Corrections for Exam 2 - Bio 203

Laayla Muhammad
Corrections for Exam 2

Question 3:
Arrange the following in the proper order from the deepest (1) to most superficial (4).

The deepest layer (1) is the endomysium since it surrounds the skeletal muscle cell (muscle fiber) and allows room for blood capillaries and nerve fibers to reach each muscle fiber. The second deepest layer is the perimysium, a thicker connective tissue sheath, as it separates each fascicle from neighboring ones. The third deepest layer is called the Epimysium since it actually covers the muscle as a whole. Therefore, the deep fascia (4) would have to be the least deep or most superficial layer of the muscle since it surrounds the actual muscles, bones, nerves, and blood vessels of the body.

Question 4:
Which three of the following descriptions apply to the dermal papillae?

The three of the following descriptions that apply to the dermal papillae are: a) they prevent slippage at dermal-epidermal boundary, d) they allow nerves and capillaries to come closer to the external surface of the body in some areas, and f) they allow regeneration of the stratum granulosum. All of these choices are true due to certain factual reasons. The boundary between the epidermis and the dermis is histologically conspicuous and usually wavy. The upward waves are fingerlike extensions of the dermis known as dermal papillae. The dermal and epidermal boundaries interlock like corrugated cardboard, which is an arrangement that resists slippage of the epidermis across the dermis. In highly sensitive areas such as the lips and the genitals, tall dermal papillae allow nerve fibers to reach close to the surface.

Question 13:
Match the muscle names with the naming criterion.

The muscle name known as transverses is not a location, but rather falls into the criterion of an orientation (5). The term itself means transverse, or in other words, situated or lying across. This term for example, is used in the muscle known as transverses abdominis.

Question 21:
Put the following events of endochrondral bone formation in the proper order.

Endochrondral bone formation involves several steps that occur in an order. (1) The first step involves chondrocyte hypertrophy and the formation of supportive bony collar. The osteoblast secretes osteoid against the shaft of the cartilage model, serving as support for the new bone. (2) The next step involves the invasion by blood vessels and creation of primary marrow space. Basically, a periosteal bud invades the cavity left by the chondrocytes and the vascularization carries osteoblasts, osteoclasts, and hemopoietic cells, which turn into bone marrow later inside. (3) Later, blood vessels grow into secondary marrow space in epiphyses. As growth develops, the proliferation of cartilage cells in the epiphyseal plate slows and stops. (4) After obliteration of the epiphyseal plate and mix of compact and trabecular bone, articular cartilage remains.

Question 22:
Match each of the joints in the following list to the joint type.

Interphalangeal joints are not condyloid joints, and in fact, are hinge joints (2). This is because the articular surfaces are moulded to each other to permit motion only in one plane, which is forward and backward; movements being extension and flexion. Altantoaxial is actually a pivot joint (4), since there is a pivot articulation between the odontoid process of the axis and the ring formed by the anterior arch and the transverse ligament of the atlas. Radiocarpal joint (wrist-joint) is a condyloid articulation (6) and allows three degrees of freedom. Movements that are permitted from this joint are flexion, extension, abduction, adduction, and circumduction, which the radiocarpal joint permits as well.

Question 26:
Which type of joint is found in the cervical, thoracic, and lumbar regions of the vertebral column?

The type of joint that is found in the cervical, thoracic, and lumbar regions of the vertebral column is symphyses (d), where two bones are joined by fibrocartilage. The joint between the bodies of two vertebrae, united by an intervertebral disc is an example of this type of joint. Therefore, each intervertebral disc permits only slight movement between adjacent vertebrae.

Question 27:
The tissues illustrated in the periphery of this cross-section of the esophagus are ...

The tissues illustrated in the periphery of this cross-section of the esophagus are a circular layer of smooth muscle surrounded by a longitudinal layer of smooth muscle (a). This is a single-unit smooth muscle and in many of the hollow viscera, it forms two or more layers, typically an inner circular layer, in which the myocytes encircle the organ and an outer longitudinal layer in which the myocytes run lengthwise along the organ. The myoctes of this type of muscle are electrically coupled to each other by gap junctions.

Question 33:
This image illustrates the relationship between nerve stimulus and muscle response. Which of the following statements is the best description of the relationship illustrated by the four graphs contained in this image?

The relationship illustrated by the four graphs contained in this image is represented by choice b) the strength of the contraction is increased when the frequency of stimulation by the nerve increases to the point where the muscle fiber cannot relax completely between twitches. The force of each twitch builds on the previous one. At high stimulus frequency, the muscle does not have time to relax at all between stimuli and exhibits a state of continual contraction with about four times as much tension as a single twitch. Therefore, tension declines as the muscle fatigues.

Question 36:
What is the functional advantage of a lack of a spinous process in C1?

The functional advantage of a lack of a spinous process in C1 is that the lateral movement of the spinous process is usually restricted by its articulation with the dorsal arch of the vertebra below it. Without it, the atlas is free to rotate (c). The spinous process provides points of attachment for ligaments and spinal muscles. Yet, the atlas does not have a body due to the fact that its body has fused with that of the next vertebra. Therefore, the atlas supports the globe of the head and is specialized to allow a greater range of motion than normal vertebrae. It allows one to nod his/her head to indicate “yes” for example.

Question 39:
Dermal papillae are numerous and form relatively high peaks in the palmar and plantar skin, but are more rare in the skin of the face and abdomen. Which of the following is an appropriate interpretation of this difference (check the 2 best answers)?

Dermal papillae form relatively high peaks in the palmar and planter skin when compared to the skin of the face and abdomen due to several reasons. The soles and palms are likely to be under shearing stress, so there is a great need to prevent slippage of the epidermis (a). The dermal and epidermal boundaries interlock like corrugated cardboard, which resists slippage of the epidermis across the dermis. There are also delicate furrows that divide the skin into tiny rectangular to rhomboid areas on hands and wrists that the dermal papillae is responsible of. In highly sensitive areas lips and genitals, tall dermal papillae allow nerve fibers to reach close to the surface. Therefore, it is important to have the papillae close to the surface to allow for a dense covering of body hair on these structures (d).