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The
Muscular
System
1. How did the term “MUSCLE” come into being?
Because flexing muscle look like mice scurrying beneath the skin, some scientist dubbed them “muscles” – Latin for “little mouse”.
2. What is the essential function of muscle?
Muscle will contract or shorten.
As a result of this, muscle is responsible for all movement.
3. How are all muscle tissue alike?
3
-1 All muscle cells are elongated , thus called MUSCLE FIBERS.
-2 All muscles will contract!
-3 Similar terminology!
Myo- or Mys = Muscle
Sarco = flesh
Question # 4 is a duplicate question!
Delete.
5. List three different types of muscle tissue:
-1 SKELETAL
-2 SMOOTH
-3 CARDIAC
6. Explain what is meant by “striated” muscle:
The muscle fibers appear to be striped.
7. Answer the following questions regarding skeletal muscle.
Body Location
Attached to bones.
Cell shape and appearance:
Single, very long, multinucleate cells with obvious striation.
Regulation of contractions.
Voluntary; via nervous system control.
Speed of contraction
Slow to fast
Rhythmic Contraction?
NO
Sketch of Skeletal muscle fiber.
8. Since Muscle tissue is extremely delicate, what keeps it from snapping into as it exerts such tremendous force?
Thousands of their fibers are bundled together by connective tissue, which provides strength and support to the muscle as a whole.
9. What is a fascile?
A bundle of muscle fibers
10. Explain the various connective tissue wrappings of skeletal muscle:
ENDOMYSIUM
A delicate connective sheath that is wrapped around each individual muscle fiber.
Perimysium:
Coarse fibrous membrane wrapped around a fascile.
Epimysium
Tough overcoat of connective tissue surrounding the entire muscle. Tendon
BONE
11. Compare and contrast tendons and the aponeuroses:
Compare: Both attach muscle to bone
Contrast:Tendon is a strong cord, the aponeuroses are sheet like tissue.
12. List the three ways that muscle fibers may be arranged:
-1 Spindle shaped.
-2 Fan pattern
-3 A circle
13. Answer the following questions regarding Smooth muscle.
Body LocationTypically in walls of hollow visceral organs.
Cell shape and appearance:
Single, fusiform, one nucleus; no striations
Regulation of contractions.
Involuntary; nervous system controls; hormones, chemicals,
stretch.
Speed of contraction
Very slow, but consistant!
Rhythmic Contraction?
Yes, in some
Sketch of Smooth muscle fiber.
nucleus
14a. Explain the “two-layer” arrangement of smooth muscle.
1 circular layer of muscle
+
1 longitudinal layer
14b. Explain how the body used this “two-layer” arrangement of smooth muscle:
As the two layers alternately contract and
relax, they change the size and shape of the
organ. Page 1 of 2
Slow and steady!
Alternate contractions push food through the digestive tract, urine through urinary system, and blood through veins.
15. Compare the muscular contractions of the smooth muscle to the contractions of the skeletal muscle:
Skeletal muscle is like a speedy windup car that quickly runs down; but smooth muscle is like a heavy-duty engine that runs SLOW BUT STEADY.
16. Answer the following questions regarding Cardiac Muscle.
Body Location
Walls of the heart.
Cell shape and appearance:
Branching chains of cells; one nucleus; complex striations.
Regulation of contractions.
Involuntary; the heart has a pacemaker; also nervous system controls; hormones
Speed of contraction
Slow!
Rhythmic Contraction?
yes
Sketch of Cardiac muscle fiber.
16. How are the muscle fibers arranged that make up the heart?
Cardiac muscle bundles are wrapped in a spiral arrangement for added strength.
17. Explain how muscles are involved in producing movement.
-1 Skeletal muscles contract and pull the bones.
-2 Smooth muscles contract and force items through the smooth muscles.
.-3 Muscles work in Antagonistic pairs!
One muscle contracts and pulls the bone one way, then its partner will contract and pull the bone the opposite way.
18. Explain how the muscles are involved in maintaining posture:
The skeletal muscles function almost continuously, making one tiny adjustment after another so that we can maintain an erect posture despite the never-ending pull of gravity.
19. Explain how the muscles are involved in stabilizing joints:
As the skeletal muscles pull on bones to cause movement, they stabilize the joints of the skeleton.
20. Explain how the muscles are involved in generating body heat:
When muscles contract, ¾ of its energy escapes as heat. This heat is vital in maintaining normal body temperature.
Begin Day #2
21. What is a sarcomere?
A single contraction unit in muscle.
22. What is a myofibril>
A muscle fiber
23. Differentiate the two kinds of filaments that make up a myofibril:
is a thin filament composed ob two beaded strains twisted together.
is thick with a bulbous head and a tail.
