Bone - MCAT Biology
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A doctor oberves a teenager who noticed that one of his legs is about two inches longer than the other. He also sees that the patient had broken one of his legs when he was 8 years old, but the patient's notes don't indicate which leg. What conclusion is the doctor likely to come to?
A doctor oberves a teenager who noticed that one of his legs is about two inches longer than the other. He also sees that the patient had broken one of his legs when he was 8 years old, but the patient's notes don't indicate which leg. What conclusion is the doctor likely to come to?
The epiphyseal plate is the site of longitudinal growth in bones. The patient likely broke the leg along the plate, which caused it to grow less than the other leg.
The epiphyseal plate is the site of longitudinal growth in bones. The patient likely broke the leg along the plate, which caused it to grow less than the other leg.
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A fetal rat's femoral cartilage is injected with a marker prior to endochondral ossification. The marker becomes deactivated as the cartilage is converted to bone. In which part of the femur would we expect to see a high concentration of the marker once the rat reaches adulthood?
A fetal rat's femoral cartilage is injected with a marker prior to endochondral ossification. The marker becomes deactivated as the cartilage is converted to bone. In which part of the femur would we expect to see a high concentration of the marker once the rat reaches adulthood?
The first important concept to understand for this question is the process of endochondral ossification. In this process, cartilage is converted into bone during the early life of an organism. Since the question specifies that the rat has reached adulthood, it must refer to the parts of the final bone product that remain as cartilage once endochondral ossification is complete.
Spongy bone and compact bone in the diaphysis have already ossified, and the medullary cavity contains bone marrow and adipose. To find cartilage in any of these regions would indicate a developmental abnormality.
The ends of bones that are in contact with other bones are protected from frictional damage by articular cartilage. Articular cartilage is essential to maintaining healthy joint function. Deterioration of this cartilage results in arthritis, or inflammation in the joints.
The first important concept to understand for this question is the process of endochondral ossification. In this process, cartilage is converted into bone during the early life of an organism. Since the question specifies that the rat has reached adulthood, it must refer to the parts of the final bone product that remain as cartilage once endochondral ossification is complete.
Spongy bone and compact bone in the diaphysis have already ossified, and the medullary cavity contains bone marrow and adipose. To find cartilage in any of these regions would indicate a developmental abnormality.
The ends of bones that are in contact with other bones are protected from frictional damage by articular cartilage. Articular cartilage is essential to maintaining healthy joint function. Deterioration of this cartilage results in arthritis, or inflammation in the joints.
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Which of the following is true relating cartilage to the skeletal system?
Which of the following is true relating cartilage to the skeletal system?
Cartilage is a flexible, avascular connective tissue. It is less flexible than muscle, but softer and more flexible than bone. These properties make it an ideal candidate for joints, providing a medium between the muscles and bones that enact forces on the joint. Cartilage is found on the epiphyses of long bones and between certain bones, such as vertebrae, to cushion the motion of the joints.
Due to its avascular nature, cartilage does not easily regenerate. It is formed by chondroblasts (cartilage cells) in a chondrin matrix. In endochondral ossification, cartilage can be used as a precursor to bone, but will never be formed as a result of bone breakdown. Finally, there are three types of cartilage: elastic cartilage, hyaline cartilage, and fibrous cartilage.
Cartilage is a flexible, avascular connective tissue. It is less flexible than muscle, but softer and more flexible than bone. These properties make it an ideal candidate for joints, providing a medium between the muscles and bones that enact forces on the joint. Cartilage is found on the epiphyses of long bones and between certain bones, such as vertebrae, to cushion the motion of the joints.
Due to its avascular nature, cartilage does not easily regenerate. It is formed by chondroblasts (cartilage cells) in a chondrin matrix. In endochondral ossification, cartilage can be used as a precursor to bone, but will never be formed as a result of bone breakdown. Finally, there are three types of cartilage: elastic cartilage, hyaline cartilage, and fibrous cartilage.
