Question

multiple choice. choose the one alternative that best completes the statement or answers the question. 1) which one of the following statements is true regarding parathyroid hormone (pth)? a) it stimulates hemopoiesis. b) it is released when blood calcium levels are high. c) it has the same function as calcitonin. d) it causes the breakdown of bone. e) it causes decreased activity of osteoclasts. 2) which one of the following statements correctly describes the location of compact bone and spongy bone? a) spongy bone is located at the epiphyses, and compact bone is located in the core of the diaphysis. b) compact bone covers the epiphyses and forms the diaphysis, and spongy bone lies within the epiphyses, deep to the compact bone. c) the epiphyses of long bones are solid compact bone, and the diaphysis is predominantly spongy bone. d) spongy bone is found on the outside of the diaphysis, and compact bone forms the hard core of the diaphysis. e) spongy bone fills the entire diaphysis and epiphyses, covered by a thin layer of compact bone. 3) which of the following is(are) an example of bone formed by intramembranous ossification? a) femur b) humerus c) phalanges of the fingers d) broad, flat skull bones 4) compact bone has _____, whereas spongy bone has ___. a) osteocytes; osteoclasts b) trabeculae; osteons c) osteons; trabeculae d) spaces that reduce the weight of bone; tightly packed matrix that is solid 5) the axial skeleton includes ___ a) the femur, tibia, and fibula. b) the radius, ulna, carpals, and phalanges. c) the skull, hyoid bone, thoracic cage, and vertebral column. d) the upper and lower limbs and pelvic and pectoral girdles. 6) articular cartilage of a long bone is found ___ a) in the spaces of the spongy bone. b) inside the medullary cavity. c) on the outer surface of the diaphysis. d) on the outer surface of the epiphyses. 7) which one of the following is true? a) osteoclasts secrete bone matrix and become osteoblasts. b) osteoclasts deposit bone matrix around themselves and become osteocytes when they are isolated in lacunae. c) osteoblasts are large, multinucleated cells that break down calcified bone matrix. d) osteoblasts deposit bone matrix around themselves and become osteocytes when they are isolated in lacunae. 8) red bone marrow functions in the formation of _____ a) red blood cells only. b) white blood cells only. c) red blood cells, white blood cells, and platelets. d) red and white blood cells only.

Explanation:

1. Parathyroid hormone (PTH) increases blood - calcium levels by promoting bone resorption (breakdown of bone), so D is correct. A is wrong as PTH doesn't stimulate hematopoiesis; B is wrong as PTH is released when blood calcium is low; C is wrong as PTH and calcitonin have opposite effects; E is wrong as PTH increases osteoclast activity.
2. Compact bone covers the epiphyses and forms the diaphysis, and spongy bone lies within the epiphyses, deep to the compact bone, so B is correct.
3. Intramembranous ossification forms broad, flat skull bones, so D is correct. Long bones like femur, humerus and phalanges form by endochondral ossification.
4. Compact bone has osteons, and spongy bone has trabeculae, so C is correct.
5. The axial skeleton includes the skull, hyoid bone, thoracic cage, and vertebral column, so C is correct. Options A, B and D are parts of the appendicular skeleton.
6. Articular cartilage of a long bone is found on the outer surface of the epiphyses, so D is correct.
7. Osteoblasts deposit bone matrix around themselves and become osteocytes when isolated in lacunae, so D is correct. Osteoclasts break down bone matrix, not secrete it (A is wrong), and osteoblasts are not multinucleated cells that break down bone (C is wrong).
8. Red bone marrow functions in the formation of red blood cells, white blood cells, and platelets, so C is correct.

Answer:

1. D. It causes the breakdown of bone.
2. B. Compact bone covers the epiphyses and forms the diaphysis, and spongy bone lies within the epiphyses, deep to the compact bone.
3. D. Broad, flat skull bones
4. C. osteons; trabeculae
5. C. the skull, hyoid bone, thoracic cage, and vertebral column.
6. D. on the outer surface of the epiphyses.
7. D. Osteoblasts deposit bone matrix around themselves and become osteocytes when they are isolated in lacunae.
8. C. red blood cells, white blood cells, and platelets.