BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
Describe the cells of the bone tissue
-Osteogenic cells
-Osteoblasts
-Osteocytes
-Osteoclasts
What membrane lines the internal canals and the small cavities of the
compact and spongy bones?
Endosteum
What is the periosteum composed of?
-Dense irregular connective tissue
-Collagen fibers
-Outer fibrous layer has fibroblasts
-Inner layer has progenitor cells that become osteoblasts
,BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
Describe the matrix of the bone tissue
-Stony matter surrounding osteocytes and lacunae
-1/3 organic (collagen and protein-carb complex) and 2/3 inorganic
(CaK, CaCO3...)
-gives bone flexibility and strength
-Minerals resist compression
-Collagen resists tension
Compare the function of the organic and the inorganic material in the
bone matrix
-Inorganic (minerals) resist compression
-Organic (protein-carb complex/collagen) resists tension
Why does calcification result in death of chondrocytes, while
ossification does not result in death of osteocytes?
,BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
Chondroblasts are surrounded by cartilage matrix and receive oxygen
and nutrients by diffusion through the matrix. When the matrix
becomes calcified, diffusion is reduced the the point that the cells die.
When osteoblasts form bone matrix, they connect to one another by
their cell processes. Thus, when the matrix is laid down, canaliculi are
formed. Even though the ossified bone matrix is dense and prevents
significant diffusion, the osteocytes can receive gases and nutrients
through the canaliculi or by movement form one osteocyte to another.
Describe the process of endochondral ossification.
1. Hyaline cartilage is covered with fibrous perichondrium
2. In middle of cartilage (primary oss. center), chondrocytes die, and
the thin wall calcify. Perichondrium cells become osteoblasts and form
bony collar-periosteum.
3. Blood vessels grow into primary oss. center. Osteoclasts come and
hollow out calcified center (primary marrow cavity). Osteoblasts come
and deposit bone, thickening shaft. Second oss. center develops at ends
of bone.
4. Second oss. center hollows out secondary marrow cavity. Dividing
line is formed-metaphysis.
5. Epiphyseal plate surrounding by metaphysis exists; enables bones to
grow in length and width.
6. No more cartilage=no more room to grow; only cartilage is articular
cartilage, which needs to stay mushy
, BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
What is the effect of inadequate levels of calcium in the diet of an adult
on the skeleton?
Since we need calcium for everything, the parathyroid hormone
stimulates osteoclast activity and breaks down bones to release
calcium. Bones become brittle and porous.
The epiphyseal cartilage becomes ossified in our youth. On the other
hand, the articular cartilage does not become ossified. Why is that
advantageous?
Growth of articular cartilage results in an increase in the size of the
epiphyses. This is only one of the functions of articular cartilage; it also
forms a smooth, resilient covering over the ends of the epiphyses
within joints. Ossified articular cartilage could not perform that
function.
A 12 year old girl produces relatively large amount of estrogen, a sex
hormone that stimulates growth of the epiphyseal plate, as well as the
rate of ossification. How will that affect her height in future months? At
the age of 25?
Describe the cells of the bone tissue
-Osteogenic cells
-Osteoblasts
-Osteocytes
-Osteoclasts
What membrane lines the internal canals and the small cavities of the
compact and spongy bones?
Endosteum
What is the periosteum composed of?
-Dense irregular connective tissue
-Collagen fibers
-Outer fibrous layer has fibroblasts
-Inner layer has progenitor cells that become osteoblasts
,BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
Describe the matrix of the bone tissue
-Stony matter surrounding osteocytes and lacunae
-1/3 organic (collagen and protein-carb complex) and 2/3 inorganic
(CaK, CaCO3...)
-gives bone flexibility and strength
-Minerals resist compression
-Collagen resists tension
Compare the function of the organic and the inorganic material in the
bone matrix
-Inorganic (minerals) resist compression
-Organic (protein-carb complex/collagen) resists tension
Why does calcification result in death of chondrocytes, while
ossification does not result in death of osteocytes?
,BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
Chondroblasts are surrounded by cartilage matrix and receive oxygen
and nutrients by diffusion through the matrix. When the matrix
becomes calcified, diffusion is reduced the the point that the cells die.
When osteoblasts form bone matrix, they connect to one another by
their cell processes. Thus, when the matrix is laid down, canaliculi are
formed. Even though the ossified bone matrix is dense and prevents
significant diffusion, the osteocytes can receive gases and nutrients
through the canaliculi or by movement form one osteocyte to another.
Describe the process of endochondral ossification.
1. Hyaline cartilage is covered with fibrous perichondrium
2. In middle of cartilage (primary oss. center), chondrocytes die, and
the thin wall calcify. Perichondrium cells become osteoblasts and form
bony collar-periosteum.
3. Blood vessels grow into primary oss. center. Osteoclasts come and
hollow out calcified center (primary marrow cavity). Osteoblasts come
and deposit bone, thickening shaft. Second oss. center develops at ends
of bone.
4. Second oss. center hollows out secondary marrow cavity. Dividing
line is formed-metaphysis.
5. Epiphyseal plate surrounding by metaphysis exists; enables bones to
grow in length and width.
6. No more cartilage=no more room to grow; only cartilage is articular
cartilage, which needs to stay mushy
, BIO 252 EXAMS 2 WITH CORRECT ANSWERS GRADED A
What is the effect of inadequate levels of calcium in the diet of an adult
on the skeleton?
Since we need calcium for everything, the parathyroid hormone
stimulates osteoclast activity and breaks down bones to release
calcium. Bones become brittle and porous.
The epiphyseal cartilage becomes ossified in our youth. On the other
hand, the articular cartilage does not become ossified. Why is that
advantageous?
Growth of articular cartilage results in an increase in the size of the
epiphyses. This is only one of the functions of articular cartilage; it also
forms a smooth, resilient covering over the ends of the epiphyses
within joints. Ossified articular cartilage could not perform that
function.
A 12 year old girl produces relatively large amount of estrogen, a sex
hormone that stimulates growth of the epiphyseal plate, as well as the
rate of ossification. How will that affect her height in future months? At
the age of 25?
