ch 6 - skeletal system

Question 1

Ossification is…?

Answer 1

the mineralization or hardening of bone

Question 2

What is os and osteo- refers to….?

Answer 2

bone

Question 3

What are osteocytes?

Answer 3

Bone cells (osteoblasts that have become trapped in the ossified matrix they have created)
osteocytes can revert back to osteoblasts and form new bone if needed

Question 4

Bone is….?

Answer 4

second hardest substance in the body, composed of cells embedded in a matrix,

Question 5

Matrix is…? Why is it so hard?

Answer 5

the intercellular material of connective tisuse - in which bone is embedded. It is hard because calcium and phosphate crystals are deposited in it

Question 6

What are functions of bone?

Answer 6

Support, protection, leverage, storage, blood cell formation (marrow)

Question 7

What are two types of bone?

Answer 7

Cancellous bone; light and spongy- long bones

Compact bone; dense and heavy - bones around head & face

Question 8

What are cancellous bone

Answer 8

Tiny “spicules” of bone that appear that appear randomly arranged
Spaces between the spicules contain bone marrow

Question 9

What is compact bone?

Answer 9

Shafts of long bone and the outside layer of all bones

Composed of haversian systems that run lengthwise with the bone

Question 10

The cells that produce bone are called..?

Answer 10

osteoblasts - they also secrete the matrix of bone and then supply the minerals necessary to harden it.

Question 11

The suffix -blast indicates…?

Answer 11

a cell that produces something

Question 12

What is the lacunae?

Answer 12

small cavities within the matrix of some connective tissues, such as cartilage and bone, within which cells (chondrocytes, and osteocytes) are contained.

Question 13

Once surrounded by bone, osteoblasts get a new name, what is that name?

Answer 13

osteocytes or bone cells

Question 14

What is canaliculi?

Answer 14

threadlike, cellular processes in tiny channels - osteocytes get food and communicate with each other through these slots (channels)

Question 15

What allows the muscles to move the joints?

Answer 15

bones act as levers for the skeletal muscles; attachment of skeletal muscles to bones via the tendons allows the muscles to move the joints

Question 16

How are bones storage sites?

Answer 16

act as storage sites for minerals, such as calcium. They enable the body to deposit and withdrawal minerals as needed to control levels in the bloodstream.

Question 17

Why is calcium important?

Answer 17

involved in important body functions including muscle contraction, blood clotting, milk secretion, and skeleton formation and maintenance.

Question 18

Two hormones act as “cashiers” at the calcium bank, what are they?

Answer 18

parathyroid hormone from the parathyroid glands, calcitonin from the thyroid gland

Question 19

Calcitonin helps prevent ________ which is too high a level of calcium in the blood, largely by depositing excess calcium in the bones.

Answer 19

hypercalcemia

Question 20

Parathyroid hormone does the opposite: it helps prevent _________ which is too low a level of calcium in the blood, in part by withdrawing calcium from the bones.

Answer 20

hypocalcemia

Question 21

What is it called when some of the bones serve as sites for blood cell formation?

Answer 21

hematopoiesis — in the blood marrow that fills their interiors

Question 22

What does the haversian canal contain?

Answer 22

blood vessels, lymph vessels, and nerves that supply the osteocytes

Question 23

What is located at the junctions between the layers of bone that make up each haversian system?

Answer 23

the osteocytes

Question 24

The outer surfaces of bones are covered by a membrane called the …?

Answer 24

periosteum

Question 25

The outer layer of the periosteum is composed of …?

Answer 25

fibrous tissue

Question 26

The inner layer of the periosteum is composed of ..?

Answer 26

bone-forming cells (osteoblasts)

Question 27

What does the inner layer of the periosteum do?

Answer 27

enables bones to increase in diameter and is involved in the healing of bone fractures

Question 28

What does the membrane endosteum do?

Answer 28

lines the hollow interior surfaces of bones - also contains osteoblasts

Question 29

What are the three types of cells that make up bone?

Answer 29

osteoblasts, osteocytes, osteoclasts

Question 30

What are osteoclasts?

Answer 30

osteocytes eat bone, necessary for remodeling - remove bone where it is not needed
osteocytes also allow the body to withdraw calcium from the bones when it is needed to raise the calcium level in the blood

Question 31

Why does the body need cancellous and compact bones?

Answer 31

two different types of bone are important because cancellous bone keeps an animal’s bod weight lower, being lighter than compact bone. Both types of bone are needed to stand up to the stresses encountered by an animals skeleton

Question 32

What is the difference between a haversian canal and a Volkmann’s canal?

Answer 32

Haversian canals are part of the haversian system of compact bone. These canals contain the blood, lymph, and nerve supply for the osteocytes.
Volkmann canals are channels through which blood vessels travel to supply bones. These canals join with the blood vessels in the haversian canals to bring nutrients to the osteocytes in the haversian systems.

Question 33

What is the nutrient foramina?

Answer 33

it is large channels where large blood vessels, along with lymph vessels and nerves enter many large bones–especially long bones

Question 34

Bone is formed by one of two mechanisms, what are they?

Answer 34

endochondral or cartilage bone formation - grows into and replaces a cartilage model or
intramembranous or membrane bone formation - fibrous tissue membranes

Question 35

Most bones develop by…?

Answer 35

endochondral bone formation - the body first creates a casrtilage “template’ that is subsequently replaced by bone

Question 36

What are cell the types that make up bone?

Answer 36

osteoblasts,

Question 37

The function of osteoblasts is?

Answer 37

Bb