A&P Chapter 7

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A&P Chapter 7
2012-11-04 14:52:00
Skeletal System

A&P Chapter 7 Skeletal System
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  1. How does the skeletal system aid in support?
    The bones of the legs, pelvic girdle and vertebral column support the weight of the erect body. The mandible supports the teeth and other bones support the teeth
  2. How does the skeletal system aid in protection?
    The bones of the skull protect the brain, ribs and sternum protect the heart and vertebrae protect the spinal cord
  3. How does the skeletal system aid in movement?
    Skeletal muscles use the bones as levers to move the body
  4. How does the skeletal system act as a reservoir?
    Holds 99% of the bodies calcium and adipose tissue (adipose found in marrow of certain bones) 85% of the bodies phosphorus is stored in bone
  5. How does hematopoiesis?
    AKA blood cell formation. All blood cells are made in the marrow of certain bones
  6. What is the Axial Skeleton?
    Forms the long axis of the body. Includes the skull, vertebral column and rib cage. Involved in protection and support
  7. What is the Appendicular Skeleton?
    Bones of the upper and lower limbs and the girdles (shoulders and hip bones) that attach them to the axial skeleton. Involved in locomotion and manipulation of the environment
  8. What are long bones?
    Much longer than they are wide, all bones of the limbs including finger bones except for the patella and bones of wrist and ankle. Consists of a shaft into expanded ends
  9. Whate are short bones?
    Roughly cube shaped. Bones of the wrist and ankle
  10. What are flat bones?
    Thin, flattened and usually a bit curved. Shoulder blades, ribs and most bones of the skull
  11. What are irregular bones?
    Have weird shapes that don't fit in other bone categories. Vertebrae, hip bones, two skull bones (sphenoid & ethmoid)
  12. What are bones composed of?
    Bone tissue, fibrous CT, cartilage, vascular tissue, adipose tissue and nervous tissue
  13. What is Compact Bone and its function?
    Consists of multiple cylindrical structural units called osteons and haversian systems
  14. What is spongy (trabecular) bone and its function?
    Appears poorly organized, lacks osteons, trabeculae, align along positions of stress and exhibit extensive cross bracing. Trabeculae are a few cell layers thick and contain irregularly arranged lamellae and osteocytes interconnected by canaliculi. No haversian canals or volkmann's canals.
  15. What are Osteoblasts?
    Bone building cells that synthezise and secrete collagen fibers and other components of bone matrix. Initiate the process of calcification. Found in the periosteum and endosteum
  16. What are Osteocytes?
    Mature bone cells that have become trapped by the secretion of matrix. They no longer secrete matrix and are responsible for maintaining the bone tissue
  17. What are Osetoclasts?
    Huge cells derived from fusion of many monocytes (a type of red blood cell). They digest bone matrix, are concentrated in the endosteum. Side of cell facing bone is ruffled and secretes degestive enzymes
  18. What are the organic components of bone?
    1/3 of bones weight. Several materials secreted by osteoblasts like collagen which provide resiliance and resistance of stretching and twising
  19. What are the in-organic components of bone?
    Mainly two salts, calcium phosphate and calcium hydroxide. They interact to form hydoxyapatite. These minerals give bone hardness and the ability to resist compression
  20. What is the diaphysis?
    The shaft of the long bone, consists of a thick collar of compact bone surrounding a central marrow cavity
  21. What is the epyphisis?
    The expanded end of the long bone. A thin layer of compact bone covering and interior of spongy bone.
  22. What is the medullary cavity?
    Cavity in the long bones, locaton of bone marrow
  23. What is the periosteum?
    Covers the external surface of the shaft of the long bone. A double layered membrane, the outer being a fibrous layer of dense irregular CT. Is richly supplied with nerve fibers, lymphatic vessels and blood vessels. Connected to bone matrix via strong strands of collagen.
  24. What is the endosteum?
    Covers the internal surface of the long bone. A delicate CT membrane that covers the trabelculae spongy bone in the marrow cavities and lines the canals that pass through the compact bone
  25. What is articular cartilage? A type of hyaline cartilage that covers the joint of the epiphysis. It cushions the bone ends and reduces friction during movement.
  26. What is red marrow and its function?
    Blood cell forming tissue in bones. In almost every bone of a child, in adults limited to axial skeleton, pectoral girdle, pelvic girdle and proximal heads of humorous and femur.
  27. What is yellow marrow and its function?
    Fat storage tissue in the medullary cavities of certain bones. In adults it fills the shafts of long bones and no longer produces blood but can in emergencies.
