Bones And Skeletal Tissues

Explanation
Hyaline cartilage is the most plentiful type of cartilage in the adult body. It is found in many areas, including the nose, trachea, and the ends of long bones. It provides support and flexibility to these areas, allowing for smooth movement and cushioning. Fibrocartilage is found in areas that require more strength, such as the intervertebral discs, while elastin cartilage is found in the external ear. Therefore, the correct answer is hyaline cartilage.

Explanation
The epiglottis and external ear cartilage are the two body structures that contain flexible elastic cartilage. The epiglottis is a flap of cartilage located at the base of the tongue, which prevents food and liquid from entering the windpipe during swallowing. External ear cartilage is the cartilage that gives shape and structure to the outer ear, allowing it to be flexible and movable. Both of these structures require flexibility and elasticity to perform their respective functions effectively.

Explanation
Cartilage grows by interstitial growth, which means that it grows from within. This process involves the division and multiplication of chondrocytes, the cells that make up cartilage, within the existing cartilage matrix. As the chondrocytes divide, they produce new matrix material, causing the cartilage to grow from the inside out. This type of growth allows cartilage to expand and maintain its structure, making it an important process for the development and repair of cartilage tissue.

Explanation
The components of the axial skeleton include the skull, vertebral column, and thoracic cage. The skull is the bony structure that protects the brain and houses the facial bones. The vertebral column, also known as the spine, consists of a series of vertebrae that provide support and protection for the spinal cord. The thoracic cage includes the ribs and sternum, forming the protective cage around the organs of the thoracic cavity, such as the heart and lungs. These components work together to provide support, protection, and flexibility to the body.

Explanation
The ribs and skull bones fall into the class of flat bones. Flat bones are thin and flat, providing protection to vital organs and serving as attachment sites for muscles. The ribs and skull bones have a flat shape and fulfill these functions, making them classified as flat bones.

Explanation
Skeletal muscles and bones have a functional relationship in the body. Skeletal muscles are attached to bones and use them as levers to generate movement. When the muscles contract, they pull on the bones, causing them to move and enabling various actions such as walking, running, or lifting objects. This relationship allows for coordinated movement and provides stability and support to the body. Therefore, the statement that skeletal muscles use bones as levers to cause movement in the body is true.

Explanation
Bone matrix is a complex structure that provides strength and support to bones. It consists of various substances, including minerals and growth factors. Minerals, such as calcium and phosphorus, are stored in the bone matrix and contribute to its hardness and rigidity. Growth factors, on the other hand, are proteins that regulate the growth and development of bone cells. They play a crucial role in bone remodeling and repair. Therefore, both minerals and growth factors are stored in the bone matrix to maintain the structural integrity and promote bone growth.

Explanation
The bone marrow cavities have two main functions. One of them is blood cell formation, where the bone marrow produces different types of blood cells, including red blood cells, white blood cells, and platelets. This process is crucial for maintaining a healthy immune system and ensuring proper oxygenation and clotting in the body. The second function is fat storage, as the bone marrow contains adipose tissue that stores and releases fat cells when needed for energy. These two functions play vital roles in maintaining overall health and homeostasis in the body.

Explanation
Bony projections are bone structures that extend outward from the surface, while bony depressions are indentations or hollows in the bone. Therefore, based on the given options, crests, tubercles, and spines are classified as bony projections rather than bony depressions.

Explanation
The endosteum is a membrane that lines the internal canals and covers the trabecular of a bone. It is composed of a single layer of cells and is responsible for bone growth, repair, and remodeling. The endosteum contains osteoprogenitor cells, which can differentiate into osteoblasts or osteoclasts, and plays a crucial role in regulating bone formation and resorption.

Explanation
Bone salts, also known as inorganic components of bone, are responsible for making it hard. These salts primarily consist of calcium and phosphate minerals, such as hydroxyapatite. They form a dense network of crystals that gives bone its strength and rigidity. In addition to bone salts, bones also contain organic components, such as osteocytes, osteoid, and osteoblasts, which play important roles in bone formation and maintenance, but it is the presence of bone salts that gives bone its hardness.

