Muscular System

1
Muscular System

• Read Ch 6
• Review Questions begin on page 198
• S/A 2, 7, 10, 12, 18, 20, 21
• At the Clinic 2, 5, 6

2
Overview

• Over ½ of bodys mass is muscle90 of that is
  skeletal muscle
• These contractile cells have high energy needs,
  so its common to see an ample blood supply
  associated with muscles

http//www.edukshun.info/wp-content/uploads/2008/0
4/big-muscles.jpg
3
Overview cont

• Blood provides glucose and oxygen while removing
  metabolic waste products
• Muscles (and nervous tissue) consume almost 70
  of the food energy taken into your body daily
• Muscle is as intensive a consumer of calcium as
  is the skeletal systemmuch of the Ca stored in
  bones is made available for the muscles needs.

4
Categorizing muscles

• Microscopically
• Nonstriated (no lines)
• Striated (lines running through)

5
Categorizing muscles

• Controllability
• Involuntary (no control)
• Voluntary (control)

6
Categorizing muscles

• Location
• Cardiac Involuntary, only found in heart
• Smooth Involuntary, lines digestive organs
• Skeletal voluntary muscles found attached to
  bones

7
Functions of the Muscular System

• Movement of body partsby pulling on bones.
  Bones act as levers, joints as the fulcrum.
• Guard entrances and exits
• Posture
• Stabilizing joints
• Create heat

8
Physiology of muscle

• Contraction is achieved by the simultaneous
  shortening of all the sarcomeres within a cell.
• Three stages
• Neural stimulation
• Contraction
• Relaxation.

9
Neural Stimulation

• Takes place at the neuromuscular junction.
• The nerve cell releases a neurotransmitter

• neurotransmittera chemical used for cell to cell
  communication.

http//www.freewebs.com/soaring_sphincter_travel_a
gency/nerve20impulse2.bmp
10
Neural Stimulation

• Muscles respond to the neurotransmitter
  acetylcholine (Ach).
• Ach binds to receptors on the sarcolemma.
• The binding of Ach affects the transport of ions
  across the sarcolemma

www.cells.de/.../Neuromuscular-junction.jpg
11
Neural Stimulation

• In a resting muscle, the concentration of sodium
  ions is normally higher in the fluid outside the
  muscle cell while the concentration of potassium
  ions is higher inside the cell.
• Sodium/potassium pumps maintain these unequal ion
  concentrations.

upload.wikimedia.org/wikipedia/commons/thumb/...
12
Neural Stimulation

• This imbalance produces an unstable condition.
  When stimulated by Ach the membrane loses its
  ability to maintain the imbalance.
• Once the membrane is stimulated, it opens the ion
  channels permitting the free flow of sodium into
  the muscle cell and potassium out of the cell.
• In turn, calcium stored in the sarcoplasmic
  reticulum is released to begin the contraction
  phase

13
Muscle Contraction
www.cvphysiology.com

• When calcium (released by the sarcoplasmic
  reticulum) binds to the troponin, contraction
  begins.
• Troponin sits on tropomyosin on the same region
  where actin binds to myosin.

14
Muscle Contraction

• Ca bumps troponin off the binding site,
  permitting myosin to attach to actin.
• Troponin also transmits info that activates ATP
  synthesis around the myosin. The ATP provides
  energy for the myosin head to swivel and pull the
  myosin toward the actin.

15
Myosin crossbridges at work
16
http//www.patrickcarlberg.dk/images/thinfilament.
jpg
17
Muscle Relaxation

• Relaxation occurs when there are no more neural
  stimulations exciting the sarcolemma. The sodium
  and potassium ion levels are completely recovered
• The sarcoplasmic reticulum has retrieved most of
  the Ca, causing the release of the myosin heads
  from the actin.
• There is no mechanism for the muscle cell to
  lengthen (so well discuss how that happens later
  in the lecture).

