159 Questions
What is the dominant tissue in the heart and in the walls of other hollow organs?
Muscle tissue
What distinguishes muscles from other tissues?
Ability to convert chemical energy into mechanical energy
Where does cardiac muscle tissue occur?
Only in the heart
What is the Latin origin of the word 'muscle'?
Nius meaning 'little mouse'
What type of muscle is not striated and is also not subject to voluntary control?
Smooth muscle
Where is smooth muscle found?
In hollow visceral organs
What type of muscle cells are striated and involuntary?
Cardiac muscle
Which muscle type contracts at a steady rate but can speed up with neural controls?
Cardiac muscle
What is the function of smooth muscle?
Regulating fluid flow
What surrounds each individual muscle fiber?
Endomysium
What is the dense irregular connective tissue that surrounds the whole muscle called?
Epimysium
What controls the activity of skeletal muscle fibers?
Nerve endings
What reinforces the muscle and supports its function?
Connective tissue sheaths
What transmits the pulling force from muscle fibers to the bone to be moved?
Connective tissue sheaths
Where do most skeletal muscles attach to bones?
At least two places
What is the connective tissue that surrounds each fascicle?
Perimysium
What are tendons mostly composed of?
Collagen fibers
What is a muscle fiber?
A single muscle cell
What are myofibrils?
Rodlike contractile elements
What is a sarcomere?
The contractile unit of a muscle
What produces muscle shortening?
Sliding of thin filaments past thick filaments
What is the average length of a sarcomere?
2 µm
What type of filaments are myosin filaments?
Contractile
What type of filaments are actin filaments?
Non-contractile
What is the most common type of muscle attachment?
Indirect attachment
What is the connective tissue that surrounds the entire muscle?
Epimysium
What is the function of a fascicle?
To segregate muscle cells from the rest of the muscle
What is the inheritance pattern of muscular dystrophy?
X-linked recessive
What is the approximate occurrence of Duchenne muscular dystrophy (DMD) in male births?
1 in 3600 births
What are the common symptoms of Duchenne muscular dystrophy (DMD) in affected boys?
Muscle weakness, clumsiness, and falls
Which protein stabilizes the sarcolemma and links cytoskeleton to the extracellular matrix?
Dystrophin
What is the function of titin in muscle cells?
Maintaining muscle cell organization and resisting excessive stretching
What structures regulate muscle contraction in skeletal muscle fibers?
Sarcoplasmic reticulum and T tubules
What is the role of myosin heads during muscle contraction?
Binding to the myosin-binding sites on actin
Which components control myosin-actin interactions during muscle contraction?
Troponin and tropomyosin
What happens to the fragile sarcolemma during muscle contraction in DMD?
It tears, leading to muscle damage
What is the aim of current treatments for DMD?
Preventing deformities and maintaining mobility
In DMD, the progression of muscle weakness occurs from extremities to which parts of the body?
Head and neck
With supportive care, how long can DMD patients typically live?
Into their 30s and beyond
What is the functional unit of a myofibril responsible for the banding pattern observed in muscle fibers?
Sarcomere
What do muscle cells contain that are the muscle equivalents of actin-containing microfilaments and myosin motor proteins?
Myofilaments
What is primarily composed of the protein myosin, with each myosin molecule consisting of six polypeptide chains?
Thick filaments
What is the 'business end' of myosin, linking to actin during contraction?
Globular heads
What is the muscle cell cytoplasm that contains large amounts of glycosomes and myoglobin?
Sarcolemma
What is the fusion product of hundreds of embryonic cells?
Skeletal muscle fiber
What is responsible for muscle contraction and depends on myosin- and actin-containing myofilaments?
Myofibrils
What acts as motors to generate force during muscle contraction?
Myosin
What is the large, cylindrical cells with multiple nuclei and sarcolemma?
Skeletal muscle fibers
What contains myofibrils, sarcoplasmic reticulum, and T tubules?
Skeletal muscle fibers
What splits ATP and uses the released energy to drive movement?
Myosin
What involves thick and thin filaments forming cross bridges and swiveling around their point of attachment?
Sarcomere
What is the approximate percentage of body mass made up by muscle tissue?
40%
Where does cardiac muscle tissue occur?
Only in the heart
What is the primary energy source used by muscles to exert force?
ATP
What is the Latin origin of the word 'muscle'?
Musculus
What is the connective tissue sheath that surrounds each individual muscle fiber?
Endomysium
What is the dense irregular connective tissue that surrounds the whole muscle called?
