Muscle Tissue Flashcards
What are the three types of muscle tissues?
Skeletal
Cardiac
Smooth
Alternating light and dark bands seen under the microscope and which muscles are these?
Striated
Skeletal
Cardiac
Are skeletal muscles voluntary or involuntary?
Voluntary
- Under conscious control (although many are also controlled subconsciously)
Are cardiac muscles voluntary or involuntary?
Involuntary
- not under conscious control
Where are smooth muscles located?
Blood vessels
Airways
Abdominopelvic organs
Does not exhibit alternating light and dark bands when viewed under the microscope and which muscle has this?
Non- striated
Smooth
Are smooth muscles voluntary or involuntary?
Involuntary
What are the muscle tissue functions?
- Producing body movements
- Stabilizing body positions
- Storing and moving substances within the body
- Generating heat (thermogenesis)
Properties of muscle tissue
- Electrical excitability (carry and respond to APs)
- Contractility (stimulated by AP)
- Extensibility (stretch w/o being damaged)
- Elasticity (return to original shape)
What is a single cell muscle?
Fiber (myofiber)
Bundle of muscle fibers (cells)
Fascicle
An organelle in a muscle fiber composed of filaments
Myofibril
Fibrous protein molecules within myofibrils (the thick and think filaments that are the contractile proteins)
Filaments
What surrounds a fiber?
Endomysium
What surrounds a fascicle?
Perimysium
What surrounds the entire muscle?
Epimysium
What is a broad flat tendon and what blends together to make them?
Aponeurosis
Endomysium
Perimysium
Epimysium
Which nerve cell supplies a group of muscle fibers?
Somatic Motor Neuron
How many neurons supply each muscle fiber?
Only one
Where does the neuron contact the muscle fiber?
Neuromuscular junction
What are skeletal muscles well supplied with and what accompanies it?
Nerves and Blood vessels
An artery and one or two veins usually accompany each nerve
Each muscle fiber is in close contact with one or more capillaries. What do these do?
- Provide nutrients and oxygen
- Remove heat and waste products of muscle metabolism
What happens to form one skeletal muscle fiber during embryonic development?
Myoblasts fuse
- this is why skeletal muscle fibers are multinucleate
The plasma membrane of a muscle fiber and enclosed the sarcoplasm and myofibrils
Sarcolemma
Just inside the sarcolemma (numerous)
Nuclei
The cytoplasm of a muscle fiber
Sarcoplasm
Bundles of filaments that are the contractile elements of the cell (striated appearance)
Myofibrils
Opening from the outside of the fiber toward the interior of the fiber
T-tubules (transverse tubules)
- propagate APs
- filled with interstitial fluid
Stores calcium ions and releases them when the muscle fiber is stimulated
Sarcoplasmic reticulum
Dilated regions that flank T-tubules
Terminal cisterns
What are two terminal cisterns flanking one T- tubule
Triad
Myofibrils are made of smaller structures called filaments. What are the two types and what proteins do they have?
Thin
- Actin: contractile proteins
- Troponin: regulatory protein
- Tropomyosin: regulatory protein
Thick
- Myosin: contractile protein
How many thin filaments to thick filaments are there?
Two think filaments for every thick filament
Filaments inside the myofibrils are arranged in carport nets called?
Sarcomeres
What is a long chain of sarcomeres?
Myofibril
Thick and think filaments overlap to a varying degree depending on what?
The contraction state of the muscle
In the sarcomeres thin and thick filaments overlap to a degree causing….
Z discs A band I band H zone M line
Where adjacent sarcomeres abut; center of an I band
Z discs
Darker zone, which comprises the length of the thick filaments and a varying overlap of thin filaments
A band
Only thin filaments
I band
Center of an A band; only thick filaments
H zone
Midline of a sarcomere
M line
The heads (cross bridges) of the myosin molecules do what?
- Bind and hydrolyze ATP (myosin ATPhase); also bind products of ATP hydrolysis (ADP and phosphate)
- Change shape ( move toward or away from M line)
- Bind reversibly
In the thin filament each individual actin molecule has?
A myosin- binding site