The end of the axon before it reaches the muscle.
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the expanded ends of the the axon termninal are
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the synaptic end bulbs
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Synaptic vesicles
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sacs inside the synaptic end bulbs
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Where are neurotransmitters...
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inside the synaptic vesicles
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Synapse
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The space between the axon terminal and the muscle fiber.
Sometimes called the synaptic cleft |
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Acetylcholine
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The neurotransmitter unique to muscles
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Sarcolema
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The muscle fibers membrane
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T (transverse) tubules
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The deep indentation in the axon terminal
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what do T tubules do?
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As the go down into the sarcoplasmic reticulum it stores calcium ions when the fiber is resting.
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the Motor end plate
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the region of the muscle fiber that is directly across from the axon that stimulates it.
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the neuromuscular junction
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made up of the axon terminal, syapses and motor end plate.
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How are muscles named? 5 ways
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Location
Function Origin and insertion number of origins shape |
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Fascia associated with muscles is actually
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CT
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What does fascia do
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It binds the muscles together and stabalizes blood vessels and nerves as they enter and exit muscles.
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What are the 2 types of fascia
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superficial: On the subcutaneous skin
Deep: the dense irregular CT that surrounds muscles, fasicles and fibers |
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What are the 6 arrangements of fasicles?
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Circular
Fusiform unipennante bipennante Multipennante parallel |
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define a circular fasicle
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arranged in a circular arrangement. ex: around the eyes and mouth.
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Define a fusiform fasicle
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nearly parallel but they taper toward the end
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Defin a unipennante fasicle
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fasicles are short and attach to a central tendon at an angle
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Define a bipennante fasicle
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fasicales are short
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Define a parallel fasicle
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fasicles are parrallel and attache to the top and bottom of a broad and flat tendon.
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What are 2 types of muscle attachement
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Direct
indirect |
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Define direct attachment on a muscle
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when epimyecin of a muscle diretly attaches to the periosteum or perichondrium
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Define indirect attachement
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when perimyecium extends beyond the muscle. And then turns into a CT cord, that attaches the muscle or some other structure.
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what are 3 types of indirect attachement
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Tendon
Aponeurosis tendon sheath |
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Describe a tendon attachement
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a type of indirect attachement that attaches a muscle to a bone
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Describe a aponeruosis attachement
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a type of indirect attachment using a broad flat tendon. Can attach a muscle to bone, skin or to another muscle.
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Describe a tendon sheath attachement
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a CT cord that secretes synoial fluid. Its only found in synovial joints.
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Muscles ususally work.....
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in pairs or groups
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Muscles can either work....
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together or oppose eachother.
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Muscles only.....
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pull. Never push
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Muscle fibers can only....
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shorten
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Under normal condition muscle fibers shoould never
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extend beyond their original length.
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The insertion of a muscle should always move toward an .....
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origin
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What is the most distal part of the muscle refered to.
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The insertion.
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Define insertion
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the most moveable part attched to the most moveable part of the bone. Its always farthest away from the trunk.
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Define the gaster
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The body or belly. Middle main part of muscle.
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Define origin
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the least moveable part that is attached to the least moveable bone. Usually closest to the trunk.
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What is the prime mover/agonist.
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The muscle in a group of muscles that produces a specific movement.
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Define the antagonist.
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The muscle in a group of muscles that opposes or reverses a specific action.
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When the prime mover is contracted the antagonist is....
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always relaxed. However sometimes it remains partially contracted to produce resisitance and smoth movements.
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the prime mover and the antagonist should always...
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be on the opposite sides of the joint over which they act.
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what are the 2 groups of muscles that help produce movement
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synergists
Fixators |
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Define synergists
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a group of muscles that helps produce movement. By creating more power for the desired moevement. also helps eliminate unnecessary movements at the joint.
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defin fixators
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a group of muscles that help produce movement by preventing the prime mover from moving when its producing its movement.
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for a muscle fiber to contract it...
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must be stumulated by a motor neruon.
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As the motor nerurons axon reaches the muscle it....
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branches out forming a neuromusclular junction
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As a motor impulse reaches the axon terminal it....
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causes the synaptic vesicle to release acetylcholine.
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What role does ACH play in a synaptic vesicle?