Epimysium
What is the functional unit of a myofibril responsible for the banding pattern observed in muscle fibers?
Sarcomere
Which protein stabilizes the sarcolemma and links cytoskeleton to the extracellular matrix?
Dystrophin
What is the most common type of muscle attachment?
Tendon attachment
What is the aim of current treatments for Duchenne muscular dystrophy (DMD)?
Manage symptoms
What is the average length of a sarcomere?
10 micrometers
What is primarily composed of the protein myosin, with each myosin molecule consisting of six polypeptide chains?
Thick filament
Where does cardiac muscle tissue occur?
Hollow visceral organs
What is responsible for muscle contraction and depends on myosin- and actin-containing myofilaments?
Sliding filament mechanism
What is the function of smooth muscle?
Regulating fluid flow
What is the connective tissue that surrounds the entire muscle?
Epimysium
What is the functional unit of a myofibril responsible for the banding pattern observed in muscle fibers?
Sarcomere
What is the muscle cell cytoplasm that contains large amounts of glycosomes and myoglobin?
Sarcoplasmic reticulum
What primarily composes the protein myosin, with each myosin molecule consisting of six polypeptide chains?
Thick filaments
What is the 'business end' of myosin, linking to actin during contraction?
Myosin globular heads
What is the large, cylindrical cells with multiple nuclei and sarcolemma?
Skeletal muscle fibers
What is the aim of current treatments for Duchenne muscular dystrophy (DMD)?
To slow disease progression and manage symptoms
What reinforces the muscle and supports its function?
Tendons
What is the Latin origin of the word 'muscle'?
Musculus
What are the common symptoms of Duchenne muscular dystrophy (DMD) in affected boys?
Muscle weakness and wasting
What is the inheritance pattern of muscular dystrophy?
X-linked recessive
What is the connective tissue that surrounds each fascicle?
Perimysium
What is the approximate occurrence of Duchenne muscular dystrophy (DMD) in male births?
1 in 10,000
What is the function of dystrophin in muscle cells?
Stabilizes the sarcolemma and links cytoskeleton to the extracellular matrix
Which protein controls myosin-actin interactions during muscle contraction?
Troponin and tropomyosin
What is the primary aim of current treatments for Duchenne muscular dystrophy (DMD)?
Prevent deformities and maintain mobility
What is the role of titin in muscle cells?
Maintains the organization of the muscle cell and helps resist excessive stretching
What are the common symptoms of Duchenne muscular dystrophy (DMD) in affected boys?
Muscle weakness, clumsiness, and falls
What structures regulate muscle contraction in skeletal muscle fibers?
Sarcoplasmic reticulum and T tubules
What causes tears in the fragile sarcolemma during muscle contraction in Duchenne muscular dystrophy (DMD)?
Dystrophin deficiency
What is the approximate occurrence of Duchenne muscular dystrophy (DMD) in male births?
1 in 3600 births
What is the function of myosin heads during muscle contraction?
Attach to the myosin-binding sites on actin
What is the inheritance pattern of muscular dystrophy?
X-linked recessive
Where is smooth muscle found?
In the walls of hollow organs
What reinforces the muscle and supports its function?
Connective tissue
What is the connective tissue that surrounds each individual muscle fiber?
Endomysium
What is the functional unit of a muscle, composed of myofilaments made up of contractile proteins?
Sarcomere
What reinforces the muscle and supports its function?
Tendons
What is the contractile unit of a muscle, averaging 2 $ extmu$m in length?
Sarcomere
What is the dense irregular connective tissue that surrounds the whole muscle called?
Epimysium
What is the role of myosin heads during muscle contraction?
Forming cross-bridges with actin
What is primarily composed of the protein myosin, with each myosin molecule consisting of six polypeptide chains?
Thick filament
What is the Latin origin of the word 'muscle'?
Musculus
What are myofibrils?
Rodlike contractile elements within the muscle cell
Where do most skeletal muscles attach to bones?
Indirectly via tendons
What is the fusion product of hundreds of embryonic cells?
Muscle fiber
What is responsible for muscle contraction and depends on myosin- and actin-containing myofilaments?
Sarcomere
What is the study of cells and tissues called?
Histology
Which branch of anatomy involves the study of body structures system by system?
Gross Anatomy
What is the study of cells called?
Cytology
Which type of anatomy studies the relationship between internal structures and the overlying skin surface?
Surface Anatomy
What is the study of diseases related to?
