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Questions and Answers
What type of muscle is found in the heart?
What type of muscle is found in the heart?
- Epithelial tissue
- Skeletal muscle
- Smooth muscle (correct)
- Cardiac muscle
What characteristic of cardiac muscle allows it to generate its own electrical impulses?
What characteristic of cardiac muscle allows it to generate its own electrical impulses?
- Involuntary muscle
- Autorhythmic (correct)
- High concentration of mitochondria
- Branching fibers
What triggers contraction in cardiac muscle cells?
What triggers contraction in cardiac muscle cells?
- Depolarization of the sarcolemma (correct)
- Actin and myosin filaments sliding past each other
- Calcium ions released from the sarcoplasmic reticulum
- Repolarization of the sarcolemma
What is the primary function of cardiac muscle?
What is the primary function of cardiac muscle?
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What allows for rapid and coordinated contraction in cardiac muscle?
What allows for rapid and coordinated contraction in cardiac muscle?
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What is the result of actin and myosin filaments sliding past each other in cardiac muscle cells?
What is the result of actin and myosin filaments sliding past each other in cardiac muscle cells?
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Study Notes
Structure
- Cardiac muscle is a type of striated muscle found in the heart
- Composed of cardiac myocytes (muscle cells) and connective tissue
- Branching fibers allow for rapid and coordinated contraction
Characteristics
- Involuntary muscle: contractions are not under conscious control
- Autorhythmic: capable of generating its own electrical impulses
- Pacemaker cells regulate heartbeat
- High concentration of mitochondria for efficient energy production
Contraction and Relaxation
- Contraction:
- Depolarization of the sarcolemma (muscle fiber membrane) triggers contraction
- Calcium ions released from sarcoplasmic reticulum bind to troponin and tropomyosin, exposing actin-myosin binding sites
- Actin and myosin filaments slide past each other, shortening the muscle fiber
- Relaxation:
- Repolarization of the sarcolemma
- Calcium ions pumped back into the sarcoplasmic reticulum
- Actin and myosin filaments return to their relaxed state
Functions
- Pumps blood throughout the body
- Regulates blood pressure
- Maintains circulation and oxygenation of tissues
Cardiac Muscle Structure
- Composed of cardiac myocytes (muscle cells) and connective tissue
- Branching fibers allow for rapid and coordinated contraction
Characteristics
- Involuntary muscle: contractions are not under conscious control
- Autorhythmic: capable of generating its own electrical impulses
- Pacemaker cells regulate heartbeat
- High concentration of mitochondria for efficient energy production
Contraction Mechanism
- Depolarization of the sarcolemma (muscle fiber membrane) triggers contraction
- Calcium ions released from sarcoplasmic reticulum bind to troponin and tropomyosin, exposing actin-myosin binding sites
- Actin and myosin filaments slide past each other, shortening the muscle fiber
Relaxation Mechanism
- Repolarization of the sarcolemma
- Calcium ions pumped back into the sarcoplasmic reticulum
- Actin and myosin filaments return to their relaxed state
Functions
- Pumps blood throughout the body
- Regulates blood pressure
- Maintains circulation and oxygenation of tissues
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