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MCAT Biology and Biochemistry > Biology Chapter 11: The Musculoskeletal System > Flashcards

Biology Chapter 11: The Musculoskeletal System Flashcards

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1
Q

Three main types of muscle

A

skeletal muscle
smooth muscle
cardiac muscle

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2
Q

Skeletal muscle

A

involved in support and movement, propulsion of blood in the venous system, and thermoregulation. It appears striated, is under voluntary (somatic) control, is polynucleated and can be divided into red fibers and white fibers

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3
Q

Red fibers

A

slow-twitch fibers that carry out oxidative phosphorylation

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4
Q

White fibers

A

fast-twitch fibers that rely on anaerobic metabolism

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5
Q

Smooth muscle

A

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

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6
Q

Cardiac muscle

A

comprised the contractile tissue of the heart, appears striated and is under involuntary (autonomic) control.

  • uninucleated
  • myogenic activity
  • cells are connected with intercalated discs that contain gap junctions.
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7
Q

Sacromere

A

the basic contractile unit of striated muscle - made of thick (myosin) and thin (actin) filaments

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8
Q

Where are troponin and tropomyosin found?

A

on the thin filament - they regulated actin myosin interactions

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9
Q

What are the lines, zones and bands of the sacromere?

A 
Z-lines (defines boundaries) 
M-line (middle) 
I-band (only thin filaments) 
H-zone (only thick filaments) 
A-band (thick filaments in their entirety)
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10
Q

Sacromeres end to end =

A

myofibrils

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11
Q

Myocyte

A

Muscle cell/muscle fiber - contains many myofibrils

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12
Q

Sarcoplasmic reticulum

A

A calcium-containing modified ER that surrounds myofibrils.

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13
Q

Sarcolemma

A

the cell membrane of myocytes

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14
Q

T-tubules

A

a system connected to the sarcolemma and oriented perpendicular to the myofibrils, allowing the incoming signal to reach all parts of the muscle.

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15
Q

Where does the muscle contraction begin?

A

the neuromuscular junction

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16
Q

What are the steps of a muscle contraction

A
  • acetylcholine released at nueromuscular junction - causes depolarization of the sarcolemma
  • Depolarization spreads from sarcolemma to the T-tubules, triggering the release of calcium ions.
  • Ca binds to troponin, causing a shift in tropomyosin, exposing the myosin-binding site on actin.
  • myosin heads bind to actin
  • form cross bridges and pull –> contraction
  • Muscle relaxes when acetylcholine is degraded.
  • ATP binds to myosin head, releases it from actin.
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17
Q

Simple twitch

A

all or nothing response by muscle cells

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18
Q

Frequency stimulation

A

addition of multiple simple twitches before the muscle has an opportunity to relax.

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19
Q

Tetanus

A

simple twitches that occur so frequently as to not let the muscle relax at all – a more prolonged and stronger contraction.

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20
Q

oxygen debt

A

the difference between the amount of oxygen needed and the amount present

21
Q

What are two ways muscle cells can reduce oxygen debt?

A
  • Creatine phosphate can transfer a phosphate group to ADP, forming ATP
  • Myoglobin is a heme-containing protein that is a muscular oxygen reserve.
22
Q

Internal skeletons

A

endoskeletons (like in humans)

23
Q

External skeletons

A

exoskeletons (like those in arthopods

24
Q

what are the two divisions of the skeletal system?

A

Axial (midline, such as skull, vertebrae, ribcage, etc.)

Appendicular (all other, including pelvis)

25
Q

What is bone derived from?

A

mesoderm

26
Q

What are the two types of bone?

A

compact and spongy or cancellous bone.

27
Q

What is the main structure of the spongy bone?

A

trabeculae - lattice-like structure

28
Q

What are the cavities of bone filled with?

A

bone marrow

29
Q

What are the three parts of the bone from middle to the outside?

A

diaphyses - long bone shafts
metaphyses
Epiphyses - contain an epiphyseal (growth) plate that causes linear growth of the bone

30
Q

Periosteum

A

Layer of connective tissue that surrounds bone

31
Q

Tendons

A

Attaches bones to muscles

32
Q

Ligaments

A

attach bones to other bones

33
Q

Lamellae

A

concentric rings that bones are organized into

34
Q

Haversian or Volkmann’s canal

A

central canal in bones

35
Q

Structural unit of bones

A

osteon

36
Q

Lacunae

A

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

37
Q

Osteoblasts

A

build bone

38
Q

Osteoclasts

A

resorb bone

39
Q

Parathyroid hormone

A

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

40
Q

Vitamin D

A

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

41
Q

Calcitonin

A

increases bone formation, decreasing calcium concentrations in the blood.

42
Q

Cartilage

A

a firm elastic material secreted by chondrocytes

  • matrix is called chondrin
  • usually found in areas that require more flexibility or cushioning.
  • avascular and not innervated
43
Q

How do bones form in fetal life?

A

endochondral ossification. Some bones, especially of the skull, form directly from undifferentiated tissue (mesenchyme) in intramembranous ossification.

44
Q

Immovable joints

A

fused together to form sutures or similar fibrous joints.

45
Q

Movable joints

A

usually strengthened by ligaments and contrain a synovial capsule.

46
Q

Synovial fluid

A

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

47
Q

Articular cartilage

A

coats bones in joints to aid in movement and provide cushioning.

48
Q

Antagonistic pairs

A

muscles that serve opposite functions - when one contracts, the other lengthens.

MCAT Biology and Biochemistry (24 decks)

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