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
T or F
The shape of the muscle will affect the action of the muscle.
T
… muscles can close an opening.
Circular
T or F
Short muscles are better at controlling movement over joints that have a large range of motion.
F
Long muscles
A muscles …. is the greatest
predictor of force generating capacity.
physiological cross sectional area
Shorter-wider muscles are better at generating larger/smaller forces, over a larger/smaller range of joint motion.
Larger
Smaller
T or F
All muscles can produce similar amounts of force.
F
Different muscles have different abilities to produce force.
What is the formula for a muscles physiological cross sectional area (PCSA)?
PCSA = Muscle volume/Fibre length
Is muscle length or muscle fibre length more important when considering a muscles maximum force generating capacity?
Muscle fibre length (see PCSA eqn)
The contractile filaments that convert the electrical signal (action potential) initiated in the nervous
system to muscle force are within the …
myofibril
T or F
Sarcomere length changes during contractions and with passive stretch of a muscle.
T
…. create the “active” component of muscle force generation.
Actin and myosin cross bridges
Optimal sarcomere
length = …% to …% of
resting length
80%-120%
T or F
Sarcomere length changes with joint position
T
What is the ‘length-tension’ aka ‘force-length relationship’?
Describes how sarcomere length changes with joint position. Which influences the amount of force that can be developed.
(Regarding Hill’s mechanical model of the muscle-tendon)
What part of a muscle forms the contractile component?
Actin and myosin cross bridges
(Regarding Hill’s mechanical model of the muscle-tendon)
What part of a muscle forms the series elastic component?
titin and tendon
(Regarding Hill’s mechanical model of the muscle-tendon)
What part of a muscle forms the parallel elastic component?
Connective tissue within the muscle - epimysium, perimysium and endomysium
T or F
Connective tissue is an important
active force, limiting over stretch.
F
passive force
T or F
Both active (CC) and passive (SEC and PEC) structures contribute to total force
T
Motor unit = how many motoneurons?
1
Are slow twitch fibres are most commonly found in power, postural or mixed muslces?
Slow muscle fibres are most commonly found in postural muscles, where fine control is needed >55%. Then mixed muscles 45-55% and then power muscles <45%.
What are the 3 types of skeletal muscle fibres?
Slow oxidative, fast oxidative and fast glycolytic.
Red muscle has high/low mitochondrial content whilst white muscle has high/low mitochondrial content.
high
low
Oxidative fibres rely on ….
aerobic respiration.
What do fast oxidative and slow oxidative muscle fibres have in common?
Aerobic respiration as a source of ATP, both have lots of mitochondria and both have a high myoglobin content (Red muscle).
Myglobin is a …-… colour.
red-brown
Myoglobin in an … storing protein.
O2
T or F
O2 binds to haemoglobin more
than myoglobin
F
vice versa.
Slow, type 1 fibres are also referred to as … because …
Cinderella fibres because they take longer to fatigue
Glycolytic fibres use … for energy source.
glycolysis (Break down of glucose into ATP)
Why are glycolytic fibres white?
Because glycolytic fibres use glycolysis for energy rather than aerobic respiration there is less O2. Less O2 means less myoglobin (which is a red-brown colour) making the muscle white.
What is the fastest fatiguing type of skeletal muscle?
Fast glycolytic
What types of skeletal muscles have a fast contraction speed?
Fast oxidative and fast glycolytic.
What is Henneman’s size principle?
When exposed to a stimulus, small motor units (within a motor unit pool) are recruited first because they reach their threshold sooner. With greater excitatory input the number of motor units increase, and the size of the recruited motor units increase.
Name the two dynamic muscle movements.
Concentric and eccentric
Name the static muscle movement.
isometric
What does isometric in reference to muscles mean?
There is no movement in the muscles.
What does eccentric in reference to muscles mean?
The muscles are moving downwards.
What does concentric in reference to muscles mean?
The muscle is moving up.
The maximum force that can be produced is dependent on the direction such that: …> … >…
(blanks are either concentric, eccentric or isometric)
eccentric>isometric>concentric
T or F
An eccentrically contracting muscle can produce more force at the same muscle length
than a concentrically contracting muscle.
T
T or F
Skeletons are always comprised of bone no matter the species.
F
Do humans have an endoskeleton, exoskeleton or hydrostatic skeleton?
Endoskeleton.
What are the three types of skeletons?
endoskeleton, exoskeleton and hydrostatic skeleton.
What are the mechanical functions of skeletons?
They support, protect and move.
What are the metabolic functions of skeletons?
Nutrient store (minerals and
lipids), blood cell formation
… bones make up the human
adult skeleton.
206
The skeleton can be divided
into … and … bones.
Axial and Appendicular
What is the difference between our axial and appendicular skeletons?
Axial skeleton: Relating to or situated in thehead and trunk region of the body Axial: relating to or forming an axis
Appendicular skeleton: relating to limbs Append: to add something to the end
There are … bones in the human axial skeleton.
80
What is the purpose of the skull?
Protects the brain. Supports soft tissues of the head. Allows movement of the jaw
during chewing.
What is the purpose of the rib cage (including the sternum)?
Rib cage including sternum:
Protects heart and lungs etc.
Supports shoulder girdle and
Allows movement e.g respiration.
What is the purpose of the vertebral column?
