BIOL 109N 1st Edition Lecture 9 Outline of Last Lecture I. Midterm Outline of Current Lecture II. List the funcitons of Skeletal systemIII. Human Bone IV. Bone is a living tissueCurrent Lecture1. Functions of the sletelal System:- Structural support- provides shape and structure including securing organs in place- Protection – shields vulnerable tissue- such as the brain and heart from external insults- Enalbling movements – muslces, which are connected to bones, generate movementwhen they contacts- Cell production- produces blood cells in bone marrow- Mineral reservoir- elements such as calcium can be released from or stored in boned in resposes to defiecencies or excesses in thebloodstream. 2. Human Bones: - The human body has 206 bones which vary in size and shape- Most bones contain both compact tissue and spongy tissue in proportions that depend on the bone’s size and shapeCompact bone: - bones hava a hard outer layer of compac bone surrounding spingy bone- is dense with few internal spaces, and forms most of the shaft of long bones- it is covered by the periosteum, containing blood vessels, nerves, and cells invoveld in bone growth and repairSpongy bone: - is a latticework of tinu beams and thin plates of bones with open areas between - is found in small, flat bones (skull) and in the head and hear the ends of the shafts of long bonesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- IN adults, the spaces of some spongy bones are filled with red marrow, which generated blood cells- The shaft is filles with yellow marrow, a fatty tissue for energy storage. Bone is Livign Tissue: - The structural unit of comact bone is called an osteon- Each osteon consists of osteocytes arranged in concentric rings around a cetnral canal- Each osteocyte (liviing bone cell) lies within a lacuna (small space within the hardmartix)- Tiny canals connect nearby lacunae, and eventually with the central canal- Nutrients, oxygen, and wastes pass from cell to cell, travelling to and from the blood vessels in the central canal- They are called a maintenance crew- Osteocytes have an average half of life of 25 years, they do not divide. - Bone growth is stimulated by growth hormone during childhood- Thyroid hormones ensure that the skeleton growth with the proper properties - At puberty, increasing levels of male ro females sex hormones initially stiumate cartilage cells to divide, but eventually bone can no longer increase in length- But they can continue to widen - Woven throughout the matrix are strands of elastic protien collagen for resilience Without it bones would be brittle and crumbly like chalk- Matrix is hardened with calcium and phosphorus salts.  Without them bones would be rubbery and flexible like a garden hose-> bowlegs<- rickets (childhood disease) 3. Types of Bones- Axial Skeleton  the bones of human body can be divided into two groups: I. Axial skeleton: protects an supports our internal organs  Components are: Skull, verberal column, sternum and rib cage Skull – pariatal bone, temporal bone, occipital bone and external auditory medius. The skull bones of a human newborn are not fused but are instead connected by fibrous connective tissue The verberal column: - 26 vertebrae: Cervical(70, thoratic (12), Lumbar (5) , sacrum (5) Coccyk (4). Curvature of spine- allows for flexibility, maintains, balance, move in multiple directions Rib cage- 12 pairs fo ribs attach at the back of the rib cage to the thoracic vertebrae. Upper 10 pairs are attached by cartilage either directly or indirectly to the sternum. Last two pairs do not attaach to the sternum and are called floating ribsII. Appendicular skeleton- allow movement and interaction with the environment Components: pectoral girdle, pelvic girdle,