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the ACH bridges othe synapes allowing the impulse to cross over to the sarcolema.
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The nerve impulse moves along the sarcolema abd down the T Tubules it causes ...
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calcium ions to be released from the sarcoplasmic reticulum.
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What does acetylcholinesterase do
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Immediatly after the nerve impulse releases the calcium ions, it deactivates the ACH.
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what if there was no aetylcholinesterase?
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The muscle would not be able to fully releax.
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where is acetylcholineterase found
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on the sarcolema
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troponin is....
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a protien in the muscle that calcium ions bind to.
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What is the CAT complex and what does it do?
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the calcium troponin complex. It conrols activits at the sarcomere.
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During contraction thethin actin filaments...
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slide over the thick myocin.
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Myocin never
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changes size
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what does the sliding of actin cause
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thin filments slide over thick
z discs move closer together the I bands get extremely small the A band is unchanged the H zone becomes very small and almost disapears. |
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explain what starts the contraction changes in the sarcomere
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the cat complex attaches to tropomyocin and makes the tropomyocin top heavy causeing it to pivot off the active site.
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tropomyocin covers
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the active binding sites in a relaxed sarcomere.
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Myocin heads are shaped like
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golf clubs
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once the active sites are exposed what causes the myocin heads to pivot upward and what do the attach to?
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AtP.
they attach to the active sites |
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what is a power stroke
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When the ative sites are exposed to ATP causing the myocin heads to pivot upward and attach to the actve sites.
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Myocin heads are called
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Cross bridges
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Once the mycin heads attach to the active sites the immediatly...
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pull actin in over myocin until the sarcomere is fully contracted.
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Explain what happens once a complete contraction occurs
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ATP will cause the crosss bridges to detach
The tropomyocin blockade is restored Calcium ions are pumped back in the sarcoplasmic reticulum The muscle relaxes. |
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What are the 3 types of muscle fibers
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1) slow twitch, non fatigable, red.
2) fast twitch, fatigable, white 3) fast twitch, non fatigable, red |
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define isotonic exercise
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when a force is moved across a distance. when muscles contract and shorten and work is being done.
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define isometric exercise.
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muscle fibers become dense but do not shorten. No work being done
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define oxygen debt
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when oxygen supply to muscles is drastically reduced during exercise there is cramping and fatigue due to a build up of lactiic acid. Muscles stays cramped till oxygen is restored.
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define muscle fatigue
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when a muscle cannot matintin the strength of its contraction
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Define twitch
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when a single muscle cell responds to a single brief stimulus that s not strong enough to cause a contraction.
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define threshold
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stimulus that is stong enough to cause a contraction.
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define tetanis
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a smooth sustained muscle contraction
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define tone
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a sustained partial contration of mucles.
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Define all or none
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a single muscle cell contracts complelty or not at all
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define stimulation
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when the strength of a contraction is increased due to rapid stimulus rates.
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What are the 2 subdivisions of the nervous system
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The CNS central nervous system
the pns, peripheral nervous system |
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What is included in the CNs
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brain
spinal chord |
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what are the parts of the pns
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somatic
autonomic |
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Define somatic
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all nerves that intervate skeletal muscles. Part of the PNS
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define autonomic
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all nerves that intevate smooth muscle, cardiac muscle, or glands. Part of the pns
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What are the two parts of the autonomic system
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sypathetic - flight or fight, emergency nervous system
parasympathetic - speeds up all body activities. Feed or breed maintinas normal. |
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what is the houskeeping system
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the parasypathetic system
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Nerve cells are called
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neurons
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what are 3 types of neurons
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sensory
motor association/internuncial |
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Define sensory nerves
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carry impulses from the external and internal environemtn and send them into the brain and spinal cord. they are ascending and afferent
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What do motor nerves do?
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Carry impulses from the cns out to effectors such as skeletal muscles and some glands. They are descending and efferent.
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Define Association/Internuncial neurons
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Always is the CNS and they connect sensory and motor neurons.
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use the acronym s.a.m.e.
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sensory afferent motor efferent.
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Define dendrite
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Nerve fibers that carry inpulses into the cell body.
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What is the soma/cell body/ perikaryon of a neuron
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Holds the cytoplasm and all organelles of the neurons.
