A & P: Ch. 9

Front 1

What are the 3 types of muscle? By what aspects do they differ?

Back 1

- skeletal, cardiac, & smooth

- microscopic anatomy, location, & how they are controlled by the nervous & endocrine system

Front 2

Skeletal Muscle Tissue

Back 2

- move bones of the skeleton
- striated & voluntary
- SNS (somatic nervous system); conscious

Front 3

Cardiac Muscle Tissue

Back 3

- only found in the heart & great vessels (enter/leave heart)
- striated & involuntary
- pacemaker cells, which initiate contraction
- auto-rhythmicity (built in rhythm)
- ANS (autonomic nervous system)
- several hormones & neurotransmitters can speed or slow heart rate

Front 4

Smooth Muscle Tissue

Back 4

- located in the walls of hollow internal structures
(i.e. blood vessels, airways, & most organs in abdominopelvic cavity)
- non-striated & involuntary
- ANS

Front 5

What are the 6 functions of skeletal muscle tissue?

Back 5

1. producing body movements
2. maintaining posture & body positions
3. stabilizing joints
4. generating heat
5. protect soft organs
6. guard openings

Front 6

Muscle Fiber

Back 6

- aka muscle cell
- long length
- many nuclei

Front 7

What are the connective tissue components of a skeletal muscle? (Gross Anatomy)

Back 7

- 3 layers of connective tissue protect & strengthen muscle
- all layers may extend beyond the muscle to form a tendon

1. endomysium
2. perimysium
3. epimysium

Front 8

Endomysium

Back 8

- layer of areolar connective tissue
- surrounds each individual muscle fiber

Front 9

Fasicle

Back 9

- b/w 10 and 100 muscle fibers bundled
- large enough to be seen w/ naked eye
- give meat its "grain"
- tear meat, separates into fasicles

Front 10

Perimysium

Back 10

- layer of dense irregular connective tissue
- surrounds each fasicle

Front 11

Epimysium

Back 11

- layer of dense irregular connective tissue
- surrounds a gross muscle (many fassicles bundled together)

Front 12

Muscle can be attached (origin/insertion) to bone either _______________ or via _____________ or _______________.

Back 12

1. directly
2. tendons
3. aponeuroses

Front 13

Tendon

Back 13

- cord of dense regular connective tissue
- composed of parallel bundles of collagen fibers
- attach @ the periosteum of a bone

Front 14

Aponeuroses

Back 14

- attachment; connective tissue elements that extend as a broad flat layer

Front 15

What penetrates a skeletal muscle for nerve & blood supply?

Back 15

- 1 artery
- 1 or 2 veins
- 1 nerve (axon extends from brain/spinal cord to a group of fibers)
- many capillaries (microscopic blood vessels; bring O2 & nutrients)

Front 16

What is the diameter of a muscle fiber?

Back 16

10 - 100 micrometers

Front 17

Why are the # of muscle cells set at birth for a lifetime?

Back 17

- during embryonic development, each muscle fiber arises from the fusion of a 100 or more myoblasts
- once fusion has occured, the muscle has lost its ability to undergo mitosis
- thus, hyperplasia (increase in # of fibers) is not possible

Front 18

Hypertrophy

Back 18

- enlargement of existing muscle fibers

Front 19

Why do a few myoblasts persist into adulthood?

Back 19

- maintain the ability to fuse w/ other myoblasts or w/ damaged muscle fibers

Front 20

Sarcolemma

Back 20

- plasma membrane of a muscle cell
- invaginates into the center of the cell in a series of T tubules

Front 21

Sarcoplasm

Back 21

- cytoplasm of a muscle cell
- stores glycogen and myoglobin (reddish protein)
[both help make energy available for contraction]

Front 22

Sarcoplasmic Reticulum

Back 22

- endoplasmic reticulum of a muscle cell
- stores calcium

Front 23

Myofibrils

Back 23

- small threads "stuffed" in sarcoplasm
- contractile organelles
- composed of protein filaments

Front 24

Sarcomere

Back 24

- functional unit of the myofibril
- contractile protein filaments, z discs, a bands, i bands, h zones, & m lines

Front 25

Muscle proteins include...?

Back 25

- 2 contractile proteins (mysoin and actin)
- 2 regulatory proteins (troponsin and tropomyosin)
- structural proteins (titan, myomesin, dystrophin)

Front 26

Rigor Mortis

Back 26

- after death, cellular membranes become leaky
- Ca+2 leak out of sarcoplasmic reticulum into the cytosol
- allow mysoin heads to bind to actin
- since ATP production ceases shortly after death, the cross bridges cannot detach

Front 27

What does the total force of a muscle contraction depend on?

