Types of Muscle
Name the 3 types of muscle tissue.
Smooth
Cardiac
Skeletal
What two protein filaments compose a sarcomere?
Actin and myosin
What is the NMJ?
Neuromuscular junction: location where a nervous cell and muscle cell meet.
What are the two types of muscle fibers?
Fast twitch and slow twitch
Give 2 differences between skeletal and cardiac muscle.
Skeletal is voluntary, multinucleated, attached to bone, branched fibers.
Cardiac is involuntary, single nucleus, in the heart, tubular fibers.
What happens to the length of a sarcomere during muscle contraction? Why?
It shortens as actin and myosin filaments slide past each other--these filaments do not shorten themselves.
What are cross bridges?
Connections between actin and myosin filaments during muscle contraction.
What type of muscle fibers would a sprinter primarily use?
Fast-twitch
Mitochondria
This is essential for high ATP production to allow for continuous contraction/beating of the heart.
What causes the striations seen in skeletal muscle?
Organization of actin and myosin produces light and dark striations.
What is the difference between an isotonic and isometric contraction?
Isometric: Muscle changes tension but not length.
Isotonic: Muscle changes length but not tension.
What chemical is produced when using fast-twitch fibers, causing a "burning" feeling in your muscles?
Lactic acid
Explain 3 processes that smooth muscle is used in.
Contractions in the digestive tract for digestion of food
Constriction/dilation of pupils to regulate light entering the eyes
Bladder expansion to allow filling
Blood vessel constriction/dilation to regulate body temperature and blood pressure
What two regulatory proteins are attached to actin filaments?
Troponin and tropomyosin
What is the role of troponin/tropomyosin in muscle contraction? What do they cover during rest and what happens to their position during contraction?
These proteins bind to myosin binding sites on actin filaments during rest. During muscle contraction, they move to expose those sites, to allow cross bridges to form.
What are the two types of respiration? Which is used primarily by fast-twitch fibers and which is used by slow-twitch fibers?
Aerobic (slow twitch) and anaerobic (fast twitch)
Name and describe the location of the 3 layers of connective tissue found in skeletal muscle.
Epimysium: surrounds whole muscle; lies beneath fascia.
Perimysium: surrounds fascicles within a muscle.
Endomysium: surrounds muscle fibers (cells) within a fascicle.
Define Z line, M line, and H zone.
H zone: myosin, middle of sarcomere
Z line: anchors actin filaments, boundaries of sarcomeres
M line: anchors myosin, in the middle of the sarcomere
Explain the full process of muscle contraction.
An action potential (nerve impulse) arrives at the NMJ and stimulates the neuron to release ACh, which stimulates the release of calcium.
Calcium binds to troponin on actin filaments (thin filaments), exposing myosin binding sites.
Actin and myosin (thick filaments) form cross bridges.
ATP hydrolysis causes thin and thick filaments to slide past each other.
Muscle shortens.
What causes muscle fatigue, biochemically?
ATP is used to trigger contraction. When there is no ATP or oxygen left for muscles to use, muscles begin to fatigue, and contractions stop.