Explanation
Osteoclasts are cells that have a ruffled border and are responsible for breaking down bone matrix. They are involved in the process of bone resorption, where they release enzymes and acids to dissolve the mineralized matrix of bone. This allows for the remodeling and reshaping of bones, as well as the release of calcium and other minerals into the bloodstream. Osteoblasts, on the other hand, are responsible for bone formation, while osteocytes are mature bone cells that help maintain bone health. Osteoflex is not a recognized cell type involved in bone metabolism.

Explanation
Bones begin with fibrous membranes and hyaline cartilages. Fibrous membranes, also known as fibrous connective tissue, serve as the initial framework for bone formation. They provide structural support and help in the attachment of muscles to bones. Hyaline cartilages, on the other hand, act as a precursor to bone formation. They are gradually replaced by bone tissue through a process called ossification. So, both fibrous membranes and hyaline cartilages play crucial roles in the development and formation of bones.

Explanation
The term "bone chases cartilage" refers to the process of endochondral ossification, where the cartilage model is gradually replaced by bone. This occurs during the development and growth of long bones in the body. Initially, the cartilage model serves as a template for bone formation, but as growth continues, the cartilage breaks down and is replaced by bone tissue. Therefore, the statement is true.

Explanation
In the hypertrophic zone of the epiphyseal plate, chondrocytes enlarge, lacunae break down, and leave holes in the cartilage matrix. This is a normal process that occurs during bone growth. As chondrocytes enlarge, they contribute to the lengthening of the bone. The breakdown of lacunae and the creation of holes in the cartilage matrix allow for the invasion of blood vessels and osteoblasts, which eventually replace the cartilage with bone tissue. This process is essential for the growth and development of long bones.

Explanation
If osteoclasts, which are responsible for breaking down bone tissue, are more active than osteoblasts, which are responsible for building new bone tissue, the overall balance of bone formation and resorption will be disrupted. This means that more bone tissue will be broken down than is being replaced, leading to a decrease in bone mass.

Explanation
Paget's disease is a bone disorder characterized by excessive deposit of weak, poorly mineralized bone. This condition causes the affected bones to become enlarged and deformed, leading to pain, fractures, and other complications. Osteoporosis, on the other hand, is a condition characterized by a decrease in bone density and strength, but not necessarily excessive bone deposition. Osteogenesis Imperfecta is a genetic disorder that causes brittle and easily fractured bones. Fibrous Dysplasia is a bone disorder where normal bone is replaced with fibrous tissue, but it does not involve excessive deposition of weak bone.

Explanation
Vitamin D, calcium, and weight-bearing exercise are three measures that may help to maintain healthy bone density. Vitamin D is essential for the absorption of calcium, which is necessary for strong bones. Calcium is a key mineral that supports bone health and helps prevent osteoporosis. Weight-bearing exercise, such as walking or weightlifting, puts stress on the bones, stimulating them to become stronger and denser. These three measures work together to promote healthy bones and reduce the risk of fractures or bone-related diseases.

Explanation
Osteomalacia is the correct answer because it refers to a condition in which the bones become soft and weak due to a vitamin D deficiency or problems with calcium and phosphorus absorption. It is commonly known as adult rickets because it shares similar symptoms and causes with rickets, a condition that affects children. Osteochondritis Dissecans, Osteopetroses, and Paget disease are all different conditions that do not specifically refer to adult rickets.

Explanation
At birth, most bones are well formed and ossified, except for their epiphysis. This is because during fetal development, the majority of the skeletal system is formed, and by the time a baby is born, the bones are already well-developed. However, the epiphysis, which are the ends of the long bones, are not fully ossified at birth. Ossification of the epiphysis continues throughout childhood and adolescence, eventually completing around the age of 20. Therefore, at birth is the stage of life when most bones are well formed and ossified, except for their epiphysis.

Explanation
The decrees in bone mass that begins in the fourth decade of life affects nearly all bones except for the skull. This is because the skull is made up of flat bones that do not undergo significant changes in bone mass with age. The humerus, clavicle, and femur are all long bones that are susceptible to the decrease in bone mass that occurs with aging.