Skeletal System Overview Exam 2

Chemical Composition of Bone -Organic components

Organic components (35%): -Cells(osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts) -Osteoid {45%} primarily collagen which gives bone its high tensile strength. Also contains glycolipids and glycoproteins

Epiphyseal line

When a bone ceases to grow in length at about 14-24, the cartilage in the epiphyseal plate is replaced by bone, the resulting bony structure is called ____________ .

Perichondrium

the connective tissue that envelops cartilage where it is not at a joint.

Chemical Composition of Bone -Inorganic components

-Crystallized mineral salts • Hydroxyapatites (55%) • Ca5(OH)(PO4)3 -Other ions present are magnesium, fluoride, potassium, and sulfate. Responsible for bone hardness and its resistance to compression This is the reason why bones last even after death Present in the form of tiny packed crystals in and around the collagen fibers

4. Mention and describe the functions of the skeletal system.

1. Support-structural framework for the body by supporting soft tissues & provide attachment points for the tendons 2. Protection- Provide a protective case for the brain, spinal cord, and vital organs 3. Assistant in movement- when skeletal muscles contract, they pull on bones to produce movement 4. Mineral homeostasis (storage and release)- Reservoir for minerals, especially calcium and phosphorus & Release and store minerals when needed 5. Blood cell formation (Hematopoiesis)- Occurs within the red marrow cavities of bones 6. Triglyceride (energy) storage as the yellow bone marrow

Microscopic Structure of Spongy (Cancellous) Bone

1. consists of poorly organized trabeculae (small needle-like pieces of bone) 2. with a lot of open space between them. 3. nourished by diffusion from nearby Haversian canals.

The skeleton is __% compact bone,and __% spongy bone.

80, 20

Periosteum

=around is a tough CT sheath and its associated blood supply that surrounds the bone shaft and it associated blood supply that surrounds the bone surface whenever it is not covered by articular cartilage.

metaphyses

=between are the regions b/w the diaphysis and the epiphyses.

diaphysis

=growing between Is the bone's shaft or body- the long, cylindrical, main portion of the bone

epiphyses

=growing over are the proximal and distal ends of the bone

Medullary Cavity

=marrow is hallow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults.

endosteum

=within is a thin membrane that lines that medullary cavity. It contains a single layer if bone-forming cells and a small amount of CT.

Name the important organic bone components

Collagen fibers, osteocytes

Hematopoiesis

Blood cell formation

Osteoclasts

Cells that break down (resorb) bone matrix Multinucleated - Largest of the bone cells

Type of cartilage that supports the external ear?

Elastic

Type of cartilage between the vertebrae

Fibrocartilage

Type of cartilage that forms the walls of the voice box (larynx)

Hyaline

What is the function of the organic matrix in bone?

Gives bone flexibility & strength

Calcium salts form the bulk of the inorganic material in bone. What is the function of the calcium salts?

Gives bone hardness & compressional strength.

Name the structural unit of the compact bone.

Osteons

What is the function of the periosteum?

The Periosteum serves as an attachment point for muscles and bones through tendons and ligaments.

Compare and contrast events occurring on the epiphyseal and diaphyseal faces of the epiphyseal plate?

The cartilage cells at the epiphyseal side are continuing to grow and divide mitotically, while the ones on the diaphyseal side are aging, dying and then osteoblasts move in to form bone.

interstitial lamellae

They are fragments of older osteons that have been partially destroyed during bone rebuilding or growth.

epiphyseal (growth) plate

a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length

Explain how cartilage grows (interstitial and appositional).

a. Appositional growth - "growth from outside". Cells in the perichondrium secrete matrix against the external face of existing cartilage b. Interstitial growth - "growth from inside" Lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within

Name the four structures that make up the skeletal system.

a. Bones make up most of the skeleton b. Cartilage occur in isolated areas such as the nose c. Ligaments connect bones and reinforce joints d. Articulations (joints) are the junctions between bones and provide mobility

A long bone consists of several parts:

a. Diaphysis (bone shaft) b. 2 epiphyses (both ends of the bone at the joints) c. 2 metaphyses (region between diaphysis and epiphysis) d. Articular cartilage covering both epiphyses e. Periosteum (connective tissue surrounding the diaphysis)

