Bone Physiology and Classification Quiz

Anatomy and Physiology Chapter 7: Bone Tissue and The Skeletal System

• Bone is a solid connective tissue.
• The primary function of bone is protection.
• Bone strength originates from its internal structure.
• Bone is capable of growth and repair after damage.
• The skeletal system consists of bone and cartilage.
• Functions of the skeletal system include: providing rigid support, allowing movement, protecting organs, storing minerals, storing energy.
• Bone functions include: attachment sites for muscles, protection of internal organs, storage of minerals, production of blood cells, storage of adipose tissue.
• Hyaline cartilage is present at joint ends, enabling smooth gliding motion; loss of this leads to osteoarthritis.
• Fibrocartilage exists in areas requiring resilience, like intervertebral discs and certain joints.
• Elastic cartilage is not a component of the skeletal system.
• The periosteum covers the outer bone surface, providing protection.
• Compact bone forms the outer shell, shielding the inner structure.
• Spongy bone holds red bone marrow, crucial for blood cell production.
• Yellow bone marrow acts as adipose tissue storage.
• Medullary cavity encloses the bone marrow.
• Articular cartilage, composed of hyaline cartilage, smooths joint surfaces.
• Ligaments join bones.
• Common protected organs include the brain, heart, and lungs.
• Professionals needing bone anatomy/physiology knowledge include radiologists, orthopedic surgeons, and chiropractors.

Bone Classification

• Bones are categorized by shape:
  • Long bones (examples: femur, tibia, humerus): longer than wide and act as levers.
  • Short bones (examples: carpals, tarsals): cube-like in shape; provide stability.
  • Flat bones (examples: ribs, sternum, skull): usually thin, aiding in organ protection.
  • Irregular bones (examples: vertebrae, facial bones): unusual shapes, providing varied support.
  • Sesamoid bones (examples: patella): small, round, within tendons or ligaments, protecting from compressive force.

Common Structures of a Long Bone

• Epiphysis: end of a long bone.
• Diaphysis: shaft of a long bone.
• Metaphysis: region between epiphysis and diaphysis.
• Epiphyseal plate/line: involved in growth; present in children, ossifying to form the line as the bone matures.
• Medullary cavity: marrow-filled space; houses yellow or red bone marrow.
• Articular cartilage: covers the epiphysis; reduces joint friction.
• Periosteum: dense irregular tissue covering the outer surface of most bones; contains blood vessels.
• Endosteum: lining of the medullary cavity; contains bone cells crucial for growth.

Cartilage Tissue

• Semi-solid connective tissue.
• Avascular (lacking blood vessels); receives nutrients through surrounding tissues.
• Covered by perichondrium: dense irregular connective tissue encasing cartilage.

Cells of Bone

• Osteogenic cells: stem cells that replicate and form osteoblasts.
• Osteoblasts: cells forming bone matrix.
• Osteocytes: mature osteoblasts residing in lacunae within the matrix.
• Osteoclasts: cells breaking down bone matrix, aiding bone remodeling.

Compact Bone

• Osteon: structural unit of compact bone.
• Concentric lamellae: rings of matrix surrounding central canal.
• Central canal: houses blood vessels.
• Perforating canals: connect central canals to periosteum, allowing nutrient and waste transport.

Spongy Bone

• Trabeculae: beams of bone forming a lattice-like structure; align along stress lines.

Bone Growth and Development

• Ossification: process of forming bone (intramembranous and endochondral).

• Intramembranous ossification: uses a fibrous connective tissue membrane model to directly create flat bones.

• Endochondral ossification: builds long bones using a hyaline cartilage model.

Cartilage Growth

• Interstitial growth: due to chondrocyte mitosis, increasing cartilage length.
• Appositional growth: occurs as chondrocytes in the perichondrium produce new cartilage matrix, increasing the width and thickness.

Bone Growth in Length

• The epiphyseal plate is composed of four zones
  • Reserve zone
  • Proliferative zone
  • Hypertrophic zone
  • Calcification zone

Bone Growth in Diameter

• Osteoblasts in the periosteum build new bone tissue on the outer surface, while osteoclasts break down bone matrix in the inner surface of the bone.

Bone Remodeling

• Bone is constantly broken down and rebuilt for maintenance and adaptation to stress.
• Remodeling is caused by injury, exercise, and other activities.
• The purpose of bone remodeling is to increase strength along lines of pressure.

Blood Calcium Regulation

• Bones store calcium and other minerals.
• Hormones (calcitonin and parathyroid hormone) regulate blood calcium levels.
• Calcitonin causes the bone to take calcium, reducing blood calcium levels.
• Parathyroid hormone (PTH) causes bone to release calcium, increasing blood calcium levels.

Hormones That Influence the Skeletal System

• Growth hormone (GH) promotes bone growth.
• Thyroid hormones (T3 and T4) promote bone growth.
• Estrogen and testosterone affect osteoblast activity for bone matrix production.
• Calcitriol increases calcium and phosphate absorption from the intestine.
• Parathyroid hormone (PTH) increases osteoclast activity, decreasing bone matrix.
• Calcitonin increases osteoblast activity, promoting bone growth, and decreases osteoclast activity.

Bone Repair

• Fracture: break in a bone.
• Steps in bone repair: hematoma formation, callus formation, callus replacement with bone, and remodeling.

Assistance with Bone Repair

• Reduction: aligning fractured bone ends.
• Surgical intervention for stabilization utilizes cylinders and screws.

Types of Fractures

• Fractures are categorized by complexity, location, and other features.
  • Common types: closed (simple), open (compound), transverse, oblique, spiral, comminuted, impacted, greenstick.

Common Types and Description of Fractures

• Table with descriptions and examples of different types of fractures.

Summary

• Chapter summary for the information covered within it.

Other Key Concepts

• Osteoporosis: reduction in bone mass, characterized by an imbalance in bone resorption and formation; often affected by age and rapidly declining estradiol levels (females).
• Importance of Vitamin D and its role in calcium absorption.
• Lifestyle and its impact on bone density.