LO 5

Question 1

What are the five functions of the skeletal system?

Answer 1

1. Support - supports and gives shape to the body
2. Protection - protects internal organs for example skull/brain, ribs/heart and lungs
3. Movement - with a help of muscles, bones make movement possible
4. Storage - calcium storage and homeostasis of blood calcium (99% of the body’s calcium)
5. Hematopoesis - formation of blood cells takes place in red bone marrow

Question 2

How many bones are in the adult human body?

Answer 2

206

Question 3

What are the four main types of Bones based on their structure?

Answer 3

1. Long - e.g. humerus (most bones except knee cap, wrists, and ankle bones)
2. Short - e.g. carpals and tarsals (wrists and ankles)
3. Flat - e.g. scapula, sternum, ribs, bones of the skull
4. Irregular - e.g. vertebrae, hip bones, sphenoid, ethmoid

Question 4

What is the fifth, less common type of bone based on structure?

Answer 4

1. Sesamoid - round bones (e.g. patella (knee cap))

Question 5

_________ is a hollow tube surrounded by hard compact bone, making bones strong and light

Answer 5

Diaphysis (shaft)

Question 6

________ is a hollow area inside the diaphysis containing yellow marrow

Answer 6

Medullary cavity

Question 7

________ contains spongy bone filled with red bone marrow

Answer 7

Epiphysis (ends of bones)

Question 8

________ is a thin layer, covers each end of the bone, cushions

Answer 8

Articular cartilage

Question 9

_______ is a strong/fibrous membrane, covers bones (not at joints)

Answer 9

Periosteum

Question 10

________ is a thin membrane that lines the medullary cavity

Answer 10

Endosteum

Question 11

What are the 6 structures of the long bones?

Answer 11

1. Diaphysis (shaft)
2. Medullary cavity
3. Epiphyses (ends of bones)
4. Articular cartilage
5. Periosteum
6. Endosteum

Question 12

What are the two major types of connective tissue that make up the skeletal system?

Answer 12

1. Bones
2. Cartilage

Question 13

In both bone and cartilage there is more ______ than cells

Answer 13

Matrix - comprised of materials such as proteins, collagens, and elastin which give structure to celln

Question 14

In addition to cells and matrix, bones contain ______, _______, and _______

Answer 14

1. Blood
2. Adipose tissue
3. Nervous tissue

Question 15

What are the two types of bones in the skeletal system based on density?

Answer 15

1. Compact bone (dense bone) - outer layer, hard and dense
2. Spongy bone - the the ends (epiphyses) of long bones

Question 16

Describe the structure of compact bone (dense)

Answer 16

1. Bones are covered by a fibrous sheath called the periosteum
2. Blood vessels pass through this covering, go into the bone, and eventually connect to the central canal
3. Contains cylindrical structural units called osteons or haversian systems (these are made of many small components)

Question 17

The Matrix of compact bone is calcified and arranged into rings called ______ that surround ______ which contains blood vessels

Answer 17

1. Concentric lamella
2. Central canal

Question 18

The spaces within the hard layers of concentric lamella in compact bone are called ______. Living bone cells, or ______, are in these spaces.

Answer 18

1. Lacunae
2. Osteocytes

Question 19

Lacunae are connected by tiny canals, _______, that connect with the central canal in each osteon. This is how nutrients get from the blood to the osteocytes.

Answer 19

Canaliculi

Question 20

Describe spongy bone

Answer 20

1. Found in the end of long bones
2. Porous texture due to thin threads of bone called trabeculae
3. Trabeculae are surrounded by a network of open spaces that may contain red bone marrow (in adults, this is mostly in flat bones and the ends of humorous and femur)

Question 21

Describe the structure of cartilage

Answer 21

1. A cartilage cell is called a chondrocyte
2. Chondrocytes are found in lacuna spaces
3. Matrix is gel-like and supported by collagenous fibers which give cartilage flexibility
4. No blood vessels means nutrients must diffuse through the Matrix to reach cells - this also makes cartilage slow to repair

Question 22

Bone is constantly being remodeled, a process requiring these two cell types

Answer 22

1. Osteoblasts - form /builds new bone
2. Osteoclasts - reabsorb bone / crashes it down

Question 23

Describe osteoblasts

Answer 23

1. Bone building cells
2. Form bone matrix
3. Secrete collagen fibers
4. Initiate the process of calcification
5. Develop into osteocytes**
6. Found in both the periosteum and endosteum

Question 24

Describe osteoclasts

Answer 24

1. Huge cells that digest bone matrix (bone resorption) - part of normal bone growth, development, maintenance, and repair
2. Concentrated in the endosteum
3. Secrete digestive enzymes to digest the bone matrix

Question 25

Describe osteocytes

Answer 25

1. Mature bone cells
2. No longer secrete Matrix
3. Responsible for maintaining the bone - they regulate the amount of calcium deposited in The Matrix
4. Located within lacunae

Question 26

Describe the process of remodeling in newborns

Answer 26

1. A newborn skeleton has many bones made of cartilage and other fibrous material - the Bones have not completely ossified
2. At approximately 8 weeks, this material gets replaced by calcified bone matrix and mature bone cells (osteocytes)
3. Most bones in the body develop via this process which is called endochondral ossification

Question 27

Break down the term endochondral ossification

Answer 27

Endo = within
Chondro = cartilage
Ossification = bone tissue formation

The term means replacing cartilage tissue with bone tissue

Question 28

Describe fontanelles

Answer 28

1. Soft spots made of fibrous membrane
2. Ossification is incomplete at birth, allowing some compression of skull as baby passes through the birth canal
3. Fontanelles typically fused by the time baby is 2 years old when rapid growth of skull is done

Question 29

Describe how bones grow in length

Answer 29

Epiphyseal cartilage of the epiphyseal plate divides to create more cartilage, while the diaphyseal cartilage of the epiphyseal plate is transformed into bone. This increases the length of the shaft

Question 30

As long as the epiphyseal plate remains between the ______ and _____, growth continues

Answer 30

Epiphyses; diaphysis

Question 31

The _______ marks were two centers of ossification have fused together

Answer 31

Epiphyseal line

Question 32

What is included in the axial skeleton?

Answer 32

1. Skull
2. Spine
3. Thorax
4. Hyoid bone

Question 33

What is included in the appendicular skeleton?

Answer 33

1. Upper extremities - including shoulder girdle
2. Lower extremities - including hip girdle

Question 34

Briefly describe the divisions of the skull

Answer 34

1. Eight cranial bones form the cranium
2. Sinuses are spaces or cavities in these bones
3. Immovable joints between cranial bones are called sutures
4. 14 bones form the face
5. Six tiny bones in the middle ear