Describe the anatomical and functional properties of Fibrocartilage including location.

a. Highly compressible with great tensile strength b. Contains of rows of chondrocytes alternating with thick collagen fibers c. Found in places subjected to both heavy pressure and stretch, such as the pad-like cartilage (menisci) of the knee and in intervertebral discs d. Lacks perichondrium since vessels penetrate up to 40% of the cartilage

Three types of cartilage tissue

a. Hyaline Cartilage b. Elastic Cartilage c. Fibrocartilage

Describe the anatomical and functional properties of Hyaline Cartilage, including location.

a. Provides support, flexibility, and resilience b. Most abundant skeletal cartilage c. Only collagen fibers present4 d. It's present in these cartilages: i. Articular - covers the ends of long bones at movable joints ii. Costal - connects the ribs to the sternum iii. Respiratory - makes up larynx, reinforces air passages iv. Nasal - supports the nose

Describe the anatomical and functional properties of Elastic Cartilage including location.

a. Similar to hyaline cartilage, but contains more stretchy elastic fibers b. Found in only two skeletal location: Elastic cartilage is springy, yellow and elastic and is found in the internal support of the external ear and in the epiglottis.

Osteoblasts

are bone building cells. They synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue, and they initiate calcification.

Short bones

are cube-like. Examples include: a. wrist bones = carpals, b. ankle bones = tarsals.

Irregular bones

are not long, short, or flat. Examples include: a. vertebrae, b. auditory ossicles

Flat bones

are thin and usually curved. Examples include: a. most skull bones, b. breast bone = sternum, c. shoulder blades = scapulae, d. ribs.

Osteoprogenitor cells

are unspecialized bone stem cells derived from mesenchyme, the tissue from which all CT are formed. They are the only hone cells to undergo cell division; the resulting cells develop into osteoblasts. They are found along the inner portion of the periosteum, in the endosteum, and int he canals within bone that contain blood vessels.

central canal

canal that runs through the center of the osteon. lined with endosteum, contains blood vessels, lymphatic vessels and nerves.

Sesamoid bones

develop within a tendon.

Compact bone

i. Found beneath the periosteum of all bones ii. Makes up the bulk of the diaphyses of long bones iii. Strongest form of bone tissue iv. Composed of osteons v. Provides protection and support vi. Resists the stresses produce by weight and movement

Short Bone

i. Thin plates of periosteum-covered compact bone on the outside with endosteum-covered spongy bone (diploë) on the inside ii. Have no diaphysis or epiphyses iii. Contain red bone marrow between the trabeculae iv. No significant marrow cavity is present

Spongy bones

i. honeycomb of trabeculae ("little beams") ii. Oriented along the lines of stress iii. filled with yellow or red bone marrow iv. Always inside of the bone v. Lighter than compact vi. Allows the bone to move more rapidly when pulled by a skeletal muscle

Articular Cartilage

is a thin layer of hyaline cartilage covering the part if the epiphysis where the bone forms an articulation (joint) with another bone. Reduces friction and absorbs shock at freely movable joints; and because it lacks a perichondrium and lacks blood vessels, repair of damage is limited.

List 4 components of an osteon

lamellae, lucunae, canaliculi, central canal

Osteocytes

mature bone cells, are the main cells in bone tissue and maintain its daily metabolism, such as the exchange if nutrients and wastes with the blood. Do not undergo cell division In contact with each other (gap junction)

Difference between the functions of osteoblasts and osteoclasts.

osteoBlast Build bone, while osteoClast Carve out bone

4. Periosteum

outer, fibrous, protective covering of diaphysis. a. richly supplied with blood & lymph vessels, nerves (nutrition): • Nutrient Foramen = perforating canal allowing blood vessels to enter and leave bone. b. Osteogenic layer contains osteoblasts (bone-forming cells) and osteoclasts (bone-destroying cells); c. serves as insertion for tendons and ligaments.

lamellae

part of osteon that are layers of calcified matrix. also present outside osteon

lacunae

part of osteon that contains tissue fluid. bone cells are imprisoned by hard layers of the lamellae

canaliculi

small canals that connect lacunae to each other and to the central canal, filed with extracellular fluid