Chapter 6: The Skeletal System

The hormone calcitonin functions to

depress calcium levels in body fluids

A joint that permits no movement and is described as an interposition of cartilage plates is called a

synchondrosis.

The following are major steps in the process of endochondral ossification: 1. Bone forms at the diaphysis surface. 2. Secondary ossification centers form in the epiphyses. 3. Chondrocytes enlarge and calcify. 4. Osteoclasts create a marrow cavity. 5. Blood vessels invade the inner cartilage and new osteoblasts form spongy bone at a primary ossification center.

3,1,5,4,2

One role of the fontanels is to

Allow for change in shape during childbirth

What covers the ends of the epiphyses?

Articular cartilage

The special movement of the thumb that allows it to grasp an object and hold onto it is called

Oppostion

What is the process where cartilage is replaced by bone?

Ossification

Immature, active bone cells that produce new bone matrix are termed

Osteoblasts

What cells break down the spongy bone?

Osteoclasts

________ are giant bone cells with 50 or more nuclei, that secrete acid and enzymes.

Osteoclasts

What type of cells are located in the endosteum

Osteoclasts and osteoblasts

Two hormones that work together to elevate calcium levels in the body are ________ and ________.

Parathyroid hormone & calcitroil

In anatomical position, when the palm is moved to face posteriorly, the movement of the wrist and hand is called ________.

Pronation

When one crosses his/her arms, which movement is performed by the clavicles?

Protraction

What is a primary function of the skeletal system in the role of red bone marrow?

Blood cell production

What is the process called where deposits of Ca are laid down?

Calcification

Channels within bone, involved with cell-to-cell communication, are called

Canaliculi

What are skeleton made up initially?

Cartilage

The pectoral girdle consists of the

Clavicle and scapula

The organic component of the matrix, which makes up around one-third of the mass of bone, is dominated by

Collagen fibers

The shaft of a long bone is called the

Diaphysis

What is the lining of the marrow cavity called?

Endosteum

The presence of ________ strongly indicates that the long bone is still growing.

Epiphyseal plate

Which cell populations are particularly sensitive to changes in calcium ion concentration?

Neurons & muscle cells

What type of cartilage is articular cartilage?

Hyaline cartilage

What begins when osteoblasts differentiate within embryonic connective tissue?

Intamembranous ossification

Narrow sheets of calcified matrix are referred to as

Lamellae

What do osteoblasts form at the primary ossification center?

Spongy bone

What type of bone is located at the ends of long bones?

Spongy bone

What is the function of yellow marrow?

Storage of energy reserves- primarily lipids

What are the ends of long bones called?

The epiphyses

Spongy bone is made up of a network of bony rods or plates called

Trabecula

Rickets is a condition marked by a softening and bending of bones that occurs in growing children, as a result of ________ deficiency.

Vitamin D3 definicency

Bone diameter increases through

appositional growth

The presence of a epiphyseal line indicates

epiphyseal growth has ended

What is the open area surrounded by diaphysis called?

Marrow cavity

Fibrous cartilage discs that act as shock absorbers in joints are called

Menisci