MCAT Biology : Other Bone Concepts

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

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Example Question #1 : Other Bone Concepts

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

Possible Answers:

I

IV

III

II

V

Correct answer:

V

Explanation:

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.  

Example Question #2 : Other Bone Concepts

Which of the following is false regarding compact bone and spongy bone? 

I. Compact bone is also called cancellous bone

II. Spongy bone has a haversian system

III. Compact bone is the site of red blood cell development

Possible Answers:

I and III

III only

I, II, and III

II and III

Correct answer:

I, II, and III

Explanation:

There are two main types of structural configurations that form bone tissue: compact bone (or cortical bone) and spongy bone (or cancellous bone). Compact bones function to maintain the structure of the body and release chemical elements, such as calcium. Compact bones are characterized by their specialized haversian system, or osteon structure. It is the fundamental unit of compact bone structure and consists of a haversian canal (a tunnel that is created by osteoclast activity to remove bone tissue) and lamellae (layers of compact bone tissue organized in concentric circles). Spongy bones do not contain these haversian systems.

Spongy bone is relatively flexible bone tissue that is found at the end of long bones (the epiphyses). One of their main functions is to develop red blood cells, as they house the red bone marrow responsible for erythropoiesis and erythrocyte maturation. Compact bones, on the other hand, contain yellow bone marrow that functions to store fat and adipose tissue.

Example Question #1 : Other Bone Concepts

Osteocytes exchange nutrients through which structures in bone tissue?

Possible Answers:

Canaliculi

Lacunae

Lamellae

Haversian canals

Correct answer:

Canaliculi

Explanation:

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.

Example Question #2 : Other Bone Concepts

Which of the following is not a function of the skeletal system?

Possible Answers:

Mineral homeostasis

Red blood cell formation

Fat storage

B-cell and T-cell development

Correct answer:

B-cell and T-cell development

Explanation:

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.

Example Question #5 : Other Bone Concepts

Slightly soluble calcium salts, such as calcium hydrogen phosphate, are found in the matrices of bone. What do these salts primarily contribute to the functions of the skeletal system?

Possible Answers:

Movement

Energy storage

Mineral storage

Blood cell production

Correct answer:

Mineral storage

Explanation:

Bone matrices store these slightly soluble calcium salts so that they can be released into the bloodstream in times of low blood calcium levels. As a result, these salts are an example of how the skeletal system provides mineral storage for the body.

Movement and bone cell production are also primary functions of the skeletal system, but are not linked to calcium salts. Energy storage is linked to the fats stored in the yellow marrow of the bone.

Example Question #3 : Other Bone Concepts

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?

Possible Answers:

Calcium

Collagen

Yellow bone marrow

Red bone marrow

Correct answer:

Calcium

Explanation:

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.

Example Question #5 : Other Bone Concepts

Which of the following is not a main mineral component of human bone?

Possible Answers:

Calcium

Potassium

Hydroxyl groups

Phosphate

Correct answer:

Potassium

Explanation:

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.

Example Question #7 : Other Bone Concepts

Rickets is a disorder that is commonly caused by a vitamin D deficiency. The disorder results in bones that can bend and cause deformities.

Based on this information, what is the effect of rickets on the bones of a patient?

Possible Answers:

There is a decrease of collagen in the bones

There is a decrease of calcium in the bones

There are not enough osteoblasts in order to create bone matrix

There is too much calcium deposited in the bones

Correct answer:

There is a decrease of calcium in the bones

Explanation:

Vitamin D aids in calcium absorption in the small intestine. In the absence of vitamin D, inadequate absorption causes a deficiency of calcium in the body. Without calcium, the bones will not have adequate tensile strength, which can cause a bowing effect in bones that support weight, such as the femurs. Collagen in the bones is associated with resistance to compression, rather than tensile strength, and is not linked to vitamin D.

Example Question #8 : Other Bone Concepts

The patella is attached to the tibia by a thick band of fibrous tissue referred to as a __________.

Possible Answers:

joint

ligament

muscle

tendon

Correct answer:

ligament

Explanation:

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.

Example Question #9 : Other Bone Concepts

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?

Possible Answers:

Lateral collateral ligament (LCL)

Anterior cruciate ligament (ACL)

Medial collateral ligament (MCL)

Posterior cruciate ligament (PCL)

Correct answer:

Medial collateral ligament (MCL)

Explanation:

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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