Module 4: Support and Movement Flashcards
What is a sarcomere?
the smallest functional unit of striated muscle tissue. It is the repeating unit between two Z-lines.
What are the 3 types of muscle tissue?
Skeletal, Smooth and Cardiac
T or F
Sarcomeres typically lengthen when contracting
F
they typically shorten
Skeletal muscle makes up … to
…% of body mass
40 to 50%
What creates the striped appearance of skeletal muscle?
The arrangement of contractile components (sarcomeres) create the striped appearance
Muscle attaches to bone via …. and produces movement around …
connective tissue (tendon)
joints
T or F
Skeletal muscle cells are long
T
Skeletal muscle cells are also called ….
muscle fibres
Skeletal muscle is controlled by
the … nervous system
somatic - can be consciously influenced
T or F
Each muscle fibre has multiple nuclei
T
Why do muscle cells have multiple nuclei?
During development, muscle fibres form by fusing multiple muscle cells
Name some places where smooth muscle can be found
The GIT, lymphatic vessels, bladder, blood vessels (e.g. artery), respiratory tract (e.g. bronchiole), skin and the iris.
Where is cardiac muscle found?
only in the contractile walls of the heart
Which muscle types are striated?
Cardiac and skeletal
What muscle tissue type am I?
I am striated
I branch (nonparallel)
Cardiac
What muscle tissue type am I?
I am striated
I am parallel
Skeletal
Cardiac muscle fibres
interconnect at an ….
intercalated disk
What is the purpose of an intercalated disk?
allows the electrical signal to pass from one muscle cell to another
There are approximately … different skeletal muscles in humans
x 2 sides!
320
T or F
Muscles can be easily characterized into one of gross, postural, or fine motor roles.
many muscles easily fit into multiple roles
Muscles are broadly characterised into what 3 control categories?
postural, fine motor and gross motor control
All skeletal muscles have what 4 characteristics?
Contractility, Excitability, Extensibility and Elasticity
What does muscle contractility refer to?
Ability to shorten and thicken, and develop tension
What does muscle excitability refer to?
Ability to respond to appropriate stimuli (action potential)
What does muscle elasticity refer to?
Ability to store some energy, and recoil to the resting length
What does muscle extensibility refer to?
Ability to be stretched without damage
T or F
A single muscle fibre (cell) is very long.
T
Muscle fibre is made from a large number of fused …..
embryonic cells
Inside each muscle cell is a bundle of …
myofibrils
T or F
Myofibrils lie antiparallel
F
They lie in parallel
Each myofibril contains a series of …
sarcomeres
The fascicles of muscle fibre are surrounded by ….
connective tissue
What function do sarcomeres perform?
The sarcomeres contain the contractile filaments that convert the
electrical signal (action potential) initiated in th
What is the basic contractile unit of skeletal muscle?
The sarcomere
Each sarcomere contains a series of thick
and thin … that move in relation to
each other during contraction
filaments
What causes regions of sarcomeres to appear dark under a microscope?
The regions that contains overlapping
thick and thin fibres look darker under
microscope, the regions which contain
only thinner fibres look lighter.
Thin filaments of sarcomeres are composed of …
actin
Thick filaments of sarcomeres are composed of …
myosin
(Regarding sarcomeres)
T or F
Myosin attach at the Z line
and actin anchors at the M
line in the centre of the sarcomere.
F
Actin attaches to the Z line and myosin anchors at the M line in the centre of the sarcomere.
T or F
When at rest, actin and myosin overlap
T
(Regarding sarcomeres)
Whole muscle shortening results as the filaments overlap more, pulling the … lines closer
Z
(Regarding sarcomeres)
What anchors myosin to the Z line?
Elastic filament: Titin
T or F
Titin contributes to the passive force in muscles.
T
Sarcomeres … when contracting
shorten
T or F
There is no overlap between myosin and actin in a relaxed muscle.
F
Some overlap of actin and myosin in relaxed muscle
T or F
There is greater overlap between myosin and actin when a muscle shortens with contraction compared to a relaxed muscle
T
T or F
Myosin and Actin are thicker protein strands
F
They are extremely thin protein strands.
Which is thicker, myosin or actin?
Myosin
What links myosin and actin filaments together?
myosin heads
What property of myosin heads allows it to bind to actin filaments?
Myosin heads have actin binding sights
When talking about sarcomeres, what is a cross bridge?
During muscle contraction, myosin heads link the myosin and actin filaments together, forming what’s called cross bridges.
(Regarding sarcomere cross bridges)
… pulls the … across, shortening
the muscle fibre and producing …
Myosin
actin
force
T or F
Both muscle + connective tissue influence muscle function
T
… attach muscle to bone
Tendons
… groups muscle fibres into a fascicle
Perimysium
… groups muscle fibres into a fascicle
Perimysium
A bundle of myofibrils is called a …
fascicle (muscle fibre)
A bundle of sarcomeres is called a …
myofibril
What is epimysium?
fibrous tissue that surrounds skeletal muscle
What is perimysium?
Perimysium groups muscle fibres into a fascicle
What does endomysium surround?
each muscle fibre (fascicle)
Muscle cells are each
innervated by a …., direct from the
spinal cord
motor neuron
What is a neuromuscular junction?
Where a motor axon extending from the spinal cord meets a muscle.
A single …. is the smallest
functional unit in the
musculoskeletal system.
motor unit
Skeletal muscle cells must get
the appropriate signal (action potential) from the …. to initiate the muscle contraction.
nervous system
When is an action potential generated?
When sufficient excitatory input to
reach firing threshold
T or F
Every action potential generated in the motor neuron generates an action potential in the motor units muscle fibres.
T
T or F
Every action potential in the muscle fibres generates a little bit of force.
T
Motor units range in … and …
Size (number of muscle fibres)
Contractile properties (speed, fatigability)
The … is the contractile unit of muscle
sarcomere
T or F
Contraction shortens a sarcomere but does not change the length of the actin or myosin filaments.
T
When … and … are released, the myosin head bends, pulling the actin.
ADP
phosphate
When … binds to a myosin head it causes it to detach from the actin
ATP
When … is broken down to … and …, the myosin head extends
ATP
ADP
Phosphate
Binding, power strokes, detaching and extension of myosin heads in muscle will continue as long as … are present
Calcium ions