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MCAT BB > Muscoskeletal System > Flashcards

Muscoskeletal System Flashcards

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MCAT flashcards
1
Q

Types of muscles

A
  1. Skeletal muscle
  2. Smooth muscle
  3. Cardiac muscle
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2
Q

Skeletal muscle functions

A
  1. Support body
  2. Allow movement
  3. Compress venous structures to propel blood and lymph
  4. Shivering
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3
Q

Skeletal muscle features

A
  1. Striated due to sarcomeres
  2. Multinucleated
  3. Has red and white fibers
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4
Q

Red fibers

A

Slow-twitch.

  1. High myoglobin content (aerobic)
  2. Mostly in muscles that contract slowly but sustain activity
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5
Q

White fibers

A

Fast-twitch.

  1. Less myoglobin, so lighter in color
  2. Less mitochondria, rely more on glycolysis
  3. Mostly in muscles that contract fast, but fatigues easily
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6
Q

Smooth muscle functions

A
  1. Involuntary movement

2. Regulation of BP

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7
Q

Smooth muscle features

A
  1. Single nucleus in center of cell
  2. Contain actin and myosin, but not well-organized
  3. Capable of more sustained contractions
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8
Q

Tonus

A

Constant state of low-level contraction

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9
Q

Myogenic activity

A

Contraction of smooth or cardiac muscle without nervous system input.

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10
Q

Cardiac muscle features

A
  1. Primarily uninucleated, but many do contain 2
  2. Involuntary, but appears striated
  3. Connected by intercalated discs that have many gap junctions
  4. Relies on calcium for contraction
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11
Q

Sarcomere

A

Thick and thin filaments

  1. Z-line
  2. M-line
  3. I-band
  4. H-zone
  5. A-band
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12
Q

During contraction, what lines decrease and what stays constant

A
  1. H-zone, I-band, distance between Z-lines, and distance between M-lines become smaller
  2. A-band size remains constant
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13
Q

Myofibrils

A

Back-to-back sarcomeres attached to one another

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14
Q

Sarcoplasmic reticulum

A

Modified ER that has a high calcium concentration that surrounds myofibrils

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15
Q

Sarcoplasm

A

Modified cytoplasm of myocyte

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16
Q

Sarcolemma

A

Cell membrane. Can propagate action potential using transverse (T) tubules

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17
Q

Myocyte

A

contains many myofibrils arranged in parallel (muscle fibers). Numerous nuclei

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18
Q

Muscle

A

Many myocytes in parallel

19
Q

Muscle contraction

A
  1. Start: neuromuscular junction, nervous system communicate via efferent neurons
  2. Travel down neuron until nerve terminal, ACh released into synapse
  3. Depolarization down sarcolemma to T-tubules
  4. When action potential reaches SR, Ca released
    , which binds to troponin triggering changes in tropomyosin.
  5. Free globular heads of myosin binds to exposed sites on actin
  6. Relaxation by ACh degradation
20
Q

Role of ATP in muscle contraction

A
  1. Myosin carrying ADP + Pi bound to myosin-binding site after calcium trigger in tropomyosin structure
  2. ATP binds to myosin head, the hydrolysis into ADP releases myosin from actin
21
Q

Skeletal structure

A
  1. Axial: basic central framework - skull, vertebral column, ribcage, hyoid bone
  2. Appendcular skeleton: limbs, pectoral girdle, pelvis
22
Q

Hyoid bone

A

In anterior neck, used for swallowing

23
Q

Bone composition

A
  1. Compact bone: dense and strong

2. Spongy (cancellous) bone: spongy

24
Q

Spongy bones

A
  1. Trabeculae: bony spicules (points)
  2. Bone marrow: fills cavities between trabeculae
  3. Long bones
25
Q

Bone marrow types

A
  1. Red marrow: filled with hematopoietic stem cells

2. Yellow marrow: fat and relatively inactive

26
Q

Long bones

A
  1. cylindrical shafts (diaphyses), then metaphysis, end with epiphysis
  2. Outer part: compact, inner part : spongy
27
Q

Periosteum

A

Fibrous sheath that surrounds long bone to protect it and serve as site of muscle attachment. Need to be healthy for bone marrow

28
Q

Tendons vs. Ligaments

A
  1. Tendons: muscle to bone

2. Ligaments: bone to bone

29
Q

Review microscopic bone structure

A

Harvesian canal, lacunae and osteocyte, cannaculi, periosteum, volkmann’s canal, ostean

30
Q

Bone matrix: organic components

A
  1. Collagen
  2. Glycoproteins
  3. Other peptides
31
Q

Bone matrix: inorganic components

A

They harden together to form hydroxypatite crystals

  1. Calcium
  2. Phosphate
  3. Hydroxide ions
32
Q

Osteons/haversian systems

A

Structures of bony matrix of organic and inorganic components.

33
Q

Lacunae

A

House osteocytes

34
Q

Canaliculi

A

Allow exchange of nutrients and wastes between osteocytes, Haversian, and Volkmann’s canals

35
Q

Osteoclasts

A
  1. Macrophages of bone that reabsorb it.

2. Polynucleated

36
Q

Chondrin

A

elastic, firm matrix

37
Q

Cartilage

A
  1. Softer, more flexible than bone

2. Avascular (no blood and lymphatic vessels), not innervated

38
Q

Endochondral ossification

A

hardening of cartilage into bone

39
Q

Intramembraneous ossification

A

Undifferentiated mesenchymal tissue transformed into bone. In bones of skull

40
Q

Mesenchymal tissue

A

embryonic connective tissue

41
Q

Synovial capsule

A

enclose joint cavity (arituclar cavity)

42
Q

Synovium

A

layer of soft tissue, secrete synovial fluid that lubricate movement in joints

43
Q

Articular cartilage

A

Coats articular surfaces of the bone so that impact is restricted to lubricated joint cartilage

MCAT BB (7 decks)

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