Biology Chapter 11: The Musculoskeletal System (2 Stars)

Question 1

There are three main types of muscle: skeletal muscle, smooth muscle, and _____ muscle.

Answer 1

cardiac

Question 2

Skeletal muscle is involved in support and movement, propulsion of blood in the venous system, and thermoregulation. It appears striated, is under voluntary (somatic) control, is _______, and can be divided into red (slow-twitch) fibers that carry out oxidative phosphorylation and white (fast-twitch) fibers that rely on anaerobic metabolism.

Answer 2

polynucleated

Question 3

Smooth muscle is in the respiratory, reproductive, cardiovascular, and digestive systems. It appears ______, is under involuntary (autonomic) control, and is uninucleated. It can display myogenic activity, or contraction without neural input.

Answer 3

nonstriated

Question 4

Cardiac muscle comprises the contractile tissue of the heart. It appears striated, is under involuntary (autonomic) control, and is uninucleated (sometimes binucleated). It can also display myogenic activity. Cells are connected with intercalated discs that contain _______

Answer 4

gap junctions

Question 5

The ______ is the basic contractile unit of striated muscle.

Answer 5

sarcomere

Question 6

Sarcomeres are made of thick (_____) and thin (____) filaments.

Answer 6

(myosin)

actin

Question 7

____ and tropomyosin are found on the thin filament and regulate actin–myosin interactions.

Answer 7

Troponin

Question 8

The _______ can be divided into different lines, zones, and bands.

Answer 8

sarcomere

Question 9

The boundaries of each sarcomere are defined by _______

Answer 9

Z-lines.

Question 10

The _____ is located in the middle of the sarcomere.

Answer 10

M-line

Question 11

The I-band contains only ____ filaments.

Answer 11

thin filaments.

Question 12

The _____ consists of only thick filaments.

Answer 12

H-zone

Question 13

The _____ contains the thick filaments in their entirety. It is the only part of the sarcomere that maintains a constant size during contraction.

Answer 13

A-band

Question 14

Sarcomeres attach end-to-end to become myofibrils, and each myocyte (muscle cell or muscle fiber) contains many ______

Answer 14

myofibrils.

Question 15

Myofibrils are surrounded by the______ , a calcium containing modified endoplasmic reticulum, and the cell membrane of a myocyte is known as the sarcolemma.

Answer 15

sarcoplasmic reticulum

Question 16

A system of ______ is connected to the sarcolemma and oriented perpendicularly to the myofibrils, allowing the incoming signal to reach all parts of the muscle.

Answer 16

T-tubules

Question 17

Muscle contraction begins at the ______ , where the motor neuron releases acetylcholine that binds to receptors on the sarcolemma, causing depolarization.

Answer 17

neuromuscular junction

Question 18

This depolarization spreads down the sarcolemma to the _______, triggering the release of calcium ions.

Answer 18

T-tubules

Question 19

____ binds to troponin, causing a shift in tropomyosin and exposure of the myosin-binding sites on the actin thin filament.

Answer 19

Calcium

Question 20

Shortening of the sarcomere occurs as _____ heads bind to the exposed sites on ____, forming cross bridges and pulling the actin filament along the thick filament, resulting in contraction. This is known as the sliding filament model.

Answer 20

myosin heads

actin

Question 21

The muscle relaxes when ______ is degraded by acetylcholinesterase, terminating the signal and allowing calcium to be brought back into the SR. ATP binds to the myosin head, allowing it to release from actin.

Answer 21

acetylcholine

Question 22

Muscle cells exhibit an all-or-nothing response called a ________

Answer 22

simple twitch.

Question 23

Addition of multiple simple twitches before the muscle has an opportunity to fully relax is called _______

Answer 23

frequency summation.

Question 24

______ that occur so frequently as to not let the muscle relax at all can lead to tetanus, a more prolonged and stronger contraction.

