Skeletal System Overview Quiz

Skeletal System Overview

• Composed of connective tissues: bones, cartilage, ligaments, and tendons.
• Bones comprise mostly calcium and phosphate crystals, collagen, and elastin fibers.
• Cartilage contains collagen and elastin fibers; it supports and cushions joints.
• Ligaments connect bone to bone, while tendons connect muscle to bone, both being dense, regular connective tissues.

Bone Functions

• Muscles attach to bones enabling movement.
• Supports body structure and shape.
• Protects vital organs (e.g., ribcage, skull, vertebrae).
• Forms blood cells in specific bones (e.g., femur, humerus).
• Stores calcium and regulates blood calcium homeostasis.
• Smallest bones in the middle ear aid in sound transmission.

Bone Structure and Cells

• Hyaline cartilage covers bone surfaces; spongy bone is lighter but provides structural support.
• Chondroblasts form cartilage, while osteoblasts form solid bone and become osteocytes for maintenance.
• Osteoclasts break down bone for remodeling and calcium release.

Bone Remodeling

• Remodeling involves changes in bone shape, size, and strength through osteoclast and osteoblast activity.
• Osteoporosis characterized by low bone density can result from an imbalance between osteoclast and osteoblast activities, particularly after menopause.

Long Bone Development

• Initially consists of hyaline cartilage which is gradually replaced by bone during fetal development.
• Growth hormone and sex hormones (estrogen/testosterone) stimulate bone growth and ossification during puberty, which leads to growth plate fusion and cessation of bone lengthening.

Hormonal Regulation of Blood Calcium

• Parathyroid hormone increases blood calcium by stimulating osteoclasts.
• Calcitonin decreases blood calcium levels by promoting osteoblasts.
• Calcium is essential for muscle contraction and nervous function.

Axial Skeleton

• Comprised of the skull and vertebral column.
• 33 vertebrae support the spinal cord and can be categorized into cervical, thoracic, lumbar, sacral, and coccyx regions.
• Intervertebral discs provide cushioning and flexibility; herniated discs can cause nerve compression.

Appendicular Skeleton

• Includes the pectoral girdle (shoulders) and pelvic girdle (hips), with differences in male and female structures.
• Limbs consist of long bones with specific names (e.g., humerus, femur).

Joints Classification

• Fibrous joints: immovable (e.g., skull sutures).
• Cartilaginous joints: slightly movable (e.g., between vertebrae).
• Synovial joints: freely movable; include hinge and ball-and-socket types, with lubricating synovial fluid.

Common Skeletal System Problems

• Dislocations occur when bones are forced out of joints, often accompanied by sprains.
• Broken bones undergo a healing process: hematoma formation, callus creation by chondroblasts, osteoclast activity for cleaning, and osteoblasts building new bone.
• Torn cartilage heals slowly due to a low blood supply; surgical intervention may be necessary for repairs.
• Arthritis involves joint inflammation, with osteoarthritis resulting from cartilage wear and rheumatoid arthritis being an autoimmune condition.

Introduction to Tissues and Skin

• Four primary types of tissues: epithelial, connective, muscle, and nervous.
• Skin functions as an organ system composed of multiple tissues.

Types of Tissues

• Epithelial Tissue: Covers body surfaces; includes epidermis, lining of blood vessels, and digestive tract.
• Connective Tissue: Supports and connects body parts; includes tendons, ligaments, cartilage, and adipose tissue.
• Muscle Tissue: Responsible for movement; categorized into skeletal, cardiac, and smooth muscle.
• Nervous Tissue: Generates electrical signals for information transmission.

Epithelial Tissues

• Comprises sheets of interconnected cells.
• Simple Epithelium: One layer, allows for diffusion and secretion.
• Stratified Epithelium: Multiple layers, provides protection against abrasion and infection.

Glands in Epithelial Tissue

• Glandular Epithelia: Produces and secretes chemicals.
  • Exocrine Glands: Release secretions into hollow organs (e.g., saliva, digestive enzymes).
  • Endocrine Glands: Secrete hormones directly into the bloodstream.

Connective Tissue Characteristics

• Composed of loosely packed cells within a protein matrix.
• Matrix includes collagen, elastin, and reticular fibers for structure and support.

Types of Fibrous Connective Tissue

• Loose Connective Tissue: Surrounds internal organs and blood vessels; flexible but weak.
• Dense Irregular Connective Tissue: Found in the dermis, strong but less flexible.
• Elastic Connective Tissue: High elastin content; found in organs that require flexibility (e.g., bladder).
• Dense Regular Connective Tissue: Contains parallel collagen fibers; forms tendons and ligaments.

Specialized Connective Tissues

• Cartilage: Provides support; heals slowly due to lack of blood vessels.
  • Hyaline cartilage (smooth, reduces friction in joints).
  • Elastic cartilage (flexible, found in ears).
  • Fibrocartilage (dense, withstands pressure in vertebral disks).
• Bone: Comprised of collagen, elastin, and a hardened matrix; enables quick healing due to blood supply.
• Blood: Contains plasma and cells; involved in transport, immune functions, and clotting.
• Adipose Tissue: Stores fat for insulation and energy.

Organ Systems

• Tissues collaborate to form organs, which in turn function in coordinated organ systems including:
  • Integumentary, nervous, skeletal, muscular, endocrine, circulatory, digestive, urinary, immune, reproductive, and respiratory systems.

Skin as Part of the Integumentary System

• Functions of Skin:
  • Prevents dehydration through keratin.
  • Protects underlying tissues from injury.
  • Defends against infections via pH barrier and immune cells.
  • Regulates body temperature through sweat and blood flow.
  • Provides sensory perceptions (touch, temperature, pain).
  • Synthesizes vitamin D when exposed to UV light.
  • Protects from UV radiation with melanin.

Skin Color Adaptations

• Dark Skin: Provides protection from skin cancer in sunny regions but may hinder vitamin D production in less sunny areas.
• Light Skin: Increases vulnerability to skin cancer in sunny regions but enhances vitamin D production in areas with less sunlight.

The Epidermis

• Composed of dead, flattened keratinocytes; serves as a nearly waterproof barrier.
• Living cells migrate towards the surface, eventually dying due to distance from blood vessels.
• Melanocytes within the epidermis produce melanin, shielding cells from UV-induced mutations.