18
Squinting
Stimulus
Receptor
Sensory Nerves
Light reduced
Motor Nerves
Effectors
Regulator
19
Video links

• http//www.hippocampus.org/Biology
• search for Biology for AP/Skeletal Muscle
  contraction
• Crash courseMuscles http//www.youtube.com/watch?
  vjqy0i1KXUO4
• Bozeman ScienceMuscles http//www.youtube.com/wa
  tch?vmejCXr7p37UlistPLCC2DB523BA8BCB53index17
  

20
Neural Stimulation Videos

• https//www.youtube.com/watch?v0mhAN4-8uWo
• https//www.youtube.com/watch?vuJTdx1GbEqUnoredi
  rect1
• http//www.youtube.com/watch?vhzXVe4RS8-A

21
Muscular Contraction videos

• http//www.youtube.com/watch?vBMT4PtXRCVA
• https//www.youtube.com/watch?vzopoN2i7ALQ
• https//www.youtube.com/watch?vf0mDFP7qn1Y

22
Animations

• http//www.wisc-online.com/objects/ViewObject.aspx
  ?IDAP2904
• http//highered.mcgraw-hill.com/sites/0072437316/s
  tudent_view0/chapter42/animations.html

23
Contraction in Action

• Planning your skit

24

• http//3dotstudio.com/contract.gif

25
http//media-2.web.britannica.com/eb-media/36/2836
-004-C63246A5.gif
26
Contraction in Action--Skit

• Links to put on website
• http//www.youtube.com/watch?vEdHzKYDxrKc
• http//www.youtube.com/watch?vmWPmUqRZYls
• http//www.youtube.com/watch?ve3Nq-P1ww5E

27
Muscle cell structure

• Animation of entire process
• Video of sarcomere shortening

28
Review

• Nerve impulse arrives at muscle cell
• Ca2 released from SR into sarcoplasm
• Ca2 combines with troponin molecules in the
  thick filaments of myofibrils (Myosin)
• Troponin without Ca2 doesnt interact like this
• Myosin interacts with Actin and pulls toward
  center
• Contraction of muscle
• Animation of entire process

29
Other factors found in muscle fibers ensuring
adequate muscle contractions

• Creatine Phosphate stores energy in muscle
  cells. It collects this energy from ATP and is
  capable of storing it for long periods of time.
• Glycogen (stored form of glucose) can supply
  glucose when muscles cells need it to produce ATP
• Myoglobin is a chemical that stores oxygen for
  certain muscle cells. This O2 permits muscle
  cells to provide large amounts of ATP during
  continuous or heavy work.

30
Muscle Attachment Fibers

• Tendonsconnect muscle to bone (cordlike)
• Aponeurosesconnect muscles to muscles
  (sheetlike)

31
Musculature terms

• Originfixed end (proximal end of bone)
• Insertionmoveable end (distal end of bone)

www.scielo.cl/.../ijmorphol/v25n4/fig37-01.jpg
32
Skeletal Muscle Action

• Muscle cells either contract or dontso we get
  graded effects based on contraction of more
  individual fibers at the same time.
• Strength is achieved by stimulating more
  individual fibers to fire
• Endurance is achieved by producing contraction
  and relaxation groups working together.

33
Skeletal Muscle Action

• Antagonistic effects occur when one muscle
  opposes or resists the action of another
  muscle.if nothing else, your muscles are acting
  against the antagonistic force of gravity
• The antagonistic actions are essential for
  pulling the relaxed muscle cells back to their
  original length.

34
Skeletal Muscle Action

• Synergistic effects occur when muscles work
  together to produce a common end resultthe
  muscles of the forearm work synergistically with
  the muscles of the fingers to produce a fist.

http//www.dkimages.com/discover/previews/779/7628
9.JPG
35
5 golden rules of skeletal muscle
http//www.omnism.com/om/images/golden-rule.jpg

• All muscles cross at least one joint
• Typically the bulk of the muscle lies proximal to
  the joint crossed
• All muscles have at least two attachments, the
  origin and the insertion
• Muscles can only pull they never push
• During contraction, the muscle insertion moves
  toward the origin

36
Body Movements

• Flexordecreases the angle of the joint by
  bringing the bones closer together
• Extensorextends a joint by increasing the angle
  between the bones

37
Body Movements

• Rotatormovement around an axis (partway around)
• Tensorimportant posture/positioning muscles that
  make a body part more rigid or tense.