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what are the 3 unique parts of the soma
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Nissl body: the rough ER of the neuron
Lipofuschin pigment: a fatty substance that gives the neuron a yellow color. Neurofibrils: protien tubes that give the neuron its shape. |
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Axon hillock
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The initial segment. A cone shaped projection where the axon exits the cell body.
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Trigger zone
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where the impulse first begins to travel down the axon
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Axon collaterals
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side branches of the axon not always present.
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Neuroglia/glial cells
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nerve glue insulate nourish and support neurons.
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Astro cyte
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a type of glial cell makes neurotransmitter and maintains the proper ion balances for conducting impulses
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Oligodendrocytes:
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make myelin a fatty covering that insulates axons
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What are microglial cells
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phagocytes that destroy bacteria
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ependymol cells
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contain cilia and circulate cerebral spinal fluid
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Neuralemmocytes/schwann cells
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make myelin in the PNS
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Satelite cells
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support cell bodys of all perepheral axons.
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What are the 2 glial cells that are located in the PNS
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schwann cells
Satelite cells |
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define excitability
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neurons ability to respond to a stimulus and then convert that stimulus to an action potential
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What is an action potential
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nerve impulse
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define stimulus
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any condition in the environment that is capable of changing resting potential from -70 to some other number
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Define threshold for a the nervous system
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strong enough to change the resting potential from -70 to -55
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if the stimulus reaches threshold the membranes permiability to Na ions
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increases greatly at the point of stimulation.
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When the stimulus's threshold is reached it opens...
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Na gated channels causeing Na to rapidly move from outside to inside.
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Describe depolarization of the membrane
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Many more Na ions are entering than exiting the membrane potential changes quickly from -70 to 0 to +30
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Describe repolarization of the membrane
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Once membrane potential reaches +30 the Na gates start to close, K gates open and membrane potential changes from +30 back to -70.
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What is an action potential
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a complete depolarization followed by a complete repolarization
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What 3 things happen when a threshold level stimulus reaches a membrane
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shuts down the Na K pump
it makes the membrane relitively impermiable to K It opens Na ion gated channels |
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The stimulus's threshold opens up the Na gates and changes the membrane potential from...
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-70 to -55
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once the membrane potential reaches -55...
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the simulus is no longer needed.
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Even through the stimulus is no longer needed because it has reached threshold ...
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The depolarization continues because of the ion concentration differences.
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describe the Hodgkins cycle
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a positive feedback loop where once the membrane potential reaches -55 the stimulus is no longer needed. the depolarization continues becuase of ion concentration differences.
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what happens when +30 is reached after the hodgkins cycle
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the depolarization stops The new charge startes to close the na gates and reopens the K gates
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In repolarization what happens after the Na gates close and the K gates reopen
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Membrane potential is dropped from +30 to -70.
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After repolarization when -70 is reached again what happens to the ions
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the end up back in their original position and the Na K pump starts to function again
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The depolarization-repolarization process continues down an entire axon...
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at a constant and maximum strength
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All the gated channels during resting potential are...
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closed
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You must have a stimulus stong enough to open a Na gated channel to...
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start an action potential
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Without a refractory period...
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you would not be able to percieve constant sensation.
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A Membrane is at potential is when.
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a neuron is resting there a considerble difference in ions concentration on each side of its membrane
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Positing of the ions causes
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the resting potential to be -70
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There is a _____ difference between the inside and the outside of the _______
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-70
neuron |
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Why is the NaK pump a major factor for maintaining ionic position?
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The active transport mechanism in the pump moves NaK from lesser to greator concentration
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The number of of ions pumped is.....
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unequal. For every 3 Na ions pumped out 2 Ks move in.
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Electrogenic is
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when the pump moves ions unequally
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since the Na ions being pumped out of the neuron are positive.....
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overall a positive charge develops outside.
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the K ions are also positive but.....
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there are not enough of themto equalize the charge because of the Pops.
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A resting neuron is ______ more perimiable to _____ than ____. What prevents _____ from moving outside.....
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100x
K Na K Pops |
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what are the 2 types of channels in the membrane
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Leakage: Always open in response to a stimulus
Gated: channels open and close in response to a stimulus. |
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The process's of the pumps and the channels opening etc causes ....
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the membrane to be negative inside and the outside to be positive. the membrane potential stays-70.