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An adolescent girl is suffering from reduced longitudinal bone growth in her humerus. Which of the following bone regions should be examined closely in order to determine the cause of the growth deficiency?
An adolescent girl is suffering from reduced longitudinal bone growth in her humerus. Which of the following bone regions should be examined closely in order to determine the cause of the growth deficiency?
Longitudinal bone growth occurs at the epiphyseal plate through the process of endochondral ossification. Cartilage cells undergo rapid mitosis in this region forming the structure that is later replaced by bone tissue.
Longitudinal bone growth occurs at the epiphyseal plate through the process of endochondral ossification. Cartilage cells undergo rapid mitosis in this region forming the structure that is later replaced by bone tissue.
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In childbirth, the child’s skull is flexible due to fontanelles, or soft regions that are composed of connective tissue. Through what process does the connective tissue of the infant’s skull become bone?
In childbirth, the child’s skull is flexible due to fontanelles, or soft regions that are composed of connective tissue. Through what process does the connective tissue of the infant’s skull become bone?
Intramembranous ossification is the process in which bones are formed within dermal tissue. This process is responsible for forming the flat bones of the skull, as well as the clavicle. Other bones of the body are formed by the process of endochondral ossification, in which cartilage is replaced by bone tissue.
Intramembranous ossification is the process in which bones are formed within dermal tissue. This process is responsible for forming the flat bones of the skull, as well as the clavicle. Other bones of the body are formed by the process of endochondral ossification, in which cartilage is replaced by bone tissue.
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What type of bone cell is responsible for resorbing bone tissue?
What type of bone cell is responsible for resorbing bone tissue?
Osteoclasts are bone cells that are responsible for resorbing—or breaking down—bone tissue. Osteoblasts, on the other hand, deposit bone tissue.
Cartilage is not a type of bone cell at all; it is a type of connective tissue consisting of chondrocytes suspended in an avascular matrix. Lacunae are small cavities within the bone matrix that house osteocytes; osteocytes are mature bone cells.
Osteoclasts are bone cells that are responsible for resorbing—or breaking down—bone tissue. Osteoblasts, on the other hand, deposit bone tissue.
Cartilage is not a type of bone cell at all; it is a type of connective tissue consisting of chondrocytes suspended in an avascular matrix. Lacunae are small cavities within the bone matrix that house osteocytes; osteocytes are mature bone cells.
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How do bones maintain a functional weight as they grow?
How do bones maintain a functional weight as they grow?
Osteoclasts dissolve bony matrix and repatriate calcium as the bone grows. This expands the meduallary cavity and maintains a manageable mass for the bones, while allowing the body to recycle valuable calcium deposits.
Osteoclasts dissolve bony matrix and repatriate calcium as the bone grows. This expands the meduallary cavity and maintains a manageable mass for the bones, while allowing the body to recycle valuable calcium deposits.
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Where are osteocytes located?
Where are osteocytes located?
Osteoytes, the long-lived star-shaped cells found in established bones, are primarily found within Haversian systems—the target-shaped tubes of bone matrix. They are encased in a bubble of interstitial fluid known as a lacuna.
Osteoytes, the long-lived star-shaped cells found in established bones, are primarily found within Haversian systems—the target-shaped tubes of bone matrix. They are encased in a bubble of interstitial fluid known as a lacuna.
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The diaphysis is able to grow in length because of thin layers of cartilage cells located in which of the following regions?
The diaphysis is able to grow in length because of thin layers of cartilage cells located in which of the following regions?
Thin layers of cartilage cells in the epiphyseal plate enable the diaphysis (bone shaft) to grow in length. The epiphyseal line forms when growth stops and ossification occurs, permanently fusing the diaphysis and epiphysis.
The periosteum is a tough connective tissue sheath that covers the outer surface of bones. The medullary cavity is a hollow cylinder inside the diaphysis. The medullary cavity contains bone marrow, which contains blood cells in different stages of development. The Haversian canals perforate bony structure and contain blood vessels, lymph vessels, and nerves.
