What are the chracterstics of cardiax muscle
Answers
Answer:
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Explanation:
Cardiac muscle cells are found only in the heart, and are specialized to pump blood powerfully and efficiently throughout our entire lifetime. Four characteristics define cardiac muscle tissue cells: they are involuntary and intrinsically controlled, striated, branched, and single nucleated.
Answer:
Characteristics of Cardiac Muscle:
Histology:
1. Size and Shape:
Short cylindrical, rectangular in longitudinal section, polyhedral in transverse section.
2. Striations:
Both longitudinal and transverse.
3. Sarcolemma:
Present and complete.
4. Nucleus:
Single and central.
5. Sarcotubular System:
Present but without terminal cisternae. T-system is more prominent and present at Z-line (in mammals).
6. Branch:
Multiple branches. In all directions three dimensional network without cytoplasmic continuity (false syncytial appearance).
7. Cell-to-cell Conduction:
Through specialised areas of intercalated use.
Properties:
1. Rhythmicity:
Present and characteristic.
2. Conductivity:
Slower, different in different parts.
a. All-or-None Law:
True for the whole heart, because of functional syncytium.
3. Contractility:
Characteristic muscle curve. Contraction, longer than relaxation.
4. Refractory Period:
Longest, whole contraction period is absolute refractory.
a. Tetanus:
Impossible
b. Fatigue:
None. Long refractory period ensures recovery.
5. Tonicity:
Independent of nerve.
Composition:
1. Protein:
Less.
2. Glycogen:
More.
3. ATP and Phosphagen:
Present.
4. Carnosine:
Less.
5. Fats:
More phosphatides and cholesterol than in other
6. Inorganic:
Na/K-1/2 i.e., more Na Ca++
Action of Ions:
1. Sodium:
Initiates and maintains heartbeat.
2. Calcium:
Increases strength of contraction and duration of systole.
3. Potassium:
Inhibits contraction and produces relaxation.
Metabolism:
1. Carbohydrates:
a. Lactic Acid:
Completely and more readily than glucose.
b. Glycogen:
Increased.
2. Blood Supply and O2 Consumption:
High.
Distribution:
Only in heart.
Control:
Not so, involuntary.
Nerve Supply:
Same as in involuntary.
Explanation:
Cardiac muscle is characterized by striped muscle fibers, connected together by intercolated disks, where the membranes are specialized to allow electrical signals to pass easily. Like smooth muscles, cardiac muscles can remain in contraction for a sustained period. Like skeletal muscles, cardiac muscles also contract quickly.
The formation of contractile proteins in cardiac muscle cells also allows for stronger contractions when the fibers are stretched, which makes the heart pump more efficiently.