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A resting membrane is always...
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polarized. It stays this way until acted on by a stimulus.
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What are pops
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very large non diffusable protiens.
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what is a absolute refractory period
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Its the period of time when a neruon cannot respond to a nd stiumuls regardless of its strength becuase the Na gated channels are open
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What does the absolute refractory period correspond to?
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Depolarization
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What is relative refractory period
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the period of time when the Na gates are closing and K gates are opening.
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In a relative refractory period, the threshold stimulus cannot...
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generate a 2nd action potential. however, an exxtremly strong stimulus, a superthreshold can reopen the Na gates before the repolarization occurs.
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If a stimulus is extrememly weak...
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an actio potential will not be generated and you will not percieve the sensation.
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If the stimulus is extremly weak it causes a very slight.....
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hypopolarization followed by a repolarization.
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What is an all or none refractory period
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A threshold stimulus will always generate an action potential. And the action potential will move along the entrie axon at a constant and maximum strength.
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continuous conduction is...
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when an action potential is traveling along an unmyelenated axon.
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saltatory conduction is...
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When whenthe fiber is myelenated.
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myelin acts as an...
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insulator. A fatty material that the action potential cannot travel through.
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Node of Ranvier
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the unmyelentaed area that the impulse jumps from on to the other.
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at the Node what occurs?
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depoloraization followed by repolarization
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Saltitory conduction tends to be...
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fast, effiecent and the cell uses less energy. But it depends on the degree of myelination and the diameter of the fiber. thicker is quicker.
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Define synapse
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the space between the axon terminal. Where 2 neurons oem toether or where a neuron meets an effector.
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What are the 2 types of neurons
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presynaptic: before the synapse
postsynaptic: after the synapse |
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What are the 2 classes of snapses
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electrical: seen frequently in an embryo and after brirth in the heart.
Chemical: seen everywhere in the body where chemicals are released to bridge the gap. |
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what are the chemicals released in a synapse called?
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Neurotransmitters
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What is a neurotransmitter
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A chemical that allows neurons to communicate with eachother or the allow a neuron to commincate with an effector , like a muscle.
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To be classed as a NT the chemical must have 3 propertys
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1) must be present in the synaptic vesicle of the axon terminal
2) once its released it must be able to open K or Na channels 3)After it completes its job the body must have a natural way to deactivate it. |
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NT's are classified 2 ways
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1) by function: do they excite or inhibit
2) Chemical based on molecular strucure |
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What is the difference between a NT that excites or inhibits
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If they excite they open Na gates causeing depolarization toward the threshold. If the inhibit they open K gates making the membrane more negative or it will hyperpolarize it.
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What are the to NT's in the PNS
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acetylcholine
norepinephrine |
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What are the 3 neuron circuits
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Divergent
convergent Reverberating |
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Explain a divergent circuit
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when 1 presynaptic neruon synapses with several post synaptic nerurons. Mostly in the brain and
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explain a convergent circuit
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when several presynaptic neurons synapse with 1 post synaptic. Mostly in neuro muscular junctions
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explain a reverberation circuit
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one neron synapses with the 2nd which synapses with a 3rd then the axon collaterals from the 3rd go back and synapse with the previous neurons
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What do excitatory synapses do?
What is this called and what does it cause? |
these lower the post synaptic dendrites resting potential from -70 to a number closer to threshold. The result of this is called facilitation. and it causes an EPSP (excitatory post synaptic potential)
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Explain how epsp works
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excitatory post synaptic potential works by opening Na gated channels and most of our synapses are exciatory.
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what are the 2 ways the synapse can function
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1) spatial summation
2) temporal summation |
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Explain spatial summation
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many axon terminals release neurotransmitters at exactly the same time producing a rapid depolarization toward threshold.
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what is temporal summation
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several axon terminals can release Nt one after the other. producing a gradual depolarization to threshold.
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Inhibitory NTs make the post synaptic dendrites membrane potential more...
What is this called and why |
negative which changes the it from -70 up toward -90. Called hyperpolorizing becuase it opens the Na gates
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When inhibitory Nts hyperpolorize the membrane it causes an
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IPSP Inhibitory post synaptic potential.
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During an IPSP to generate future action potentials...
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the stimulus must be superthreshold.
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