Bone Tissues

What are the six functions of the skeletal system?

Provide support, protect internal organs, assist body movements, store and release calcium and phosphorus, participate in blood cell production, and store triglycerides in yellow marrow.

What is hematopoiesis?

The process of blood cell production, which occurs in the red bone marrow.

How does bone store energy?

By storing triglycerides in adipose cells of yellow marrow.

Why is bone considered a dynamic tissue?

Because it is constantly remodeling, which involves building up and breaking down.

What are the two main types of bone tissue?

• Compact bone and spongy bone.

Where is compact bone typically found?

In the diaphysis of long bones and the external layer of all bones.

What is the function of spongy bone?

To provide lightweight support and protect red bone marrow.

What structure allows spongy bone to resist stress without breaking?

Trabeculae, which are oriented along lines of stress.

What are the three regions of a long bone?

Diaphysis (shaft), epiphyses (ends), and metaphyses (where the diaphysis and epiphyses meet).

What are the three types of cartilage?

Hyaline cartilage, fibrocartilage, and elastic cartilage.

What type of cartilage is found at the ends of long bones?

Hyaline cartilage.

What is the function of the perichondrium?

It provides blood, nerves, and a source of new cartilage cells.

What is articular cartilage?

A thin layer of hyaline cartilage that covers the epiphysis of long bones at joints.

What are osteoblasts?

Bone-building cells that synthesize and secrete collagen fibers and other organic components.

What are osteocytes?

Mature bone cells that maintain daily bone metabolism.

What are osteoclasts?

Large cells that break down bone by releasing lysosomal enzymes and acids.

From which type of cells do osteoclasts originate

White blood cells (monocytes).

What are the inorganic components of bone?

Calcium phosphate, calcium carbonate, and other trace elements like magnesium and fluoride.

What is the function of collagen fibers in bone?

To provide flexibility and tensile strength.

What is an osteon?

The structural unit of compact bone, consisting of concentric lamellae around a central canal.

What are canaliculi?

Small channels that connect lacunae and allow nutrient and waste exchange.

What is the function of Volkmann’s canals?

To allow blood and lymphatic vessels to transit to the outer cortex of the bone.

What are the two types of ossification?

Intramembranous ossification and endochondral ossification.

Which bones are formed by intramembranous ossification?

Flat bones of the skull, mandible, and clavicle.

What happens during endochondral ossification?

Cartilage is replaced by bone.

What is the role of the epiphyseal growth plate?

To enable bone elongation during growth.

What vitamins are important for bone health?

Vitamins A, C, D, K, and B12.

How does growth hormone affect bone growth?

It stimulates the liver to produce IGF-1, promoting chondrocyte proliferation and bone growth.

What causes rickets and osteomalacia?

Vitamin D deficiency, which disrupts calcium absorption and leads to inadequate calcification of bone.

How many bones make up the human skeleton?

The human skeleton consists of 206 named bones.

What are the two principal divisions of the skeleton?

The axial skeleton and the appendicular skeleton.

What does the axial skeleton consist of?

Skull bones, auditory ossicles, hyoid bone, ribs, sternum, and the vertebral column.

What is the appendicular skeleton made of?

Bones of the upper and lower limbs, and the girdles connecting them to the axial skeleton.

How many bones are in the axial skeleton?

• There are 80 bones in the axial skeleton.

What are the main components of the axial skeleton?

Skull, vertebral column, ribs, and sternum.

What is the primary function of the skull?

To protect and support the brain and sensory organs.

How many cranial bones form the braincase?

Eight cranial bones.

Name the cranial bones.

Frontal bone, parietal bones (2), temporal bones (2), occipital bone, sphenoid bone, and ethmoid bone.

How many facial bones are there?

There are 14 facial bones.

Which bone is referred to as the "keystone" of the cranial bones?

The sphenoid bone.

What are sutures in the skull?

Immovable joints between skull bones.

How many cervical vertebrae are there?

• Seven cervical vertebrae (C1-C7).

How many thoracic vertebrae are there?

