Ch.6 Bone and Skeletal Tissue

Growth of Cartilage: •Cartilage grows in two ways:

-Appositional growth •Cartilage-forming cells in perichondrium secrete matrix against external face of existing cartilage -New matrix laid down on surface of cartilage -Interstitial growth •Chondrocytes within lacunae divide and secrete new matrix -New matrix made within cartilage •Calcification of cartilage occurs: -normal bone growth in youth -old age

Long Bone Classification by shape:

1. Long Bones - longer than they are wide •All limb bones except for patella and wrist/ankle •Named for shape not size •What is a very short long bone?

what are the functions of bones?

1. Support - Framework for body and soft organs - Pillar of lower limbs, rib cage for thoracic 2. Protection - Brain, spinal cord, vital organs 3. Movement/Anchorage - Levers for muscle action 4. Mineral and growth factor storage •Ca, P; checking account 5. Blood cell formation •Hematopoiesis - red marrow cavities of certain bones 6. Triglyceride storage •Fat, for energy, is stored in bone cavities, esp. in medullary of long bones (yellow marrow) 7. Hormone production •Osteocalcin - regulate bone density, insulin secretion, glucose levels, and metabolism

Short bone Classification by shape:

2. Short bones -Cube-shaped bones -Bones that form within tendons (patella)

Flat bone Classification by shape:

3. Flat bones - thin, flattened, and a bit curved (scapula, ribs, skull bones)

irregular bone classification by shape:

4. Irregular bones - bones w/complicated shapes (vertebrae, hip bones) - Can you name a irregular bone in the skull?

What is a Compact bone (lamellar) ?

Dense outer layer; smooth and solid

What are the three types of Cartilage?

Hyaline, Elastic Fibrocartilage

What is a Spongy bone (Trabecular)?

Inner layer w/honeycomb of trabeculae filled w/red or yellow marrow

Basic Structure, Types, and Locations

Skeletal cartilage: highly resilient, molded cartilage tissue that consists 1o of H2O -Resilience and compression -No nerves or blood vessels • Perichondrium: layer of dense CT surrounding cartilage like spanx -Resist outward expansion -Vascularized for nutrient delivery to cartilage

Similarities between the three types of cartilage?

The main similarities between all three types of cartilage is that they are all connective tissues which have chondrocytes locates in the lacunae. All three also are abundant in the extracellular matrix and hold water.

What is Fibrocartilage?

is made up of thick collagen fibers, which have tensile strength. This type of cartilage usually resists tension and compression. Fibrocartilage surrounds the lacunae and it is found in articular disks in some joints or the annulus fibrosus parts of the vertebral disks.

What is Hyaline Cartilage?

is transparent and it is the most abundant type of cartilage found in the bodies joints, ribs, larynx, and nose tip. Hyaline cartilage is made up of collagen fibers only and it provides support, flexibility, and resilience. It also holds resistance to compression and large amounts of water. The collagen found in Hyaline cartilage is also found in elastic cartilage. Types of hyaline cartilage: cricoid, thyroid

What is Elastic Cartilage?

similar to Hyaline cartilage is also made up of same collagen fibers, but it also contains elastic fibers. This type of cartilage is found in the external ear (mostly where some people get cartilage piercings in their ears) and the epiglottis. Elastic cartilage is very flexible.

2. How many bones are there in the human body? Describe the differences between the bones of the lower and upper limb and briefly state why these differences exist. Quiz Q:

• In the human body, there are 206 bones. The difference between the bones of the lower and upper limb are that lower limbs of the body carry mostly all of the body's weight and the bones have the ability to hold exceptional force. Lower limb bones are usually thicker and stronger. The upper limbs of the body allow more flexibility and mobility, which means that they are most likely smaller and lighter; they are less stern and stiff. These differences exist in order to allow the body to move freely for example walking, raising our hands, doing pushup, etc. Our femur (lower limb) is strong and can hold exceptional force, this is why women are able to hold babies inside of them because the human body is designed to have our legs hold all the weight of the body because of strong dense bones. Our upper limbs which contain more cartilage and small bones, like our shoulder joints, which allow mobility and free movement

What does the structure of long bones consist of?

• Long bones consist of a diaphysis (shaft) and an epiphysis (ends) • Diaphysis -Tubular shaft that forms the axis of long bones -Composed of compact bone that surrounds the medullary cavity -In adults, yellow bone marrow (fat) is contained in the medullary cavity Structure of Long Bone • Epiphyses -Broader ends of long bones -Exterior is compact bone and the interior is spongy bone -Joint surface covered w/articular (hyaline) cartilage to cushion the bone ends during movement and absorbs shock **•Epiphyseal line separates the diaphysis from the epiphyses (remnant of the epiphyseal plate)

Bone Membranes

• Periosteum- double-layered protective membrane that covers the entire external surface (except the joint surfaces) -Outer fibrous layer is dense irregular CT -Inner osteogenic layer is composed of osteoblasts (bone forming cells) and osteoclasts(bone destroying cells) -Richly supplied with nerve fibers, blood, and lymphatic vessels, which enter the bone diaphysis via nutrient foramina -Secured to underlying bone by perforating fibers (Sharpey's fibers) which consist of dense collagen fibers -The periosteum is the anchoring point for tendons and ligaments