Muscle quiz Flashcards
What is myology?
The study of muscles
What are the 3 types of muscle?
Smooth, skeletal, and cardiac
How many skeletal muscles are there in the human body?
669
All skeletal muscles are attached to…
The skeleton
What 4 things does each skeletal muscle have?
- Own blood supply
- Own nerve supply
- Place where they start
- Place where they end
Skeletal muscle is also called…
Striated
Many nuclei are found below the sarcoplasm. So skeletal muscles are…
Multinucleated
What are the 6 functions of muscles?
- Movement
- Stability
- Control of body passages and openings
- Thermogenesis
- Hormone secretion
- Glycemic control
What is the movement function of muscles?
Muscles enable us to move from place to place and to move individual body parts.
They move body contents in the course of breathing, blood circulation, feeding and digestion, urination, and childbirth; and they serve various roles in communication – speech, writing, facial expression, and other body language.
What is the stability function of muscles?
Muscles maintain posture by preventing unwanted movements.
Some are called antigravity muscles because, at least part of the time, they resist the pull of gravity and prevent us from falling or slumping over. Many muscles also stabilize the joints by maintaining tension on tendons and bones.
What is the control of body passages and openings in muscles?
Muscles encircling the mouth serve not only for speech but also for food intake and retention of food while chewing. In the eyelid and pupil, they regulate the admission of light to the eye. Internal muscle rings control the movement of food, bile, blood, and other materials within the body. Muscles encircling the urethra and anus control the elimination of waste. (Some of these muscles are called sphincters, but not all).
What is the thermogenesis function of muscles?
The skeletal muscles produce 20% to 30% of the body’s heat at rest and up to 85% during exercise.
This body heat is vital to the functioning of enzymes and therefore to all metabolism. When it is lacking, people die of hypothermia.
What is the hormone secretion function of muscles?
Exercised muscles secrete hormones (myokines) that stimulate glucose synthesis by the liver and breakdown of visceral (body-cavity) fat.
What is the glycemic control function of muscles?
The regulation of blood glucose concentration within its normal range.
The skeletal muscles absorb, store, and use a large share of one’s glucose and play a highly significant role in stabilizing its blood concentration. In old age, in obesity, and when muscles become deconditioned and weakened, people suffer and increased risk of type 2 diabetes mellitus because of the decline in this glucose-buffering function.
What is peristalsis?
How food is moved through the body from the esophagus to the anus.
Peristalsis in the digestive tract begins in the esophagus. After food is swallowed, it is moved down the esophagus by peristalsis. The muscles in the stomach, small intestine, and large intestine continue the process. Food is further digested and broken down as it moves through the digestive tract, aided by digestive juices that are added along the way. Bile, which is an important part of the digestive process, is produced in the gallbladder and is moved from the gallbladder into the duodenum (a section of the small intestine) via peristalsis. At the end of its journey through the body via peristalsis, the digested food is excreted through the anus as stool.
What is the belly (body) of the muscle?
The “belly” of the muscle is typically the largest or thickest portion of the muscle.
What is the origin of the muscle?
The place where the muscle starts; usually stationary.
What is the insertion of the muscle?
The place where the muscle ends. Moves towards the origin when the muscle contracts; this is called actin.
What is actin? What does it do?
A contractile protein. It does the work of contraction along with myosin.
What is muscle electrical excitability?
Responsiveness; they respond to electrical signals.
What is muscle contractibility?
Muscle fibers shorten in length when contracted.
What is muscle extensibility?
Capable of being stretched between contractions.
What is muscle elasticity?
Muscle returns to its original rest length after being stretched.
What is epimysium?
A connective tissue that covers the entire skeletal muscle.
What is perimysium?
A connective tissue that bundles muscle fibers into fascicles.
What is endomysium?
A connective tissue that surrounds each muscle fiber.
What is a tendon?
A strip of collagenous tissue attaching muscle to bone.
What is a tendon sheath?
An elongated cylindrical bursa wrapped around a tendon; abundant in hand and foot
What is aponeurosis?
A broad, flat sheet of tendon-like material that anchors a muscle or connects it with the part that the muscle moves.
What is sarcolemma?
The plasma membrane of a muscle fiber.
What are myofibrils?
Rod-like long protein cords occupying ¾ of the sarcoplasm.
What drives muscle contraction and relaxation?
Myofibrils
What are myofibrils composed of?
Muscle filaments or myofilaments.
What is the glycogen component of muscle fiber?
Carbohydrate stored to provide energy for exercise.
What is the myoglobin component of muscle fiber?
Red pigment, provides some oxygen needed for muscle activity.
What are transverse T tubules?
Tubular infoldings of the sarcolemma which penetrate through the cell.
Why are transverse T tubules needed?
So electrical signals can pass through the muscle.
What is sarcoplasm?
