The muscular system

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The muscular system How skeletal muscle works A
few words about cardiac and smooth
muscle Organization of skeletal muscle The
major muscle groups
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Organization of skeletal muscle
A muscle fiber (cell)
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The skeletal muscle cell the muscle fiber May
be as long as the muscle itself Several nuclei
and many mitochondria Extensive sarcoplasmic
reticulum Striations due to actin and myosin
filaments (myofibrils) Sarcomere is the
functional unit
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Neuromuscular junction
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A motor unit
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Overview of the sliding filament model
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Sources for ATP? Respiration (aerobic and
anaerobic) anaerobic when oxygen runs
out pyruvate is converted to lactic
acid fatigue lactic acid is carried in blood to
liver, and converted back to glucose Creatine
phosphate Myoglobin (stores oxygen) Heat
produced in process helps sustain body
temperature
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A muscle twitch

• Many cells contract
• Muscle activity controlled by how many cells
  contract, and how often

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Slow twitch and fast twitch fibers

• Slow twitch- more blood, myoglobin, mitochondria
• Aerobic respiration
• Fatigue resistant
• Fast twitch
• Anaerobic
• Susceptible to fatigue
• Fibers can get bigger and more powerful with use

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This will cause a muscle to contract
A motor unit can stimulate many cells
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skeletal
smooth
cardiac
http//www.udel.edu/biology/Wags/histopage/colorpa
ge/cmu/cmu.htm
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Smooth muscle contains actin and
myosin filaments arranged differently
from skeletal muscle Regulated differently-
calmodulin Multiunit- separate fibers iris,
blood vessel walls Visceral (internal
organs) stimulus is transmitted from one
cell to another Rhythmicity- pattern of
contractions self-activated
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Cardiac muscle striated, involuntary
muscle Cells are short and branched Calcium
channels regulate flux of calcium twitches last
longer than in skeletal muscles Intercalated
discs connect one cell to another help with
rapid transmission of signals How does cardiac
muscle act differently from skeletal muscle?
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Summary three types of muscle tissue