test 1 questions

Identify the steps involved in the process by which a bone grows in diameter.

A bone grows in diameter by appositional growth, wherein the outer surface of the bone grows as cells of the periosteum differentiate into osteoblasts that contribute to the bone matrix. Eventually, these cells become surrounded by matrix and differentiate into osteocytes. Additionally, the bone matrix is removed from the inner surface by osteoclasts to expand the medullary cavity.

Compare and contrast the strength and stability of a joint with respect to the amount of mobility in the joint.

A joint cannot be both highly mobile and very strong. The greater the range of motion at a joint, the weaker it is. The stronger the joint, the lesser its range of motion. For example, a synarthrosis, which is the strongest type of joint, does not permit any movement.

Explain what is happening to a person who is cyanotic, and what body structures would show this condition most easily.

A person who is cyanotic has a sustained reduced blood flow to the skin. As a result, the skin takes on a bluish coloration, called cyanosis, which is especially apparent in areas of thin skin, such as the lips or beneath the nails.

Compare and contrast the functions of a tendon and a ligament.

A tendon is made of cords of dense regular connective tissue that attach a skeletal muscle to a bone. Ligaments resemble tendons, but they usually connect one bone to another bone. They also contain significantly more elastic fibers than tendons.

Describe how Marfan syndrome develops.

An abnormal protein affects the elastin fibers within the matrix of connective tissue proper. This results in abnormally long and thin digits, vision difficulty, and cardiovascular defects.

How do articular cartilages differ from other cartilages in the body?

Articular cartilages cover articulating surfaces of bones. They resemble hyaline cartilages elsewhere in the body, but they have no perichondrium, and the matrix contains more water than other cartilages have.

identify the events that signal the end of long bone elongation.

At maturity, the rate of epiphyseal cartilage growth slows down, while the rate of osteoblast production increases, narrowing the region of the epiphyseal plate. When the plate disappears, the epiphysis and diaphysis of the bone grow together, and elongation stops.

A small child falls off a bicycle and breaks an arm. The bone is set correctly and heals well. After the cast is removed, an enlarged bony bump remains at the region of the fracture. After several months this enlargement disappears, and the arm is essentially normal in appearance. What happened during this healing process?

At the fracture point, bleeding into the area creates a fracture hematoma. An internal callus forms as a network of spongy bone that unites the inner surfaces, and an external callus of cartilage and bone stabilizes the outer edges. Together, these are visible as the enlargement. A swelling initially marks the location of the fracture. Over time this region will be remodeled, and little evidence of the fracture will remain.

Compare and contrast exocrine and endocrine secretions.

Exocrine secretions occur in ducts that lead onto surfaces; endocrine secretions occur in the interstitial fluid and then enter into blood vessels.

What factors limit the range of motion of a mobile diarthrosis?

Factors that limit the range of movement of a joint include accessory ligaments and collagen fibers of the joint capsule, the shapes of the articulating surfaces that allow movement in some directions while preventing it in others, the tension in the tendons attached to the articulating bones, and the bulk of the muscles surrounding the joint.

Explain why fair-skinned individuals have greater need to shield themselves from the sun than do dark-skinned individuals.

Fair-skinned individuals produce less melanin in their melanocytes, and are therefore less able to prevent the absorption of potentially damaging ultraviolet radiation. Since more UV radiation reaches the deeper skin layers, it may cause a greater amount of damage.

Most young children who break a bone in their upper or lower limbs experience a greenstick fracture. This type of fracture is rare in an adult. What is the reason for this difference?

In children, the long bones are relatively supple and easily deformed because the relative proportion of collagenous fibers to ossified calcium and phosphate salts is higher. This makes a greenstick fracture more common in children than in adults. With increased age, the proportion of collagenous fibers to ossified calcium and phosphate salts decreases, making the bones more brittle, thereby decreasing the frequency of greenstick fractures.

Identify the factors that determine the type of ossification that occurs in a specific bone.

In intramembranous ossification, bone develops from mesenchyme or fibrous connective tissue. In endochondral ossification, bone replaces an existing cartilage model.

Describe how the protein keratin affects the appearance and function of the integument

Keratin is produced in large amounts in the stratum granulosum. Fibers of keratin interlock in the cells in this layer during the process of keratinization. The cells become thinner and flatter; subsequently, they dehydrate. Keratin is important in maintaining the structure of the outer part of the epidermis and making it water resistant. Additionally, keratin forms the basic structural component of hair and nails.

Smoking destroys the cilia found on many cells of the respiratory epithelium. Formulate a hypothesis as to why this contributes to a "smoker's cough."

Mucus is produced by the respiratory epithelium in response to irritation from smoking. The cilia found on many cells of the respiratory system beat upward, thereby moving mucus produced by the respiratory epithelium up to the level of the esophagus, where it can be swallowed and eliminated. Destruction of the cilia prevents the elimination of this mucus. Therefore, coughing is the only mechanism by which the mucus can be removed.

