sc notes

  1. increase in connective tissue size, strength, and endurance need to take place in order to
    • accommodate changes in skeletal muscle performance.
    • ct addaptions must take place to accommodate changes in muscle performance
  2. connective tissue structrs inclued
    • bones
    • tendons
    • ligament
    • fascia
    • cartilage
  3. adaptions in ct resulting from training are critical for how
    • muscle for is transmitted to bone
    • joint stability
    • injury prevention
  4. loading
    initiates the adptation process
  5. ct can only adapt when it is
    progressivly loverloaded by increasing stress
  6. mechanical stress
    • interanl force observed divided by the cross sectional area of the ct structure
    • less mechanical stress is placed on ct when the cross sectional area increases per level of force  encountered
    • thus ct increase tolerance for loading by increasing size and or by altering structural properties.
    • these have important ramifications for injury prevention in sports and force transmission from muscle to bone
  7. stress
    • the force applied to ct
    • the level of force encountered by a tissue
  8. three most common types of stress
    • shear stress
    • compression
    • tension
  9. tension stress
    • result in pulling forces on the tissue
    • stretching or elongation occurs as is the case with tendons during muscle contraction
  10. compression stresses
    • result in pushing the structur inwards, or compressing its longitudinal length
    • spine when performing the squat exercis or the humerus  when performing a push up
    • when tissue is compressed its longitudianl height decreases but it laterally expands
  11. shear stresses
    • result in skewing where force is encountered obliquely.
    • scissors during cutting and the knee during a kee extension exercise.
    • tends to be more injurious when encountered athletically
    • in some cases a twisting effect or torsion is seen
    • reult of stress is defrmation to ct
  12. defromation
    leads to adaptation and is proportional  to the level of stress encountered
  13. strain
    is the magnitued of deformation that takes place in proportion to the amount of stress applied
  14. two types of strain
    • linear
    • shear
  15. linear strain
    results forom compressive and tensile stresses where the tissue (tendons, ligaments) changes length, and the quantification of linear strain is expressed as a percentage relative to resting length
  16. shear strain
    results in bending of the tissue(bone) and it quantified by the angle of deformation
  17. possions ratio
    • the ratio of strain in the longitudinal direction to strain in the lateral direction
    • this ratio is useful measure to examine compression in articular cartilage and intervertebral disks (where to great of a strain can lead to a rupture)
  18. toe region on the stress to strain graph
     at complete rest there is a small degree of slack in the tendon. upon low level of muscle contraction, the tendon elongates to its normal length
  19. linear region on the stress to strain graph
    with greater stress then toe region, there is a proportional increse in strain
  20. failure region of stress to strain graph
    if the level of stress is too high, injury can result
  21. elasticity
    upon elongation as a result of stress, the tendon can return to its normal length when the stress is removed.
  22. plasticity
    • chronic stetching to a tissue can cause transient or permanent defromation where the tissue remains at least partially elongated and dose not return entirely to its original length
    • plasticity is good whe tendons in response to chronic flexibility training
    • and bad with ligaments in response to damage over time
  23. the skeletal system is deivided into two mahor subdivsions
    • axial skeleton
    • appendicular
  24. acial skeleton
    consists of 80 bones of the skull and trunk( vertebral column , ribs, sternum, sacrum, and coccyx)
  25. appendicular skeleton
    consist of 126 bones of the limbs, shoulders, and pelvic girdle
  26. skeletal system in human function
    • provides support. area for muscular attachemtn. and protction to several organs.
    • bones produce movement upon skeletal muscle contraction.
    • bones provide a storage site for minerals in times where dietary intake may be low
    • bones produce red blood cells which are essential  for transporting oxygen
    • consist of approximately 25-30% of water
    • each bone has its own rate of metabolism so some bones fully reach their final lenght by age 18 and some may take as long as 25 years.
  27. five forms of bone
    • long bones
    • short bones
    • flat bone
    • irregular bones
    • sesamoid bones
  28. long bones
    • femur humerus
    • contribute greatly to human height and limbe lengths
  29. short bones
    • carpals and tarsals of the hand and feet
    • typically found in areas where mobility is critical
  30. flat bones
    • ribs, scapula, bones of the skull, sternum
    • are especially important for protection
  31. irregular bones
    • vertebrae
    • are uniquely shaped because the perform a mulutitude of functions
  32. sesamoid bones
    • patella
    • help creat a more favorable line of pull for muscles that span their surface area
  33. eipiphyses
    • polar ends of the bone
    • growth plates (epiphyseal plates) are located here and are the sites of longitudinal bone growth during the developmetnal years
    • enlarge by growth of cartilage and bone replacemetn as the diaphisys extends.
