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Questions and Answers
What is primarily found in the I band of a muscle fiber?
What is primarily found in the I band of a muscle fiber?
What is the role of calcium ions (Ca++) released from the sarcoplasmic reticulum during muscle contraction?
What is the role of calcium ions (Ca++) released from the sarcoplasmic reticulum during muscle contraction?
What occurs during muscle contraction in the H zone?
What occurs during muscle contraction in the H zone?
What happens to the I bands during muscle contraction?
What happens to the I bands during muscle contraction?
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Which structure acts as the cytoplasm of muscle fibers?
Which structure acts as the cytoplasm of muscle fibers?
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What is tetanus in terms of muscle contraction?
What is tetanus in terms of muscle contraction?
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What triggers the release of Ca++ ions into the sarcoplasm during muscle contraction?
What triggers the release of Ca++ ions into the sarcoplasm during muscle contraction?
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What can happen if a muscle receives repeated strong stimulations without time to relax?
What can happen if a muscle receives repeated strong stimulations without time to relax?
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What is the primary reason for the occurrence of rigor mortis after death?
What is the primary reason for the occurrence of rigor mortis after death?
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Which of the following areas of the body typically exhibit rigor mortis first?
Which of the following areas of the body typically exhibit rigor mortis first?
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Which layer of skin is responsible for the protection of the inner body layers from external effects?
Which layer of skin is responsible for the protection of the inner body layers from external effects?
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What is one of the primary functions of skin in terrestrial organisms?
What is one of the primary functions of skin in terrestrial organisms?
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Which component is NOT typically found in the skin of multicellular organisms?
Which component is NOT typically found in the skin of multicellular organisms?
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What happens to muscle fibers undergoing rigor mortis when placed in an oxygen-rich environment?
What happens to muscle fibers undergoing rigor mortis when placed in an oxygen-rich environment?
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How does the skin contribute to thermoregulation in higher organisms?
How does the skin contribute to thermoregulation in higher organisms?
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What is the primary layer of skin generated from ectoderm?
What is the primary layer of skin generated from ectoderm?
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What is the primary function of keratin in the upper section of the epidermis?
What is the primary function of keratin in the upper section of the epidermis?
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Which type of receptors in the dermis is sensitive to high pressure?
Which type of receptors in the dermis is sensitive to high pressure?
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What role do blood vessels in the dermis play?
What role do blood vessels in the dermis play?
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Where are sebaceous glands not typically found?
Where are sebaceous glands not typically found?
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Which gland is involved in the secretion of sweat?
Which gland is involved in the secretion of sweat?
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What is sebum, and what is its primary function?
What is sebum, and what is its primary function?
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What characterizes the structure of sweat glands in the dermis?
What characterizes the structure of sweat glands in the dermis?
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What is primarily responsible for the skin color?
What is primarily responsible for the skin color?
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What is the primary function of capillaries in the circulatory system?
What is the primary function of capillaries in the circulatory system?
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Which structure is responsible for separating the two halves of the heart?
Which structure is responsible for separating the two halves of the heart?
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What does the term 'cardiovascular' refer to?
What does the term 'cardiovascular' refer to?
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How much blood does the average human heart pump daily?
How much blood does the average human heart pump daily?
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In which circuit does blood travel to the lungs for oxygenation?
In which circuit does blood travel to the lungs for oxygenation?
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What is the weight range of an adult male heart?
What is the weight range of an adult male heart?
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What role do arterioles play in the circulatory system?
What role do arterioles play in the circulatory system?
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What does the term 'bicuspid valve' refer to?
What does the term 'bicuspid valve' refer to?
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What is the primary function of blood plasma?
What is the primary function of blood plasma?
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What is the density of blood plasma compared to other components of blood?
What is the density of blood plasma compared to other components of blood?
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Which plasma protein is critical for blood clotting?
Which plasma protein is critical for blood clotting?
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What role do heparin or citrate play in the centrifugation process?
What role do heparin or citrate play in the centrifugation process?
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What is the main composition of blood plasma?
What is the main composition of blood plasma?
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What is hematocrit a measure of?
What is hematocrit a measure of?
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How do the densities of the components in blood change when centrifuged?
How do the densities of the components in blood change when centrifuged?
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Which function is NOT performed by blood?
Which function is NOT performed by blood?
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What is one major difference between vertebrate and invertebrate hemoglobin?
What is one major difference between vertebrate and invertebrate hemoglobin?
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Which vitamin is crucial for the production of erythrocytes?
Which vitamin is crucial for the production of erythrocytes?
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What physiological adaptation do erythrocytes have that assists in oxygen transport?
What physiological adaptation do erythrocytes have that assists in oxygen transport?
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What happens to old erythrocytes in the circulatory system?
What happens to old erythrocytes in the circulatory system?
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What is the role of erythropoietin in the body?
What is the role of erythropoietin in the body?
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Why do mature erythrocytes have a limited lifespan of approximately 80-120 days?
Why do mature erythrocytes have a limited lifespan of approximately 80-120 days?
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How does the structure of erythrocytes facilitate their passage through capillaries?
How does the structure of erythrocytes facilitate their passage through capillaries?
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What component of the heme group is turned into bilirubin after erythrocytes are digested?
What component of the heme group is turned into bilirubin after erythrocytes are digested?
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Study Notes
Muscular Contraction
- Muscles are stimulated by impulses from the brain or spinal cord, at the neuromuscular junction
- Impulses cause a potential difference in the muscle membrane
- Muscle contraction only occurs in the presence of a stimulus
- The all-or-none rule describes a muscle's response at a given threshold level
- Energy for contraction comes from the muscle cell, not the nerve impulse
- Contraction happens in three phases: latent phase, contraction phase and relaxation phase
Latent Phase
- The interval between stimulation and the initiation of contraction
- Approximately 0.005 seconds
Contraction Phase
- The interval between the initiation of contraction and the initiation of relaxation
- Approximately 0.04 seconds
Relaxation Phase
- The interval between the initiation of relaxation and returning to the original position
Mechanism of Contraction
- Myosin (100-150 Å wide and 1.5 microns long, thicker) and Actin (50-70 Å wide and 2 microns long, thinner) fibers slide over each other during contraction
- Myosin has protruding branches (heads) giving a folded appearance
- Actin fibers are made of three types of protein: spherical actin, tropomyosin, and tropin
- Sarcomeres are repeating units between Z lines with thick myosin filaments and thin actin filaments
- I bands (light) contain only actin; A bands (dark) contain overlapping actin and myosin; H zone has only myosin
- Sarcolemma is the muscle fiber membrane; sarcoplasm is the cytoplasm; and sarcoplasmic reticulum is the endoplasmic reticulum
- T tubules are extensions of the sarcolemma that penetrate into the cell
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Description
Test your knowledge on the mechanism of muscular contraction, including the phases and the physiological processes involved. This quiz covers topics such as the latent phase, contraction phase, relaxation phase, and the role of myosin and actin in muscle function.
