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MCAT Biology > Biology: Chapter 11: Musculoskeletal System > Flashcards

Biology: Chapter 11: Musculoskeletal System Flashcards

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1
Q

what is skeletal muscle

A

involved in support and movement, propulsion of blood, and thermoregulation; appears striated, under voluntary control, polynucleated; red fiber and white fibers

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2
Q

what are red fibers

A

Slow twitch fibers that carry out oxidative phosphorylation

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3
Q

what are white fibers

A

fast twitch fibers that carry out anaerobic metabolism

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4
Q

what is smooth muscle

A

respiratory, reproductive, cardiovascular, and digestive systems; nonstriated, involuntary, uninucleated; displays myogenic activity

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5
Q

what is cardiac muscle

A

contractile muscle of the heart; striated, involuntary, uninucleated (sometimes binucleated); myogenic activity; cells connected with intercalated discs that contain gap junctions

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6
Q

what is the basic unit of muscle

A

sacromere

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7
Q

what are sarcomeres

A

made of thick (myosin) and thin (actin) filaments; troponin and tropomyosin found on thin filament and regulate actin-myosin interactions

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8
Q

what are Z lines

A

define the boundaries of each sarcomere

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9
Q

what is the M line

A

located in the middle of sarcomere

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10
Q

what is the I band

A

contains only thin filaments

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11
Q

what is the H zone

A

consists of only thick filaments

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12
Q

what is the A band

A

contains thick filaments in their entirety; only part of the sarcomere that maintains a constant size during contraction

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13
Q

what are myofibrils

A

sarcomeres attached end to end; surrounded by the sarcoplasmic reticulum

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14
Q

what is the sarcoplasmic reticulum

A

calcium containing modified endoplasmic reticulum

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15
Q

what are T tubules

A

connected to the sarcolemma and oriented perpendicularly to the myofibrils allowing the action potential to reach all parts of the muscle

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16
Q

what is the first step of muscle contraction

A

begins at the NMJ where the neuron releases Acetylcholine that binds to receptors on the sarcolemma causing depolarization

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17
Q

what is the second step of muscle contraction

A

depolarization spreads down the sarcolemma to the T tubule triggering the release of calcium ions

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18
Q

what is the third step of muscle contraction

A

calcium binds to troponin causing a shift in tropomyosin and exposure of the myosin binding sites on the actin thin filament

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19
Q

what is the four step of muscle contraction

A

shortening of the sarcomere occurs as myosin heads bind to the exposed sites on action, forming cross bridges and pulling actin filament along the thick filament which results in contraction (sliding filament model)

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20
Q

what is the fifth step of muscle contraction

A

acetylcholine is degraded by acetylcholinesterase and the muscle relaxes allowing calcium to be brought back into the SR; ATP binds to the myosin head allowing its release from actin

21
Q

what is a simple twitch

A

all or nothing muscle response

22
Q

what is frequency summation

A

addition of multiple twitches before muscle has opportunity to relax

23
Q

what is oxygen debt

A

difference between oxygen needed and oxygen present

24
Q

what is tetanus

A

simple twitches occur so frequently as to not let the muscle relax at all leading to a stronger more prolonged contraction

25
Q

what is creatine phosphate

A

can transfer a phosphate group to ADP forming ATP

26
Q

what is myoglobin

A

heme containing protein that is a muscular oxygen reserve

27
Q

what is the axial skeleton

A

skull, vertebral column, rib cage, and hyoid bone

28
Q

what is the appendicular skeleton

A

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

29
Q

what is bone derived from

A

embryonic mesoderm

30
Q

what is compact bone

A

provides strength of the bone and is dense

31
Q

what is spongy/cancellous bone

A

lattice like structure consisting of spicules known as trabeculae; cavities filled with bone marrow

32
Q

what is the periosteum

A

layer of connective tissue surrounding the bone

33
Q

what are tendons

A

attaches bone to muscle

34
Q

what are ligaments

A

attaches bone to bone

35
Q

what is the structure of long bones

A

shafts called diaphyses flare to form metaphyses and terminate in epiphyses

36
Q

what are epiphyses

A

contain an epiphyseal growth plate that causes linear growth of the bone

37
Q

what is the bone matrix

A

composed of organic (collagen, glycoproteins and peptides )and inorganic compounds (hydroxyapatite)

38
Q

what is the structural unit of a bone

A

osteon

39
Q

what are lamellae

A

concentric rings that organize bones

40
Q

what are lacunae

A

between lamellar rings where osteocytes reside; connected with canaliculi to allow for nutrient and waste transfer

41
Q

what are osteoblasts

A

build bone

42
Q

what are osteoclasts

A

cells that resorb bone

43
Q

what is cartilage

A

firm, elastic material secreted by chondrocytes; avascular and not innervated

44
Q

what is endochondral ossification

A

fetal cartilage turns into bone

45
Q

what is intramembranous ossification

A

bones form directly from undifferentiated tissue

46
Q

what are immovable joints

A

joints that are fused together to form sutures or similar fibrous joints

47
Q

what are movable joints

A

usually strengthed by ligaments and contain a synovial capsule

48
Q

what is synovial fluid

A

secreted by synovium; aids in motion by lubricating the joing

49
Q

what is articular cartilage

A

each bone in the joint is coated with it to aid in movement and provide cushioning

MCAT Biology (11 decks)

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