Anatomy and Physiology Homework #9

Questions and Answers

What is the function of the medullary cavity?

The medullary cavity contains the red bone marrow and the yellow bone marrow.

Where is articular cartilage found and how is it nourished?

Articular cartilage is found covering both epiphyseal portions of articulating bone and nutrients diffuse from synovial fluid within the joint.

The periosteum contains all the following EXCEPT __________.

motor nerves

________ accounts for almost two-thirds of the weight of bone.

Calcium phosphate Signup and view all the answers

Bone is composed of ________ percent cells.

2 Signup and view all the answers

What do the lacunae of osseous tissue contain?

osteocytes. Signup and view all the answers

What is the most abundant cell type in bone?

osteocytes. Signup and view all the answers

________ are stronger than steel when stretched.

Collagen fibers Signup and view all the answers

________ free calcium from bone to maintain blood calcium levels.

Osteoclasts Signup and view all the answers

If osteoclast activity exceeds osteoblast activity in a bone, how will bone mass be affected?

The bone mineral content will decrease and thus bone mass will decrease. Signup and view all the answers

What are the structural units of mature compact bone called?

osteons. Signup and view all the answers

What does the central canal of an osteon contain?

blood vessels. Signup and view all the answers

Which structural features of spongy bone are oriented along stress lines and are cross-braced extensively?

trabeculae. Signup and view all the answers

Is a sample of bone with lamellae not arranged in osteons more likely from the epiphysis or from the diaphysis?

epiphysis Signup and view all the answers

During appositional growth, what happens to bones?

Bones grow wider. Signup and view all the answers

What is the lining of the medullary cavity called?

endosteum. Signup and view all the answers

As a bone increases in diameter, what happens to the medullary cavity?

The medullary cavity increases in diameter because bone matrix is removed by osteoclasts. Signup and view all the answers

Define appositional growth.

Appositional growth is an increase in bone diameter due to the addition of bone matrix at the bone's outer surface. Signup and view all the answers

A hard ossified bone in an adult actually begins within the embryo as a miniature version composed of __________.

hyaline cartilage Signup and view all the answers

What structure allows a bone to grow in length?

epiphyseal cartilages. Signup and view all the answers

Endochondral ossification begins with the formation of a(n) __________.

cartilage model. Signup and view all the answers

When the epiphyseal plate is replaced by bone, what happens?

Long bones have reached their adult length. Signup and view all the answers

When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, what happens to bones?

Bones grow longer. Signup and view all the answers

Where does endochondral lengthening occur?

3 Signup and view all the answers

What process is shown at '6'?

secondary ossification. Signup and view all the answers

Which of the following is formed by intramembranous ossification?

Both the roof of the skull and the clavicle. Signup and view all the answers

Intramembranous ossification begins with differentiation of __________ cells.

mesenchymal. Signup and view all the answers

Define intramembranous ossification.

Intramembranous ossification is bone formation within connective tissue without the prior development of a cartilage model. Signup and view all the answers

During intramembranous ossification, bone replaces which type of tissue?

Embryonic, or fibrous connective tissue. Signup and view all the answers

Which of the following statements regarding the homeostasis regulation of blood calcium is FALSE?

The three main organs that serve as the site for the regulation of blood calcium levels are the bones, the intestines, and the pancreas. Signup and view all the answers

Elevated levels of calcium ion in the blood stimulate the secretion of which hormone?

calcitonin. Signup and view all the answers

What is the intestinal response to PTH secretion when calcium ion levels are low?

Calcium is absorbed quickly. Signup and view all the answers

Identify the hormone that stimulates the release of calcium ions from bone matrix and explain its mechanism of action.

Parathyroid hormone; increases osteoclast break down of bone matrix. Signup and view all the answers

List the steps involved in fracture repair, beginning just after the fracture occurs.

Fracture hematoma formation, callus formation, spongy bone formation, compact bone formation. Signup and view all the answers

Study Notes

Medullary Cavity

Houses red and yellow bone marrow, crucial for blood cell production and fat storage.

Articular Cartilage

Covers epiphyseal portions of articulating bones.
Nourished by nutrients diffusing from synovial fluid in joints.

Periosteum Composition

Contains various structures except motor nerves.

Calcium Phosphate

Comprises nearly two-thirds of bone weight, providing strength and rigidity.

Bone Cellular Composition

Only about 2% of bone tissue consists of cells.

Lacunae

Small cavities in osseous tissue that contain osteocytes, vital for bone maintenance.

Osteocytes

The most abundant cell type in bone, responsible for maintaining bone tissue.

Collagen Fibers

Stronger than steel when stretched, contributing to bone flexibility and resilience.

Osteoclasts

Cells that release free calcium from bone to help maintain blood calcium levels.

Bone Mass and Osteoclasts

When osteoclast activity surpasses that of osteoblasts, bone mass decreases.

Osteons

Structural units of mature compact bone, consisting of concentric layers of mineralized matrix.

Central Canal of Osteon

Contains blood vessels, crucial for nutrient delivery and waste removal in bone.

Spongy Bone Structure

Trabeculae are oriented along lines of stress and extensively cross-braced, providing structural support.

Lamellae Arrangement

If lamellae are not arranged in osteons, the sample is likely from the epiphysis rather than the diaphysis.

Appositional Growth

Refers to the process in which bones grow wider, adding bone matrix at the outer surface.

Endosteum

The lining of the medullary cavity, providing a surface for bone growth and repair.

Medullary Cavity Changes

As bone diameter increases, osteoclast activity enlarges the medullary cavity.

Appositional Growth Definition

An increase in bone diameter due to the addition of bone matrix at the outer surface.

Ossification in Adults

Hard, ossified bone starts as a hyaline cartilage model in embryos.

Bone Growth Length

Epiphyseal cartilages facilitate lengthening of bones during growth.

Endochondral Ossification

Begins with the formation of a cartilage model, leading to bone development.

Epiphyseal Plate Replacement

When the epiphyseal plate is replaced by bone, long bones reach their adult length.

Cartilage and Bone Growth

When cartilage production at the epiphyseal side equals the deposition of bone on the opposite side, bones grow longer.

Location of Endochondral Lengthening

Occurs in the region where cartilage is converted to bone.

Secondary Ossification

Refers to the process involved in the formation of bones after initial ossification.

Intramembranous Ossification

Responsible for forming bones such as the roof of the skull and the clavicle.

Cell Differentiation in Intramembranous Ossification

Begins with the differentiation of mesenchymal cells into bone-forming cells.

Definition of Intramembranous Ossification

Bone formation directly within connective tissue without a prior cartilage model.

Tissue Replacement in Intramembranous Ossification

Bone replaces embryonic or fibrous connective tissue during the ossification process.

Blood Calcium Regulation

False statement: The pancreas is not one of the main organs for regulating blood calcium levels.

Calcitonin Hormone

Secreted in response to elevated blood calcium levels, helping to decrease calcium in blood.

Parathyroid Hormone and Calcium Absorption

PTH stimulates rapid absorption of calcium in the intestines when blood calcium levels are low.

Parathyroid Hormone Mechanism

Stimulates osteoclasts to break down bone matrix, releasing calcium ions into the bloodstream.

Fracture Repair Steps

Includes fracture hematoma formation, callus formation, spongy bone formation, and compact bone formation.

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Test your understanding of anatomy and physiology with these flashcards from Module 6.3. Focus on key concepts such as the medullary cavity and articular cartilage, and how these structures function in the human body. Perfect for reinforcing your learning or preparing for exams.