Chapter 6 - Bones and Bone Tissues

Bone cells that are found in the endosteum and periosteum and build bone are called __________.

Osteoblasts perform the process of bone deposition, during which they build up the bone ECM. An easy way to remember what they do is to remember the mnemonic "osteoBlasts Build Bone."

endochondral ossification

chondroblasts differentiate into osteoblasts

The layers of bone tissue immediately deep to the periosteum are:

circumferential lamellae. page 191

Appositional growth allows bones to grow in width. In actively growing bones, appositional growth is primarily responsible for thickening the compact bone of the ______________.

diaphysis

Charlie has a break in the shaft of his thigh bone. He broke the __________.

diaphysis

Primary ossification centers develop in long bones in the __________.

diaphysis

What stimulates the release of parathyroid hormone (PTH)?

low blood calcium ion levels

The skeletal system is important for

mineral storage and acid-base homeostasis

What prompts the closure of the epiphyseal plate around age 18-21?

ossification of the zone of proliferation

What cells participates in the process of bone deposition?

osteoblasts

Where tension is placed, _____________ are stimulated and bone deposition occurs.

osteoblasts

Bones are constantly undergoing resorption for various reasons. Which of the following cells accomplishes this process?

osteoclast

promotes bone resorption

pressure. Where continuous pressure is placed, osteoclasts are stimulated and bone resorption occurs.

Cells that develop into osteoblasts are:

osteogenic cells.

The structural units of mature compact bone are called __________.

osteons

structure of compact bone

page 191

What hormone promotes an increase in the activity of osteoclasts?

parathyroid hormone (PTH)

Which cells participate in the process of bone deposition?

Osteoblasts

As a result of the increase of testosterone at puberty for males, __________.

appositional bone growth increases (width)

As a result of the increase of testosterone at puberty for males:

appositional bone growth increases. (width)

For a person who starts running for exercise, __________. (compression)

bone deposition exceeds bone resorption. osteoblasts are making bone faster than the osteoclasts can reabsorb it = stronger bones.

Which canals connect lacunae together?

Canaliculi

What hormones are important for bone remodeling and calcium ion homeostasis?

- Vitamin D (actually functions as a hormone!) - Parathyroid Hormone PTH (when Ca+ in blood low, osteoclasts) - Calcitonin (takes Ca+ from blood, adds to bone, osteoblasts)

Bone growth and remodeling depends on adequate intake of __________.

- calcium ion intake - vitamin D - vitamin C - vitamin K - protein intake

effects of growth hormone on bones

- directly stimulates osteoblasts in the periosteum to promote appositional growth. - increases the rate of mitosis in the epiphyseal plate of growing bones. - increases the activity of osteogenic cells.

What are the hormones involved in bone growth?

- growth hormone, length (longitudinal) - testosterone, width (appositional growth) - estrogen, width, promotes closure

list the steps of endochondral ossification

1. Perichondrium is invaded by blood vessels. 2. Perichondrial cells differentiate into osteogenic cells then into osteoblasts. 3. Osteoblasts build the bone collar on the external surface of the bone. 4. Chondrocytes die. 5. In the primary ossification center, osteoblasts replace calcified cartilage with early spongy bone.

Predict the effect of growth hormone deficiency during childhood.

A deficiency in growth hormone causes stunted or even halted growth. Children with this disorder are affected by dwarfism, grow slowly, and have puberty that may be delayed by several years or even indefinitely.

What type of bone growth do you think a 40-year-old male experiences?

Appositional growth (width)

What cartilage in long bone persists for life?

Articular cartilage

Which hormone, produced by the thyroid gland, works opposite to parathyroid hormone (PTH)?

Calcitonin

The hormone calcitonin causes an increase in __________.

Calcitonin causes a decrease in osteoclast activity and an increase in bone deposition, so excess calcium is removed from blood and deposited in bones.

Flat bones such as the bones of the skull form via __________.

During intramembranous ossification, embryonic connective tissue called mesenchyme is replaced with bone.

What is the function of red bone marrow?

Hematopoiesis, or blood cell formation, happens inside red bone marrow.

What tissue serves as the model for bones formed during endochondral ossification?

Hyaline cartilage

vertebra is an example of what type of bone?

Irregular bone have an irregular shape.

an effect of parathyroid hormone (PTH)?

It stimulates the intestines to absorb calcium. This causes an increase in blood calcium to restore homeostasis.

intramembranous ossification

Mesenchymal cells differentiate into osteoblasts

Bones are constantly undergoing resorption for various reasons. What cell accomplishes this process?

Osteoclast

_____________ are responsible for bone resorption, during which they break down the bone ECM.

Osteoclasts

______________ are surrounded by bone matrix in a small cavity known as a lacuna.

Osteocytes

Bones located within tendons, such as the patella, are called __________.

Sesamoid bones are generally small, relatively flat, and oval-shaped. They give the tendon a mechanical advantage, providing better leverage for muscles, and also reduce wear and tear on the tendon.

In the epiphyseal plate, cartilage grows:

by pushing the epiphysis away from the diaphysis.

The major organic component of bone extracellular matrix is __________.

The predominant protein fiber in osteoid is collagen.

_____________ are small, branching "ribs" of bone found in spongy bone.

Trabeculae

Within the epiphyseal plate, which zone houses actively dividing cartilage cells in their lacunae?

Zone of proliferation

A radiograph reveals epiphyseal lines in the long bones of a 12-year-old's hand. Which of the following statements is correct?

epiphyseal lines are matured epiphyseal/ growth plates and will no longer grow. OR The epiphyseal plates have ossified and further growth in length is not possible.

What structure allows the diaphysis of the bone to increase in length?

epiphyseal plate

Appositional growth produces __________.

growth in width

Blood cells are made in the red bone marrow of bones, a process known as __________.

hematopoiesis

Calcitonin functions to:

increase bone deposition

Whose bone marrow is mostly red?

infants

The term diploë refers to the:

internal layer of spongy bone in flat bones.

PTH is a hormone involved in calcium homeostasis. It causes bone resorption, when it senses that Ca in the blood is to low.

sensor: parathyroid --> control center: parathyroid --> releases: parathyroid hormone when amt of Ca+ in the blood is too low, breaks bone down to release into blood stream by activating --> osteoclasts

calcitonin

sensor: thyroid --> control center: thyroid --> releases calcitonin --> effector/ response: osteoblasts. when Ca+ in the blood is too high, calcitonin is released to signal osteoblasts to start putting Ca+ back into bone (building new bone)

The function of yellow bone marrow is:

triglyceride storage.

The ribs and sternum are classified as flat bones because they are thin and broad.

true