Muscular System Flashcards
Muscle tissue makes up ___% to ___% of body weight.
40
50
The word muscle comes from the Latin word mus, meaning “little mouse.”
As muscles contract, the muscle movements under the skin resemble the movement of mice scurrying around - thus the name mus, or muscle.
What enables the body to move about by pulling on underlying bones?
Muscle
What propels body contents such as air, blood, and food to move?
Muscle
What maintains the stability of joints, thereby contributing to the flexibility of the skeletal system?
Muscle
What contraction generates heat, thereby contributing significantly to body temperature?
Muscle
What contributes to the ability to communicate through speaking, writing, facial expressions, and other nonverbal means?
Muscle
What are the three muscle types?
Skeletal
Smooth
Cardiac
Which muscle type is generally attached to bone?
Skeletal
What is another name for skeletal muscle?
Voluntary
Because it can be controlled by choice (choosing to move an arm).
Which muscle cells are long, shaped like cylinders or tubes, and composed of proteins arranged to make the muscle appear striped, or striated?
Skeletal
Which muscle type produce movement, maintain body posture, and stabilize joints?
Skeletal
Which muscle type produces considerable heat and therefore helps maintain body temperature?
Skeletal
Which muscle type has limited capacity for regeneration if damaged?
Skeletal
Smooth muscle is generally found in the walls of the viscera, such as the stomach, and is called ___ muscle.
visceral
Which muscle type is found in tubes and passageways such as the bronchioles (breathing passages) and blood vessels?
Smooth
Because smooth muscle functions automatically, it is called ___ muscle.
involuntary
Unlike skeletal muscles, smooth muscle does not appear striped, or striated, and is therefore called ___ muscle.
nonstriated
Smooth muscle contraction is ___ and continues for a ___ period.
This characteristic allows for a continuous partial contraction of the smooth muscle, called smooth muscle ___.
slower
longer
tone
Which smooth muscle characteristic plays an important role physiologically?
Tone
Which smooth muscle characteristic in blood vessels helps maintain blood pressure?
Tone
If the muscle tone were to decrease, the person might experience a life-threatening decline in blood pressure.
Smooth muscle has a greater degree of ___ as compared with skeletal muscle.
stretchiness
Which smooth muscle characteristic allows the walls of organs such as the uterus, urinary bladder, and stomach to expand to store their contents temporarily?
Stretchiness
___ of the smooth muscle of the organ then expels its content.
Contraction
For example, the urinary bladder expands to store urine.
When the bladder fills, the smooth muscle of the urinary bladder contracts, thereby expelling the urine.
Similarly, contraction of the smooth muscles of the stomach mixes solid food into a paste and then pushes it forward into the intestine.
Which muscle type has a decent capacity for regeneration if injured?
Smooth
Which muscle type is found only in the heart, where it functions to pump blood throughout the body?
Cardiac
Which muscle cells are long branching cells that fit together tightly at junctions called intercalated discs?
Cardiac
Which disks promote rapid conduction of electrical signals throughout the heart?
Intercalated
Which muscle type is classified as striated and involuntary?
Cardiac
Which muscle type has no capacity for regeneration if damaged?
Capacity
Heart Attack
Three Types of Muscle
If you touch your anterior thigh, you will feel a large muscle.
What you are actually feeling are thousands of elongated muscle ___ (cells), ___ ___, and ___ that are packaged together by various layers of connective tissue.
fibers
blood vessels
nerves
What are the tough connective tissue layers that surround the large skeletal muscle?
Fascia
What is the outer layer of fascia?
Epimysium
Which connective tissue layer surrounds smaller bundles of muscle fibers?
Perimysium
What are the bundles of muscle fibers?
Fascicles
Individual muscle fibers are found within the fascicles and are surrounded by a third layer of connective tissue called the ___.
endomysium
The ___, ___, and ___extend toward and attach to the bone as a tendon, a long cordlike structure.
epimysium
perimysium
endomysium
What separates the muscles into isolated sections or compartment in the limbs (an extensive amount)?
Fascia
Muscles form attachments to other structures in three ways:
1) ___ attach the muscle to the bone.
2) ___ attach directly (without a tendon) to a bone or soft tissue.
3) a flat sheetlike fascia called ___ connects muscle to muscle or muscle to bone.
tendons
muscles
aponeurosis
The muscle cell is an elongated muscle ___.
fiber
What long cylindrical structures compose each muscle fiber?
Myofibrils
What muscle membrane surrounds the muscle fiber?
Sarcolemma
What does the cell membrane sarcolemma form when penetrating deep into the interior muscle fiber at several points?
Transverse Tubules (T Tubules)
What is the specialized endoplasmic reticulum (ER) within the muscle fiber and surrounding the myofibrils?
Sarcoplasmic Reticulum (SR)
What envelope-like structure is the storage site of calcium (Ca2+) in the unstimulated muscle?
Sarcoplasmic Reticulum (SR)
What contractile unit makes up each myofibril in series?
Sarcomeres
Each ___ extends from Z line to Z line and is formed by a unique arrangement of contractile proteins, referred to as thin and thick ___.
sarcomere
filaments
Which filaments extend toward the center of the sarcomere from the Z lines?
Thin
Which filament is composed of the proteins actin and troponin–tropomyosin complex?
Thin
What contains binding sites for the myosin?
Actin
Troponin–Tropomyosin
The ___ myosin filaments sit between the ___ filaments.
thick
thin
Extending from the thick myosin filaments are structures called myosin ___.
heads
The arrangement of the thin and thick filaments in each sarcomere gives skeletal and cardiac muscle their ___ appearances.
striated
The sliding filament mechanism describes how muscle ___.
To pull, muscles ___.
When muscles ___, they shorten.
contract x 3
Muscles shorten because the___ length shortens, and the ___ length shortens because the thin and thick filaments slide past each other.
sarcomere x 2
The following statements explain how the sarcomere shortens:
When the contractile apparatus is stimulated, the sarcomere is flooded with ___. This enables the myosin ___ to make contact with special sites on the ___, forming temporary connections called ___-___.
calcium
heads
actin
cross-bridges
Once the ___-___ are formed, the myosin ___ rotate, pulling the ___ toward the center of the sarcomere.
cross-bridges
heads
actin
The rotation of the myosin ___ causes the thin filaments to slide past the thick filaments and sarcomere length ___.
heads
shortens
Muscle ___ occurs when the ___-___ are broken, and the thin and thick filaments return to their original positions; the sarcomere ___.
relaxation
cross-bridges
lengthens
Because of this sliding activity of the thin and thick filaments, muscle contraction is called the sliding ___ mechanism of muscle contraction.
filament
___ length shortens not because the thin and thick filaments shrink or shrivel up, but because they slide past one another.
Sarcomere
The sliding is like a trombone. The trombone shortens because the parts slide past one another, not because the metal shrinks. The thin and thick filaments do the same thing - they slide.
Muscle Structure
Relaxed State
calcium
Innervation of a Skeletal Muscle
A) Motor Unit
B) The Four Steps in the Transmission of the Signal at the Neuromuscular Junction (NMJ)
