Part A Skeletal Cartilages, Classification of Bones, and Functions of Bones

Without Bones We would look like Slugs

Skeletal Cartilages Cartilage tissue consists primarily of water –Accounts for its resilience (ability to spring back to its original shape after being compressed) Contains no blood vessels or nerves Surrounded by the perichondrium

Perichondrium Surrounds skeletal cartilage Made from dense irregular connective tissue Resists outward expansion when cartilage is compressed Contains blood vessels from which nutrients diffuse through matrix to reach cartilage cells –This limits cartilage thickness

Skeletal Cartilages Three types of Skeletal Cartilages –Hyaline –Elastic –Fibrocartilage All contain chondrocyte cells and an extracellular matrix of ground substance and fibers

Hyaline Cartilage Looks like frosted glass when freshly exposed Provides support, flexibility, and resilience Is the most abundant skeletal cartilage Contains fine collagen fibers

Hyaline Cartilage Is present in these cartilages: –Articular – covers the ends of long bones –Costal – connects the ribs to the sternum –Respiratory – makes up the larynx and reinforces air passages –Nasal – supports the nose

Hyaline Cartilage in Blue Figure 6.1

Elastic Cartilage Similar to hyaline cartilage but contains more elastic fibers –Better able to stand repeated bending

Elastic Cartilage Found in the external ear and the epiglottis –Epiglottis is the flap that covers the opening of the larynx when we swallow

Elastic Cartilage in Green Figure 6.1

Fibrocartilage Highly compressible with great tensile strength Contains thick collagen fibers

Fibrocartilage Found in sites subjected to both heavy pressure and stretch –menisci of the knee –intervertebral discs

Fibrocartilage in Red Figure 6.1

Growth of Cartilage Cartilage grows in two ways 1. Appositional – Growth from outside –cells in the perichondrium secrete matrix against the external face of existing cartilage

Growth of Cartilage Cartilage grows in two ways 2. Interstitial – Growth from inside –lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within

Growth of Cartilage Typically cartilage growth ends during adolescence (same time as skeleton) Calcification of cartilage occurs under certain conditions –During normal bone growth in youth –During old age

Growth of Cartilage Calcified cartilage is not bone Calcification is when calcium salts are deposited in the matrix and harden

Classification of Bones Two basic types of bone tissue –Compact Bone Homogeneous Dense - looks smooth and solid to the naked eye

Classification of Bones Two basic types of bone tissue –Spongy Bone Honey comb of small needle- like pieces of bone Many open spaces

Classification of Bones The 206 named bones of the human skeleton are divided into two groups: –Axial skeleton –Appendicular skeleton

Axial Skeleton Includes bones of the skull, vertebral column, and rib cage Most involved in protecting, supporting, or carrying other body parts

Axial Skeleton in dark tan Figure 6.1

Appendicular Skeleton Includes bones of the upper and lower limbs, shoulder, and hip

Appendicular Skeleton Locomotion –Helps us move –Helps us manipulate our environment

Appendicular Skeletons in yellow Figure 6.1

Classification of Bones by Shape Long Bones Short bones Flat bones Irregular bones

Long Bones Longer than they are wide Has a shaft with heads at both ends Contains mostly compact bone Figure 6.2a

Long Bones Examples of long bones –Humerus –Femur –The bones in your fingers Figure 6.2a

Short Bones Contains mostly spongy bone Cube shaped –Wrist and ankles Carpals – Tarsals

Short Bones Sesamoid bones –shaped like a sesame seed –Special bones that form within tendons Example: Patella

Flat Bones Thin & Flattened Usually curved Thin layers of compact bone around a layer of spongy bone Figure 6.2c

Flat Bones Examples –Sternum –Ribs –Scapulae –most skull bones Figure 6.2c

Irregular Bones Irregular shape Bones with complicated shapes or ones that do not fit into other categories Figure 6.2d

Irregular Bones Examples –vertebrae –hip bones Figure 6.2d

Function of Bones Support Protection Movement Mineral storage Blood cell formation

Function of Bones Support of the body –form the framework that supports the body and cradles soft organs Protection of soft organs –provide a protective case for the brain, spinal cord, and vital organs Movement due to attached skeletal muscles –provide levers for muscles

Function of Bones Storage of minerals and fats –reservoir for minerals, especially calcium and phosphorus Blood cell formation –hematopoiesis occurs within the marrow cavities of bones

Study Guide You should be able to complete pages of the study guide for the study guide check.

Next time! If you snooze, you lose.