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Pathophysiology > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

skeletal muscle fiber characteristics

A

large, multinucleate cells that appear striped or striated under the microscope.

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2
Q

Cardiac muscle fiber characteristics

A

also striated but they are smaller, branched, and uninucleate. Cell sare joined in series by junctions called intercalated discs, which help transmit rapid signaling.

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3
Q

satellite cells

A

multi potent cells that eventually differentiate into muscle cells.

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4
Q

skeletal muscle breakdown

A

made of several muscle fascicles which are bundles of muscle fibers.

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5
Q

Muscle Cell ::___

A

muscle fiber

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6
Q

cell membrane ::__

A

Sarcolemma

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7
Q

Cytoplasm ::__

A

Sarcoplasm

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8
Q

Endoplasmic reticulum ::__

A

Sarcoplasmic reticulum

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9
Q

T Tubules

A

extensions of the cell membrane (sarcolemma)that associate with the ends (terminal cisternae) of thesarcoplasmic reticulum. brings actionpotentials into interiorof muscle fiber.

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10
Q

Sarcoplasmic reticulum

A

stores Ca2+

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11
Q

Thick filaments

A

~ 250 myosin molecules join to create a thick filament

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12
Q

Thin filaments

A

Actin is a protein that makes up thin filaments.

Multiple single actin molecules (G-actin) line up to form F-actin filaments; in skeletal muscle, 2 F-actin polymers twist together to create thin filaments

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13
Q

Myofibril structure

A
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14
Q

I band

A

Z disc is in the middle

contains actin only

from one myosin/actin overlap to another, with actin the only thing in the middle

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15
Q

A band

A

from I band to I band

edges contain actin and myosin overlap

H zone in the middle

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16
Q

H zone

A

Myosin only

in the middle of the sarcomere

edges are where myosin/actin overlaps are

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17
Q

M Line

A

Smack dab in the middle of the sarcomere

Myosin linked with accessory proteins

In the middle of the H band

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18
Q

Z disc

A

the Z shaped line that occurs when titin:Actin: titin connects with Actin:Actin

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19
Q

Titin

A

a giant accessory protein that spans the distance from one Z disc to the neighboring M line

Provides elasticity and helps align myosin

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20
Q

Nebulin

A

a giant accessory protein that lies along the thin filament and attaches to a z disc.

Does not extend to the M line.

It helps align actin

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21
Q

muscle tension

A

•force created by muscle contraction

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22
Q

Load

A

weight or force opposing contraction

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23
Q

Contraction

A

•creation of tension in muscle

(requires ATP)

24
Q

Relaxation

A

•release of tension caused by a contraction

25
Q

strucutre of sarcomere during contraction

A

sarcomere shortens during contraction, as actin and myosin slide past one another

the H zone and I band both shorten

The A band remains the same size

26
Q

During relaxed state …

A

Myosin head is cocked

Tropomyosin partially blocks binding site on actin

Myosin is weakly bound to actin

27
Q

In rigor state…

A

Myosin is bound to G protien on actin.

No ATP or ADP is bound to myosin

This is very brief!

Ends when ATP binds to myosin, which releases myosin from G protein

28
Q

myosin head re-cocking

A

Myosin hydrolyzes ATP –> ADP. The energy released rotates the myosin head back to a cocked position, where it weakly binds/associates with the actin G protein.

29
Q

Power stroke

A

myosin:ADP is weakly associated with actin G protien.

Ca signal comes in, and Ca binds to Troponin–> this makes tropomyosin shift, exposing the binding site on Actin

Myosin binds strongly to actin, and actin shifts.

This is the power stroke.

Myosin releases ADP at the end of the stroke.

30
Q

Motor end plate

A

a
region of muscle membrane that
contains high concentrations of
ACh receptors.

31
Q

The neuromuscular junction

A

consists of axon terminals, motor end plates on the muscle membrane, and Schwann cell
sheaths.

32
Q

To end a muscle contraction, Ca2+ needs to be removed from the sarcoplasm…

A
  1. Ca-ATPase pumps Ca back into the sarcoplasmic reticulum
  2. overallt decreas of Ca concentration causes Ca to unbind from troponin

3.

33
Q

Excitation- Contraction coupling

A

End plate potential–> twitch–> latent period

34
Q

End plate potential

A

caused by depolarization at the muscle

35
Q

Muscle twitch

A

A single contraction- relaxation cycle

36
Q

latent period

A

•the short delay between the muscle action potential and beginning of muscle tension development
–this represents the time required for calcium release and binding to troponin

37
Q

slow twitch fiber

A

•Rely primarily on oxidative phosphorylation

Darker in color, fatigue less easily.

Marathon runners have more slow twitch

38
Q

fast twitch fiber

A

–Develop tension faster
Split ATP more rapidly

Rely primarily on anaerobic glycolysis

•Use oxidative and glycolytic metabolism

Lighter in color- fatigue more easily.

Sprinters have more fast twitch fibers.

39
Q

Length- tension relationship

A

There is an ideal resting tension of the actin and myosin filaments. Anything greater or lesser than the optimal length is going to decrease the ability of the fiber to contract to its fullest potential.

40
Q

Summation

A

Stimuli closer together do not
allow muscle to relax fully

41
Q

unfused tetanus

A

many small rapid contractions are happening and summating to the point where they are at their maximum tension. There are small wave breaks.

42
Q

complete tetanus

A

Muscle reaches steady tension. If muscle fatigues, tension decreases rapidly.

43
Q

motor unit

A

one motor neuron and all the muscle fibers it innervates. A muscle may have many motor units of different types

44
Q

contraction force

A

•Recruitment of additional motor units by the nervous system increases contraction force
•Asynchronous recruitment of motor units helps avoid fatigue
–Different motor units take turns maintaining tension

45
Q

isotonic contraction

A

concentric action creates a shortening

eccentric action creates a lengthening

isotonic contraction creates a force to move a load

46
Q

isometric contraction

A

the muscle isnt changing in size.

creates a force, without moving a load

47
Q

bones form ___

A

levers

48
Q

joints form ___

A

Fulcrums

49
Q

relaxed phasic smooth muscle contraction graph

A

Example: esophagus

50
Q

Cyclicly contracting phasic smooth muscle

A

like the intestines

51
Q

Tonic smooth muscle that is usually contracted

A

ex: a sphincter that relaxes to allow material to pass

52
Q

tonic smooth muscle with varied contraction

A

ex: vascular smooth muscle

53
Q

Single unit smooth muscle cells

A

connected by gap junctions- allows muscles to act as one functional unit.

ex: Contracting uterus

54
Q

multi-unit smooth muscle cells

A

are not electrically linked.

each cell has to be stimulated independently.

ex: eyeball

55
Q

smooth muscle properties

A

acts slower

uses less energy

one nucleus

not arranged in sarcomeres

controlled by ANS

More actin, less myosin

no Troponin

No t-tubules–> caveolae

Ca2+ from the extracellular fluid initiates a cascade ending with phophorylation of myosin light chain and activation of myosin ATPase

Pathophysiology (8 decks)

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