The cytoplasm of a muscle fiber.
What is sarcoplasmic reticulum (SR)?
Smooth endoplasmic reticulum that forms a network around each myofibril.
What does sarco- mean?
Flesh
What is a triad??
It is a 3 element complex consisting of 2 terminal cisterns and a T tubule in the middle.
Where are triads located?
At the junction of the A band and I band.
What does myo- or mys- mean?
Little mouse
What are terminal cisterns?
They are dilated ends sacs that store and release calcium. Portions of the sarcoplasmic reticulum which are adjacent to the T tubules.
What are muscle fiber nuclei?
Muscle fibers have numerous sausage-shaped nuclei pressed against the inside of the sarcolemma.
What are mitochondria in the muscle?
Mitochondria convert nutrients into the molecule ATP, which stores energy.
Muscle has a high demand for ATP and therefore possesses an exceptionally large number of mitochondria wedged in between the myofibrils. Mitochondria near the sarcolemma have the typical bean shape seen in many other cells, but deep inside the muscle fiber, they form a more dynamic, ever-changing tubular network influenced by exercise.
In what order are skeletal muscles organized?
- Skeletal muscle
- Fasciculus
- Fiber
- Myofibrils
- Myofilaments
- Thick myofilaments called myosin, Thin myofilaments called actin.
What are skeletal muscles?
Skeletal muscles are voluntary, striated muscle usually attached to bones.
What are fascicles?
Bundles of muscle fibers.
How many fascicles make up 1 muscle fiber?
100’s to 1000’s of bundles make up 1 muscle fiber
What are muscle fibers?
Skeletal muscle cells are called fibers because they are long and cylindrical.
What are muscle fibers filled with?
Rod-like bands called striations
How much of the muscle fiber is filled with striations?
3/4 of the muscle fiber
What is the sarcomere?
A segment from Z disc to Z disc; functional contractile unit of muscle fiber.
What is the distance between the 2 Z disc/Z lines?
2 micrometers
What is the functional contractile unit of muscle fiber?
Sarcomere
What is the structural and functional unit of a skeletal muscle?
Sarcomere
What are the 3 components of thin filaments?
They are composed of 3 different protein types: filament F actin, tropomyosin, and troponin.
What is the thickness of thin filaments?
8 nanometers
What do thin filaments look like?
Look like 2 strings of beads intertwined.
What is each string of beads in a thin filament called?
Filament F actin
What are thick filaments made of?
Made of several hundred myosin molecules.
What is the thickness of thick filaments?
16 nanometers
What are thick filaments?
A-band myofibrils.
How many myosin make up 1 thick filament?
300
What are the 5 structures of thin filaments?
- Actin
- Myosin-binding site
- Troponin
- Calcium-binding site
- Tropomyosin
What is the actin of thin filaments?
Fibrous f actin are 2 intertwined strands of globular (g) actin subunits, each with an active site that can bind to the head of a myosin molecule.
What is the myosin-binding site of thin filaments?
Each G actin has an active site that can bind to the head of a myosin molecule.
What is troponin of thin filaments?
Small calcium-binding protein on each tropomyosin molecule.
What is the calcium-binding site of thin filaments?
What is tropomyosin of thin filaments?
Each blocks 6 or 7 active sites on G actin subunits and prevents myosin from binding to them.
What does tropomyosin look like?
Looks like the string through a string of beads.
What are troponin and tropomyosin called? Why?
Regulatory proteins because, together, they act like a switch to determine when the fiber can contract and when it can’t.
What are the 4 structures of thick filaments?
- Myosin
- Myosin heads
- ATP binding-site
- Myosin tails
What is myosin in thick filaments?
It’s a motor protein that has globular heads of ATPase that bind to actin molecules.
What does myosin look like?
One myosin molecule looks like 2 golf clubs: 2 chains intertwined to form a shaft-like tail and a double globular head.
What are the myosin heads?
The heads can be found in either energized or non-energized forms. The heads become energized through the binding and hydrolysis of ATP, which includes conformational change, energizing it and preparing it for muscle contraction.
What must myosin heads have bound to them?
An ATP molecule
What is the ATP binding site of thick filaments?
Myosin ATPase, an enzyme in the head, hydrolyzes this ATP into ADP and phosphate. The energy released by this process activates the head, which “cocks” into an extended, high-energy position.
What are myosin tails?
What are striations?
Alternating A-bands (dark) and I-bands (light).
What is an A-band?
A dark band
Where is the darkest part of an A-band?
Where thick filaments overlap a hexagonal array of thin filaments
What is an H-band? Where are they located?
The middle of an A-band. It’s not as dark. In thick filaments only.
What is an M-band?
A dark, transverse protein in the middle of an H-band
What is an I-band?
A light band
What is a Z disc/Z line?
Protein complex that provides anchorage for thin filaments and elastic filaments.