Thin layers of cartilage cells in the epiphyseal plate enable the diaphysis (bone shaft) to grow in length. The epiphyseal line forms when growth stops and ossification occurs, permanently fusing the diaphysis and epiphysis.
The periosteum is a tough connective tissue sheath that covers the outer surface of bones. The medullary cavity is a hollow cylinder inside the diaphysis. The medullary cavity contains bone marrow, which contains blood cells in different stages of development. The Haversian canals perforate bony structure and contain blood vessels, lymph vessels, and nerves.
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An individual with long cancer is advised to undergo radiation therapy. The radiation therapy destroys all of his bone marrow. Which of the following will be deficient in this individual?
An individual with long cancer is advised to undergo radiation therapy. The radiation therapy destroys all of his bone marrow. Which of the following will be deficient in this individual?
The primary function of red bone marrow is to make red blood cells in the process known as erythropoiesis. If all bone marrow is destroyed, then an individual will lose the ability to make red blood cells.
Myogenesis is performed by muscle fibers and satellite cells. Osteogenesis is performed by osteoblasts. Neurogenesis primarily occurs during early development and is performed by neural stem cells.
The primary function of red bone marrow is to make red blood cells in the process known as erythropoiesis. If all bone marrow is destroyed, then an individual will lose the ability to make red blood cells.
Myogenesis is performed by muscle fibers and satellite cells. Osteogenesis is performed by osteoblasts. Neurogenesis primarily occurs during early development and is performed by neural stem cells.
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Hematopoietic stem cells are the cells that are targeted in bone marrow transplants. These stem cells are found in the red marrow of the bone. Which part of a long bone would be targeted in order to extract hematopoietic stem cells for a transplant?
Hematopoietic stem cells are the cells that are targeted in bone marrow transplants. These stem cells are found in the red marrow of the bone. Which part of a long bone would be targeted in order to extract hematopoietic stem cells for a transplant?
Red bone marrow is filled with hematopoietic stem cells. Red bone marrow is found in the heads, or epiphyses, of long bones. Yellow marrow fills the medullary cavity and consists mostly of fats. The diaphysis contains the medullary cavity and therefore contains no red marrow. The periosteum has no marrow in it at all.
Red bone marrow is filled with hematopoietic stem cells. Red bone marrow is found in the heads, or epiphyses, of long bones. Yellow marrow fills the medullary cavity and consists mostly of fats. The diaphysis contains the medullary cavity and therefore contains no red marrow. The periosteum has no marrow in it at all.
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Hypoxia would result in which of the following?
Hypoxia would result in which of the following?
Since red bone marrow is a site of red blood cell and platelet production, hypoxia (low oxygen) would result in an increase in red marrow and therefore RBC concentration. Yellow bone marrow (typcially adipocyte-filled) can be converted into red bone marrow under conditions of low oxygen or blood loss.
Since red bone marrow is a site of red blood cell and platelet production, hypoxia (low oxygen) would result in an increase in red marrow and therefore RBC concentration. Yellow bone marrow (typcially adipocyte-filled) can be converted into red bone marrow under conditions of low oxygen or blood loss.
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What is the main function of red bone marrow?
What is the main function of red bone marrow?
Red bone marrow is primarily located in flat bones (such as the sternum and pelvis) and in the epiphyses of long bones. It is responsible for producing red blood cells, a process known as erythropoiesis. At birth, all bones of the human skeleton carry out erythropoesis, but many bones stop this function as the newborn ages.
It is important to note that yellow bone marrow is found in the medullary cavity within the diaphyses of long bones and assists in fat storage.
Red bone marrow is primarily located in flat bones (such as the sternum and pelvis) and in the epiphyses of long bones. It is responsible for producing red blood cells, a process known as erythropoiesis. At birth, all bones of the human skeleton carry out erythropoesis, but many bones stop this function as the newborn ages.
