Lesson 3 - Skeletal System

Skeletal system

Consists of the entirety of bones and their cartilage

Calcium and phosphorus

The skeletal system functions in mineral homeostasis as bone tissue stores several minerals, especially ___ and ____

Long bones

Type of bone that has a greater length than width and consist of a shaft and a variable number of ends

Long bones

Femur is what type of bone?

Long bones

Tibia and fibula is what type of bone?

Long bones

Humerus is what type of bone?

Long bones

Ulna is what type of bone?

Long bones

Radius is what type of bone?

Long bones

Phalenges is what type of bone?

Short bones

Type of bone that are somewhat cube-shaped and nearly equal in length and width

Short bones

Wrist and ankle bones are under what type of bone?

Flat bones

Type of bones that are thin and afford considerable protection, and provide extensive surfaces for muscle attachment

Flat bones

Cranial bones is what type of bone?

Flat bones

Sternum is what type of bone?

Flat bones

Scapulae is what type of bone?

Irregular bones

These bones have complex shapes and cannot be grouped

Irregular bones

The vertebrae and some facial bones are classified as what kind of bones?

Diaphysis

The bone's shaft or body

Epiphyses

The distal and proximal ends of the bone

Metaphyses

Regions where the diaphysis joins the epiphyses

Articular cartilage

A thin layer of hyaline cartilage covering the regions of the epiphyses where the bone articulates with other bones

Periosteum

A sheath of dense irregular connective tissue and blood vessels that surround the parts of the bone outside of the articular cartilage

Medullary cavity

A hollow space within the diaphysis that contains the fatty yellow bone marrow

Endosteum

The thin membrane that lines medullary cavity

Osteoprogenitor cells

Stem cells that develop into osteoblasts

Osteoblasts

Synthesize and secrete the extracellular matrix that calcifies into "bone"

Osteocytes

The most numerous cells in bone tissue and they maintain bone tissues

Osetoclasts

Breaks down extracellular matrix to release nutrients; hence, helps bones grow and heal

Compact bone

A dense bone and arranged in osteons

Osteonic canal

This is present in each osteon that is essential for blood supply and rings the concentric lamellae

Lacunae

Located within the concentric lamellae and within this is the ____ where the osteocytes live

Spongy bone

Bone density wherein this describes a bone with no osteons and is arranged irregularly in the trabeculae

Spongy bone

Cavities are filled with red bone marrow

Trabeculae

Compact bone

80% of the skeleton is composed of ____ for strength and protection

Spongy bone

20% is composed of the ____ for lightness

Intramembranous ossification

Bone forms directly within mesenchyme that is arranged in sheetlike layers that resemble membranes

Endochondral ossification

Bone forms within hyaline cartilage that develops from mesenchyme

Ossification centers

It is where osteoblasts differentiate and begin secreting bone matrix

Calcification

The extension of oseteocytes into the osteon's canaliculi and deposit minerals that calcify that hardens into more matrix

Trabeculae formation

This creates a spony bone with abundant blood vessels and red bone marrow

Periosteum development

This is around the periphery of the spongy bone that creates a compact bone to surround the underlying spongy bone

Calcification

Calcium and other mineral salts are deposited and extracellular matrix calcifies

Endochondral ossification

Replaces cartilage with bone matrix

Lacunae

The death of chondroblasts as the matrix calcifies creates the?

Cartilage model

Is formed when chondroblasts secrete the cartilage matrix

Primary ossification center

Develops as a blood vessel stimulates cells to become osteoblasts; hence, replaces the cartilage matrix with bone matrix

Medullary cavity

Develops as osteoblasts digest spongy bone to form the medullary cavity inside the diaphysis

Secondary ossification centers

Forms as blood vessels enter the epiphyses.

Articular cartilage

Forms from hyaline cartilage

Epiphyseal plate

The "growth plate" for long bones

Bone resorption

The removal of minerals and collagen by osteoclasts

Bone deposition

The addition of minerals and collagen by osteoblasts

Bone remodeling

A continous process as old bone tissue is replaced with new tissue

Partial fracture

An incomplete break across the bone, such as a crack

Complete fracture

Fracture wherein the bone is broken into two or more pieces

Closed (simple) fracture

The fractured bone does not break through the skin

Open (compound) fracture

The broken ends of the bone protrude through the skin

First step of fracture repair

Phagocytes begin to remove any dead bone tissue

Second step of fracture repair

Chondroblasts form fibrocartilage at the fracture site that bridges the broken ends of the bone

Third step of frature repair

The fibrocartilage is converted to spongy bone tissue by osteoblasts

Fourth step of fracture repair

This is where bone remodeling occurs, in which dead portions of bone are absorbed by osteoclasts and spongy bone is converted to compact bone

Parathyroid hormone

A negative feedback loop that controls calcium levels, where a high level can stimulate osteoclasts to break down more bone matrix while lower levels slow osteoclast activity

Calcium and phosphorus

Hardens bone extracellular matrix

Magnesium

Forms bone extracellular matrix

Fluoride

Strengthens bone extracellular matrix

Maganese

Activates enzymes involved in synthesis of bone extracellular matrix

Vitamin A

Vitamin needed for activity of osteoblasts during remodeling of bone; deficiency stunts bone growth; toxic in high doses