LO 5 Flashcards
What are the five functions of the skeletal system?
- Support - supports and gives shape to the body
- Protection - protects internal organs for example skull/brain, ribs/heart and lungs
- Movement - with a help of muscles, bones make movement possible
- Storage - calcium storage and homeostasis of blood calcium (99% of the body’s calcium)
- Hematopoesis - formation of blood cells takes place in red bone marrow
How many bones are in the adult human body?
206
What are the four main types of Bones based on their structure?
- Long - e.g. humerus (most bones except knee cap, wrists, and ankle bones)
- Short - e.g. carpals and tarsals (wrists and ankles)
- Flat - e.g. scapula, sternum, ribs, bones of the skull
- Irregular - e.g. vertebrae, hip bones, sphenoid, ethmoid
What is the fifth, less common type of bone based on structure?
- Sesamoid - round bones (e.g. patella (knee cap))
_________ is a hollow tube surrounded by hard compact bone, making bones strong and light
Diaphysis (shaft)
________ is a hollow area inside the diaphysis containing yellow marrow
Medullary cavity
________ contains spongy bone filled with red bone marrow
Epiphysis (ends of bones)
________ is a thin layer, covers each end of the bone, cushions
Articular cartilage
_______ is a strong/fibrous membrane, covers bones (not at joints)
Periosteum
________ is a thin membrane that lines the medullary cavity
Endosteum
What are the 6 structures of the long bones?
- Diaphysis (shaft)
- Medullary cavity
- Epiphyses (ends of bones)
- Articular cartilage
- Periosteum
- Endosteum
What are the two major types of connective tissue that make up the skeletal system?
- Bones
- Cartilage
In both bone and cartilage there is more ______ than cells
Matrix - comprised of materials such as proteins, collagens, and elastin which give structure to celln
In addition to cells and matrix, bones contain ______, _______, and _______
- Blood
- Adipose tissue
- Nervous tissue
What are the two types of bones in the skeletal system based on density?
- Compact bone (dense bone) - outer layer, hard and dense
- Spongy bone - the the ends (epiphyses) of long bones
Describe the structure of compact bone (dense)
- Bones are covered by a fibrous sheath called the periosteum
- Blood vessels pass through this covering, go into the bone, and eventually connect to the central canal
- Contains cylindrical structural units called osteons or haversian systems (these are made of many small components)
The Matrix of compact bone is calcified and arranged into rings called ______ that surround ______ which contains blood vessels
- Concentric lamella
- Central canal
The spaces within the hard layers of concentric lamella in compact bone are called ______. Living bone cells, or ______, are in these spaces.
- Lacunae
- Osteocytes
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.
Canaliculi
Describe spongy bone
- Found in the end of long bones
- Porous texture due to thin threads of bone called trabeculae
- 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)
Describe the structure of cartilage
- A cartilage cell is called a chondrocyte
- Chondrocytes are found in lacuna spaces
- Matrix is gel-like and supported by collagenous fibers which give cartilage flexibility
- No blood vessels means nutrients must diffuse through the Matrix to reach cells - this also makes cartilage slow to repair
Bone is constantly being remodeled, a process requiring these two cell types
- Osteoblasts - form /builds new bone
- Osteoclasts - reabsorb bone / crashes it down
Describe osteoblasts
- Bone building cells
- Form bone matrix
- Secrete collagen fibers
- Initiate the process of calcification
- Develop into osteocytes**
- Found in both the periosteum and endosteum
Describe osteoclasts
- Huge cells that digest bone matrix (bone resorption) - part of normal bone growth, development, maintenance, and repair
- Concentrated in the endosteum
- Secrete digestive enzymes to digest the bone matrix
Describe osteocytes
- Mature bone cells
- No longer secrete Matrix
- Responsible for maintaining the bone - they regulate the amount of calcium deposited in The Matrix
- Located within lacunae
Describe the process of remodeling in newborns
- A newborn skeleton has many bones made of cartilage and other fibrous material - the Bones have not completely ossified
- At approximately 8 weeks, this material gets replaced by calcified bone matrix and mature bone cells (osteocytes)
- Most bones in the body develop via this process which is called endochondral ossification
Break down the term endochondral ossification
Endo = within
Chondro = cartilage
Ossification = bone tissue formation
The term means replacing cartilage tissue with bone tissue
Describe fontanelles
- Soft spots made of fibrous membrane
- Ossification is incomplete at birth, allowing some compression of skull as baby passes through the birth canal
- Fontanelles typically fused by the time baby is 2 years old when rapid growth of skull is done
Describe how bones grow in length
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
As long as the epiphyseal plate remains between the ______ and _____, growth continues
Epiphyses; diaphysis
The _______ marks were two centers of ossification have fused together
Epiphyseal line
What is included in the axial skeleton?
- Skull
- Spine
- Thorax
- Hyoid bone
What is included in the appendicular skeleton?
- Upper extremities - including shoulder girdle
- Lower extremities - including hip girdle
Briefly describe the divisions of the skull
- Eight cranial bones form the cranium
- Sinuses are spaces or cavities in these bones
- Immovable joints between cranial bones are called sutures
- 14 bones form the face
- Six tiny bones in the middle ear