It is important to note that yellow bone marrow is found in the medullary cavity within the diaphyses of long bones and assists in fat storage.
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Which of the following is not a component of a typical long bone?
I. A periosteal and soft tissue envelope
II. Nutrient artery foramina
III. A metaphysis
IV. Articular cartilage
V. All of these are normal components of a long bone
Which of the following is not a component of a typical long bone?
I. A periosteal and soft tissue envelope
II. Nutrient artery foramina
III. A metaphysis
IV. Articular cartilage
V. All of these are normal components of a long bone
Bone is living tissue and it therefore requires a blood supply, which is brought to the bone itself by the vital soft tissue envelope around it. Articular cartilage routinely caps the epiphysis (end) of a long bone. The region adjacent to the epiphysis is termed the metaphysis, whereas the shaft of a long bone is the diaphysis.
Bone is living tissue and it therefore requires a blood supply, which is brought to the bone itself by the vital soft tissue envelope around it. Articular cartilage routinely caps the epiphysis (end) of a long bone. The region adjacent to the epiphysis is termed the metaphysis, whereas the shaft of a long bone is the diaphysis.
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Several ligaments act together to join the femur and tibia, forming the knee joint. The complexity of the knee makes it prone to injury. A direct blow to the anterior upper tibia can damage the posterior cruciate ligament, while a blow to the posterior upper tibia can damage the anterior cruciate ligament. The collateral ligaments are located medial and lateral to the joint, and can be damaged from blunt trauma to the sides of the knee.
A skier falls, twists his right knee, and experiences excruciating pain at the inner side of the knee. Upon consulting a physician, the skier learns that he has torn one of the ligaments in his knee. The location of pain and cause of injury are most consistent with what kind of ligament tear?
Several ligaments act together to join the femur and tibia, forming the knee joint. The complexity of the knee makes it prone to injury. A direct blow to the anterior upper tibia can damage the posterior cruciate ligament, while a blow to the posterior upper tibia can damage the anterior cruciate ligament. The collateral ligaments are located medial and lateral to the joint, and can be damaged from blunt trauma to the sides of the knee.
A skier falls, twists his right knee, and experiences excruciating pain at the inner side of the knee. Upon consulting a physician, the skier learns that he has torn one of the ligaments in his knee. The location of pain and cause of injury are most consistent with what kind of ligament tear?
Skiers and American football players are prone to medial collateral ligament (MCL) injuries. The MCL is a major ligament of the knee that resides on the inner (medial) side of the knee. The MCL is connected to the tibia and femur, as well as the meniscus and anterior cruciate ligament, making compound injuries common.
The anterior cruciate ligament resides at the front (anterior) side of the knee, while the posterior cruciate ligament resides to the back (posterior) of the knee. The medial meniscus is a fibrocollagen band that is fused with the MCL.
Skiers and American football players are prone to medial collateral ligament (MCL) injuries. The MCL is a major ligament of the knee that resides on the inner (medial) side of the knee. The MCL is connected to the tibia and femur, as well as the meniscus and anterior cruciate ligament, making compound injuries common.
The anterior cruciate ligament resides at the front (anterior) side of the knee, while the posterior cruciate ligament resides to the back (posterior) of the knee. The medial meniscus is a fibrocollagen band that is fused with the MCL.
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Which of the following is not a function of the skeletal system?
Which of the following is not a function of the skeletal system?
The skeletal system is responsible for a variety of functions in the body. Long bones contain both red and yellow bone marrow, which are the sites for fat storage and hematopoeisis respectively. Bones are also responsible for the storage of calcium and phosphate, which can be released in order to maintain normal levels in the blood.
White blood cells are derived from stem cells in the bone marrow. B-cells continue to develop in the bone marrow, but T-cells develop in the thymus.
The skeletal system is responsible for a variety of functions in the body. Long bones contain both red and yellow bone marrow, which are the sites for fat storage and hematopoeisis respectively. Bones are also responsible for the storage of calcium and phosphate, which can be released in order to maintain normal levels in the blood.