Answer 24

Simple twitches

Question 25

_____ have additional energy reserves to reduce oxygen debt (the difference between the amount of oxygen needed and the amount present) and forestall fatigue.

Answer 25

Muscle cells

Question 26

__________ can transfer a phosphate group to ADP, forming ATP.

Answer 26

Creatine phosphate

Question 27

______ is a heme-containing protein that is a muscular oxygen reserve.

Answer 27

Myoglobin

Question 28

Internal skeletons (like those in humans) are called ______; external skeletons (like those in arthropods) are called exoskeletons.

Answer 28

endoskeletons

Question 29

The human skeletal system can be divided into_____ and _________

Answer 29

axial and appendicular skeletons.

Question 30

The ______ skeleton consists of structures in the midline such as the skull, vertebral column, ribcage, and hyoid bone.

Answer 30

axial

Question 31

The ______ skeleton consists of the bones of the limbs, the pectoral girdle, and the pelvis.

Answer 31

appendicular

Question 32

Bone is derived from embryonic ______ and includes both compact and spongy (cancellous) types.

Answer 32

mesoderm

Question 33

Compact bone provides strength and is _____

Answer 33

dense.

Question 34

Spongy or cancellous bone has a lattice-like structure consisting of bony spicules known as _____. The cavities are filled with bone marrow.

Answer 34

trabeculae.

Question 35

_____ contain shafts called diaphyses that flare to form metaphyses and that terminate in epiphyses. The epiphysis contains an epiphyseal (growth) plate that causes linear growth of the bone.

Answer 35

Long bones

Question 36

Bone is surrounded by a layer of connective tissue called ______

Answer 36

periosteum.

Question 37

____ are attached to muscles by tendons and to each other by ligaments.

Answer 37

Bones

Question 38

______ has both organic components, like collagen, glycoproteins, and other peptides, and inorganic components, like hydroxyapatite.

Answer 38

Bone matrix

Question 39

Bone is organized into concentric rings called _____ around a central Haversian or Volkmann’s canal. This structural unit is called an osteon or Haversian system.

Answer 39

lamellae

Question 40

Between lamellar rings are ______, where osteocytes reside, which are connected with canaliculi to allow for nutrient and waste transfer.

Answer 40

lacunae

Question 41

Bone remodeling is carried out by _____ and osteoclasts.

Answer 41

osteoblasts

Osteoblasts build bone, while osteoclasts resorb bone.

Question 42

______ increases resorption of bone, increasing calcium and phosphate concentrations in the blood.

Answer 42

Parathyroid hormone

Question 43

_______ also increases resorption of bone, leading to increased turnover and, subsequently, the production of stronger bone.

Answer 43

Vitamin D

Question 44

Calcitonin _____ bone formation, decreasing calcium concentrations in the blood.

Answer 44

increases

Question 45

Cartilage is a firm, elastic material secreted by chondrocytes. Its matrix is called ______

Answer 45

chondrin.

Question 46

_____ is usually found in areas that require more flexibility or cushioning.

Answer 46

Cartilage

Question 47

_____ is avascular and is not innervated.

Answer 47

Cartilage

Question 48

In fetal life, bone forms from cartilage through ______ ossification. Some bones, especially those of the skull, form directly from undifferentiated tissue (mesenchyme) in intramembranous ossification.

Answer 48

endochondral

Question 49

_____ may be classified as immovable or movable.

Answer 49

Joints

Question 50

Immovable joints are fused together to form sutures or similar ______ joints.

Answer 50

fibrous

Question 51

Movable joints are usually strengthened by ligaments and contain a ______ capsule.

Answer 51

synovial

Question 52

______, secreted by the synovium, aids in motion by lubricating the joint.

Answer 52

Synovial fluid

Question 53

Each bone in the joint is coated with ______ cartilage to aid in movement and provide cushioning.

Answer 53

articular

Question 54

Muscles that serve opposite functions come in _______ pairs; when one muscle contracts, the other lengthens

Answer 54

antagonistic