Back 27

1. rate @ which nerve impulses arrive @ neurotransmitter junction
2. amount of muscle fiber stretch prior to contraction
3. nutrient & oxygen availability
4. # of muscle fibers contracting in unison

Front 28

Motor Unit

Back 28

Consist of:
- 1 somatic motor neuron
- all of the skeletal muscle fibers it stimulates
- all muscle fibers in a motor unit contract in unison

e.g. larnyx has 2 to 3 muscle fibers in motor unit
biceps have 2,000 to 3,000 muscle fibers

Front 29

Twitch Contraction

Back 29

- brief contraction of all muscle fibers in a motor unit
- response to a single action potential in the motor neuron
- can be recorded in a myogram

Front 30

What are the 3 parts of a twitch contraction?

Back 30

1. latent period (steps 1-8)
2. contraction period (9-10)
3. relaxation period (1-3 reset)

*know major events in each

Front 31

Wave Summation

Back 31

- when a 2nd stimulus occurs before a skeletal muscle has time to completely relax, the 2nd contraction will be stronger than the first

Front 32

Unfused Tetany

Back 32

- fiber stimulated @ a rate of 20 to 30 times per second

Front 33

Fused Tetany

Back 33

- fiber stimulated @ a rate of 80 to 100 times per second

Front 34

Motor Unit Recruitment

Back 34

- weakest units are recruited first
- progressively stronger motor units added if the task requires more force
- delays muscle fatigue and allows sustained contraction of gross muscle

Front 35

What is muscle tone?

Back 35

- small amount of tautness or tension in the muscle
- due to weak, involuntary contractions of motor units
- even at rest, skeletal muscles exhibits muscle tone

Front 36

What is an isotonic contraction?

Back 36

- tension developed by the muscle remains almost constant while the muscle changes its length

Front 37

What is an isometric contraction?

Back 37

- tension generated is not enough to exceed the resistance of the object to be moved
- muscle does not change length

Front 38

What is the length-tension relationship in muscle contraction?

Back 38

- when the sarcomeres are too short (not stretched), little or no force is generated b/c the filaments have already slid to the M line (e.g. 1.8 um)
- when the sarcomeres are too long (over stretched), the thick and thin filaments are no longer overlapping & crossbridges cannot form; no force is generated (e.g. 3.8 um)
- when sarcomeres are at an optimum length, muscle contraction produces the strongest tension and force (e.g. 2.2 um)

Front 39

What are the three ways muscle fibers have to produce ATP?

Back 39

1. creatine phosphate
2. anaerobic cellular respiration
3. aerobic cellular respiration

Front 40

What is muscle fatigue?

Back 40

- the inability of a muscle to maintain force of contraction after prolonged activity

Factors:
1. inadequate release of Ca+2 from the SR
2. depletion of creatine phosphate
3. insufficient O2
4. depletion of glycogen
5. build up of lactic acid

Front 41

_________ fatigue often precedes _________ fatigue.

Back 41

1. psychological
2. physiological

Front 42

What is oxygen debt?

Back 42

- during prolonged periods of muscle contraction, the body responds with increasing (1) breathing rate and (2) blood flow to enhance O2 delivery to the tissue.
- after contraction stopped, heavy breathing continues
- oxygen debt is the amount of oxygen over the typical amount that is taken in during this time

Front 43

After prolonged periods of muscle contraction, what is the excess oxygen used for?

Back 43

1. convert lactic acid to glycogen in the liver
2. re synthesize creatine phosphate
3. replace oxygen removed from myoglobin

Front 44

What are the 3 muscle cell types?

Back 44

1. slow oxidative fibers
2. fast oxidative-glycolitic fibers
3. fast glycolytic fibers

Front 45

What is an origin?

Back 45

- the attachment of the tendon to the stationary bone
- stays stationary
- usually proximal

Front 46

What is an insertion?

Back 46

- the attachment of the tendon to the moveable bone
- pulled toward the origin during contraction
- usually distal

Front 47

Agonist

Back 47

- prime mover
- contracts to cause motion

e.g. bicep

Front 48

Antagonist

Back 48

- stretches & yields to the effects of the prime mover
- opposite side of the agonist

e.g. tricep

Front 49

Synergists

Back 49

- contract & stabilize intermediate joints
- prevent unwanted movements
- aid in the movement of the agonist/prime mover

Front 50

Fixator

Back 50

- stabilize origin of the prime mover

fixatOR.. o = origin

Front 51

How are skeletal muscles named?

Back 51

- patterns of the fascicles
- size
- shape
- action
- # of origins
- location of muscle
- sites of its origin & insertion