biology chapter 11“During muscle contraction, which of the following regions decrease(s) in length? 1 only 1 and 2 only 3 and 4 only 2, 3, and 4 only” Excerpt From MCAT Biology Review 2023-2024 Kaplan Test Prep This material may be protected by copyrigh

Question: What is frequency summation?

Answer: Addition of multiple simple twitches before the muscle has an opportunity to fully relax.

Flashcard 16: Question: What is a simple twitch in muscle cells?

Answer: An all-or-nothing response of muscle cells.

Question: What is an osteon or Haversian system?

Answer: An osteon is the structural unit of compact bone, consisting of concentric lamellar rings around a central canal.

Question: What are antagonistic pairs, and how do they function?

Answer: Antagonistic pairs are muscles that serve opposite functions. When one muscle contracts, the other lengthens.

Question: How is the human skeletal system divided?

Answer: Axial skeleton (midline structures) and appendicular skeleton (limbs, pectoral girdle, and pelvis).

Question: How is bone matrix organized, and what are its components?

Answer: Bone matrix is organized into concentric rings called lamellae around a central Haversian or Volkmann's canal. It contains organic components (collagen, glycoproteins) and inorganic components (hydroxyapatite).

Question: Provide insights into the complex process of bone remodeling and its significance.

Answer: Bone remodeling involves the coordinated action of osteoblasts, which build bone, and osteoclasts, which resorb bone. This dynamic process ensures bone integrity, adapts to mechanical demands, and contributes to mineral homeostasis in the body.

Question: How is bone remodeling carried out, and what are the roles of osteoblasts and osteoclasts?

Answer: Bone remodeling is carried out by osteoblasts (build bone) and osteoclasts (resorb bone).

Question: What surrounds bones, and what is its role?

Answer: Bones are surrounded by periosteum, a layer of connective tissue.

Question: In what ways does bone contribute to overall homeostasis beyond its structural role?

Answer: Bones, in addition to providing structural support, play a crucial role in mineral storage, particularly calcium and phosphorus. Bone marrow is involved in blood cell production, contributing to hematopoiesis. Furthermore, bones act as a reservoir for various growth factors and hormones, influencing metabolic processes.

Question: How is bone remodeling carried out?

Answer: By osteoblasts (build bone) and osteoclasts (resorb bone).

Question: What are the characteristics of cardiac muscle?

Answer: Cardiac muscle is striated, under involuntary control, uninucleated or binucleated, and displays myogenic activity. Cells are connected with intercalated discs containing gap junctions.

Question: What is cartilage, and where is it found?

Answer: Cartilage is a firm, elastic material secreted by chondrocytes. It is usually found in areas requiring flexibility or cushioning.

Question: What are the two types of bone tissue?

Answer: Compact bone (dense, provides strength) and spongy or cancellous bone (lattice-like structure).

Question: What are the unique properties of compact bone that make it suited for its functions?

Answer: Compact bone is dense and provides strength to resist mechanical stress. Its organized structure into osteons with concentric lamellae and central canals ensures efficient nutrient and waste exchange through canaliculi, promoting overall bone health.

Question: What helps muscle cells reduce oxygen debt and forestall fatigue?

Answer: Creatine phosphate, myoglobin, and additional energy reserves.

Question: What triggers the release of calcium ions in muscle contraction?

Answer: Depolarization of the sarcolemma triggers the release of calcium ions.

Question: Compare and contrast endochondral ossification and intramembranous ossification in bone development.

Answer: Endochondral ossification involves the replacement of cartilage with bone and is the primary process for most long bones. In intramembranous ossification, bone forms directly from undifferentiated tissue and is characteristic of certain flat bones, such as those in the skull.

Question: What is endochondral ossification, and when does it occur?

Answer: Endochondral ossification is the process by which bone forms from cartilage and occurs in fetal life.

Question: How are joints classified?

Answer: Immovable joints (fused, e.g., sutures) or movable joints (usually strengthened by ligaments, contains a synovial capsule).

Question: What are the two types of skeletons?

Answer: Internal skeletons (endoskeletons) and external skeletons (exoskeletons).

Question: What is intramembranous ossification, and where does it occur?

Answer: Intramembranous ossification is the direct formation of bone from undifferentiated tissue (mesenchyme). It occurs, for example, in the skull.

