4.1: Skeletal Muscle Flashcards
Structure and Function
What percentage of cells in our bodies are muscle tissue cells?
60%
What is the study of activities and functions of the living body and support systems?
Physiology
smallest unit of chemical compound, always in motion, made up of atoms that are held together by chemical bonds formed from sharing or exchanging electrons
Molecule
any organized/specialized structure within a living cell (nucleus, mitochondria)
Sub-Cellular / Organelle
known as the ‘building blocks of life’, able to independently replicate themselves,; smallest structural and functional unit of all living things.
Cell
What are the two types of cells?
Prokaryotic and Eukaryotic
What type of cell has no nucleus (ie. bacteria) ?
prokaryotic
What type of cell has a nucleus (animals, plants, humans) ?
eukaryotic
collection of similar cells from the same origin that function together for a specific purpose
Tissue
group of tissues joined together to function for a specific purpose inside living organism
Organ
group of organs working together
Organ system
the material structure, as a whole, of any living thing
Organism
What are the 3 different “germ layers”?
ectoderm, mesoderm, endoderm
What is the endoderm?
becomes inner layer; becomes nervous system, and linings of various tubes and vessels
What is the ectoderm?
becomes outer layer; skin and other outer covering structures
What is the mesoderm?
becomes middle layer; skeleton, connective tissue, heart and muscle tissue
What is skeletal muscle?
under voluntary control and responsible for movement at all bodily joints; striated muscle
A muscle that has the shape of a spindle, wider in the middle and narrows at both ends. Greater range of motion but limited strength.
Fusiform
Muscle that is square shaped, with parallel fibers that run directly from origin to insertion
Quadrate
Muscle with wide origin that converges to a narrow insertion resembling a triangular shape
Triangular
Muscle with parallel fibers consisting of tendinous intersections that run perpendicular to the direction of the fibers
Longitudinal
Muscle fibers that run obliquely with respect to the tendon
Pennate muscles
Muscle where fibers are on the same side of the tendon
Unipennate
Muscle where fibers on both sides of the central tendon
Bipennate
Muscle where central tendon branches within a pennate muscle
Multipennate
Involuntary muscle; no “conscious control” over the muscle’s contraction; under control of the autonomic nervous system
Smooth Muscle
What do smooth muscles in the blood vessels do?
vasoconstriction (narrowing) and vasodialation (widening)
What systems are smooth muscles found?
blood vessels, digestive tract, reproductive, respiratory and urinary systems
What has a striated appearance and can hypertrophy but is involuntary and exhibits rhythmicity of contraction like smooth muscle.
Cardiac Muscle
Myofibrils are only found in which muscle fiber tissue type?
Skeletal
Which muscle tissue fatigues the quickest?
Skeletal
Which muscle tissue does not fatigue at all?
Cardiac
Which muscle tissue is controlled by the autonomic nervous system?
smooth
Which muscle tissue is controlled by the central nervous system?
cardiac
Which muscle tissue is stimulated by the nervous system to work?
skeletal
What are the 3 main functions of the skeletal muscles?
motion / resistance to external force; stabilization; heat production
When a muscle contracts, it ______.
shortens
Several muscles must activate to _______ the joint that is not moving so a force can be transferred to a moving joint.
stabilize
Different muscles of the same group may have more than one ________ but share a common ________.
origin (starting point); insertion (ending point)
A sheath of connective, fibrous and elastic tissue (deep fascia) that surrounds an entire muscle group
epimysium
contains bundles of muscle fibers
muscle Fascicle
Fascicles (bundles of muscle fibers) are held together by a sheath of connective tissue that surround it called ______
Perimysium (gives the “shredded” appearance)
a thin layer of connective tissue that surrounds each individual muscle fiber in a muscle. It’s the innermost sheath that covers the muscle fiber
endomysium
the individual muscle fiber is also called ______. It is the actual cell found in muscle tissue.
myocyte
Long, tubular cells that are stimulated to contract by motor neurons that send signals through the transmitting axon branch.
Muscle fibers
Consists of one motor neuron, its axon and the muscle fiber that in innervates (stimulates to action).
motor unit
There are several nuclei in the muscle tissue cells. (T/F)
True
Nuclei contain _______ which controls all cellular function and responds to various hormonal stimulations.
DNA
DNA transfers info from the ______ to the ________
nucleus; mRNA
The mRNA is located in the _______.
nucleolus
‘This’ takes instructions from the DNA to the ribosomes which convert ‘it’ into protein.
mRNA
Converts mRNA into protein.
ribosomes
How does protein synthesis occur?
