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SUMPHYS2 > NEURO-Skeletal Contraction and Dystrophies > Flashcards

NEURO-Skeletal Contraction and Dystrophies Flashcards

1
Q

What is purpose of our muscles?

A

40% of body, move bones. 1. Only shortens- Antagonist contract/shorten to stretch agonist

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2
Q

How are msk packed?

A

Fascia- skeletal muscle -perimysium -epimysium- fascicle myofibrils: cells contractile proteins bundles into fibers.

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3
Q

The membrane of a musle cell is called?

A

Sarcolemma. Sacroplasmic reticulum stores calcium

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4
Q

What are the two long F polymers strands coiled around each other that are attached to z-disk w/in sacromere?

A

ACTIN- Thin filament

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5
Q

This structure is multple protein wraped around actin?What is ontop of this structure? What does it cover

A

Tropmyosin- cover G-actin active site ADP. Troponin is on top of tropomyosin

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6
Q

This structure has two helical proteins composed 6 polypetide chains as a tail with two head groups to as attachment sites?

A

MYOSIN-THICK

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7
Q

How is a fiber innervated?

A

Contraction begins with a nerve stimulation, 1 nerve does not stimulate all fibers. Paralle stack, not like cardiac. Contracts different fiber diff times

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8
Q

Individual nerve fiber and all the muscles that are innervated by it?

A

motor unit- LARGE groups have fewer motor units, less fine tuning. SMALL group-hand, have more motor units smaller

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9
Q

This space is where the neuron sits in the synaptic gutter in the sarclema which is folded w/ ACH receptor?

A

Neuromuscular juntcion

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10
Q

What ion is used to release NT into the synpatic gutter?

A

Ca

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11
Q

What is release in the NMJ and binds to ligand channel gated channel on the motor end plate (aka postsynaptic).

A

2 ACH create + charge, opens a Na, for influx thus moving potential to Na reveral potential for an AP

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12
Q

This AP caused what to happen in the sarcoplasma reticulum?

A

Release calcium storage- Na cause AP of nerve__Ca influx in nerve cell__vesicles move to synapse to release NT__ACH__ACH bind to post synaptic membrane on MSK___+charge opens Na on MSK membrane__AP d/t reversal potential of Na__cause SR to release calcium___Ca initiates tension/contraction

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13
Q

What is made up of tropoin and where are its attachment sites?

A

3 protein units- Ti- ACTIN, TT-tropomyosin, TC-calcium

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14
Q

At rest where is the tropomyosin/tropoin proteins?

A

Covering G-actin ADP active site on actin

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15
Q

What causes myosin head to attach to actin?

A

NA AP released Ca from SR. Ca binds to TC__ Changes structure pulls tropomyosin off binding site__ATP binds to myosin head__Binding creates Hydrolysis ATP to ADP myosin OPEN state__myosin attaches to G-actin site__ADP get kicked off___another shape change__ pulls actin closer__ATP bind again to kick off myosin__resets

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16
Q

What pulls the Z-disk together?

A

ATP helps Bending of the myosin heads attached on actin. Hydolyis forms ADP+P

17
Q

Why is max force 110% of sacromere length?

A

Normal resting length is max tension developed.
Shortened/compressed- tension limits force b/c z-disk block by myosin ends.
No cross bridges at myosin center= no force generation Lengthen to far- actin cant bind to myosin

18
Q

What is work?

A

Load x Distance move. Greater load, greater velocity

19
Q

What is the meaning of life?

A

Phosphorylation. Creatine from arginine kidney, made in liver. Creatine phosphate stored in muscle. Fast but short lived. 4m/sec

20
Q

What is ideal energy source but long to develop, and last longer bc produce 6xmor ATP?

A

Oxidative phosphorylatin from food. Glycolysis=INC ATP

21
Q

What are types of tension development?

A
  1. Isometric-Tension=load no change in length.
  2. Isotonic- Tension >Load
  3. Lengthening= Tension < load, heavy
22
Q

WHat fiber fatigues faster, larger, strong, Large SR, fast ion release, INC enzymes, blood supply reduced, fewer mitochondria?

A

FAST twitch

23
Q

What fiber less fatigue, more mitochondria, more blood supply, large myoglobin, depends on sugars and oxidatavie phosphy, generate more tension?

A

Slow twitch

24
Q

What motor units are more excitable?

A

Spatial summation- space multiple units. Smaller unit contract 1st, but as signal grows large kick in. Smooth movement d/2 alternating various units

25
Q

What is state of sustained contraction over time?

A

Tetanus- temporal frequency summation. Every moment

26
Q

What occurs during period of rest within sarcoplasmic retiuc that influence strength of contraction?

A

Stepwise rest periods show inc in Ca with each rest

27
Q

What contriubute to mucle tone at rest?

A

Slow level of release of Ach from low baseline rate of nerve impulses. Provides bulk via trophic effect. IE Cerebral palsy-tonic contracture protective, UMN

28
Q

What occurs with loss of glycogen storage resulting in loss of strength/tension/contraction?

A

Fatigue- transmission of nerve also reduced with prolonged stimulation. Less ACH, Less CA, less strength IE. do PE neuro once

29
Q

Muscle apply tension at insertion on bone, this creates what type of system?

A

Lever system- force related to distance from fulcrum and length of lever arm. If LONG lever arm, close load to fulcrum= less force generation, easy

30
Q

What occurs with muscle hypertrophy?

A

fibers larger, more enzymes,

new sarcomeres with size of stretch fiber

31
Q

What does muscle atrophy take place?

A

Fatigue- the more stimulation the more burning thru glyco stores
IF lose ACH, lose trophic effect
Denervation Starts immediately BUT cannot see til late.

32
Q

What occures with denervation?

A

Fibers destroyed replaced with fibrous scar or fat.

Neighbors motor units can sprout, but loss dexterity

33
Q

What is characteristic of mixed muscle atrophy, hypertrophy, fiber replaced with scar and fat material, progressive in weakness as MC SX?

A

Dystrophies >30. 1. Mostly boys. 2Onset 3-5y. 3.Walk on tip toes 4. clumsy. Runs awkward. Fall often. 5. Walks up from seated position. 6. Lordosis

34
Q

This disorder requires dystophin- msk structure, but is inhertibly abscent?

A

Duchenne MD Onset 3-5yo. Most cant walk by age 12.

35
Q

This disorder is less severe form of dys dystophin

A

Becker MD

36
Q

This MD slowly progressive disorder of face, arms, shoulder beginning in teen?

A

Fascioscapulohumeral

37
Q

MC adult form characterized by cardiac abnormalities and cataracts, swan neck (from inability to support the weight of the head), drooping eyelids

A

Myotonic

38
Q

What is most life threatening of MD?

A

Heart and breathing muscles get weak- Child usually dies before age 20 from heart failure or pneumonia.

SUMPHYS2 (27 decks)

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