Compare and contrast the processes of ossification and calcification.

Ossification is the process of replacing other tissues with bone, while calcification refers to the deposition of calcium salts within a tissue.

How does the classification of a joint change when an epiphysis fuses at the ends of a long bone?

Prior to fusion, the two parts of a single bone are united by a line of cartilage and are called a synchondrosis. Once the cartilaginous plate is obliterated, there is no more joint, and it becomes an immovable synostosis.

Compare and contrast the advantages of spongy bone and compact bone in an area such as the expanded ends of long bones.

Spongy bone is found where bones receive stresses from many directions. In the expanded ends of the long bones, the epiphyses, the trabeculae in the spongy bone are extensively cross-braced to withstand stress applied from different directions. In contrast, compact bone is heavier and is best suited for resisting stresses that are parallel to the shaft of a long bone.

Identify what stem cells are and analyze their functions.

Stem cells are usually found in the deepest layer of the epithelium. They divide to replace cells lost or destroyed at the epithelial surface.

You are about to undergo surgery. Explain why you want your physician to have an excellent understanding of the tension lines of the skin.

Tension lines are important because a cut that runs parallel to a tension line closes more easily, whereas a cut made at right angles to a tension line will sever elastic fibers in the skin and thus be pulled open as the fibers recoil. A parallel cut will also heal faster and with less scarring than a cut at right angles to tension lines.

What other types of connective tissue would be affected by abnormal elastin?

The abnormal elastin of Marfan's syndrome would also affect loose areolar connective tissue beneath the skin and beneath the epithelial lining of the digestive, respiratory, and urinary tracts, and blood vessels throughout the body.

What common mechanism holds together immovable joints such as skull sutures and the gomphoses, holding teeth in their alveoli?

The edges of the bones are interlocked and bound together at the suture by dense connective tissue. A different type of synarthrosis binds each tooth to the surrounding bony socket. This fibrous connection is the periodontal ligament

Explain why a healed area of bone is less likely to fracture in the same place again from similar stresses.

The final repair is slightly thicker and stronger than the original bone.

What role do capsular ligaments play in a complex synovial joint? Use the humeroulnar joint to illustrate your answer.

The joint capsule that surrounds the entire synovial joint is continuous with the periostea of the articulating bones. Accessory ligaments are localized thickenings of the capsule. Extracapsular ligaments are on the outside of the capsule; intracapsular ligaments are found inside the capsule. In the humeroulnar joint, the capsule is reinforced by strong ligaments. The radial collateral ligament stabilizes the lateral surface of the joint. The annular ligament binds the proximal radial head to the ulna. The medial surface of the joint is stabilized by the ulnar collateral ligament.

How can pronation be distinguished from circumduction of a skeletal element?

The movement of the wrist and hand from palm-facing-front (supination) to palm-facing-back is called pronation. Circumduction is a special type of angular motion that encompasses all types of angular motion: flexion, extension, adduction, and abduction

Analysis of a glandular secretion indicates that it contains some DNA, RNA, and membrane components such as phospholipids. What mode of secretion is this? Explain your answer.

The presence of DNA, RNA, and membrane components suggests that the cells were destroyed during the process of secretion. This is consistent with a holocrine type of secretion.

Analyze the significance of the cilia on the respiratory epithelium.

The presence of the cilia at the surface of the epithelium means that the mucous layer, which rests on the epithelium surface, will be kept moving and the respiratory surface will be kept clean (or clear).

Analyze why pinching the skin usually does not distort or damage the underlying muscles.

The skin is separated from the muscles by a layer of loose connective tissue. The loose connective tissue provides padding and elastic properties that permit a considerable amount of independent movement of the two layers. Thus, pinching the skin does not affect the underlying muscle.

List the characteristics that make the subcutaneous layer a region commonly used for hypodermic injections.

The subcutaneous layer, as compared to other body layers, (a) is quite elastic, (b) has a high density of blood vessels to facilitate the transport of the drug, and (c) has no vital organs.

what is the significance of the orientation of the spongy bone?

The trabeculae in spongy bone allow the bone to withstand pressure from the side. The compact bone is arranged in parallel layers which give the bone strength when pressure is received down a bone but can not withhold pressure recieved from the side. Trabeculae have no organized arrangment it allows the bone to be able to take blows from a lateral angle. An example is in the distal epiphysis pressure is directed along the knee joint to the tibia as to not injure the patella.

Compare a tendon to an aponeurosis.

While a tendon is made of cords of dense regular connective tissue, an aponeurosis is made of a sheet or ribbon of connective tissue that resembles a flat tendon. Aponeuroses may cover the surface of muscles and assist superficial muscles in attaching to one another or to other structures.

what are the components of a synovial joint

articular surface joint capsule synovial fluid bursae articular capsule

what is the role of the serous membrane in the body

helps to keep organs intact provide lubrication and moist covering to prevent organ damage and friction