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42 Cards in this Set
- Front
- Back
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Motor Unit
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– single motor nueron and all muscle fibers innervated by it
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Multiple motor unit summation
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– threshold stimuli – contraction of one motor unit
– submaximal stimuli– APs in axons of addition motor units – maximal stimuli – APs in all motor units in a muscle – supramaximal stimuli – greater stimulus stength produces no additional affect |
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Treppe
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– graded response in a muscle fiber after long period of rest
– why warming up is important |
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Tetanus
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– caused by clostridium tetani
– sustained muscle contraction – incomplete – muscle partially relax between contractions – complete – no relaxation between contraction – multiple wave summation – contraction strength increases as frequency increases |
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3 types of muscle fatigue
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– psychological
– muscular – no atp – synaptic – no AcH |
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Physiological contracture
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– muscles can niether contract nor relax due to lack of atp
– causes rigor mortis |
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EPOC
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– oxygen defecit when you start working out
– excess post–exercise oxygen consumption after working out |
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slow twitch muscle fibers
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– type 1, red muscle, contract more slowly, use atp more slowly, more fatigue resistant
– mostly in lower body |
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fast twitch muscle fibers
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– type 2, white muscle, quicker response, contains myosin which breaks down atp more quickly, upper limbs
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muscle changes
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– muscles can change type from exercise
– excerise can cause hypertrophy (increase in size) – atrophy also possible |
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properties of muscle
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– contractillity – can shorten w/ force
–excitability – respond to stimulus – extensibility – stretched to resting length and beyond – elasticity – can recoil to resting length after stretching |
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skeletal muscle structure
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– composed of cells, blood vessels, connective tissue, nerves
– fibers are long, cylindrical, multinucleated – striated |
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connective tissue coverings of muscle
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– epinysium – surrounds whole muscle
– perimysium – surround fasicle (group of fibers) – endomysium – surrounds muscle fiber |
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muscle anatomy from small to large
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– muscle fiber (cell)
– endomysium – fascicle – group of muscle fibers – perimysium – muscle – epimysium |
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sarcolema
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– plasma membrane found just inside the endomysium
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transverse tubules (t tubules)
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– invaginations in the sarcolema
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sarcoplasmic reticulum and terminal cisternae
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– smooth ER – surround myofibril
– enlarged areas of sarcoplasmic reticulum that surround the t tubules |
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structure of myfibrils
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– made up of myofilaments (actin and myosin)
– sarcomeres repeating units of actin and myosin myofilaments |
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structure of actin
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– 2 strands of actin monomers forming a double helix
– tropomyosin – protein that winds along groove of the actin double helix – troponin – 3 subunits, one binds to actin, one binds to tropomyosin, one binds to calcium – active sites on actin binds to myosin during a contraction |
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structue of myosin
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– can use gold club heads to bind to actin and form cross bridge
– rod attached by bendable hinge region – ATPase enzymes – break down atp |
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Z disk
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– attachment site for myofilaments
– boundry of a sarcomere |
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I bands, A bands, H zone, M line
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which part of sarcomere shortens to produce a muscle contractions
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– actin slides along myosin
– shortens H zone and I zone |
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excitation contraction coupling
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– AP moves down sarcolema into t tubules where it causes Ca+ to be released from terminal cisternae to myofibrils
– Ca2+ binds to troponin on actin filaments causing tropomysin to move from the active sites on the actin – head of myosin myofilaments bind to actin forming cross bridges –> contractions |
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Flexes, abducts, medial rotates arm |
- pectoralis major - pectoral nerves |
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abducts the arm |
- deltoid - axillary nerve |
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extends, adducts, medially rotates arm |
- latissimus dorsi - thoracodorsal nerve |
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rotator cuff |
- infraspinatus - laterally rotates arm - subscapularis - medially rotates arm - suprascapularis - abducts arm - teres minor - laterally rotates arm |
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extends , medially rotates, and adducts humerus |
- teres major |
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flexes and adducts humerus |
- coracobrachialis - muscolocutaneous nerve |
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extends forearm |
- triceps brachii - antagonist of forearm flexors - radial nerve |
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flexes shoulder and elbow, supinates forearm and hand |
- bicep brachii - musculocutaneous nerve |
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flexes elbow |
- brachioradialis - radialis |
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flexes, abducts, medially rotates thigh, flexes knkee |
- sartorius - femoral nerve |
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quadriceps femoris group |
- rectus femoris - extends knee, flexes thigh - vastus lateralis, medialis, and intermedius - extend knee - femoral nerve |
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absducts and medially rotates thigh |
- gluteal muscles |
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hamstring group |
- biceps femoris, semitendinosisus, semimembranosus - extend thigh and flex knee - sciatic nerve |
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dorsiflexes foot |
- tibialis anterior |
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plantar flexes foot |
- gastrocnemius - superficial muscle with two bellies - soleus - deep to gastrocnemius |
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layers of smooth muscle |
- longitudinal layer - fibers paralle to long axis of organ, allow organ to shorten - circular layer - circumfrence of organ, contraction elongates organ |
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smooth muscle contraction |
- ca2+ enters cells and binds to protein calmoduln which activates myosin kinase which brings phosphate group to myosin - relaxion caused by myosin phosphate which removes the phosphate group |
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ATPases |
- during relaxation, ATP is added to myosin head to replace atp used during contraction - ATPase hydrolysizes the ATP |