  28. What is the structure of Short, irregular and flat bones?
    Thin plates of periosteum covered compact bone on the outside and endosteum covered spongy bone within. Have no diaphysis or epiphysis, contain bone marrow between their trabeculae but no marrow cavity
  29. What is the structure and function of osteons?
    A single central canal known as a haversian canal (allow passage of blood vessels, lymphatic vessels and nerve fibers), surrounded by concentric layers of calcified bone matrix (allows bone to better withstand twisting forces).
  30. What are Volkmann´┐Żs canals?
    They run perpendicular to haversian canals and they connect the blood and nerve supply in the periosteum to those in the haversian canals and the medullary cavity.
  31. What are canaliculi?
    They allow the osteocytes to exchange nutrients, wastes and chemical signals to each other via intercellular connections.
  32. Bone development of flat and irregular bone vs long and short bones
  33. What is intramembranous ossification?
    The development of bone from a fibrous membrane. Some bones of the skull, the facial bones, clavicles, pelvis, scapulae and part of the mandible are formed by this process
  34. What are the steps of intramembranous ossification?
    1. An ossification center appears in the fibrous CT membrane. 2. Bone matrix is secreted within the fibrous membrane. 3. Woven bone and periosteum form. 4. Bone collar of compact bone forms and red marrow appears and the CT around the bone becomes the periosteum.
  35. What is endochondral ossification?
    The replacement of hyaline cartilage with bone, most bones of the body develop via this model
  36. What is the first step of endochondral ossification?
    Chondrocytes near the center of the shaft of the hyaline cartilage model increase greatly in size. As they enlarge their lacunae expand and the matrix is reduced to a series of thin struts which begin to calcify. The chondrocytes soon die from lack of nutrients.
  37. What is the second step of endochondral ossification?
    Blood vessels grow into the perichondrium surrounding the shaft of the cartilage. The cells of the perichondrium then differentiate in to osteoblasts. Perichondrium is now the periostium and the inner osteogenic layer soon produces a thin layer of bone around the shaft of cartilage. This bony collar provides support.
  38. What is the third step of endochondral ossification?
    Blood supply to the periosteum and capillaries and fibroblasts migrate into the heart of the cartilage invading the spaces left by disintegrating chondrocytes. The calcified cartilaginous matrix breaks down, fibroblasts differentiate into osteoblasts that replace it with spongy bone. Bone development begins at this primary center of ossification and spreads to both ends.
  39. What is the fourth step of endochondral ossification?
    The primary ossification center enlarges proximally and distally while osteoclasts breakdown the newly formed spongy bone and open up a medullary cavity. As osteoblasts move towards the epiphysis the epiphyseal cartilage is growing as well.
  40. What is the final step of endochrondral ossification?
    Capillaries and osteoblasts migrate into the epiphysis and create secondary ossification centers. The epiphysis will be transformed into spongy bone but the epiphyseal plate will remain at the juncture between the epiphysis and the diaphysis.
  41. How do bones grow in length?
    Epiphysial cartilage of the epiphyseal plate devides to create more cartilage while the diaphyseal cartilage of the epiphyeal plate is transformed into bone. This increases the length of the shaft.
  42. What factors influence bone growth during puberty and why/when does it stop
    Growth during puberty is increased by growth, thyroid and sex hormones. Osteoblasts begin producing bone faster than the rate of epiphyseal cartilage expansion. The epiphyseal plate gets narrower and ultimately disappears, stopping growth. Estrogen causes faster closure of the epiphyseal plate than androgens so girls are typically shorter.
  43. What is an open (compound) fracture?
    Bone ends penetrate the skin
  44. What is a closed (simple) fracture?
    Bone ends don't penetrate skin
  45. What is a comminuted fracture?
    Bone fragments into three or more pieces, common in elderly
  46. What is a greenstick fracture?
    Bone breaks incompletely. One side bent, one side broken, common in children whose bone contains more collagen.
  47. What is a spiral fracture?
    Ragged break caused by excessive twisting forces, common in sports injuries
  48. What is an impacted fracture?
    One bone fragment is driven into the medullary space or spongy bone of another
  49. What nutrients are essential for bone growth?
    Calcium and phosphate, vitamins D, C, A, K and B12
  50. What two hormones influence bone growth?
    Growth hormone produced by the pituitary gland and thyroxine produced by the thyroid gland
  51. How does parathyroid affect bone?
    PT hormone and calcitonin are two hormones that antagonistically maintain blood calcium at homeostatic levels. The bone is the body's main calcium reservoir, these two hormones affect bone resorbtion and deposition.
  52. What is the function of calcitonin?
    Released by the C cells of thyroid in responce to high blood calcium. Causes decreased osteoclast activity which decreases calcium released into blood. Also stimulates osteoblast activity so calcium is taken from blood and deposited as bone matrix.