Pathophysiology
Which body system is responsible for the transportation of nutrients, gases, and wastes?
Cardiovascular system
What is the primary energy source used by muscles to exert force?
ATP
What is the primary aim of current treatments for Duchenne muscular dystrophy (DMD)?
To improve muscle strength
What reinforces the muscle and supports its function?
Connective tissue
What is the maintenance of a constant internal environment despite changes in the external environment known as?
Homeostasis
Which characteristic distinguishes muscles from other tissues?
Responsiveness
What are the survival needs essential for maintaining life?
Nutrients, oxygen, water
What is the primary focus of developmental anatomy?
Structural changes from fertilization to maturity
What does physiology emphasize in the context of structure and function?
Complementarity of structure and function
What is the role of feedback mechanisms in maintaining physiological limits?
To maintain physiological limits
Which organ system is responsible for the production of offspring?
Reproductive system
Which body cavity contains the stomach, intestines, and other organs?
Abdominopelvic cavity
Which type of feedback loop is more prevalent in the body?
Negative feedback
Which type of muscle is not striated and is not subject to voluntary control?
Smooth muscle
What type of anatomical terminology allows accurate description of body parts and positions?
Regional terms
What type of body cavity has two subdivisions, the cranial cavity and the vertebral cavity?
Dorsal body cavity
Which body cavity contains the heart and lungs?
Thoracic cavity
What type of body cavity is larger and anterior, and includes the thoracic and abdominopelvic cavities?
Ventral body cavity
What are the body planes used for anatomical studies and imaging?
Transverse and sagittal planes
Which body cavity is lined by a serous membrane and is not physically separated into abdominal and pelvic cavities?
Abdominopelvic cavity
What division of the body is designated by regional terms?
Axial division
What type of feedback system can be maintained through feedforward and feedback systems?
Negative feedback system
What is the primary function of anatomical terminology such as directional terms and regional terms?
To describe body positions
Which branch of anatomy involves the study of body structures system by system?
Gross anatomy
What is the primary focus of developmental anatomy?
Studying the structural changes that occur in the body throughout the lifespan
What is responsible for muscle contraction and depends on myosin- and actin-containing myofilaments?
Myofibrils
What is the aim of current treatments for Duchenne muscular dystrophy (DMD)?
To slow down the progression of muscle degeneration and improve quality of life
Which type of feedback loop is more prevalent in the body?
Negative feedback loop
What type of cavity contains the stomach, intestines, and other organs?
Abdominopelvic cavity
What is the function of anatomical terminology such as directional terms and regional terms?
To describe body parts and positions accurately
What divides the body into axial and appendicular parts?
Body planes
What are the subdivisions of the dorsal body cavity?
Cranial cavity and vertebral cavity
What covers the walls of the ventral body cavity and the outer surfaces of the organs it contains?
Serous membrane
What is the main function of the ventral body cavity?
Housing internal organs
What is the role of body planes in anatomical studies and imaging?
To provide reference points for describing the body
What is the primary purpose of feedforward and feedback systems in maintaining homeostasis?
To maintain stability in the body's internal environment
What are the two subdivisions of the dorsal body cavity?
Cranial cavity and vertebral cavity
What are the main organs contained in the thoracic cavity?
Lungs, heart, and other thoracic organs
What is the main function of negative feedback loops?
To maintain stability in the body's internal environment
Which of the following is a subdivision of physiology?
Pathophysiology
What is the primary emphasis of physiology?
Homeostasis
Which characteristic is NOT included in the major body organ systems?
Metabolic
What is a key component of survival needs for the body?
Normal body temperature
What is the primary aim of homeostasis?
To rely on feedback mechanisms
What is the approximate range for blood glucose level to be maintained?
70-110mg/100ml
Which of the following is NOT a basic life process?
Photosynthesis
What is the study of mechanical, physical, and biochemical functions at organ and cellular levels?
Physiology
What is the primary emphasis of developmental anatomy?
Structural changes from fertilization to maturity
Which of the following is a subdivision of physiology?
Neurophysiology
What is NOT a characteristic of the body's characteristics?
Aging
What is the primary study of diseases?
Pathology
Study Notes
Microscopic Anatomy of Skeletal Muscle Fiber
- Skeletal muscle fibers are large, cylindrical cells with multiple nuclei and sarcolemma.
- Each fiber is produced by the fusion of hundreds of embryonic cells.
- Sarcolemma, the muscle cell cytoplasm, contains large amounts of glycosomes and myoglobin.
