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BIO 264 EXAM 3|227 QUESTIONS AND ANSWERS 2024
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BIO 264 EXAM 3|227 QUESTIONS AND ANSWERS 2024
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BIO 264 EXAM 3|227 QUESTIONS ANDANSWERS 2024
3 types of muscle - -skeletal, smooth, cardiac
-muscle functions - -movement, body heat, maintenance of posture,
respiration, communication, constriction of organs & vessels (smooth
muscle), heart beat (cardiac muscle)
-muscle structure - -composed of muscle fibers (# of fibers fairly constant
after birth), cells connect end to end
-if muscle mass increases - -muscle gets bigger (cells fill with protein)
-epimysium - -outer most layer
-fasiculus - -bundle of muscle fibers (held together by perimysium)
-muscle physiology - -contorl of skeletal muscle contractions
-neurons - -physical connections between brain and muscle
-K+ concentration - -high in cell
-Ca2+ concentration - -high outside of cell
-Na+ concentration - -high outside of cell
-Cl- concentration - -high outside of cell
-non-gated ion channels - -fascilitated diffusion (open all of the time)
-ligand-gated - -chemical that binds to receptor to open gate (gate closed
on default) [key]
chemical signal
-voltage-gated - -electrical impulses (can open or close gated channel)
electrical signal
-resting membrane potential - -there is an electrical charge difference
across the plasma membrane of all cells (-70 to -90 mV in skeletal muscle
and nerves)
the inside of the cell is negative
, -2 factors when considering RMP - -concentration gradient (k+ really wants
to get out), charge (attracted to "-" charge)
-depolarization - -charge inside the membrane becomes more positive (Na+
enters the cell), signal to contract
-repolarization - -charge becomes more negative (K+ moves out of the cell)
-sodium potassium pump - -used to return cell to RMP;Uses ATP to pump K⁺
against its concentration gradient and keep it in high concentration gradient
and keep it in high concentration inside the cell and to pump Na⁺ against its
concentration gradient and keep it in high concentration outside the cell.
Three Na⁺ are transported out of the cell and two K⁺ are transported into the
cell for each ATP molecule used.
-activation gate - -outside of cell
-inactivation gate - -inside of cell
-threshold potentail - -when voltage gates will open (-50mV)
-voltage gated K+ channels - -slow to open and slow to close and only have
1 gate
-when cell contracts - -cell already repolarized
-membrane potential - -= determined by what's inside
-depolarization and repolarization - -only occur during an action potential
-action potential phases - -depolarization, repolarization, hyperpolarization
-myofilaments - -actin and myosin (striations)
-sarcomere - -fxnl unit of muscle
-z disks - -attachment sites for actin
-filament length - -they do not get shorter, they slide past each other
(accordian)
-actin - -Thin myofilament within the sarcomere within the sarcomere;
composed of two F actin molecules, tropomyosin, and troponin molecules.
-sarcoplasm - -cytoplasm
, -saarcolemma - -plasma membrane
-sarcoplasmic reticulum - -smooth er (where Ca2+ is stored)
-transverse tubule (T-tubule) - -little tubes of plasma membrane which wrap
around the different bundles. Allows action potential to experience
repolarization and depol inside the cell
-myofibril - -name of protein bundles in cells
-myofilament - -string of actin or myosin
-tropomyosin - -covers active sites (Ca2+ binds with troponin and
tropomyosin slips off and myosin head reaches up and pulls)
-wound repair - -wound fills with blood, clot forms, infection/inflammation,
fibroblasts migrate into clot and begin to form new CT, original tissue =
regenerated or replaced
-neuromuscular junction - -synapse
-steps of myosin head to contract - -1. cross bridge formation 2. power
stroke 3. recovery stroke (ATP) 4. cocking of head (muscles always cocked
ready to go)
-rigor mortis - -once organism dies no more ATP to tell myosin to release
(Ca2+ will leak out and cause cycle... more time more rigid the contraction)
-motor units - -changes force of contraction. The brain precalculates about
how many muscle fibers you need to use when you pick something up...can
occasionally miscalculate
-acetylcholinesterase - -breaks choline away from acetic acid and the
acetylcholine is broken down. Continues to break down ACh until there is not
enough to bind to channels. (choline is pumped back into neuron)
-botulism toxin - -blocks ACh from having effect on channels (flacid
paralysis= muscle unable to contract
-1 motor unit - -has many fibers it innervates
-isometric contractions - -length of muscle does not change
-isotonic contractions - -length of muscle changes
-concentric - -muscle shortens
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