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MCAT > Biology: Chapter 11 > Flashcards

Biology: Chapter 11 Flashcards

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MCAT flashcards
1
Q

Types of muscle

A

skeletal, cardiac, smooth

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2
Q

Skeletal muscle

A

-Responsible for voluntary movement, is innervated by the somatic nervous system, and is multinucleated
-Appears striped or striated due to arrangement of actin and myosin into repeating units called sarcomeres
-slow-twitch fibers and fast-twitch fibers

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3
Q

Red fibers/slow-twitch fibers

A

-high myoglobin and primarily derive their energy aerobically
-Carry many mitochondria to carry out oxidative phosphorylation
-Muscles that contract slowly but sustain activity contain a predominance of these

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4
Q

White fibers/fast-twitch fibers

A

-contain less myoglobin and are lighter in color because there is less iron
-Muscles that contract rapidly, but fatigue quickly contain mostly these

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5
Q

Myoglobin

A

oxygen carrier that uses iron in a heme group to bind oxygen

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6
Q

Smooth muscle

A

-Responsible for involuntary action, controlled by the autonomic nervous system, and have a single nucleus
-Contain actin and myosin, but fibers aren’t as well organized and striations cannot be seen
-Capable of more sustained contractions contained to skeletal muscle
-Can contract without nervous system input in what is known as myogenic activity

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7
Q

Tonus (smooth muscle)

A

a constant state of low-level contractions

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8
Q

Cardiac muscle

A

-Primarily uninucleated (can have two nuclei), contract involuntarily, and innervated by the autonomic nervous system
-Appears striated
-Cardiac muscle cells are connected by intercalated discs, which contain gap junctions. Gap junctions allow for the flow of ions directly between cells which allows for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle
-Able to define and maintain their own rhythm

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9
Q

Sarcomere

A

-Basic contractile unit of skeletal muscle
-Made of thick and thin filaments

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10
Q

Thick filaments (sarcomere)

A

organized bundles of myosin

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11
Q

Thin filaments (sarcomere)

A

made of actin along with troponin and tropomyosin. Troponin and tropomyosin help to regulate the interaction between actin and myosin filaments

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12
Q

Titin (sarcomere)

A

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

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13
Q

Z-line (sarcomere)

A

define the boundaries of each sarcomere

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14
Q

M-line (sarcomere)

A

runs down the center of the sarcomere, through the middle of the myosin filaments

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15
Q

I-band (sarcomere)

A

region containing exclusively thin filaments

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16
Q

H-zone (sarcomere)

A

contains only thick filaments

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17
Q

A-band (sarcomere)

A

contains thick filaments in their entirety, including any overlap with thin filaments

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18
Q

A sarcomere during contraction

A

the H-zone, I-band, the distance between Z-lines and the distance between M-lines all become smaller while the A-band’s size remains the same

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19
Q

Myofibrils

A

sarcomeres that are attached end to end

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20
Q

Sarcoplasmic reticulum

A

-surround myofibrils
-specialized endoplasmic reticulum that contains a high concentration of Ca2+ ions

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21
Q

Sarcolemma

A

-the cell membrane of a myocyte
-The sarcolemma is capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle through using transverse tubules (T-tubules)
-T-tubules are oriented perpendicularly to the myofibrils

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22
Q

Myocyte

A

-muscle cell
-each myocyte contains many myofibrils arranged in parallel and can also be called a muscle fiber

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23
Q

Muscle

A

many myocytes in parallel

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24
Q

Simple twitch

A

-response of a single muscle fiber to a brief stimulus at or above threshold
-consists of a latent period, contraction period, and relaxation period

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25
Q

Latent period (simple twitch)

A

-time between reaching threshold and the onset of contraction
-it is during this time that the action potential spreads along the muscle and allows for calcium to be released from SR

26
Q

Frequency summation

A

-if a muscle fiber is exposed to a frequent and prolonged stimulation and has insufficient time to relax
-This causes the contractions to combine, become stronger and more prolonged

27
Q

Tetanus

A

-if the contractions become so frequent that the muscle is unable to relax at all
-Prolonged tetanus will result in muscle fatigue

28
Q

2 Supplemental energy reserves in muscle

A

-Creatine phosphate: created by transferring a phosphate group from ATP to creatine during times of rest. This reaction can then be reversed during muscle use to quickly generate ATP from ADP
-Muscle contains myoglobin which binds to oxygen with high affinity. As exercising muscles run out of oxygen, they use myoglobin reserves to keep aerobic metabolism going

