Chapter 11: The Musculoskeletal System

Question 1

What are the 3 types of muscle?

Answer 1

1. skeletal
2. smooth
3. cardiac

Question 2

Sarcomeres are repeating units of ________ and ____________.

Answer 2

actin; myosin

Question 3

____ fibers, also known as ____-________ fibers, have high myoglobin content and primarily derive their energy aerobically.

Answer 3

red; slow-twitch

Question 4

____________ is an oxygen carrier that uses iron in a heme group to bind oxygen.

Answer 4

myoglobin

Question 5

________ fibers, known as ________-________ fibers, contain much less myoglobin.

Answer 5

white; fast-twitch

Question 6

Muscles that contract slowly, but can sustain activity, contain a predominance of ____ fibers.

Answer 6

red

Question 7

Muscles that contract rapidly but fatigue quickly contain mostly ____ fibers.

Answer 7

white

Question 8

Compared to skeletal muscle, smooth muscle is capable of more sustained contractions; a constant state of low-level contraction, as may be seen in the blood vessels, is called ________.

Answer 8

tonus

Question 9

smooth muscle can contract without nervous system input in what is known as ____________ activity; the muscle cells contract in response to stretch or other stimuli

Answer 9

myogenic

Question 10

Cardiac muscle has characteristics of what?

Answer 10

Both smooth and skeletal muscle types

Question 11

Cardiac muscle cells are connected by ____________ ________, which contain many gap junctions.

Answer 11

intercalated discs

Question 12

Gap junctions (connections between cytoplasm) in cardiac muscle allow for what?

Answer 12

Flow of ions directly between cells; allows for rapid and coordinated depolarization of muscle cells and efficient contraction

Question 13

Starting at the ____________ node, depolarization spreads using conudction pathways to the ________________ node.

Answer 13

sinoatrial; atrioventricular

Question 14

From the AV node, depolarization spreads to the ________ of ____ and its branches, and then to the ________ fibers.

Answer 14

bundle of His; Purkinje

Question 15

The ________ nerve provides parasympathetic outflow to the heart and slows the heart rate.

Answer 15

vagus

Question 16

____________ from sympathetic neurons or ____________ from the adrenal medulla binds to adrenergic receptors in the heart, causing increased HR and greater contractility.

Answer 16

norepinephrine; epinephrine

Question 17

Epinephrine increases heart rate by doing what?

Answer 17

Increasing intracellular calcium levels within cardiac myocytes

Question 18

Cardiac contraction, like all types of muscle, relies on ________.

Answer 18

calcium

Question 19

The ____________ is the basic contractile unit of skeletal muscle.

Answer 19

sarcomere

Question 20

Sarcomeres are made of ________ and ________ filaments.

Answer 20

thick; thin

Question 21

The thick filaments are organized bundles of ____________, whereas the thin filaments are made of ________ along with 2 other proteins, which are?

Answer 21

myosin; actin; troponin and tropomyosin

acTin with a T for troponin and tropomyosin

Question 22

Another protein, ________, acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle.

Answer 22

titin

Question 23

____-lines define the boundaries of each sarcomere.

Answer 23

Z-lines

Question 24

The ____-line runs down the center of the sarcomere, through the middle of the myosin filaments.

Answer 24

M

Question 25

The ____-band is the region containing exclusively thin filaments, whereas the ____-zone contains only thick filaments.

Answer 25

I; H

Question 26

The ____-band contains the thick filaments in their entirety, including any overlap with thin filaments.

Answer 26

A

Question 27

Sarcomere are attached end-to-end to form ____________.

Answer 27

myofibrils

Question 28

Myofibrils are surrounded by a covering known as the ________________ ____________, a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions.

Answer 28

sarcoplasmic reticulum

Question 29

The ____________ is a modified cytoplsm just outside the sarcoplasmic reticulum.

Answer 29

sarcoplasm

Question 30

The cell membrane of a myocyte is known as the ________________.

Answer 30

sarcolemma

Question 31

What does the sarcolemma do?

Answer 31

Propagates an action potential and distributes AP to all sarcomeres

Question 32

The sarcolemma distributes AP to all sarcomeres in a muscle using a system of ____________ ____________ that are oriented perpendicularly to the myofibrils.

Answer 32

transverse tubules

Question 33

Each ____________, or muscle cell, contains many myofibrils arranged in parallel and can also be called a ________ ________.

Answer 33

myocyte; muscle fiber

Question 34

Contraction starts at the ____________ ________, where the nervous system communicates with muscles via ________ ____________.

Answer 34

neuromuscular junction; motor neurons

Question 35

The signal from the neuromuscular junction travels down the neuron until it reaches the ________ ____________, or ____________ ________.

