Muscle Types Flashcards
What are the three types of muscle tissue?
Smooth, Cardiac & Skeletal
What are the properties of smooth muscle tissue?
Non-striated and contract involuntarily
Where is smooth muscle tissue found?
In the walls of internal organs
What are the properties of cardiac muscle tissue?
Striated and contract involuntarily
Where can cardiac muscle tissue be found?
In the walls of the heart
What are the properties of skeletal muscle tissue?
Striated and contract voluntarily
Where can skeletal muscle tissue be found?
Attached to the bones of the skeleton
What are the four main functions of skeletal muscles?
-They support the body
-Make bones move
-Maintain body temperature
-Help protect the internal organs and stabilize joints
Do skeletal muscles pull or push?
All skeletal muscles pull and cannot push
How do skeletal muscles work?
They work in antagonistic pairs which means they react opposite of each other. When one muscle contracts, the other will relax
What are skeletal muscles made of?
Bundles of muscle fibres made of myofilaments which are proteins
What are the two types of myofilaments?
Actin (thin filament) and Myosin (thick filament)
What are the properties of the myosin
They are protein molecules wound together and they have “heads that stick out”
Where does the myosin head attach to?
The actin filament
What is the sliding filament model?
As a muscle contracts, the actin “slides” past the myosin. This is known as the sliding filament model
What is the “Z line?”
A “Z” line is a striated muscle. When a muscle contracts, the actin moves along with it and the Z line also moves
What prevents myosin heads from binding to an actin when a muscle is relaxed?
A protein called tropomyosin
What is tropomyosin similar to?
A competitive inhibitor in an enzyme
How can the tropomyosin be moved to open up the binding site?
It can be moved by another protein called troponin which actives when bonded to calcium
What is the first step of the sliding filament theory?
A nerve impulse is sent from the central nervous system
What is the second step of the SFT?
Calcium ions are released from the sarcoplasmic reticulum and diffuse into the sarcoplasm
What is the third step of the SFT?
Calcium binds to troponin (a protein) and troponin moves tropomyosin off of the actin binding sites
What is the fourth step of the SFT?
Once troponin has cleared the binding sites, a myosin head attaches to the actin and pulls it to the centre of the sarcomere in a power stroke.
What is the fifth step of the SFT?
Myosin pulls the actin to shorten the muscle
What is the sixth step of the SFT?
Calcium is actively transported back to the sarcoplasmic reticulum
What is the seventh step of the SFT?
Tropomyosin goes back to block the binding sites and myosin releases
What is the final step of the SFT?
The muscle will either lengthen or relax
How does the power stroke gain energy?
From the hydrolysis of ATP
What are the skeletal muscle fibre types?
Slow, intermediate and fast
What are the qualities of the slow twitch muscle?
-They use aerobic cell resp
-They have lots of mitochondria and are red in colour
-Their rate of fatigue is slow
-They are used for endurance activities (marathons)
What are the qualities of the intermediate muscle?
-They use both aerobic and anaerobic cell resp
-They have a medium amount of mitochondria and are pink
-They fatigue at a medium rate
-They are used for activities that require bursts of power and endurance (hockey)
What are the qualities of the fast twitch muscle?
-They use anaerobic cell resp (lactic acid)
-They have very few mitochondria and are white
-They fatigue very quickly
-They are used for quick power activities (sprinting)
What are the 5 main pathologies (muscular system disorders?)
Fibromyalgia, Myositis, DOMS, hypertrophy, atrophy
What is fibromyalgia
A chronic disorder that causes muscle pain and tenderness with no known cause. Possible causes could be genetic or physical stress.
What is myositis?
A genetic disorder that causes extreme muscle fatigue, difficulty climbing stairs, raising arms etc. There is no cure and no way to prevent this.
What is DOMS?
Delayed Onset Muscle Soreness. This is caused by overworking a muscle during intense exercise. The soreness and pain tends to show up 1-2 days after exercise
What is hypertrophy?
A rare muscle condition that causes the size of muscles to increase. The actin and the myosin get bigger.
What is atrophy?
The thinning of muscle tissue over time that can cause one limb to be smaller than another and potentially end up handicapping an individual
What is a muscle twitch?
When a muscle is stimulated to a certain degree and contracts too quickly or “twitches”