- Muscle cells contain myofibrils, sarcoplasmic reticulum, and T tubules.
- Myofibrils consist of myofilaments, which are the muscle equivalents of actin-containing microfilaments and myosin motor proteins.
- Muscle contraction depends on myosin- and actin-containing myofilaments.
- Thick filaments are primarily composed of the protein myosin, with each myosin molecule consisting of six polypeptide chains.
- The globular heads of myosin are the "business end" of myosin, linking to actin during contraction.
- Myosin splits ATP and uses the released energy to drive movement, with each thick filament containing about 300 myosin molecules.
- Muscle contraction involves thick and thin filaments forming cross bridges and swiveling around their point of attachment.
- Myosin acts as motors to generate force during muscle contraction.
- The sarcomere, the functional unit of a myofibril, extends from one Z disc to the next and is responsible for the banding pattern observed in muscle fibers.
Skeletal Muscle Structure and Function Overview
- Each fascicle is surrounded by a layer of dense irregular connective tissue called perimysium
- In direct attachments, the epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage
- Indirect attachments of muscles are more common due to their durability and small size
- Tendons, mostly tough collagen fibers, anchor muscles to skeletal elements or other muscles
- A muscle consists of hundreds to thousands of muscle cells, connective tissue wrappings, blood vessels, and nerve fibers
- A fascicle is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath
- A muscle fiber is an elongated multinucleate cell with a banded appearance
- Myofibrils are rodlike contractile elements that occupy most of the muscle cell volume
- A sarcomere is the contractile unit of a muscle, composed of myofilaments made up of contractile proteins
- Contractile myofilaments are of two types: thick (myosin) and thin (actin) filaments
- The sliding of thin filaments past thick filaments produces muscle shortening
- A sarcomere is the smallest contractile unit of a muscle, averaging 2 µm in length
Homeostasis and Anatomical Terms: Key Concepts in Human Biology
- Homeostasis is disrupted by external stimuli like intense heat, cold, and lack of oxygen, as well as internal stimuli like psychological stresses and exercise.
- Homeostasis involves receptors, a control center, and effectors, and can be maintained through feedforward and feedback systems.
- Feedback systems include negative and positive feedback loops, with negative feedback being more prevalent in the body.
- Anatomical terminology, such as directional terms and regional terms, allows accurate description of body parts and positions.
- The body is divided into axial and appendicular parts, with regional terms used to designate specific areas within these divisions.
- Body planes, including sagittal, frontal, and transverse planes, are used for anatomical studies and imaging.
- The dorsal body cavity has two subdivisions, the cranial cavity and the vertebral cavity, protecting the nervous system organs.
- The ventral body cavity, larger and anterior, includes the thoracic cavity and the abdominopelvic cavity, housing internal organs.
- The thoracic cavity contains the lungs, heart, and other thoracic organs, while the abdominopelvic cavity contains the stomach, intestines, and other organs.
- The abdominopelvic cavity is not physically separated into abdominal and pelvic cavities and is lined by a serous membrane.
- The bowl-shaped pelvis tips away from the perpendicular, causing the abdominal and pelvic cavities to be misaligned.
- The serous membrane covers the walls of the ventral body cavity and the outer surfaces of the organs it contains, including the heart.
Anatomy and Physiology Overview
- Developmental anatomy studies structural changes from fertilization to maturity
- Physiology focuses on mechanical, physical, and biochemical functions at organ and cellular levels
- Subdivisions of physiology include pathophysiology, exercise physiology, and neurophysiology
- Physiology emphasizes the principle of complementarity of structure and function and homeostasis
- Physiology is also the study of diseases
- Major body organ systems include integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, urinary, digestive, and reproductive
- The body's characteristics include metabolism, responsiveness, movement, growth, differentiation, digestion, and reproduction
- Basic life processes include metabolism, digestion, excretion, responsiveness, movement, growth, differentiation, and reproduction
- Survival needs include nutrients, oxygen, water, normal body temperature, and appropriate atmospheric pressure
- Homeostasis is the maintenance of a constant internal environment despite changes in the external environment
- Homeostasis relies on feedback mechanisms to maintain physiological limits
- For example, blood glucose level is kept within a narrow range of 70-110mg/100ml
Test your knowledge of the microscopic anatomy of skeletal muscle fibers with this quiz. Explore the structure and components of muscle cells, including myofibrils, myofilaments, sarcomeres, and the role of myosin and actin in muscle contraction.
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