Cardiac Muscle Tissue Flashcards
(23 cards)
Where is cardiac muscle tissue found?
Only in the heart
What is the primary function of cardiac muscle?
Pumps blood into the vessels of the circulatory system
How is cardiac muscle similar to skeletal muscle?
Both are striated and organized into sarcomeres
What is the typical nucleus count in cardiac muscle fibers?
Usually one nucleus
Where is the nucleus located in cardiac muscle cells?
In the central region of the cell
What do cardiac muscle fibers possess that aids in ATP production?
Many mitochondria and myoglobin
What type of metabolism primarily produces ATP in cardiac muscle?
Aerobic metabolism
How are cardiac muscle fibers structured?
Extensively branched and connected at their ends by intercalated discs
What is the purpose of intercalated discs in cardiac muscle?
Allows cardiac muscle cells to contract in a wave-like pattern
What structures are contained within intercalated discs?
- Gap junctions
- Desmosomes
What is the role of gap junctions in cardiac muscle?
Allow depolarizing current to flow between cardiac muscle fibers
What is electric coupling in cardiac muscle?
Quick transmission of action potentials and coordinated contraction
What functional unit of contraction is created by electrically connected cardiac muscle cells?
Syncytium
What is the function of desmosomes in cardiac muscle?
Anchors the ends of cardiac muscle fibers together
What type of cells control heart rate in cardiac muscle?
Pacemaker cells
Can cardiac muscle be consciously controlled?
No
How do pacemaker cells respond to heart rate signals?
Respond to signals from the autonomic nervous system
What is the term for the self-excitable feature of pacemaker cells?
Autorhythmicity
What initiates the wave of contraction in the heart?
Pacemaker cells
What is unique about the action potentials in cardiac muscle fibers?
Relatively long action potentials with a sustained depolarization plateau
What produces the plateau in cardiac muscle action potentials?
Ca++ entry through voltage-gated calcium channels
Where does a large percentage of Ca++ that initiates contraction in cardiac muscle come from?
Outside the cell
How does the contraction duration in cardiac muscle compare to skeletal muscle?
Longer contraction duration
