chapter 6- skeletal system; bones and bone tissue

interstitial growth

chondrocytes in the center of the tissue divide and add more matrix in-between the existing cells

three types of bone cells

osteoblasts, osteocytes, osteoclasts

bone matrix is

35% organic (collagen and proteoglycans) and 65% inorganic material (hydroxyapatite)

ossification

Bone formation; also called osteogenesis. occurs by appositional growth on the surface of previously existing material.

osteoblast

Bone-forming cell. have an extensive endoplasmic reticulum and numerous ribosomes. Secret matrix vesicles which contain high concentrations on Ca2+ and PO4(^3-) which form hydroxyapatite crystals

canaliculi

Hairlike canals that connect lacunae to each other and the central canal

articular cartilage

Hyaline cartilage covering the ends of bones within a synovial joint. Has no perichondrium, blood vessels, or never.

osteoclast

Large, multinucleate cell that absorbs bone. as bone is broken down, the calcium (2+) goes back into the blood

osteocyte

Mature bone cell surrounded by bone matrix. osteocytes come from osteoblast once it has secreted sufficient bone matrix. account for 90-95% bone cells.

hydroxyapatite

Mineral with the empiric formula 3 Ca3(PO4)2 ∙ Ca(OH)2; the main mineral of bone and teeth.

Perichondrium

Most cartilage is covered by this double-layered connective tissue sheath. the inner layer has fewer fibers and contain chondroblast. blood vessels and nerves penetrate the outer layer only.

lacuna

Small space or cavity; potential space within the matrix of bone or cartilage normally occupied by a cell that can be visualized only when the cell shrinks away from the matrix during fixation; space containing maternal blood within the placenta.

lacuna (pl., lacunae)

Small space or cavity; potential space within the matrix of bone or cartilage normally occupied by a cell that can be visualized only when the cell shrinks away from the matrix during fixation; space containing maternal blood within the placenta.

appositional growth

To place one layer of bone, cartilage, or other connective tissue against an existing layer.

two types of cartilage growth

appositional and interstitial

What minerals are stored in bones?

calcium, phosphorus, and adipose tissue (fat)

skeletal system functions

body support, organ protection, body movement, mineral storage, blood cell production

bones in organ protection

bones are hard and protect the organs they surround

the 4 components of the skeletal system

bones, cartilage, tendons, and ligaments

osteogenesis imperfecta

brittle bone disease. connective tissue disease caused by mutations that reduce type 1 collagen which is the major collagen of bone, tendon, and skin. abnormal shape of the femur and excessive curve of the tibia and fibula.

hyaline cartilage matrix

contains collagen and proteoglycans

collagen fibers in bone matrix

give flexible strength

mineral components of bone matrix

give weight-bearing strength

the 3 main types of cartilage

hyaline, elastic, fibrocartilage

strong bone in body support

is well suited for bearing weight and supporting the body

joints in body movement

joints, which are formed where two or more bones come together, allow movement between bones

ligaments in body movement

ligaments allow some movement between bones but prevent excessive movements

ligaments in body support

ligaments are strong bands of fibrous connective tissue, they hold bones together.

proteoglycans

makes cartilage resilient by trapping water

blood cell production of bones

many bones contain cavities filled with red bone marrow, which gives rise to blood cells and platelets

suffix -blast

means "seed" or "bud". as most human cells start out in an undeveloped state and then differentiate into their final form

hyaline cartilage

most comm on type of cartilage, most bones start out as a hyaline cartilage model. growth in bone length and bone repair often involve making hyaline cartilage first, then replacing it with bone

hyaline cartilage chondrocyte

once the matrix has surrounded the chondroblast, it has differentiated into a chondrocyte

Suffix: -cyte

once the undifferentiated cell has grown and developed into its final form

cartilage in body support

provides a firm yet flexible support within certain structure such as: nose, external ear, thoracic cage, and the trachea

collagen

provides strength

Chondrocytes

rounded cells that occupy a space called a lacuna

hyaline cartilage chondroblasts

secret a matrix, which surrounds the chondroblasts

skeletal muscles in body movement

skeletal muscle attach to bones by tendons, which are strong bands of connective tissue

smooth cartilage in body movement

smooth cartilage cover the ends of bones within some joints, allowing the bones to move freely

mineral storage of bones

some minerals in the blood are stored in bone. if blood levels of these minerals decrease, the minerals are released from bone into the blood.

hydroxyapatite crystals

stimulates further formation and generalization of the matrix