  34. diaphysis or shaft
    • the long region of the bone
    • consist of the medullary cavity witch houses the bone marrow
  35. two types of long bones
    • compact bone
    • spongy bone
    • the ratio of each within a bone dicatates the degree of strength and plaibility of the bone
  36. compact bone
    • located on the perimeter and is much stronger thatn spongy bone
    • comprised of osteons
  37. spongy bone
    • trabecular bone
    • is located withing and helps give bone its pliability
  38. periosteum
    • the outer most layer of the bone
    • has two layers of importance
    • the outer most layer provides a firm base for ct attachment
    • the innermost layer secretes cells involved in bone remodeling
  39. endosteum
    • is the innermost layer that surronds the medullary cavity which also secrets cells involved in bone remodeling
    • medullary cavity houses bone marrow
  40. osteon
    • resembles a concentric layer with a cntral canal that provides a conduit for nerves and blood vessels
    • cellular look shows osteocytes as well as the surrounding bone matrix comprise osteons
  41. osteocytes
    • mature bone cells
    • are housed withine the lacunae(space) andis surrounded by canaliculi
  42. conaliculi
    • act similar to a capillar bed in that nutrents are dispersed thoughout therby supplying the osteocyte.
    • play major role in how bones afdapt to loading as the deform during fluid movement wich stimulates osteocytes
  43. bone matrix
    • area surrounding the osteocyte
    • consists of an organic 35% and inorganic 65%
  44. organic region of the bone matirx
    consists primarily of protein. most of which is in the form of collagen which helps give bone strength and pliability
  45. inorganic region of bone matrix
    • consists of minerals and specialized cells that help ossify bone known as hydroxapatites
    • this region is important for giving bone its stiffness and compression strength.
  46. osteoblast
    • bone formation is brought about by osteoblast activation
    • are cells that secrete a collagen rich ground substance( to help the bone matrix) that aids in bone formation
    • they are secreted by the periosteum and endosteum and secrete a substance called osteocalcin
    • secret an enzyme known as bone alkalin phophatase
  47. osteocalcin
    serves as a blood marker for bone metabolism
  48. bone aklaline phospatase
    • involved in bone mineralization
    • has been used as a blood marker of bone metabolism
  49. osteoclast
    • cells involved in bone resorption or breakdown
    • they digest the meneralized bone matrix  via acids and lysosomal enzymes therby breaking down bone
  50. both osteoblast and osteoclast
    develop from stem cells and are activated from parent moleculees under the control of hormone, growth factors, immune cells, nutrients, and physical activity
  51. bone remodeling
    takes 3-4 months for one complete bone remodeling cycle consisting of bone resorpion, formation, and mineralization to occur, measurable changes in bone mass take at least 6-8 months
  52. longitudinal bone growth
    • occurs during the developmental years and occurs primarily in two ways
    • intamembranous ossification- bone growth resulting from ct membranse
    • endochondral ossification- growth frokm cartilage
    • after the first few years of life, bones continue to develop mostly by endochondral ossification
    • longitudinal bone growth takes place at the growth plate
  53. appositional growth
    changing in bone with
  54. adaptations to exercise is the process by witch skeletal loading increases
    • bone with
    • cross sectional area allows bone to tolerate greater loading
    • muscle strength and size gains increase the force exerted on the bones.
    • stronger forces of contraction increase the mechanical stess and strain on bone, and bone must increase its size to accommodate larger muscles
  55. mechanotransduction
    • bones responds to loading intracellularly by this process
    • transduction of mechanical force into a local cellular signal
    • mechanical loading applied to bone causes deformation or bending of the bone
    • bending is proportional to the magnitued and rate of loading applied, thereby demonstrating the importance of exercise intensity
    • bending may occur as a result of direct compressive loading to the skeletal system or by forces associated with tendons pulling during muscular contraction
    • deformation to bone causes fluids to move within the bone
  56. process of mechanotransduction
    • a sensor is needed to percieve a stimulus
    • the sensor in bone is osteocyte.
    • the osteocyte is activated by stretching the membrane via fluid movement or by electrical charges resulting from ion movement within the fluids
    • both stimuli open ion channels (calcuim and soduim) on the osteocyte, and calcium influx is critical to mediating a slew of reactions within the osteocyte.
    • the main result is to increase gene transcription and translation of proteins ultimately leading to bone deposition and structural changes.
    • collagen fibers form a scaffold, minerals and hydroxyapatites migrate, and osteoblasts reach the targeted area reulting in bone ossification.
    • although these processes are engaged quickly, measurable bone growth is very slow and may take several monts
  57. minimal essential strain
    • has been defined as the minimal threshold stimulus( volume and intensity) that is needed for new bone formation.
