SKELETAL

Skeletal System

Consists of bones, cartilages, tendons, and ligaments.

Functions of the skeletal system

Support the body, protection of organs, body movement, mineral storage, blood cell production, energy storage.

Osteoblasts

Cells responsible for the formation of new bone, derived from osteogenic cells.

Ossification

The formation of new bone by osteoblasts.

Osteocytes

Mature bone cells that maintain bone matrix, formed from osteoblasts.

Lacunae

Spaces within the bone matrix that house osteocytes.

Canaliculi

Narrow spaces that connect osteocytes and transport nutrients and waste.

Osteoclasts

Cells responsible for bone resorption.

Bone resorption

The process by which osteoclasts break down bone to mobilize calcium.

Bone matrix composition

Approximately 35% organic (collagen, proteoglycans) and 65% inorganic (hydroxyapatite).

Lamellae

Thin, concentric sheets or layers of bone.

Spongy bone

Bone with less matrix and more space, consisting of trabeculae.

Compact bone

The solid, outer layer of bone, containing osteons.

Osteon

The functional unit of compact bone composed of concentric rings of matrix.

Central canal

The central part of an osteon that contains blood vessels and nerves.

Trabeculae

Interconnecting rods or plates of bone within spongy bone.

Bone shape classification

Long, short, flat, sesamoid, and irregular bones.

Diaphysis

The thick-walled, hollow center of a long bone composed of compact bone.

Epiphyses

The ends of a long bone composed mostly of spongy bone.

Articular cartilage

Hyaline cartilage that covers the surfaces of the epiphysis in joints.

Epiphyseal plate

A region of hyaline cartilage that allows bone to grow in length.

Red marrow

Soft tissue found in the cavities of spongy bone that is the location of blood-forming cells.

Yellow marrow

Soft tissue in the diaphysis that is mostly adipose tissue.

Periosteum

The connective tissue layer wrapping the outer surface of a bone.

Endosteum

The connective tissue layer lining the internal surfaces of cavities within bones.

Intramembranous ossification

Bone formation that occurs within embryonic connective tissue membranes.

Endochondral ossification

Bone formation that begins with a hyaline cartilage model.

Ossification centers

Areas where osteoblasts begin to produce bone during intramembranous ossification.

Bone remodeling

The process of bone resorption by osteoclasts and deposition of new bone by osteoblasts.

Calcium regulation

The role of bone remodeling in maintaining proper calcium levels in the body.

Osteoporosis

An extreme loss of bone mass that increases the risk of fractures.

Bone mass decline

The reduction of bone mass, which can occur due to inactivity or aging.

Microgravity effects on bones

Astronauts may experience significant bone mass loss in microgravity conditions.

Hydroxyapatite

The inorganic material primarily found in bone, consisting of calcium phosphate crystals.

Collagen

The primary organic component of bone matrix, providing structural support.

Proteoglycans

Organic components in bone matrix that help with hydration and compression resistance.

Bone surface cells

Osteoblasts and a few osteoclasts cover the surfaces of trabeculae in spongy bone.

Bone growth

The process of lengthening a bone at the epiphyseal plate.

Epiphyseal line

The ossified epiphyseal plate, marking where length growth has stopped.

Soft tissue in bones

Includes marrow, which is either red (blood-forming) or yellow (adipose tissue).

Function of osteoclasts

To break down bone and release minerals such as calcium into the bloodstream.

Location of red marrow in adults

Most red marrow is found in the flat bones.

Structure of flat bones

Consist of two layers of compact bone with spongy bone in between.

Hyaline cartilage

A type of cartilage that covers bone surfaces in joints and is involved in endochondral ossification.

Importance of vitamin D

Critical for calcium absorption and bone health.

Sedentary lifestyle

A lifestyle characterized by little physical activity, which can lead to bone mass decline.

Blood vessels in bones

Contained within central canals of osteons, supplying nutrients to bone.

Function of osteocytes

To maintain the bone matrix and regulate bone remodeling.

Role of chondrocytes

Cells involved in the growth and maintenance of cartilage.

Bone adaptation to stress

The structural changes in bones based on the stresses placed upon them.

Function of periosteum

Provides a surface for muscle attachment and contains blood vessels and nerves.

Components of spongy bone

Composed of trabeculae, marrow, and blood vessels.

Long bone examples

Humerus and femur.

Short bone examples

Carpal bones.

Flat bone examples

Sternum.

Sesamoid bone example

Patella.

Irregular bone example

Vertebrae.

Bone density

A measure of the amount of mineral matter per square centimeter of bones.

Role of exercise in bone health

Stimulates the deposition of bone matrix, enhancing bone density.

Bone repair process

Involves resorption and deposition of bone to heal fractures and injuries.

Role of osteogenic cells

Stem cells that differentiate into osteoblasts.

Calcium ion importance

Essential for various bodily functions and is mobilized by osteoclast activity.

Bone structural adaptation

Changes in bone structure in response to mechanical forces.

Risk factors for osteoporosis

Inactivity, aging, and inadequate calcium and vitamin D availability.

Effects of aging on bones

Reduced bone density and increased risk of fractures.

Composition of bone matrix

Made of organic materials (like collagen) and inorganic materials (like hydroxyapatite).

Bone marrow functions

Hematopoiesis (blood cell formation) and fat storage.

Spongy vs compact bone

Spongy bone has less matrix and more open space compared to compact bone.

Canaliculus function

To connect lacunae and facilitate the exchange of nutrients and waste.

Medullary cavity

The hollow center of a long bone that contains marrow.

Haversian system

Another name for the osteon, representing the structural unit of compact bone.

Structure of trabeculae

Framework of spongy bone providing support and housing marrow.

Epiphyseal growth plate

A layer of hyaline cartilage that allows for longitudinal growth of bones.

Regeneration of bone tissue

The ability of bone to heal and regenerate through the activity of osteoblasts and osteoclasts.

Bone composition changes with age

A decrease in organic content, leading to stronger, more brittle bones.

Influences on bone growth

Nutritional factors, mechanical stress, and hormonal levels.

Skeletal system overview

The complex structure of bones, cartilage, tendons, and ligaments supporting the body.