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MCAT Bio > Muscular and Skeletal System (Chp 11) > Flashcards

Muscular and Skeletal System (Chp 11) Flashcards

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1
Q

skeletal muscle

A

Function: voluntary muscle - contracts in response to conscious intent
Location: on the bone
Appearance: striated

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2
Q

cardiac muscle

A

found only in wall of the heart

striated

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3
Q

smooth muscle

A

found in walls of all hollow organs (GI tract, urinary system, uterus, etc) - no conscious control bc they are only innervated by autonomic nervous system

involuntary
unstriated
uninucleate

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4
Q

(3) muscle types

A

skeletal
cardiac
smooth

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5
Q

tendons

A

attach muscles to bones

strong connective tissue formed primarily of collagen

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6
Q

Ways skeletal muscle moves (4)

A
  1. flexing - decreasing angle of joint
  2. extending - increasing angle of joint
  3. abducting - moving away from body’s midline
  4. adducting - moving toward body’s midline
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7
Q

origin vs insertion (muscle)

A 
origin = point where muscle attaches to bone 
insertion = point where muscle attaches to bone more distant from the center of the body
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8
Q

antagonistic

A

muscles that are responsible for movement in opposite directions

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9
Q

synergistic

A

muscles that move a joint in the same direction

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10
Q

fascicles

A

bundles of connective tissues that holds contractile tissue together (bundles of myofibers)

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11
Q

myofiber

A

muscle cell

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12
Q

myofibrils

A

small units within myofiber (strings of sacromere)

>gives striated appearance

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13
Q

proteins in myofibril that generate contraction

A

actin (thin filaments) and myosin (thick filaments)

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14
Q

steps of contractile cycle

A
  1. cross bridge formation - myosin head binds to myosin binding site on actin (ADP and P bound)
  2. power stroke - myosin head moves to low E conformation and pulls actin chain toward center of sarcomere (ADP released)
  3. new ATP binds for release of actin by the myosin head
  4. ATY hydrolysis occurs and myosin head is cocked (high E conformation)
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15
Q

neuromuscular junction

A

synapse between an axon terminus (synaptic knob) and a myofiber

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16
Q

acetylcholinesterase

A

hydrolyzes ACh to choline and acetyl unit

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17
Q

(2) ways to increase force of contraction (via nervous system)

A
  1. motor unit recruitment

2. frequency summation -

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18
Q

Muscle fiber types

A
  1. Slow twitch fibers

2. fast twitch fibers

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19
Q

Type 1 Slow twitch fibers

A

aka red slow twitch or red oxidative fibers because of high myoglobin content and have better blood supply than fast twitch fibers > allow to maintain contraction for extended periods without fatigue

  • slow contraction
  • low force generated
  • high mitochondria
  • v dense capillaries
  • high fatigue resistance

(these are the fibers that allow marathoners to run for hours)

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20
Q

Type 2 Fast twitch fibers

A

two subcategories

  1. Type II A - fast twitch oxidative fibers - somewhat resistant to fatigue
    - intermediate contraction
    - medium force generated
    - some mitochondria
    - medium capillaries
    - medium fatigue resistance (30 mins)
  2. Type II B - white fast twitch fibers - due to lack of mitochondira these contract very quickly with great force BUT fatigue very quickly (1 minute)
    - very fast contraction
    - high force generated
    - very few mitochondria
    - v few capillaries
    - low fatigue resistance (1 min)
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21
Q

hematopoiesis

A

synthesis of formed elements of the blood (red blood cells, white blood cells. platelets)

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22
Q

vertebrate endoskeleton components

A

axial - skull, vertebral column, rib cage

appendicular - all other bones

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23
Q

bone is an example of _____

A

connective tissue

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24
Q

types of connective tissue

A

loose - packing tissues (areolar tissue and adipose tissue)

dense - contain large amounts of fiber (tendons, ligaments, cartilage, and bone)

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25
Q

primary bone shapes

A
  1. flat (scapular, ribs, skull) - location of hematopoiesis and important for protection of organs
  2. long (limbs) - important for support and movement
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26
Q

long bone anatomy

A

epiphysis - flared end of bone
-contains spongey bone - contains red bone marrow

diaphysis - main shaft of long bone
-contains medullary cavity - contains yellow bone marrow (fat)

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27
Q

bone marrow

A

non-bony material found in shafts of long bones and in pores of spongy bones

28
Q

red marrow

A

found in spongey bone within flat bones = site of hematopoiesis
(activity increases in response to erythroprotein)

