ch.6

The main role of the axial skeleton is to help us manipulate our environment.

-true -false answer: false It is the appendicular skeleton, along with the skeletal muscles that attach to it, that allows us to manipulate our environment. The axial skeleton is mostly involved in protecting, supporting, or carrying other body parts.

Which statement regarding the classification of bones is FALSE?

Irregular bones include the vertebrae and hip bones. Long bones include all limb bones except the patella. The sternum is an example of a flat bone. Sesamoid bones form within certain tendons. answer: B This is false; long bones include all limb bones except the patella, tarsals, and carpals.

Which of the labeled parts of the bone is composed primarily of compact bone?

a b c d e answer: D The shaft of an adult long bone is composed of compact bone.

What would be the physical sign that a bone cannot continue longitudinal growth?

an epiphyseal line the presence of hyaline cartilage on the ends of the bone the presence of osteons the presence of osteoblasts answer: A The epiphyseal plate is a zone of hyaline cartilage between the epiphysis and diaphysis of a long bone. When the cartilage is replaced with bone and the plate closes, the bone has reached its maximum length. This ossified remnant of the "growth plate" is called the epiphyseal line.

Which of the following hormones is currently thought to decrease plasma calcium levels in pregnant women and children?

calcitriol parathyroid hormone (PTH) calcitonin thyroid hormones answer: C Yes, calcitonin is currently thought to decrease plasma calcium levels in children and pregnant women.

The structure indicated by the arrow is composed primarily of what tissue?

dense connective tissue mesenchyme hyaline cartilage fibrocartilage answer: B The cartilage models used to form bones are composed of hyaline cartilage. This tissue persists within the epiphyseal plate at the boundary between primary and secondary ossification centers until early adulthood.

Which bone-forming process is shown in the figure?

endochondral ossification intramembranous ossification bone remodeling bone fracture repair answer: A The figure illustrates a step in the embryonic formation of a bone from a cartilage model.

Which of the following is a site for a muscle or ligament attachment?

groove foramen sinus fossa trochanter answer: E A trochanter is a type of bone projection; projections often protrude from the bone because of the interaction forced upon them by muscle or ligaments.

Which of the following would NOT be a way that parathyroid hormone (PTH) could alter plasma calcium levels? (Which one of the following is FALSE?)

increase reabsorption of calcium in the kidney increase osteoblasts on bone increase osteoclasts answer: B Correct. This answer is false. PTH would NOT increase osteoblasts. Osteoblasts store calcium on bone, thus lowering plasma calcium levels.

The blood vessels and nerve in the figure are found within which type of space?

marrow cavity central (Haversian) canal perforating (Volkmann's) canal canaliculi answer: B A central (or Haversian) canal runs lengthwise at the center of each osteon.

Which of the following is the major component of the part of the bone labeled E?

osseous tissue dense connective tissue blood adipose tissue answer: D Yellow bone marrow within the medullary cavity is composed primarily of adipose tissue (fat).

Which of the following is UNLIKELY to affect bone remodeling?

parathyroid hormone low blood Ca2+ concentration mechanical stress glucagon answer: D Glucagon's main action is to increase blood glucose levels by triggering the breakdown of glycogen in the liver; it does not affect bone remodeling.

Which hormone works directly in the intestine to increase plasma calcium levels?

parathyroid hormone (PTH) calcitriol calcitonin answer: B Yes, parathyroid hormone (PTH) activates Vitamin D into calcitriol in the kidney. Calcitriol then increases absorption of calcium in the intestine.

PTH promotes the formation of which hormone?

thyroid hormones calcitriol vitamin D calcitonin answer: B Yes, parathyroid hormone promotes the formation of calcitriol.

Which of the following structures contain receptors that monitor changes in head rotation?

utricle saccule semicircular canals cochlea answer: C The receptor for rotational acceleration, called the crista ampullaris or simply crista, is a minute elevation in the ampulla of each semicircular canal. The semicircular canals monitor changes in head rotation, called our sense of dynamic equilibrium.