Chapter 10 - Muscles & Muscle Tissue

Question 1

Skeletal muscle

Answer 1

voluntary, striated muscle attached to & covering skeleton; most abundant type; function: to move bones; length of muscle = length of cell; involved in reflexes–fastest contraction & w/greatest force; downside-gets tired easily;
cells = long, thick, straight cells; striped

Question 2

Cardiac muscle

Answer 2

involuntary, striated muscle in the heart wall; not as long as skeletal; interconnected & branched; can contract by itself–only tissue that does this; steady rate of contraction–rhythmic

Question 3

Smooth muscle

Answer 3

involuntary, nonstriated muscle in the hollow visceral organs (except heart & blood vessels); not as long as skeletal muscle tissue; (ex. stomach, intestines, bladder, uterus, blood vessels); slowest rate of contraction–doesn’t tire out

Question 4

4 Characteristics of Muscle tissue

Answer 4

1. Excitability or Irritability
2. Contractility
3. Extensibility
4. Elasticity

Question 5

Excitability or Irritability

Answer 5

ability to receive & respond to a stimulus

Question 6

Contractility

Answer 6

ability to shorten

Question 7

Extensibility

Answer 7

ability to be extended or stretched

Question 8

Elasticity

Answer 8

can recoil after being stretched & return to original resting length

Question 9

Muscle fiber

Answer 9

muscle cells

Question 10

Fascicles

Answer 10

bundles of muscle fibers

Question 11

Gross anatomy of a muscle (3 CT coverings)

Answer 11

consists of many skeletal fibers; continuous; connected to each other @ the ends

1. Endomysium
2. Perimysium
3. Epimysium

Question 12

Endomysium

Answer 12

CT sheath which surrounds each muscle fiber

Question 13

Perimysium

Answer 13

CT sheath which covers each fascicle

Question 14

Epimysium

Answer 14

CT sheath which surrounds the entire muscle

Question 15

Insertion

Answer 15

site of attachment of muscle to a movable bone

Question 16

Origin

Answer 16

site of attachment of muscle to an immovable or less movable bone; always proximal to insertion

Question 17

2 Main types of muscle attachment

Answer 17

1. Tendons - rope-like attachments to bone; most common attachment of muscle to bone; dense regular CT; collagen fibers
2. Aponeuroses - flat sheet-like attachments of muscle to other muscle or to bone; dense regular CT; abdominal muscles

Question 18

Muscle Actions

Answer 18

usually work together to from opposite movements;

1. Flexor - muscle which decreases the angle of the joint
2. Extensor - muscle which increases the angle of the joint

Question 19

Sarcolemma

Answer 19

plasma membrane of muscle fibers; can carry electrical signals

Question 20

Sarcoplasm

Answer 20

cytoplasm of muscle fibers; includes cytosol, organelles & inclusions

Question 21

Myoglobin

Answer 21

muscle protein that binds oxygen

Question 22

Myofibrils

Answer 22

organelles in the sarcoplasm which contain contractile elements; structures that shorten (contract); consists of thick filaments & thin filaments;

Question 23

Sarcomeres

Answer 23

smallest contractile units in muscle fibers; length of a sarcomere is from Z disc to the next Z disc; repeating unit making up myofibril

Question 24

Thick filament

Answer 24

made of the structural protein myosin; darker region

Question 25

Thin filament

Answer 25

made of the structural protein actin, and 2 regulatory proteins (not actively involved in muscle contraction): tropomyosin & troponin; lighter region

Question 26

Sarcoplasmic reticulum

Answer 26

smooth ER of muscle fibers, stores Ca++ ions

Question 27

Terminal cisterns

Answer 27

end regions of the sarcoplasmic reticulum

Question 28

T tubule

Answer 28

sarcolemma which penetrates muscle cell interior; found between neighboring sarcoplasmic reticulum; made of same material as sarcolemma; electrical signals can go inside cell

Question 29

Triad

Answer 29

consists of a T tubule between 2 terminal cistern; 3 structures–terminal cisterns on either side & t-tubule

Question 30

Functions of Muscles

Answer 30

-Produces movement - of bones, blood, food digestion; applies to all 3 types of muscle tissue
The below 3 apply to Skeletal muscle tissue only:
-Maintains posture
-Stabilizes joints
-Generates heat - transforms chem energy (ATP) to mechanical energy & releases heat

Question 31

Skeletal muscles are organs

Answer 31

700 muscles; richly vascularized; have all 4 tissue types (CT, muscle tissue, epitheleal & smooth muscle tissue, nervous tissue); plus very specific function

Question 32

“myo”, “mys” & “sarco”

Answer 32

“muscle”

Question 33

Example of Flexor muscle

Answer 33

1. biceps - decreases elbow joint

2. hamstrings (knee) - bends knee

Question 34

Example of Extensor muscle

Answer 34

1. Triceps

2. Quadriceps - can’t bend knee; can only extend

Question 35

Microscopic anatomy of skeletal muscle fibers

Answer 35

long, thick cells; many, many nuclei (100s or 1,000s); 2nd longest cells in body–some over 1 foot long; nerve cells are the longest cells

Question 36

Embryonic development

Answer 36

100s of myoblasts line up to form one long skeletal muscle (cell): fusion of many myoblasts

Question 37

Special names given to structures inside cell

Answer 37

bc unusual

Question 38

Inclusions (in sarcoplasm)

Answer 38

stockpile of carbs & O2 built in & can quickly make ATP;

-glycogen granules & myoglobin

Question 39

Glycogen granules (inclusions)

Answer 39

polysaccharide (carb); stored nutrients right inside cell; allow it to have carbs right there; so not entirely dependable upon blood

Question 40

Interaction between thick & thin filaments

Answer 40

allows myofibrils to shorten; arrangements of thick & thin filaments give cell striated look

Question 41

Myosin

Answer 41

fibrous protein w/2 globular regions (myosin heads) @ end; q protein made of amino acids (myosin tail)–thin part

Question 42

Muscle contraction occurs when

Answer 42

myosin interacts w/actin

Question 43

Regulatory proteins (in thin filament)

Answer 43

block contraction or release muscle so it can contract;

• Troponin - binds calcium (trigger for muscle contraction)
• Tropomyosin - blocks binding sites on actin