38
Body Movements

• Abductionmoving away from the midline
• Adductionmoving toward the midline

39
Body Movements

• Depressorproduce a downward movement
• Levatatorprovide an upward movement
• Sphincterdecreases the size of an opening

www.mda.org
www.cescg.org
40
Special Movements

• Pronatormotion of palm downward
• Supinatorpalm moves upward

41
Special Movements

• Inversionturning the sole of your foot medially
• Eversionturning the sole of your foot laterally

42
Special Movements

• Dorsiflexionpointing your toes up toward your
  shin
• Plantar Flexionpointing your toes downward

43
Muscular System

• Pathologies

44
Rigor Mortis

• Calcium leakage out of the sarcoplasmic reticulum
  into the sarcomere. Common after death.
  Eventually, the muscle cells structures start to
  decay, causing the muscles to become soft and
  loose.

45
Strain

• Most common muscle ailment
• An injury due to overworking the muscles force
  on the joints.
• Injury to the tendon or muscle tissue

http//www.nlm.nih.gov
http//www.fairview.org
46
Sprain

• A sprain is an injury to a ligament. (A ligament
  is a thick, tough, fibrous tissue that connects
  bones together.)
• Ligaments prevent abnormal movements. When too
  much force is applied to a ligament they can be
  stretched or torn.

www.eorthopod.com
47
Contusion

• Bruising of the muscle

www.bruisepatch.com
48
Muscle Spasms

• Involuntary, abnormal contractions of a muscle or
  muscle group
• Caused by a wide range of medical conditions

www.cure-back-pain.org
49
Muscle Cramp

• Painful contraction of a muscle
• Extreme muscle exertion is the most common cause
  of cramps, although certain poisons and bacterial
  infections can also cause muscle cramping

www.answers.com
50
Paralysis

• Complete failure of a muscle function
• Rigid paralysisexcessive muscle stiffness
• Flaccid paralysiscomplete lack of muscle
  contraction
• Many causesincluding spinal injury and poisoning
• Eg Tetanus--Caused by soil bacteria that
  produces poisons that cause rigid paralysis

51
Dermatomyositis

• Inflammation of the muscle and overlying skin.
• Cause unknown, but it can be treated with drugs
  (to reduce inflammation) and sun avoidance

www.nytimes.com
52
Muscular dystrophies

• Group of conditions that involve progressive
  weakness in the voluntary muscles.
• Usually due to the inability of the nervous
  system to stimulate muscle action
• Eventually results in muscle atrophy and wasting.

esciencenews.com
53
Tetany

• Calcium imbalance disease that causes extended
  periods of spasms in the arm and leg muscles.
• Do NOT confuse this with the bacterial disease
  tetanus!

54
Cachexia

• Type of muscle loss associated with diseases such
  as AIDS and cancer.

• Also found in starvation and a common consequence
  of anorexia and bulimia

www.aids-images.ch
55
Cachexia

• A slower form is a normal consequence of aging
  b/c the body reduces its ability to rebuild
  muscle structure as you age.
• Brought about by sedentary lifestylesresulting
  from other age related illnesses
• Neural stimulation also is lessened as you age
  important for muscle upkeep

56
Nutritional issues with muscle loss

• Protein turnover muscles need lots of protein to
  maintain their integrity
• Malnutrition and undernutrition as we age greatly
  affects protein turnover.
• Can be caused by poor diets or income levels
• Lack of appetite as we age is another
  contributing factor
• As we age, our digestive system cant absorb some
  of the impt amino acids needed for muscle cell
  growth/maintenance.

57
Muscle atrophyother causes

• Decline in sex hormones and other chemical
  messages needed for muscle cell growth,
  maintenance and repair.
• Insulin-like growth factor-1 known to lessen
  with maturity
• Cytokines cause muscle atrophy and are known to
  increase with age