Connecting one amino acid at a time so that it can be used as part of a larger protein.
What are the two classifications of ribosomes?
“free” and “memebrane-bound”
What do “free” ribosomes do?
Float inside cell cytoplasm (cytosol) and make proteins to be used specifically inside the cell.
Another word for cytoplasm is _______
cytosol
What do “membrane-bound” ribosomes do?
They occur in the rough sarcoplasmic reticulum, making proteins needed within the plasma membrane.
What is the rough sarcoplasmic reticulum?
A specific type of endoplasmic reticulum that is located around and along the entire length of the myofibril components as a point of “deposit” for proteins
What are ribosomes?
the “assembly line” that actually builds and repairs the contractile proteins, actin and myosin, in the damaged myofibrils, using available intracellular amino acids, resulting in growth of tissues.
What are contractile proteins?
actin and myosin
What are myofibrils?
contractile components that allow for strength and performance of the muscles—composed of repeating sarcomeres that give skeletal muscle the striated look.
What protein filaments (myofilaments) are myofibrils made of?
actin and myosin
What creates different muscle types?
various arrangements of myofilaments
functional units of skeletal muscle occurring in repeating segments along the myofibril
sarcomeres
the “end caps” of the sarcomere, discs in between the I-bands, where actin is secured
Z-line
the area that contains the Z-line, where thin filaments, actin, are found
I-band
area where the entire length of a single thick filament, myosin, is found
A-band
section inside the A-band where the thick filament doesn’t mix with the thin filament; it contains only thick filament, myosin
H-zone
middle of the sarcomere, within the H-zone, where a cross bridge occurs between the myofilaments
M-line
Sliding filament theory
the muscle contractile process: cycle of thin filaments (actin) sliding over thick filaments (myosin), generating tension, thus shortening the length of the sarcomere which shortens the length of the muscle fiber, enabling contraction.
What do the proteins tropomyosin and troponin do?
regulate and control the interaction of actin and myosin
What does tropomyosin do?
Located in the groove of actin, acts as a blocking mechanism to the myosin-binding sites in actin.
How do nerve impulses work in relation to activating contraction?
nerve impulse creates a chain of reactions, releasing calcium ions from the sarcoplasmic reticulum (SR), which then transmit electrical impulses to “excite” the sarcolemmal membrane into releasing the calcium ions and activating the contraction.
What is the sarcoplasmic reticulum (SR)?
system of tubules, surrounding each myofibril; releases calcium ions during muscle contraction, and absorbs them during relaxation.
What is calcium’s role in muscle contraction?
Calcium binds to troponin and changes the position of tropomyosin-troponin in the actin filament—leading to contraction. When calcium level diminish, toponin-tropomyosin shift back and block the myosin-binding sites.
Heavy, intense, low rep resistance training (that is too frequent) has its primary effect on actin and myosin in the myofibril.
Is this damage sufficient to stimulate adaptation and complete repair?
No
What is the process where actin and myosin are repaired?
hypertrophic protein synthesis
What is the key to myofibril gowth?
“controlled” damage (exercise) and repair (recovery) of the actin and myosin
What is hypertorphy?
Body repairing and adding girth to muscle fiber to prepare for future demand of that muscle.
the “powerhouse” of the cell; organelles inside a cell that work to produce the energy needed for daily activity and recovery—providing cell respiration and energy production
mitochondria
What is atrophy?
When a fiber will shrink as the result of it getting no use.
the number of mitochondria in a cell depends on ________
the need for energy in the particular organ or tissue within they are working
the muscle fibers’ cell membrane where myofibrils are contained
sarcolemma
gelatinous viscous material that fill the sarcolemma
sarcoplasm
Mitochondria in skeletal muscle is found within the _____
sarcoplasm
What is the primary function of the mitochondria in skeletal muscle?
To produce aerobic (oxygen dependent) energy in the form of ATP (adenosine triphosphate).
What is ATP used for?
contraction at the actin-myosin cross bridge—a continuously recycled molecule that transports chemical energy within cells for metabolim.
Low intensity, long duration cardio training helps mitochondria be more efficient at burning _________
fatty acids for ATP
the chemical reactions that are required for maintaining a living state of cells in a organism.
Metabolism
Regular and intense high rep training causes the cell to adapt and build more ______
mitochondria
Building more mitochondria also boosts ________ production and the capacity to save ________
ATP; glycogen
substance deposited in bodily tissue as a store of carbs in the muscle when needed.
glycogen
