heart muscle

• How many different tissues are found within the heart?

  Three
• What are the three types of tissues within the heart?

  • Cardiac muscle tissue
  • Skeletal muscle tissue
  • Smooth muscle tissue
• What is the arrangement of cardiac muscle cells?

  They are branching cells that connect closely to each other

  
• What sources of calcium do cardiac muscle cells utilize for contraction?

  From the sarcoplasmic reticulum and extracellular fluid

  
• What specific proteins are involved in cardiac muscle contraction?

  Tropomyosin and Troponin

  
• How is the contraction of cardiac muscle tissue controlled?

  It is involuntary and not under voluntary control
• Where is cardiac muscle tissue exclusively found?

  In the heart
• What is the structure of cardiac muscle cells?

  They are striated branching fibers interconnected by intercalated discs

  
• What happens when one cardiac muscle cell contracts?

  The adjacent cells also contract
• How many nuclei are typically found in cardiac muscle cells?

  One or two nuclei
• What proteins are present in cardiac muscle cells that are important for contraction?

  Actin and Myosin

  
• How does contraction in cardiac muscle compare to skeletal muscle?

  Contraction occurs in the same manner as in skeletal muscle
• Why do cardiac muscle cells have many mitochondria?

  Because contraction depends on aerobic metabolism
• Are all cardiac muscle cells innervated by nerves?

  No, not every cardiac muscle cell is innervated
• What is the role of the T-tubule system in cardiac muscle cells?

  It relates a lot of calcium which is key for contraction

  
• How developed is the sarcoplasmic reticulum in cardiac muscle tissue?

  It is poorly developed compared to skeletal muscle
• What determines the strength of cardiac muscle contraction?

  The influx of calcium from extracellular space and the sarcoplasmic reticulum

  
• What are intercalated discs in cardiac muscle tissue?

  Membrane junctions that hold adjacent cells together

  
• What is the function of gap junctions in cardiac muscle cells?

  They allow interchange and communication between connected cells

  
• What types of junctions are found in intercalated discs?

  Gap junctions, desmosomes, and fasciae

  
• How does calcium flow between cardiac muscle cells?

  Through junctions that allow calcium to flow from cell to cell
• What are the three major types of cardiac muscles?

  1. Atrial muscle
  2. Ventricular muscle
  3. Specialized excitatory and conductive muscle fibers
• What are autorhythmic cells in the heart?

  Cells that produce electrical impulses to help contract the heart
• What is the role of pacemaker cells in the heart?

  They set the rhythm of electrical excitation
• Where are pacemaker cells located in the heart?

  In special spaces throughout the heart
• What is the sequence of pacemaker activity in the heart?

  SA Node → AV Node → Bundle of His → R&L bundle branches → Purkinje fibers

  
• What is autorhythmicity in cardiac muscle?

  The ability to generate and discharge an electrical impulse without external stimulation
• What is excitability in cardiac muscle cells?

  The ability of the cell to respond to an electrical impulse

  
• What is conductivity in cardiac muscle cells?

  The ability to transmit an electrical impulse from one cell to the next
• What is refractoriness in cardiac muscle cells?

  The inability to initiate another action potential for some duration of time
• What percentage of cardiac muscle cells are contractile cells?

  99%
• What is contractility in cardiac muscle cells?

  The ability of the cell to contract in response to stimulation

  
• What is extensibility in cardiac muscle cells?

  The ability of the cell to stretch
• What are the two functional syncytia in the heart?

  • Atrial syncytium: walls of the two atria
  • Ventricular syncytium: walls of the two ventricles
• What does the all-or-none response mean in the context of cardiac muscle contraction?

  Either both atria contract, or both do not contract at all
• How does the division of the heart into two functional syncytia benefit its function?

  It allows the atria to contract a short time ahead of the ventricles
• What separates the atria from the ventricles in the heart?

  Fibrous tissue
• What is the conducting system of the heart composed of?

  • Modified cardiac muscle cells
  • Sequence:

  1. Sinoatrial Node (SAN)
  2. Atrioventricular Node (AVN)
  3. Bundle of His
  4. R and L bundle branches
  5. Purkinje fibers

  
• What is the role of pacemaker cells in the conducting system?

  They generate electrical impulses that initiate heartbeats

  
• What is the significance of autorhythmicity in cardiac muscle?

  It allows the heart to contract rhythmically without external stimulation