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Aug 27
Cardiac muscle is a type of muscle tissue that is found in the walls of the heart. It is striated, meaning it has a striped appearance under a microscope, and is involuntary, meaning it contracts without conscious control. Cardiac muscle is responsible for pumping blood throughout the body and is highly specialized to perform this function efficiently.
Unlike skeletal muscle, which is under voluntary control, cardiac muscle cells are interconnected by intercalated discs, which allow for rapid communication between cells and coordinated contraction of the heart. This allows the heart to beat in a synchronized manner, pumping blood effectively to all parts of the body.
Cardiac muscle cells have a high density of mitochondria, which provide the energy needed for the constant contraction and relaxation of the heart. They also have a unique ability to generate their own electrical impulses, allowing the heart to beat rhythmically even in the absence of external stimulation.
Overall, cardiac muscle is essential for maintaining the circulation of blood throughout the body and is a key component of the cardiovascular system.
Unlike skeletal muscle, which is under voluntary control, cardiac muscle cells are interconnected by intercalated discs, which allow for rapid communication between cells and coordinated contraction of the heart. This allows the heart to beat in a synchronized manner, pumping blood effectively to all parts of the body.
Cardiac muscle cells have a high density of mitochondria, which provide the energy needed for the constant contraction and relaxation of the heart. They also have a unique ability to generate their own electrical impulses, allowing the heart to beat rhythmically even in the absence of external stimulation.
Overall, cardiac muscle is essential for maintaining the circulation of blood throughout the body and is a key component of the cardiovascular system.
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Google Gemini AI
Aug 27
Cardiac Muscle
Structure:
- Bundles of elongated, branched cells called cardiomyocytes.
- Intercalated discs: Specialized junctions between cardiomyocytes that allow rapid electrical conduction.
- Striated appearance due to sarcomeres (contractile units) arranged in a parallel pattern.
Characteristics:
- Involuntary: Contracts rhythmically without conscious control.
- Autorhythmic: Initiates its own contractions through specialised pacemaker cells (sinoatrial node).
- Refractory: Does not respond to repeated stimuli during contraction, preventing tetanus.
- Resistant to fatigue: Can contract repeatedly for prolonged periods without exhaustion.
Function:
- Pumps blood through the circulatory system.
- Contracts rhythmically to maintain blood pressure and deliver oxygen and nutrients to tissues.
- Can increase its contraction rate (positive chronotropy) or force (positive inotropy) in response to demands.
Contractile Mechanism:
- Sarcomeres contain actin and myosin filaments.
- Calcium ions bind to troponin, causing it to change shape and expose myosin-binding sites on actin.
- Myosin heads bind to actin, forming cross-bridges.
- Myosin heads undergo a power stroke, pulling the actin filaments towards the center of the sarcomere, causing contraction.
Electrical Conduction:
- Electrical impulses are initiated in the sinoatrial node.
- Impulses spread through the intercalated discs, causing synchronized contraction of cardiomyocytes.
Innervation:
- Sympathetic nervous system: Increases heart rate and force of contraction.
- Parasympathetic nervous system: Decreases heart rate and force of contraction.
Clinical Significance:
- Cardiac arrhythmias: Irregular heartbeats due to disturbances in electrical conduction.
- Heart failure: Inability of the heart to pump blood effectively, often caused by damage to cardiac muscle.
- Cardiomyopathy: Disease of the cardiac muscle, characterized by abnormal structure and function.
Structure:
- Bundles of elongated, branched cells called cardiomyocytes.
- Intercalated discs: Specialized junctions between cardiomyocytes that allow rapid electrical conduction.
- Striated appearance due to sarcomeres (contractile units) arranged in a parallel pattern.
Characteristics:
- Involuntary: Contracts rhythmically without conscious control.
- Autorhythmic: Initiates its own contractions through specialised pacemaker cells (sinoatrial node).
- Refractory: Does not respond to repeated stimuli during contraction, preventing tetanus.
- Resistant to fatigue: Can contract repeatedly for prolonged periods without exhaustion.
Function:
- Pumps blood through the circulatory system.
- Contracts rhythmically to maintain blood pressure and deliver oxygen and nutrients to tissues.
- Can increase its contraction rate (positive chronotropy) or force (positive inotropy) in response to demands.
Contractile Mechanism:
- Sarcomeres contain actin and myosin filaments.
- Calcium ions bind to troponin, causing it to change shape and expose myosin-binding sites on actin.
- Myosin heads bind to actin, forming cross-bridges.
- Myosin heads undergo a power stroke, pulling the actin filaments towards the center of the sarcomere, causing contraction.
Electrical Conduction:
- Electrical impulses are initiated in the sinoatrial node.
- Impulses spread through the intercalated discs, causing synchronized contraction of cardiomyocytes.
Innervation:
- Sympathetic nervous system: Increases heart rate and force of contraction.
- Parasympathetic nervous system: Decreases heart rate and force of contraction.
Clinical Significance:
- Cardiac arrhythmias: Irregular heartbeats due to disturbances in electrical conduction.
- Heart failure: Inability of the heart to pump blood effectively, often caused by damage to cardiac muscle.
- Cardiomyopathy: Disease of the cardiac muscle, characterized by abnormal structure and function.
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