Answer 35

nerve terminal (synaptic bouton)

Question 36

At the nerve terminal, ____________ is released into the synapse.

Answer 36

acetylcholine

Question 37

In the case of the neuromuscular junction, the nerve terminal can also be called the ________ ____ ________.

Answer 37

motor end plate

Question 38

Acetylcholine binds to receptors on the ____________, causing depolarization.

Answer 38

sarcolemma

Question 39

Each nerve terminal controls a group of myocytes. Together, the nerve terminal and its myocytes constitute a ________ ________

Answer 39

motor unit

Question 40

Depolarization triggers an AP. What order does it pass through?

Answer 40

1. Sarcolemma 2. T-tubules 3. Muscle tissues 4. Sarcoplasmic reticulum

Question 41

What happens after an action potential reaches the sarcoplasmic reticulum?

Answer 41

Ca2+ is released

Question 42

After Ca2+ is released, what do they bind to? What happens next?

Answer 42

Troponin; since troponin is bound to tropomyosin, tropomyosin undergoes a confirmational change

Question 43

What happens when tropomyosin changes?

Answer 43

Myosin-binding sites are exposed on the actin thin filament

Question 44

What recocks the myosin head for the next actin-myosin cross-bridge cycle?

Answer 44

hydrolysis of ATP to ADP and Pi

Question 45

The repetitive binding and releasing of myosin heads on actin filaments causing the sliding of the thin filament across the thick filament is known as what?

Answer 45

sliding filament model

Question 46

Actin filaments are ________.

Answer 46

thin | "Acthin"

Question 47

Acetylcholine is degraded in the synapse by the enzyme known as ________________.

Answer 47

acetylcholinesterase

Question 48

Once acetylcholine is degraded, what happens?

Answer 48

1. Signal terminates at neuromuscular junction 2. Sarcolemma repolarizes 3. Calcium release ceases 4. SR takes up calcium from sarcoplasm

Question 49

The ________ period is the time between reaching threshold and the onset of contraction.

Answer 49

latent | when AP spreads along muscle and allows Ca2+ to be released from SR

Question 50

If a muscle fiber is exposed to frequent and prolonged stimulation, it will have insufficient time to relax. Contractions will combine and become stronger/prolonged. This is ____________ ____________.

Answer 50

frequency summation

Question 51

When contractions become so frequent that the muscle is unable to relax at all, this is known as ____________.

Answer 51

tetanus

Question 52

Slow-twitch muscle fibers have high levels of ____________.

Answer 52

mitochondria

Question 53

What process do muscles use to make ATP? Why?

Answer 53

oxidative phosphorylation, because they have lots of mitochondria

Question 54

There are two supplemental energy reserves in muscle. What are they?

Answer 54

1. Creatine phosphateis 2. Anaerobic glycolysis

Question 55

____________ ____________ is created by transferring a phosphate group from ATP to creatine during times of rest. How is ATP created from this when muscles are being used?

Answer 55

creatine phosphate; the reaction can be reversed to quickly generate ATP from ADP | creatine + ATP <--> creatine phosphate + ADP

Question 56

When muscles run out of oxygen during exercise, ____________ reserves are used to keep aerobic metabolism.

Answer 56

myoglobin

Question 57

________-________ muscle fibers have fewer mitochondria and must rely on glycolysis and fermentation to make ATP under most circumstances.

Answer 57

fast-twitch

Question 58

Sometimes, even ________-________ muscle fibers must switch to anaerobic metabolism and produce lactic acid, at which point the muscle begins to fatigue.

Answer 58

slow-twitch | (red fibers)

Question 59

The difference between the amount of oxygen needed by muscles and the actual amount present is called what?

Answer 59

oxygen debt

Question 60

After strenuous exercise, the body must metabolize all of the lactic acid it has produced. Most lactic acid is converted back into ____________, and enters what cycle?

Answer 60

pyruvate; citric acid cycle

Question 61

The axial skeleton consists of what 4 parts?

Answer 61

1. Skull 2. Vertebral column 3. Rib cage 4. Hyoid bone

Question 62

The appendicular skeleton consists of what?

Answer 62

1. bones of limbs 2. pectoral girdle 3. pelvis

Question 63

Bone is derived from?

Answer 63

embryonic mesoderm

Question 64

Bone's strength comes specifically from ____________ bone.

Answer 64

compact

Question 65

What are the other types of bone besides compact bone?

Answer 65

1. spongy 2. cancellous

Question 66

Spongy bone has bony spicules (points) known as ____________.

Answer 66

trabeculae

Question 67

The cavities between trabeculae are filled with bone ____________, which can be red or yellow.