Vertebral column:
Protects the spinal cord
Supports the rib cage
Allows movement of the trunk
There are … bones in the adult human appendicular skeleton.
126
What is the sagittal anatomic plane?
Divides the body into left & right.
What is the parasagittal anatomic plane?
Divides the left and right sides of the body in half. (Whole body in quarters)
What is the coronal anatomic plane?
divides the body into dorsal & ventral or back & front, or
posterior & anterior.
What is the transverse anatomic plane?
Divides the body into cranial & caudal or head & tail or superior & inferior.
Curl your fingers into a fist. What joint movement just occurred.
Flexion
What movement did Michael Jackson make when performing his anti-gravity lean?
Extension
Adduction moves a body part
towards/away the midline, abduction moves it towards/away from the midline.
towards
away
Adduction and Abduction movements occur in what anatomical plane?
the frontal plane.
Lateral rotation refers to a joint rotating …
externally
Medial rotation refers to a joint rotating …
internally
Name the 3 types of joints in the skeleton.
Fibrous, Cartilaginous, Synovial.
T or F
Some fibrous joints cannot move at all.
T
e.g. skull sutures hold the skull bones tightly in place.
The extent a fibrous joint can move is dependent on…
depends on the length of the
connective tissue.
Cartilaginous joints contain …
cartilage
T or F
Cartilage tissue can move more than a fibrous joint but less than
most synovial joints.
T
Cartilage serves to…
cushion forces.
T or F
Synovial joints are one of the only joints that have a space (a synovial
cavity filled with fluid) between the adjoining bones.
F
They are the only joint with this.
T or F
Synovial joints allow the greatest range of movement.
T
… and … are important to keep bones “together” and guide motion of the joint.
Cartilage and ligaments
Which one of these is NOT a joint?
Saddle joint
Synovial joint
Hinge joint
Clasp joint
Clasp joint
Which one of these is NOT a joint?
Condyloid joint
Beta joint
Pivot joint
Plane joint
Beta joint
T or F
Hinge joints restrict movement to a single plane.
T
T or F
Opposing muscles (acting in opposing directions over a joint) are required to return the skeleton to its original place.
T
Back and forth movement of a body part is accomplished by … muscle pairs applying active force to the skeleton.
antagonist
During flexion the biceps … and the triceps …
contract
relax
During extension the biceps … and the triceps …
relax
contract
…. during childhood and adolescence is a strong determinant of peak bone mass and the eventual risk of osteoporosis.
Bone acquisition
11 weeks prior to birth a foetus has … ossification centres.
800
Neonates have … ossification centres.
450
2/3 of a neonates skeleton is
…
cartilage
…% of an adult skeleton is cartilage.
10%
What are the 4 types of bone structure?
Long, short, flat and irregular
What two types of bone structures undergo Hematopoiesis (make blood)?
Flat and irregular
Square shaped bones are an example of … bones.
short
T or F
High loads can modify the shape of bones.
F
The protein collagen makes up …% of bones dry weight.
40%
Calcium and salts make up …% of bones dry weight.
60%
T or F
The collagen fibres within bone are randomly distributed in
children.
T
What does collagen do for bones?
Provides flexibility ie fracture resistance
What do calcium and salts do for bones?
Provides rigidity
T or F
Collagen is laid down between the calcium and salt fibres of bone
F
vice versa.
What are the four types of bone cells?
Osteoblasts, Osteocytes, Osteoclasts and Osteogenic cells.
What bone cell type is located on the surface of a bone?
Osteoblasts
Which bone cell is also a stem cell?
Osteogenic cells.
Which bone cell am I?
I am a very large cell
I have many nuclei
I breakdown the bone matrix, destroy and resorb bone
Osteoclast
… respond to mechanical stress
‘Dig tunnels’ to be lined with collagen by the osteoblasts
osteoclasts
Which bone cell am I?
Line the tunnels with collagen. Create bone matrix, build bone (construction)
Osteoblasts
Which bone cell differentiates into osteocytes when trapped in bone?
osteoblasts
Which bone cell am I?
Maintain bone matrix, hold bone together.
Mineralise the bone matrix (calcium and salts)
Long cytoplasmic extensions, can supply
nutrients into the bone matrix
Osteocyte
Which bone cell am I?
I develop into an osteoblast
(to form bone) and then an
osteocyte (to maintain bone)
osteogenic cell
T or F
Trabecular bone (spongy bone) has a greater surface area compared to compact bone.
T
T or F
Trabeculae form along lines of stress in compact bone.
F
In trabecular bone
Do trabeculae or compact bone produce red blood cells and lymphocytes, and support the immune system.
Trabeculae
Does trabecular or compact bone store calcium?
Compact bone
Why are long bones thickest midway along the shaft?
because that is where bending stress is the greatest.
T or F
A bone does not grow or remodel in response to forces applied upon it.
F
It does.
How can you tell whether a human skeleton was right or left-handed?
Handedness (right or left handed) results in bone of one upper
limb being thicker and stronger.
What is the most medial digit in the hand?
The pinkie
… describes a position in a limb that is nearer to the trunk.
Proximal (e.g. in anatomical position the elbow is proximal to the wrist)
… describes a position in a limb that is further to the trunk.
Distal (e.g. the wrist is distal to the elbow.