29
Q

yellow marrow

A

found in shafts of long bone - filled with fat and is inactive

30
Q

ingredients of bone

A
  1. collagen

2. hydroxyapatite - solid material consisting of calcium phosphate crystals

31
Q

ligaments

A

connect bone to other bone

32
Q

tendons

A

connect bone to muscle

33
Q

joint

A

point where one bone meets another

34
Q

synarthroses

A

immovable joints - where bones are fused together

ex: skull

35
Q

amphiarthroses

A

slightly movable joints - provide movability and support

ex: vertebral joints

36
Q

diarthroses

A

freely movable joints - all are supported by ligaments

ex: ball and socket

37
Q

synovial fluid

A

lubricate movable joints

38
Q

endochondral ossification

A

hyaline cartilage is produced and then replaced by bone

39
Q

intramembranous ossification

A

synthesis of bone from an embryonic tissue called mesenchyme

40
Q

osteoblasts

A

cells that make bone by laying down collagen and hydroxyapatite
-synthesize bone until it is surrounded by bone > now called an osteocyte and space it resides in is called a lacuna

41
Q

PTH (parathyroid hormone)

A
  • stimulates osteoclast activity
  • effect on kidney: increases reabsorption of calcium and stimulates conversion of vitamin D into calcitriol
  • effect on intestines: indirectly (via calcitriol) increases intestinal calcium absorption

> stimulates bone breakdown
increases blood calcium

42
Q

Calcitriol

A

effect on bones: may stimulate osteoclast activity (but minor)
effect on kidney: increases reabsorption of phosphorous, decreases CA
effect on intestines: increases absorption of CA

> stimulates bone formation
decreased blood calcium

43
Q

calcitonin

A

effect on bones: inhibits osteoclast activity

effect on kidneys: decrease reabsorption of calcium

44
Q

osteoclast

A

continually destroy bone by dissolving hydroxyapatite

45
Q

actin

A

think filament

46
Q

myosin

A

thick filament

47
Q

muscle heirarchy

A

protein filaments (actin and myosin) > sarcomere (unite of contraction) > myofibril (string of sarcomeres) > muscle cell (bundle of myofibrils) > fascicle (bundle of muscle cells > while muscle

48
Q

sarcomere regions

A

H: just myosin
I: just actin
A: overlap of myosin and actin and just myosin section

H and I region decreased during muscle contraction

49
Q

what is characteristic of power stroke in muscle contraction

A

release of ADP > myosin returns to low E state

common mistake is that this uses ATP when it doesn’t

50
Q

in absence of ATP muscle can’t ___

A

relax

think of rigor mortitis

51
Q

muscle excitation-contraction coupling

A

dependent on CA

  • tropomyacin - covers myocin binding site on actin
  • troponin - when bound to CA causes conformational change on tropomyacin that reveals myocin binding sites

> myosin binds to actin > contraction

52
Q

Muscle E sources (3)

A
  1. creatine + ADP > creating + ATP (short and explosive)
  2. glycolysis > 2 net ATP and lactic acid (3-4 minutes)
  3. aerobic respiration > 30 ATP, CO2, and H20 (slow but most E)
53
Q

hemoglobin shifts L/R when Bohr conditions present

A

Right
increased CO2
increased T
decreased pH

CO2 + H2O = H2CO3 = H+ + HCO3-

54
Q

“___“-blast

A

immature cell that still divides
produces matrix
ex: osteoblast (bone) and condroblast (cartilage)

55
Q

“____“-cyte

A

mature cell that usually doesn’t divide

maintains matrix

56
Q

matrix components

A

fibers

  • collogen - strong
  • elastic - recoil

glob (ground substance)

  • liquid (blood plasma)
  • solid (bone)
57
Q

osteon

A 
unit of compact bone 
cross section shows:
-bone in concentric rings
-central canal 
-osteocytes - dormant not dead >needs waste exchange> has elaborate tunnel system between each other and central canal forming caniculi
58
Q

describe inspiration during ventilation

A

contract diaphragm
> increases size of chest cavity
> decreases pressure
>air rushes in

59
Q

describe relaxed expiration of ventilation

A

relax diaphragm
> decrease chest cavity size
> increase pressure
> air pushed out

60
Q

skin layers

A
  1. epidermis - made of epithelial tissue
  2. dermis - connective tissue
  3. hypodermis - fat
61
Q

epidermis

A

made of epithelial tissue

top layer

62
Q

dermis

A

connective tissues of skin

63
Q

hypodermis

A

fat layer of skin

64
Q

thermoregulation when cold weather

A

no sweat
shiver
vasoconstriction - diverts blood to core and away from skin surface

65
Q

thermoregulation when hot weather

A

activate sweat glands to cool body with evaporative cooling
no shivering
vasodilation - bring blood to surface

66
Q

sarcoplasmic reticulum

A

storage unit for calcium

67
Q

alveolar pnuemocytes

A

type 1 - walls of alveoli

type 2 - produce surfactant (soapy substance) that reduces surface tension > keeps alveoli open

MCAT Bio (6 decks)

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