29
Q

Slow-twitch fibers (ATP

A

-have high levels of mitochondria and use oxidative phosphorylation to make ATP
-High concentrations of oxygen are required to generate the large amounts of ATP muscle cells need

30
Q

Fast-twitch fibers (ATP)

A

have fewer mitochondria and must rely on glycolysis and fermentation to make ATP under most circumstances

31
Q

Oxygen debt

A

the difference between the amount of oxygen needed by the muscles and the actual amount present

32
Q

Axial skeleton

A

consists of skull, vertebral column, rib cage, and hyoid bone; provides basic central framework for the body

33
Q

Appendicular skeleton

A

consists of bones of the limbs, the pectoral girdle, and pelvis

34
Q

Compact bone

A

hard outer portion of bone that gives it strength

35
Q

Spongy/Cancellous bone

A

-internal core of bone
-trabeculae
-bone marrow

36
Q

Trabeculae

A

bony spicules (points) that make up lattice structure of spongy bone

37
Q

Bone marrow

A

-fill the cavities of trabeculae
-Red marrow: filled with hematopoietic stem cells which are responsible for the generation of all cells in our blood
-Yellow marrow: composed primarily of fat and is relatively inactive

38
Q

Diaphysis (long bone)

A

cylindrical shafts of long bones

39
Q

Metaphysis (long bone)

A

swell at the end of each diaphyses and terminate in epiphyses

40
Q

Epiphysis (long bone)

A

-the end part of a long bone
-initially growing separately from the shaft

41
Q

Epiphyseal plate

A

-cartilaginous structure and the site of longitudinal growth
-Prior to adulthood, this is filled with mitotic cells that contribute to growth
-During puberty, these close and vertical growth is halted

42
Q

Periosteum

A

A fibrous sheath that surrounds the long bone to protect it as well as serve as a site for muscle attachment

43
Q

Tendons

A

attach muscle to bone

44
Q

Ligaments

A

hold bones together at joints

45
Q

Bone matrix

A

-where the strength of bone comes from
-Has both organic and inorganic components

46
Q

Organic components of bone matrix

A

collagen, glycoproteins, and other peptides

47
Q

Inorganic components of bone matrix

A

calcium, phosphate, hydroxide ions

48
Q

Osteons/Haversian systems

A

structural units of the bony matrix

49
Q

Lamellae (osteons)

A

concentric circles of bony matrix that each osteon contains

50
Q

Haversian canals (osteons)

A

-longitudinal channels
-contain blood vessels, nerve fibers, and lymph vessels

51
Q

Volkmann’s canals (osteons)

A

-transverse channels
-contain blood vessels, nerve fibers, and lymph vessels

52
Q

Lacunae

A

small spaces between lamellar rings that house mature bone cells known as osteocytes

53
Q

Canaliculi

A

tiny channels that interconnect lacunae and allow for the exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann’s canals

54
Q

Osteoblasts

A

build bone

55
Q

Osteoclasts

A

resorb or break bone down

56
Q

Parathyroid hormone (bone formation)

A

promotes resorption of bone, increasing the concentration of calcium and phosphate in the blood

57
Q

Calcitonin

A

released in response to high blood calcium and promotes bone formation, lowering blood calcium levels

58
Q

Cartilage

A

-Softer and more flexible than bone
-Consists of a firm but elastic matrix called chondrin which is secreted by chondrocytes
-Differs from bone by being avascular (without blood and lymphatic vessels) and is not innervated

59
Q

Endochondral ossification

A

-creation of bone through the hardening of cartilage
-how a majority of long bones in the body are created

60
Q

Intermembranous ossification

A

undifferentiated embryonic connective tissue is transformed into, and replaced by, bone; occurs in bones of the skull

61
Q

Immovable joints

A

consist of bones that are fused together to form sutures; found primarily in the head

62
Q

Movable joints

A

-permit bones to shift relative to one another
-Strengthened by ligaments which are pieces of fibrous tissue that connect bone to one another
-Synovial capsule: encloses the actual joint cavity
-Synovium: layer of soft tissue that secretes synovial fluid
-Synovial fluid: lubricates the movement of structures in the joint space
-Articular cartilage: contributes to the joint by coating the articular surfaces of the bones so that impact is restricted to the lubricated joint cartilage, rather than the bones

MCAT (38 decks)

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