MCAT Biology Muscular and Skeletal Systems

Question 1

The band of the sarcomere that extends the full length of the thick filament

Answer 1

A band

Question 2

The __ includes regions of thick and thin filament overlap, as well as regions of thick only filament

Answer 2

A band

Question 3

The __ alternates with the I band to give skeletal and cardiac muscle tissue a striated appearance

Answer 3

A band

Question 4

___ does NOT shorten during muscle contraction

Answer 4

A band

Question 5

A contractile protein, in skeletal muscles __ form the thin filaments

Answer 5

Actin

Question 6

A hormone produced from vitamin D that acts to INCREASE serum calcium levels

Answer 6

Calcitriol

Question 7

___ is produced by C-cells of the thyroid gland that decreases serum calcium levels. It targets bones to stimulate osteoblasts and the kidney to REDUCE calcium reabsorption

Answer 7

Calcitonin

Question 8

A cytoplasmic Ca2+- binding protein. __ is important in smooth muscle cells, where binding of Ca2+ allows __ to activate myosin light-chain kinase, the first step in smooth muscle cell contraction

Answer 8

Calmodulin

Question 9

A strong connective tissue with varying degrees of flexibility.__

Answer 9

Cartilage

Question 10

The hollow center of an osteon, known as the Haversian canal

Answer 10

Central canal

Question 11

The __ contains blood vessels, lymphatic vessels, and nerves, bone is laid around this in concentric rings called lamellae

Answer 11

Central canal

Question 12

Bone is laid around the central (haversian) canal in concentric rings called__

Answer 12

Lamellae

Question 13

A protein fiber with a unique triple-helix structure that gives it great strength

Answer 13

Collagen

Question 14

Tissues with a lot of __ are typically very strong such as bone, tendon, ligaments etc.

Answer 14

Collagen

Question 15

___ forms the diaphysis of the long bones, and the outer shell of the epiphysis and all other bones

Answer 15

Compact bone

Question 16

What are the four basic tissue types in the body?

Answer 16

• epithelial
• connective
• muscle
• nervous

Question 17

An energy storage molecule used by muscle tissue

Answer 17

Creatine phosphate

Question 18

The phosphate from __ can be removed and attached to an ADP to generate ATP quickly in muscle tissue

Answer 18

Creatine phosphate

Question 19

The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory)

Answer 19

Cross bridge

Question 20

The shaft of a long bone is termed__

Answer 20

Diaphysis

Question 21

__ is hollow and made entirely of compact bone

Answer 21

Diaphysis

Question 22

The fraction of the end-diastolic volume ejected from the ventricles in a single contraction of the heart

Answer 22

Ejection fraction

Question 23

The __ is normally around 60% of the end-diastolic volume

Answer 23

Ejection fraction

Question 24

__ is found in great amounts in lung tissue, arterial tissue, skin, and the epiglottis

Answer 24

Elastin

Question 25

The depolarization of the motor end plate on a muscle cell

Answer 25

End plate potential

Question 26

A band of cartilage (hyaline) found between the diaphysis and the epiphysis of long bones during childhood and adolescence

Answer 26

Epiphyseal plate

Question 27

Cell proliferation in the middle of the __ is essentially forces the diaphysis and epiphysis further apart, while the older cartilage at the edges of the plate is replaced with bone.

Answer 27

Epiphyseal plate

Question 28

The __ gets thinner and thinner the older a person gets, until finally it fuses (the diaphysis and epiphysis connect) in late adolescence, preventing further elongation of the bones

Answer 28

Epiphyseal plate

Question 29

A bundle of skeletal muscle cells. __ group together to form skeletal muscles

Answer 29

Fascicle

Question 30

The region at the center of an A band of a sarcomere that is made up of myosin only. The __ gets shorter ( and may disappear) during muscle contraction

Answer 30

H zone

Question 31

The region of a sarcomere made up only of thin filaments. The ___ is bisected by a Z line.

Answer 31

I band

Question 32

The __ alternates with A bands to give skeletal and cardiac muscle a striated appearance. The ___ gets shorter and may disappear completely, during muscle contraction

