Cardiac and Smooth Muscle

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Cardiac and Smooth Muscle

• Chrissy Benson

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Cardiac Muscle

• cardiocytescardiac muscle cells
• 10-20µm in diameter 50-100µm in length
• Single nucleus
• Myofibrils and accessory muscle contraction
  proteins to those in skeletal muscle
• Most of these are encoded by genes specifically
  expressed in cardiocytes.

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Cardiac Muscle
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Cardiac Muscle

• Contractile cells
• -pump heart
• -Do not initiate their own AP
• Autorhythmic cells
• Do not contract
• Initiate and conduct APs
• No resting potential neural input not necessary
  to initiate an AP
• Pacemaker activity instead Slow depolarization,
  drift to threshold, then firing

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Cardiac Muscle
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Cardiac Muscle
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Smooth Muscle

• Long cells
• Spindle-shaped
• Surround
• blood vessels
• digestive tract
• organs (ie. stomach, bladder uterus)

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Smooth Muscle
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Smooth Muscle

• Myofilaments of the cells are not parallel as
  they are in skeletal and cardiac muscle
• Symmetrical patterns of thick and thin filaments
  not evident
• No troponin complex

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Smooth Muscle
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Smooth Muscle

• contracts in all directions, not just linearly
• more force/cross sectional area (fewer other
  organelles)

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Smooth Muscle

• activation 
• autonomic nervous system, varicosities and
  receptors all over cell
• hormones like nor epinephrine released from
  neurons or in the blood
• connected in sheets with gap junctions so
  contractions can spread into neighboring cells
• can also be stretch activated (uterus) or
  spontaneously activated (gut)

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Smooth Muscle

• excitation/contraction
• activated by opening calcium channels on the
  cells surface, influx of extra-cellular calcium
  (small, thin cells, slow)
• calcium activates myosin and frees up actin (no
  tryptomyosin)

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Smooth Muscle
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Cardiac Muscle Disorders

• Dilated Cardiomyopathy
• -will not limit quality/duration of life
• risk of sudden death
• heart enlarges, functions poorly
• muscle becomes weak, and unable to pump blood
  efficiently causing fluid build up in the lungs,
  and results in a feeling of breathlessness
  called left heart failure.
• right heart failure causes fluid build up in the
  tissues and organs of the body (ie. legs, ankles,
  liver, and abdomen)

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Cardiac Muscle Disorders
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Cardiac Muscle Disorders

• Symptoms
• Shortness of breath
• Swelling of the ankles
• Tiredness
• Palpitations and Syncope
• Chest pain

• Causes
• Viral Infection
• Auto-Immune Disease
• Excessive alcohol consumption/exposure to toxic
  compounds
• Pregnancy
• Familial disease

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Cardiac Muscle Disorders

• Hypertrophic Cardiomyopathy
• -thickening of muscle may thicken in normal
  individuals as a result of high blood pressure or
  prolonged athletic training. In this case,
  thickening occurs without an obvious cause
• -normal alignment of muscle cells is absent and
  this abnormality called myocardial disarray

                                                                                                            
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Cardiac Muscle Disorders
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Cardiac Muscle Disorders
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Cardiac Muscle Disorders

• Symptoms
• Shortness of breath
• Chest pain
• Palpitation
• Light-headedness and blackouts

• Causes
• Dominant mutation
• myosin, troponin T, alpha tropomyosin, cardiac
  myosin binding protein-C, or the essential and
  regulatory light chains.
• important proteins for the contraction of the
  heart.

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References

• lthttp//www.apsu.edu/schillerj/Biology202010/Unit
  20Reviews/Unit20320Review/CH200920Smooth20an
  d20Cardiac20Muscle.htmgt.
• lthttp//www.cardiomyopathy.org/html/which_card_hcm
  .htmgt.
• lthttp//facstaff.elon.edu/shouse/physiology/physio
  l15/Lecture9.htmlgt.
• lthttp//www.ns.pacificu.edu/bswanson/oct_19.htmgt.
  
• Pasternak, Jack J. An Introduction to Human
  Molecular Genetics Mechanisms of Inherited
  Diseases. 2nd Edition. 2005. pp. 373 382-389.
• lthttp//www.udel.edu/Biology/Wags/histopage/colorp
  age/cmu/cmu.htmgt.