Chapter 6 Bones and Skeletal Tissues Part A
Chapter 6 Bones and Skeletal Tissues Part A Skeletal Cartilages, Classification of Bones, and Functions of Bones
Without Bones We would look like Slugs
Skeletal Cartilages
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
• Looks like frosted glass when freshly exposed • Provides support, flexibility, and resilience • Is the most abundant skeletal cartilage • Contains fine collagen fibers Hyaline Cartilage
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
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 needlelike 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. 2 a
Long Bones • Examples of long bones – Humerus – Femur – The bones in your fingers Figure 6. 2 a
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
• Thin & Flattened • Usually curved • Thin layers of compact bone around a layer of spongy bone Flat Bones Figure 6. 2 c
Flat Bones • Examples – Sternum – Ribs – Scapulae – most skull bones Figure 6. 2 c
Irregular Bones • Irregular shape • Bones with complicated shapes or ones that do not fit into other categories Figure 6. 2 d
Irregular Bones • Examples – vertebrae – hip bones Figure 6. 2 d
Functions of Bones
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 120122 of the study guide for the study guide check.
Quiz Next time! If you snooze, you lose.
- Slides: 45