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ODU BIOL 109N - Exam 2 Study Guide

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BIOL 109 1st EditionExam# 2 Study Guide Lectures: Lecture 9 The Skeletal System I. There are 5 main functions of the skeletal system: 1. Structural support- provides shapes and structure, including securing organs in place 2. Protection – shields vulnerable tissue- such as the brain and heart- from external insults3. Enabling movement – muscles which are connected to bones, generate movement whenthey contract 4. Cell production – produces blood cells in bone marrow5. Mineral reservoir – elements such as calcium can be released from or stored in bones in response to deficiencies or excesses in the bloodstream. 6. Bones do not synthesize growth hormones. 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 have a hard outer layer of compact bones surrounding spongy bone. Compact bone is dense with few internal spaces, and forms most of the shaft of long bones. It iscovered by the periosteal (layers),containing blood vessels, nerves, and cells involved in bone growth and repair. Spongy bone – is a latticework of tiny beams and thin plated of bones with open areas between. Spongy bone is found in small, flat bones (skull), and in the head and near the end of the shaft of long bones. Produces blood cellsIn adults, the spaces of some spongy bones are filled with red marrow, which generated blood cells. The shaft is filled with yellow marrow, a fatty tissue for energy storage. II. Bone is Living tissue- the structural unit of compact bone is called osteon (straw like). Each osteon consists of osteocytes arranged in concentric rings around a central canal.Each osteocyte (living bone cell) lies within a lacuna (small space within the hard matrix). 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. Maintenance crew. Each osteocyte have an average half-life of 25 years, they do not divide. Types of bones - Osteocyte- maintains bone tissue- Osteoblast- form bone matrix, bon-forming cells found in the collar of long bones. They are the precursors to osteocytes. - Osteogenic cell – stem cell- Osteoclast – are cells that release minerals important for nerves and muscles. Bone growth is stimulated by growth hormone during childhood. Thyroid hormones ensure that the skeleton grows with the proper proportions. At puberty, increasing levels of male orfemale sex hormones initially stimulate cartilage cells to divide, but eventually bone can no longer increase in length. However, they can continue to widen. The first step in bone development is the formation of a cartilaginous model of bone at two months of fetal development. The bone collar is formed by the osteoblasts, beginning at about the 3rd prenatal month. Shaft is part of the mature long bone which is hollow, is infiltrated by blood vessels, and has spongy fill-ins. Secondary growth centers begins at about the time of birth and continues throughout childhood. The cartilage on the ends of the long bones is for protection in areas where the bones come together. Once you reach adulthood, your bones continually remodel themselves based on stresses. Woven throughout the matrix are strands of elastic protein called 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 an flexible like a garden hose-> bowlegs<- rickets (childhood disease) If you break your arm, fibroblast cells willmake a collagen link over the break PTH does not stimulate bone growth Bone remodeling - deposits and absorb the bone minerals. Calcium is important in remodeling. When there is not adequate calcium intake to the bones, calcium is not available to be deposited during remodeling. III. Axial SkeletonThe bones of human body can be divided into two groups: 1. Axial skeleton – protects and supports our internal organs- Components: skull, vertebral column, sternum and rib cage. - Cranium = 8 bones, face = 14 bones - The skull bones of a human newborn are not fused but are instead connected by fibrous connective tissue. The “soft spot” called fontanels between a baby’s skull bones will eventually develop into fibrous joints. - Vertebral column consists of 26 vertebrae – Cervical (7), Thoracic (12), Lumber (5), Sacrum (5), Coccyx (4). Curvature spine allows for flexibility, maintains balance, move in multiple directions. - Rib cage – 12 pairs of ribs attach at eh 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 attach to the sternum and are called “floating ribs” 2. Appendicular skeleton – allows movement and interaction with the environment - Components –  Pectoralgirdle – part of the appendicular skeleton and is composed of the shoulder blades (scapulae), and the collar bones (clavicles)  Pelvic girdle LimbsReplacement of the hip involves the joint between the pelvic griddle and the femur. The cartilaginous joint of the pelvis of women loosens during pregnancy to allow slight movement during childbirth. Someone is most likely to have thinner, weaker bones from resting in bed for a few weeks during vacation.Ligament connects bone to bone. Osteoarthritis – occurs when cartilage wears down. Lecture 10 The Muscular System Muscular system produces movement There are 3 types of muscles:  Skeletal – are voluntary muscles responsible or moving our body and maintaining posture. Skeletal muscles work in pairs. - Each muscle is attached to a bone by a tendon (a band of connective tissue) - The origin of the muscle is the end attached to eh bone that remains stationary during movement - The insertion Is the end attached to the bone that moves- Bones act as levels in working with skeletal muscles to produce movement. The body has more than 600 skeletal muscles. Most muscles are arranged in pairs, called antagonistic pairs that work in opposition to one another.Muscles that must contract at the time to cause movement are called synergistic muscles. Flexion – the biceps contracts and pulls the forearm up, flexing the arm. The relaxed triceps is stretched.Extension – the biceps contracts and pulls the forearm down, extending the arm.


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