Question: How are joints classified, and what are examples of joint types?

Answer: Joints may be classified as immovable (e.g., sutures) or movable (e.g., synovial joints).

Question: What are the components of compact bone?

Answer: Lamellae, Haversian or Volkmann's canal, lacunae, and osteocytes connected by canaliculi.

Question: What are the components of a long bone?

Answer: Long bones have diaphyses (shafts), metaphyses (flared portions), and epiphyses (ends). The epiphysis contains an epiphyseal plate for linear growth.

Question: Where does muscle contraction begin?

Answer: Muscle contraction begins at the neuromuscular junction.

Question: How does muscle relaxation occur?

Answer: Muscle relaxes when acetylcholine is degraded, terminating the signal, and allowing calcium to be brought back into the sarcoplasmic reticulum. ATP binds to the myosin head, allowing it to release from actin.

Question: What are antagonistic pairs in muscle?

Answer: Muscles that serve opposite functions, contracting and lengthening together.

Question: Explain the role of osteocytes and their spatial arrangement within bone.

Answer: Osteocytes, residing in lacunae, maintain bone homeostasis by detecting mechanical strain and orchestrating bone remodeling. Their connection via canaliculi allows for the exchange of nutrients and waste, contributing to the overall health of the bone tissue.

Question: How do hormones such as parathyroid hormone, vitamin D, and calcitonin influence bone metabolism?

Answer: Parathyroid hormone and vitamin D enhance bone resorption, leading to increased calcium and phosphate levels in the blood. Calcitonin, on the other hand, promotes bone formation, reducing blood calcium concentrations.

Question: How do hormones influence bone resorption and formation?

Answer: Parathyroid hormone and vitamin D increase resorption. Calcitonin increases bone formation.

Question: What is tetanus in muscle contraction?

Answer: Prolonged and stronger contraction due to simple twitches occurring so frequently that the muscle does not relax at all.

Question: What are sarcomeres made of?

Answer: Sarcomeres are made of thick (myosin) and thin (actin) filaments.

Question: How do sarcomeres attach to form myofibrils?

Answer: Sarcomeres attach end-to-end to become myofibrils, and each myocyte contains many myofibrils.

Question: What are the characteristics of skeletal muscle?

Answer: Skeletal muscle is striated, under voluntary control, polynucleated, and can be divided into red (slow-twitch) and white (fast-twitch) fibers.

Question: What are the three main types of muscle?

Answer: Skeletal muscle, smooth muscle, and cardiac muscle.

Question: Where is smooth muscle found, and what are its characteristics?

Answer: Smooth muscle is found in the respiratory, reproductive, cardiovascular, and digestive systems. It is nonstriated, under involuntary control, and uninucleated.

Question: What is the function of synovial fluid, and where is it produced?

Answer: Synovial fluid aids in joint motion by lubricating the joint. It is produced by the synovium.

Question: What aids in joint motion by lubricating the joint?

Answer: Synovial fluid secreted by the synovium.

Question: Explain the roles of synovial fluid and articular cartilage in joint function.

Answer: Synovial fluid, secreted by the synovium, lubricates joints, reducing friction during movement. Articular cartilage covers joint surfaces, providing a smooth, low-friction surface that aids in movement and absorbs shock.

Question: What distinguishes the appendicular skeleton, and how does it contribute to bodily movement?

Answer: The appendicular skeleton, composed of the bones of the limbs, the pectoral girdle, and the pelvis, facilitates movement and locomotion. Limb bones provide a framework for muscle attachment, the pectoral girdle supports the upper limbs, and the pelvis anchors the lower limbs and supports body weight.

Question: What are the two divisions of the human skeletal system? Flashcard 32: Flashcard 33: Question: What structures constitute the appendicular skeleton? Answer: The bones of the limbs, the pectoral girdle, and the pelvis. Flashcard 34: Question: What is the origin of bone? Answer: Bone is derived from embryonic mesoderm. Flashcard 35: Question: What are the two types of bone tissue, and what are their characteristics? Answer: Compact bone provides strength and is dense, while spongy or cancellous bone has a lattice-like structure with cavities filled with bone marrow. Flashcard 42: Flashcard 43: Flashcard 44: Flashcard 45: Flashcard 46:

Answer: The axial skeleton and the appendicular skeleton.

Question: How does the axial skeleton contribute to the structural framework of the human body?