    • if the stimulus does not reach this threshold, then there is no need for bones to adapt favorably
  58. bone mineral density
    • exercis needs to be of sufficient intensity and volume to elicit increase in bmd
    • bmd is used to study bone adaptions
    • bone strength can increase independently of changes in bmd
    • bones can become stronger at a much larger rate and magnitude(via architectural changes) than the potential increases seen in bmd
    • have much longer adaptional period, short term training program may not increase bmd
    • changes are typically seen after 6 months of training and onlly if an individual trains beyond their curren threshold level of adaptation, or minimal essential strain
  59. what type of exercise would increase bmd
    • dynamic, high intensity loading to the skeletal system is paramount
    • weigh bearing exercise is more effective that of non weight bearing exercise for increasing bmd as loading magnitude and rate is higher when an individual has to bear his or her body weight
  60. recommending training guidelines for increasing bone mass
    • weight bearing endurance exercises, activities that involve jumping, and rt
    • moderate to high exercise intensities
    • endurance exercise frequency of 3-5 days per week, rt frequency of 2-3 days per week
    • exercise for 30-60 minutes per day involving multiple training modalities
  61. what is the importance of osteogenic bone markers
    markers in the blood can be meausred to investigat potential increases in activation of bone anabolic processes despit no changes in bone size taking place at that time
  62. what are two markers of bone growth
    • bone alkalin phosphatase
    • osteocalcin
  63. what elevate osteocalcin concentrations
    • high intensity  anaerobic exercise
    • rt
    • and the magnitude of the concentration is affected by protein intake
  64. training programs designed to stimulate bone growth need to incorporate
    • specificity of loading
    • speed and direction of loading
    • volume
    • proper exercise selection
    • progressive overload
    • variation
  65. tendons and ligaments are dense fibrous connective tissue composed predominantly of
    • water(60-70%)
    • fibroblast- collagen producing cells
    • fibrocytes- mature cells
    • elastin-protien that gives ct ist elastic quality
    • collagen- strongest most aboundant prtoein in the human body
    • ground substances- help provide structural stability to ct
  66. collagen
    • most abundatn protein in the human body (20-25%)
    • provieds great tensile strength which is why it is found in tissues requiring support and strength
    • typeI collagen is found in skin, bones, and ligaments
    • type II is found in cartilage
  67. first reason collagen provide strength
    • it is stacked in parallel to form larger components. collagen molecules are self assembled or stacked in parallel to form microfibril, microfibrils are stacked in parallel to form fibrils, fibrils are stacked in parallel to form fibers, and fibers form a collagen bundle that forms the structure of tendons
    • fibril is the load bearing unit
  68. second reason collagen provide strength
    • collagen is activated from its parent molecule, procollagen, and consist of three chains of amino acids in each. collagen consist mostly of three amiio acids, proline(25%), hydroxyproline(25%), and glycine (33%). these amino acids are essential because they help form very thigh hydrogen bondds in between the three chains.
    • these bonds are called cross links and provide great strength to the collagen fibers similar to what may be seen in a rope
  69. collagen turnover
    • the net change in collagen content from synthesis and degradation
    • important ct strength and is highly related to stretch and loading
  70. tendons and ligaments
    • have a higher proportio of collagen wheras ligaments posses a higher proportion of elastin
    • collagen content in tendons and ligaments are both higher thatn bone and much larger that skeletal muscles
    • tendons provide great strength and passive energy abosrption whereas legaments tend to be more pliable
    • tendons connect bones to muscles and ligametns connects bone to bone
    • tendons metabolism is slower beacuse of poor circulation
  71. fascia
    • ct that surrond and separate differen organizational levels within skeletal muscle
    • contains bundles of collagen fibers arranged in differen directions
    • fascia within skeletal muscle converges to form a tendon through wich the force of muscle contraction is tranmitted to bone
  72. stretching of the cyto skeleton in response to loading appears to be the stimulus leadng to
    greater net collagen synthesis and ct growth
  73. tendon stiffness
    • force transmitted per unit of strain
    • increases as a result of rt
    • and may comprise collagen organizational resturcturing changes leading to increased tendon strength initally in the absence of hyperthrophy
  74. cartilage
    • composed of fluids(60-80%)
    • type II collagen
    • elctrolytes
    • and other ground substances
    • unique to cartilage is that it lacks its won blood supply and must receive its nutrients from synovial fluid.
    • thus cartiilage injuries have very long recovery periods and often times require surgery
    • compression and decompression of cartilage creates a pressure gradient by wich synovail fluid may be absorbed into cartilage
  75. articular cartilage or hyaline
    • is the type that covers the ends of long bones at hoint and is found within the growth plate
    • are central to adaption resulting from exercise as collectivel they provide a smooth surface for joint motion, act as a shock absorber, and assist in providing strength to tendon and ligament attachment to bone
    • concerns regardign articular cartilage is potential for joint degeneration that can result in a pathological conditon know as osteoarthritis
  76. fibrous cartilage
    is found within intervertebral disk, menisci, and at the point of insertion into bone for tendons and ligaments
  77. elastic cartilage
    is flexible and found in the ear.
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