White blood cells are derived from stem cells in the bone marrow. B-cells continue to develop in the bone marrow, but T-cells develop in the thymus.
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Rickets is a condition typically found in immature mammals. The disease is characterized by a telltale "bowing" curvature to bones when pressure is placed upon them. Which of the following deficiencies in bone would result in rickets-like symptoms?
Rickets is a condition typically found in immature mammals. The disease is characterized by a telltale "bowing" curvature to bones when pressure is placed upon them. Which of the following deficiencies in bone would result in rickets-like symptoms?
When it comes to the strength and resilience of bone, both collagen and calcium play important roles. Collagen provides bones with great tensile strength, and calcium (usually in the form of hydroxyapatite) provides bones with great compressive strength. In the event of a calcium deficiency, weight placed on bones would cause them to bend irregularly, resulting in the characteristic bending of bones found with rickets.
A deficiency in collagen would cause damage to the bone during extension or stretching forces. Bone marrow does not play an important structural role, and is more important for bone function.
When it comes to the strength and resilience of bone, both collagen and calcium play important roles. Collagen provides bones with great tensile strength, and calcium (usually in the form of hydroxyapatite) provides bones with great compressive strength. In the event of a calcium deficiency, weight placed on bones would cause them to bend irregularly, resulting in the characteristic bending of bones found with rickets.
A deficiency in collagen would cause damage to the bone during extension or stretching forces. Bone marrow does not play an important structural role, and is more important for bone function.
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The patella is attached to the tibia by a thick band of fibrous tissue referred to as a __________.
The patella is attached to the tibia by a thick band of fibrous tissue referred to as a __________.
Ligaments connect a bone to another bone, while tendons attach a muscle to a bone. Since two bones are being connected by the fibrous band of tissue in question, we can confirm that it is a ligament.
Muscle does not actually form a functional connection; rather, muscle will transition to a tendon, which will connect to a bone. Joints are comprised of several different structures and tissues, and are the articulations between two bones.
Ligaments connect a bone to another bone, while tendons attach a muscle to a bone. Since two bones are being connected by the fibrous band of tissue in question, we can confirm that it is a ligament.
Muscle does not actually form a functional connection; rather, muscle will transition to a tendon, which will connect to a bone. Joints are comprised of several different structures and tissues, and are the articulations between two bones.
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Which of the following is not a main mineral component of human bone?
Which of the following is not a main mineral component of human bone?
Bone consists of calcium-phosphate crystals, known as hydroxyapatite, in a collagen matrix. The molecular formula for hydroxyapatite is 
. Collagen's structure depends on hydroxylysine and hydroxyproline for stability. Potassium is not required in bone.
While these specific formulas are not generally tested knowledge, it is important to know what molecules may influence bone composition and growth.
Bone consists of calcium-phosphate crystals, known as hydroxyapatite, in a collagen matrix. The molecular formula for hydroxyapatite is
While these specific formulas are not generally tested knowledge, it is important to know what molecules may influence bone composition and growth.
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Osteocytes exchange nutrients through which structures in bone tissue?
Osteocytes exchange nutrients through which structures in bone tissue?
Osteocytes are differentiated osteoblasts that have become imbedded in hydroxyapatite bone matrix. The osteocytes are found in small gaps in bone matrix called lacunae and exchange nutrients with the blood using small canals called canaliculi. Lamellae are the concentric regions of osteocytes that are arranged around the central Haversian canal. The canal houses blood vessels and nerves to nourish and stimulate the osteocytes via the canaliculi.
Osteocytes are differentiated osteoblasts that have become imbedded in hydroxyapatite bone matrix. The osteocytes are found in small gaps in bone matrix called lacunae and exchange nutrients with the blood using small canals called canaliculi. Lamellae are the concentric regions of osteocytes that are arranged around the central Haversian canal. The canal houses blood vessels and nerves to nourish and stimulate the osteocytes via the canaliculi.
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