Answer: The axial skeleton, consisting of the skull, vertebral column, rib cage, and hyoid bone, provides essential support and protection for vital organs. The skull protects the brain, the vertebral column supports the body and encases the spinal cord, the rib cage safeguards the thoracic organs, and the hyoid bone is crucial for tongue and neck muscle attachment.

Question: Elaborate on the significance of the periosteum in bone function.

Answer: The periosteum, a connective tissue layer surrounding bones, serves as a site for tendon and ligament attachment. It also participates in bone growth and repair by containing osteoprogenitor cells, which can differentiate into osteoblasts for bone formation.

Question: What is the basic contractile unit of striated muscle?

Answer: The sarcomere.

Question: What structures make up the axial skeleton?

Answer: The skull, vertebral column, rib cage, and hyoid bone.

Question: What is the structural unit of compact bone, and what are its components?

Answer: The structural unit is an osteon or Haversian system, consisting of concentric lamellar rings around a central canal. Lacunae house osteocytes connected by canaliculi.

Question: How does bone form in fetal life?

Answer: Through endochondral ossification or intramembranous ossification.

Question: What are the components of the thin filament in a sarcomere?

Answer: Troponin and tropomyosin.

Question: What are the divisions of a sarcomere?

Answer: Z-lines, M-line, I-band, H-zone, and A-band.

"When the knee moves back and forth during walking, what prevents the surfaces of the leg bones from rubbing against each other?" Articular cartilage Epiphyses Synovial fluid Smooth muscle

a

Which of the following cells is correctly coupled with its definition? Osteoblasts—bone cells involved in the secretion of bone matrix Osteoclasts—immature bone cells Osteocytes—polynucleated cells actively involved in bone resorption Chondrocytes—undifferentiated bone marrow cells"

a

To facilitate the process of birth, an infant's head is somewhat flexible. This flexibility is due in part to the two fontanelles, which are soft spots of connective tissue in the infant's skull. With time, the fontanelles will close through a process known as: endochondral ossification. intramembranous ossification. bone resorption. longitudinal growth.

b

Which type(s) of muscle is/are always multinucleated? Cardiac muscle Skeletal muscle Smooth muscle I only II only III only I and II only

b

"An X-ray of the right femur in a child shows that it is shorter than the opposite femur, and below the average length for a child of this age. Which region of the bone is most likely to have caused this abnormality? Diaphysis Metaphysis Epiphysis Periosteum

c

"With which of the following molecules does Ca2+ bind after its release from the sarcoplasmic reticulum to regulate muscle contraction? Myosin Actin Troponin Tropomyosin

c

A young patient presents to the emergency room with a broken hip. The patient denies any recent history of trauma to the joint. Blood tests reveal a calcium concentration of 11.5 mgdL (normal: 8.4-10.2). Which tissue is likely responsible for these findings? Thyroid Cartilage Parathyroid Smooth muscle

c

Region 1 refers to: the thick filaments only. the thin filaments only. the A-band. the I-band.

c

"During muscle contraction, which of the following regions decrease(s) in length? 1 only 1 and 2 only 3 and 4 only 2, 3, and 4 only

d

"Which of the following bones is Not a part of the appendicular skeleton? The triquetrum, one of the carpal bones The calcaneus, which forms the heel The ischium, one of the fused pelvic bones The sternum, or breastbone

d

"Which of the following statements regarding the periosteum is INCORRECT? The periosteum serves as a site of attachment of bone to muscle. Cells of the periosteum may differentiate into osteoblasts. The periosteum is a fibrous sheath that surrounds long bones. "The periosteum secretes fluid into the joint cavity."

d

"Which region represents one sarcomere?" "1 2 3 4

d

"Which type(s) of muscle has/have myogenic activity? Cardiac muscle Skeletal muscle Smooth muscle I only II only III only I and III only

d

Red bone marrow is involved in erythrocyte formation. In contrast, yellow bone marrow: is involved in leukocyte formation. is responsible for drainage of lymph. causes the formation of spicules. contains predominantly adipose tissue"

d

Which of the following Incorrectly pairs a type of muscle fiber with a characteristic of that fiber? Red fibers—rich in mitochondria Red fibers—high levels of myoglobin White fibers—fast-twitching White fibers—predominantly use aerobic respiration

d