Answer 32

I band

Question 33

Small cavities in bone or cartilage that hold individual bone or cartilage cells

Answer 33

Lacunae

Question 34

``` The relationship of muscle length to its ability to generate strong contractions. Maximum tension (contraction strength) is achieved at sarcomere lengths between 2.0 and 2.2 microns. Tension decreases outside of this range ```

Answer 34

Length-tension relationship

Question 35

A strong band of connective tissue that connects bone to one another

Answer 35

Ligament

Question 36

The most common class of bone in the body, __ have a well-defined shaft (diaphysis) and two well-defined ends (epiphyses)

Answer 36

Long bone

Question 37

The portion of the muscle cell membrane at the neuromuscular junction; essentially the postsynaptic membrane at this synapse

Answer 37

Motor end plate

Question 38

A motor and all the skeletal muscle cells it innervates

Answer 38

Motor unit

Question 39

Larger __ are tpically found in large muscles (thighs, buttocks) and produce gross movement

Answer 39

Motor unit

Question 40

A mechanism for increasing tension (contractile strength) in a muscle by activating more motor units.

Answer 40

Motor unit recruitment

Question 41

A skeletal muscle cell, also known as a muscle fiber. Skeletal muscle cells are formed from the fusion of many smaller cells (during development) consequently they are very long and are multinucleate.

Answer 41

Myofiber

Question 42

A string of sarcomeres within a skeletal muscle cell. Each muscle cell contains hundreds of __

Answer 42

Myofibril

Question 43

One of the contractile proteins in muscle tissues. IN skeletal and cardiac muscle, __ forms the thick filaments.

Answer 43

Myosin

Question 44

__ has intrinsic ATPase activity and can exist in two conformations, either high energy or low energy

Answer 44

Myosin

Question 45

A kinase in smooth muscle cells activated by calmodulin in the presence of Ca2+. As its name implies this phosphorylates myosin, activating it so that muscle contraction can occur

Answer 45

Myosin light-chain kinase (MLCK)

Question 46

A hormone produced and secreted by the parathyroid glands that increases serum calcium levels

Answer 46

Parathyroid hormone (PTH)

Question 47

___ targets bones (stimulates osteoclast), the kidneys (increases calcium reabsorption), and the small intestine (increases calcium absorption)

Answer 47

Parathyroid hormone (PTH)

Question 48

The step in the sliding filament theory during which myosin undergoes a conformational change to its low energy state, in the process dragging the thin filaments (and the attached Z lines) toward the center of the sarcomere.

Answer 48

Power stroke

Question 49

__ requires ATP only indirectly: to set the myosin molecule in its high-energy conformation during a different step of the sliding filament theory

Answer 49

Power stroke

Question 50

Skeletal muscle cells that contract slowly but are fatigue resistant due to high concentrations of myoglobin and a good blood supply

Answer 50

Red slow twitch fibers

Question 51

The plasma membrane of a muscle cell

Answer 51

Sarcolemma

Question 52

The unit of muscle contraction

Answer 52

Sarcomere

Question 53

__ are bounded by Z lines, to which thin filaments attach. Thick filaments are found in the center of them, overlapped by thin filaments

Answer 53

Sarcomere

Question 54

Sliding of thin and thick filaments over one another during contraction reduces the distance between Z lines, shortening the __

Answer 54

sarcomere

Question 55

The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir. The __ widens around each myofibril in the muscle cell

Answer 55

Sarcoplasmic reticulum (SR)

Question 56

Explain four steps of sliding filament theory

Answer 56

1. Myosin binds actin 2. Myosin pulls actin towards the center of the sarcomere 3. Myosin releases actin 4. Myosin resets to its high-energy conformaton

Question 57

Muscle tissue that is non-striated, uninucleate, and under involuntary control (controlled by the ANS)

Answer 57

Smooth muscle

Question 58

A looser, more porous type of bone tissue found at the inner core of the epiphyses in long bones and all other bone types

Answer 58

Spongy bone

Question 59

__ is filled with red bone marrow, important in blood cell formation

Answer 59

Spongy bone

Question 60

A lubricating, nourishing fluid found in joint capsules

Answer 60

Synovial fluid

Question 61

Strong bands of connective tissue that connect skeletal muscle to bone

Answer 61

Tendon

Question 62

A smooth sustained muscle contraction, such as occurs in skeleletal muscle when stimulation frequency is high enough (this is the normal type of contraction exhibited by skeletal muscle)

Answer 62

Tetanus

Question 63

In skeletal and cardiac muscle tissue a filament composed of bundles of myosin molecules. The myosin head groups attach to the thin filaments during muscle contraction and pull toward the center of the sarcomere

Answer 63

Thick filament

Question 64

In skeletal and cardiac muscle tissue, a filament composed of actin, tropomyosin, and troponin. __ are attached to the Z lines of the sarcomeres and slide over thick filaments during muscle contraction

Answer 64

Thin filament

Question 65

A helical protein that winds around actin helices in skeletal and cardiac muscle cells to from the thin filament of the sarcomere.

Answer 65

Tropomyosin

Question 66

In the absence of Ca2+___ covers the myosin-binding sites on actin and prevents muscle contraction. When calcium is present, a conformational change in __ occurs so that the mysoin-binding sites are exposed and muscle contraction can occur.

Answer 66

Tropomyosin

Question 67

A globular protein that associates with tropomyosin a part of the thin filament of the sarcomere`

Answer 67

Troponin

Question 68

__ is the protein that binds Ca2+, which causes the conformational change in tropomyosin required to expose the myosin-binding sites on actin and initiate muscle contraction

Answer 68

Troponin

Question 69

Also called transverse tubules, these are deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell

Answer 69

T-tubules

Question 70

Also known as red slow twitch or red oxidative fibers, these are skeletal muscle cells that contract slowly and are extremely resistant to fatigue

Answer 70

Type 1 fibers

Question 71

Also known as fast twitch oxidative fibers, these are skeletal muscle cells that contract quickly and are somewhat resistant to fatigue

Answer 71

Type 2A fibers

Question 72

Also known as white fast twitch fibers, these are skeletal muscle cells that contract quickly and fatigue quickly

Answer 72

Type 2B fibers

Question 73

The ends of a sarcomere are its__

Answer 73

Z-line