Twelve thoracic vertebrae (T1-T12).

How many lumbar vertebrae are there?

Five lumbar vertebrae (L1-L5).

What is the purpose of intervertebral discs?

To absorb vertical shock and allow movement of the spine.

What are the four normal spinal curvatures?

Cervical and lumbar (convex), thoracic and sacral (concave).

What is scoliosis?

A lateral bending of the vertebral column.

What does the thoracic cage consist of?

Thoracic vertebrae, sternum, ribs, and costal cartilages.

What are "true ribs"?

The first seven rib pairs that attach directly to the sternum.

What are "floating ribs"?

Ribs 11 and 12, which do not attach to the sternum.

How many bones are in the appendicular skeleton?

126 bones.

What are the main divisions of the appendicular skeleton?

Upper and lower limbs, including the pectoral and pelvic girdles.

What bones form the pectoral girdle?

Scapula and clavicle.

What is the only bone in the arm?

The humerus.

What two bones make up the forearm?

Radius (lateral) and ulna (medial).

How many carpal bones are in the wrist?

Eight carpal bones.

How many phalanges are in each finger (except the thumb)?

Three phalanges (proximal, middle, distal).

What bones form the pelvic girdle?

Two hip bones, each made of the ilium, ischium, and pubis.

What is the longest and strongest bone in the body?

The femur.

What are the structural classifications of joints?

Fibrous joints, cartilaginous joints, and synovial joints.

How are joints classified functionally?

Synarthrosis (immovable), amphiarthrosis (slightly movable), and diarthrosis (freely movable).

Which structural joint type is held together by dense collagen fibers?

Fibrous joints.

What type of joint is the pubic symphysis, and how is it classified functionally?

Cartilaginous joint; classified as amphiarthrosis.

Which functional classification includes the shoulder and hip joints?

Diarthrosis.

What connects bones in fibrous joints?

Dense connective tissue made of collagen fibers.

Do fibrous joints have a joint cavity?

No, fibrous joints lack a joint cavity.

What is the primary functional classification of fibrous joints?

Synarthrosis, though some are amphiarthrosis.

Name the three subtypes of fibrous joints.

Suture, syndesmosis, and gomphosis.

Where are sutures found, and how are they held together?

In the skull; held together by short dense fibrous tissue and interlocking bone projections.

What type of fibrous joint is held together by long fibers or ligaments?

Syndesmosis.

Give an example of a syndesmosis joint.

The interosseous membrane between the radius and ulna.

What is a gomphosis joint, and where is it found?

A peg-in-socket fibrous joint, found in the articulations of teeth with their sockets.

What membrane holds teeth in their sockets?

6. The periodontal ligament.

What material unites bones in cartilaginous joints?

Cartilage.

Do cartilaginous joints have a joint cavity?

No, they lack a joint cavity.

What is an example of a cartilaginous joint classified as amphiarthrosis?

The pubic symphysis.

What is the unique feature of synovial joints?

They have a synovial cavity between the bones.

What encloses the synovial cavity?

A two-layered capsule: an outer fibrous capsule and an inner synovial membrane.

What is the function of synovial fluid?

To reduce friction, lubricate the joint, and absorb shocks.

What does the synovial membrane supply to the cartilage?

Oxygen and nutrients.

Name three major joints that are synovial.

• Shoulder, hip, and knee joints.

How are synovial joints classified based on bone surface shapes?

Into six types.

What age-related joint condition is common by age 80?

Osteoarthritis.

How does aging affect articular cartilage and synovial fluid?

Articular cartilage thins, and synovial fluid production decreases.

What happens to ligaments as people age?

They shorten and lose elasticity.

What is joint arthroplasty?

The surgical implantation of an artificial joint.

Which joints are most commonly replaced in arthroplasty?

Hips, knees, and shoulders.

What is the difference between partial and total hip replacements?

Partial hip replacements involve only the femur, while total replacements include both the acetabulum and the femoral head.

What are potential complications of joint arthroplasty?

Infection, blood clots, and nerve injury.