Muscle Anatomy and Contraction Flashcards
How many muscles in body?
600
Characteristics of muscle (4)
extensibility: stretch without damaging
elasticity: return to original shape
contracting: shorten when stimulated
excitability: respond to stimuli by producing action potential
Functions of muscle (4)
motion
stabilizing body positions
regulating organ volumes
movement of substances
3 muscle types
skeletal, cardiac, smooth
Characteristics of skeletal muscle (4)
striated
attaches to bone via tendon
multinucleated, peripheral nuclei
voluntary control
Characteristics of cardiac muscle (4)
striated
one, central nucleus
involuntary control
auto-rhythmic
Characteristics of smooth muscle (3)
non-striated
one, central nucleus
involuntary control
Skeletal muscle: what is the sarcolemma?
muscle cell membrane
Skeletal muscle: what is the sarcoplasm?
muscle cell cytoplasm, filled with myofibrils
Skeletal muscle: what is the transverse (T) tubule?
invaginations of sarcolemma into the centre of the cell
Skeletal muscle: what is the sarcoplasmic reticulum?
stores Ca2+ in a relaxed muscle cell
Skeletal muscle: what is the mitochondria?
provide energy for contraction
Skeletal muscle: what is glycogen?
stored energy for muscle
Skeletal muscle: what is myoglobin?
red pigment that binds O2
Skeletal muscle: what are myofibrils?
fill sarcoplasm of muscle cell, composed of myofilaments
What are thick filaments called?
myosin
What are thin filaments called?
actin
What are striations formed from?
overlapping thick and thin filaments
What happens during skeletal muscle contraction?
thin filaments slide over thick, do not change in length, actin slides inwards
Purpose (4) and colour of connective tissue in muscle
protect, bring in blood vessels, group muscle cells together to increase power of contraction, tendons
white
What is endomysium?
surrounds each muscle cell
What is perimysium?
surrounds bundles (fascicles) of 10-100 muscle cells
What is epimysium?
surrounds entire muscle
How are cardiac muscle cells connected to each other?
intercalated discs, concentrated patches of adhering desmosomes and gap junctions for communication
Does cardiac muscle have larger or smaller T tubules than skeletal?
More mitochondria?
Less well developed sarcoplasmic reticulum?
How long does it take for Ca2+ to be delivered?
Larger
More
Yes
10-15 times longer
What can autorhythmic cells do?
contract without stimulation from nervous cells
Does smooth muscle have:
T tubules?
Sarcoplasmic reticulum?
Orderly arranged filaments?
no
little
no
What are the two types of smooth muscle?
visceral and multiunit
What is visceral tissue? Where is it found?
single unit
autorhythmic
most blood vessels
gap junctions between walls of hollow organs so contract in unison
What is multiunit tissue? And were is it found?
individual cells have own motor nerve endings
large arteries, airways, arrector pili muscles, iris
How does skeletal muscle grow and repair?
growth is enlargement of cells, fibres cannot divide after first year
satellite cells and bone marrow can repair some cells, otherwise fibrosis
How does cardiac muscle heal?
cannot divide or regenerate
healing done via fibrosis (scar formation)
How does smooth muscle regenerate?
hypertrophy
some cells can hyperplasia (eg. uterus)
What is the origin of skeletal muscle?
attachment to bone
point that remains stationary during contraction
usually proximal end
Longer muscle cells equals….
more range
How are muscles named? (6)
direction, location, size, shape, number, action
What 4 things ensure coordinated action of muscle groups?
prime mover
antagonist
synergist
fixator
What does prime mover do?
produces most force
What does antagonist do?
opposes prime mover, relaxes
What does synergist do?
stabilize nearby joint to prevent rotation
What does fixator do?
prevents movement of bone that prime mover is attached to