Answer 67

marrow

Question 68

____ marrow is filled with hematopoietic stem cells.

Answer 68

red

Question 69

________ marrow is composed of fat and is relatively inactive

Answer 69

yellow

Question 70

Bones in the appendicular skeleton are typically ________ bones, and are characterized by cylindrical shafts called ____________ that swell at each end to form ____________, and terminate in ____________.

Answer 70

long; diaphyses, metaphyses, epiphyses

Question 71

The epiphyses use their ________ cores to disperse force and pressure at joints.

Answer 71

spongy

Question 72

At the internal edge of the epiphysis is an ____________ (growth) plate, which is a cartilaginous structure and the site of longitudinal growth.

Answer 72

epiphyseal

Question 73

What happens to the epiphyseal plate during puberty?

Answer 73

closes and stops vertical growth

Question 74

A fibrous sheath called the ____________ surrounds the long bone to protect it and serve as a site for muscle attachment.

Answer 74

periosteum

Question 75

________ attach muscle to bone, ____________ attach bone to bone.

Answer 75

tendon; ligament

Question 76

The strength of compact bone comes from the bone ________.

Answer 76

matrix

Question 77

The organic components of bone matrix are?

Answer 77

1. collagen 2. glycoproteins 3. other peptides

Question 78

The inorganic components of bone matrix are?

Answer 78

1. calclium 2. phosphate 3. hydroxide ions

Question 79

What happens to the hydroxide ions in matrix?

Answer 79

They harden together to form hydroxyapatite crystals.

Question 80

The bony matrix is ordered into structural units known as what?

Answer 80

osteons, or Haversian systems

Question 81

Each osteon contains concentric circles of bony matrix called ____________ surrounding a central microscopic channnel.

Answer 81

lamellae

Question 82

Longitudinal channels (axis parallel to bone) are known as ____________ ________

Answer 82

Haversian canals

Question 83

Transverse channels (perpendicular to bone) are known as ____________ ____________.

Answer 83

Volkmann's canals

Question 84

Between lamellar rings are spaces called ____________, which house mature bone cells known as ____________.

Answer 84

lacunae; osteocytes

Question 85

Lacunae are interconnected by tiny channels called ________________ that allow exchange of nutrients/wastes between osteocytes and Haversian/ Volkmann's canals.

Answer 85

canaliculi

Question 86

____________ build bone, and ____________ resorb it.

Answer 86

build; resorb

Question 87

____________ hormone (released by glands of a similar name in response to low blood calcium) promotes resorption of bone.

Answer 87

parathyroid

Question 87

____________ hormone (released by glands of a similar name in response to low blood calcium) promotes resorption of bone.

Answer 87

parathyroid

Question 88

________ ____, which is activated by parathyroid hormone, also promotes the resorption of bone.

Answer 88

Vitamin D | p434

Question 89

________________, released by the parafollicular cells of the thyroid in response to high blood calcium, promotes bone formation, lowering blood calcium levels.

Answer 89

calcitonin

Question 90

Cartilage consists of a firm but elastic matrix called ________ that is secreted by cells called ____________.

Answer 90

chondrin, chondrocytes

Question 91

Cartilage differs from bone how?

Answer 91

1. avascular 2. not innervated

Question 92

Most bones are created by the hardening of cartilage into bone. This is called what?

Answer 92

endochondral ossification

Question 93

Bones can also be formed through ____________ ____________, in which undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into, and replaced by, bone.

Answer 93

intramembranous ossification

Question 94

____________ joints consist of bones that are fused together to form sutures.

Answer 94

immovable

Question 95

Movable joints are strengthened by ligaments and consist of a ____________ ____________, which encloses the actual joint cavity.

Answer 95

synovial capsule

Question 96

A layer of soft tissue called the ____________ secretes synovial fluid, which does what?

Answer 96

synovium; lubricates movement of structures in joint space.

Question 97

The ____________ ____________ contributes to the joint by coating the articular surfaces of bones so that impact is restricted to the lubricated joint cartilage, rather than to the bones.

Answer 97

articular cartilage

Question 98

The end of the muscle with a larger attachment to bone is called the ________.

Answer 98

origin

Question 99

The end with the smaller attachment to bone is called the ____________

Answer 99

insertion

Question 100

A ________ muscle decreases the angle across a joint.

Answer 100

flexor

Question 101

An ____________ muscle increases or straightens this angle.

Answer 101

extensor

Question 102

An ____________ moves a part of the body away from the midline.

Answer 102

abductor | take away, kidnap

Question 103

An ____________ moves a part of the body toward the midline.

Answer 103

adductor

Question 104

A ________ rotator rotates the axis of a limb TOWARD the midline.

Answer 104

medial

Question 105

A ____________ rotator rotates the axis of a limb away from the midline.

Answer 105

lateral

Question 105

A ____________ rotator rotates the axis of a limb away from the midline.

Answer 105

lateral