24. Explain the sliding – filament model of muscle contraction:
a) Each sarcomere consist of two sets of actin filaments that are attached at each end of the sarcomere.
b) In between the attached actin filaments is a single unattached myocin filament.
c) Fiber tow-chains called “Cross bridges” shoot out from the myosin and anchor on to the actin filaments.
d) As the myosin contracts, it tows along the actin which shortens the muscle fiber. After contraction, the cross bridges release.
25. Discuss the control pathway of muscular contraction:
The nervous system sends a signal to the muscle.
At the neuromuscular junction, acetylcholine
Causes the release of calcium ions which causes an action potential in the muscle.
26. Explain the control mechanism of muscular contraction:
a) When the muscle is at rest, the actin binding sites are blocked and myosin cannot form cross bridges with them.
b) The release of calcium ions clears the binding sites – so the contraction proceeds;
c) Afterwards, calcium ions are actively transported back into the membrane storage system.
27. Where does the energy come from for contraction?
a)Short Intense contraction:
Creatine phosphate used to recreate ATP from ADP.
b) Moderate contraction:
ATP created from electron transport phosphorylation.
c) Intense, Prolonged Contraction:
Anaerobic fermentation occurs. Small amounts of ATP released. SORE muscles result from LACTIC ACID buildup.
28. What is the relationship between muscle tension and contraction?
a) The cross-bridges tht form during contraction exert muscle tension.
b) When muscle tension is greater than the force opposing it – contraction occurs. (muscles shorten)
When the opposing force is greater – muscles lengthen and contraction stops.
29. List three things that determine muscle strength:
A.
MUSCLE
SIZE
B.
Number of muscle cells contracting.
c.
The speed at which the nervous system is stimulating the
muscle cells.
30. What is meant by a motor unit?
A motor neuron and the muscle cells under its
control.
31.
Differentiate a TWITCH and TETANUS:
A BRIEF contraction caused by a single brief
stimulus is a muscle TWITCH.
Rapid, Continuous, repeated stimulation that will NOT let go is
TETANUS.
32. What causes Muscle Fatique?
“Continuous high frequency stimulation”
33. Discuss the differences in recovery time necessary from
muscle fatigue:
a. BRIEF INTENSE EXERCISE:
RECOVER QUICKLY!
b. Prolonged, moderate exercise
Recovery much more slowly.
33. List the 5 Golden Rules of skeletal muscle
activity:
1.All muscles cross at least one joint.
2.Typically, the bulk of the muscle lies proximal to the joint crossed.
3. All muscles have at least two attachments:
The origin and the
insertion.
4. Muscles can only pull; they never push.
5. During contraction, the muscle insertion moves toward the origin.
33. Differentiate the muscular
POINT OF ORIGIN and the
POINT OF INSERTION.
Point of origin =
Attachment to immovable
bone.
Insertion:
Attachment to bone that will move!
34. Identify the following common body movements
DELETE
35. Define the following types of
muscle:
Prime MoverThe one muscle within a group of muscles that does most of the work
during a common movement.
SynergistMuscles that either pull with the prime mover, or reduces
unnecessary movement
FixatorThey hold a bone still or stabilize the origin for a prime mover.
36. Explain how muscles are
named:
a)Direction of the muscle fiber:
Rectus = muscle is straight up and down.
Oblique = slanted muscle
b)Size of the muscle:
Maximus = largest
Minimus = smallest
Longus = long
c) Location of the muscle:
Some muscles are named for the bones they are associated with.
d)Number of Origins
Biceps = two points of origin!
Triceps = three points of origin
Quadriceps?
Four points of origin!
e) Location of the muscle’s origin and insertion:
Occasionally, muscles are named after both their attachment sites.
sternocleidomastoidOrigin
Sternum
Clavicle
Insertion:
Mastoid process of
the temporal
bone
f) Shape of the muscle:
Some muscles have a distinctive shape!
Ex. Deltoid = triangular
g) Action of the muscle
When muscles are named for their action, their name refers to the type of movement they cause.
“Straightens forearm at elbow.”
“Draws the arm forward and in toward body”
“Draws shoulder blade forward, helps riase arm, assist in pushes”
“Compresses the Abdomen, permits lateral rotation”
“Depresses the chest cavity, compresses the abdomen, and bends the backbone”
“Bends the thigh at hip and bends lower leg at knee; rotates the thigh in outward direction”
“Flexes, laterally rotates, and draws thigh toward body”
“Flexes the thigh at the hip; extends the leg at knee”
“Flexes the foot toward the shin”
“Bends the forearm at the elbow”
“Raises the Arm”
“Lifts the shoulder blade and braces the shoulder; draws the head back”
“Rotates, and draws arm backward and toward body”
“Extends and rotates thigh outward when walking, running, and climbing.”
“(hamstring) draws the thigh backward or bends the knee”
“Bends lower leg at the knee when walking; extends the foot when jumping.
