skeletal system: bone minerals, growth and joints Flashcards

1
Q

what is a common injury

A

ligament or tendon tear

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2
Q

when do bones grow

A

fetal development, growing up, bone remodeling, fracture repair, yearly replacement (5-10% of bones)

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3
Q

in an embryo the skeleton starts as what

A

hyaline cartilage and fibrous connective tissue

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4
Q

what is intramembranous ossification

A

when cells of fibrous connective tissue differentiate into various bone forming cells

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5
Q

what are the 2 types of bone growth

A

longitudinal and appositional

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6
Q

how does longitudinal growth work

A
  1. chondrocytes just under the side of the epiphyseal plate form the proliferation zone + divide rapidly, new cells being formed push the epiphysis away from the diaphysis
  2. older chondrocytes die off and the extracellular matrix calcifies + degrades, blood vessels invade the place
  3. osteoblasts + osteoclasts work to replace the former cartilage tissue w/ new bone
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7
Q

how does appositional growth work

A
  1. osteoblasts found in the periosteum lay down more extracellular matrix on the outer surface of the bone (called bone deposition)
  2. osteoblasts breakdown some bone on the inside of the medullary cavity (called bone resorption)
  3. a deposition will outpace resorption so bone grows outwards
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8
Q

what is bone remodelling

A

constantly replacing older bone with new bone tissue, balance between bone resorption and bone deposition

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9
Q

what are the 2 reasons for bone remodelling

A
  1. calcium homeostasis: the body needs a constant concentration of ca in the blood to keep cellular processes working
  2. maintaining bone strength: extracellular matrix of old bone tissue is more brittle and needs to be replaced, forces applied to bones may require bones to be strengthened
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10
Q

how is bone remodeling regulated

A

by hormones and mechanical forces acting on the bone

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11
Q

what do hormones determine in bone remodeling regulation

A

whether remodeling happens and when it happens

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12
Q

what does mechanical stress determine in bone remodeling regulation

A

where it happens

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13
Q

what is the process of hormonal regulation for Ca homeostasis when Ca levels are decreased

A
  1. Ca levels drop
  2. chemoreceptors detect the drop in Ca
  3. the parathyroid gland secretes parathyroid hormone (PTH) into the blood
  4. PTH stimulates osteoclasts to resorb bone
  5. Ca is released into the blood
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14
Q

what is the process of hormonal regulation for Ca homeostasis when Ca levels are increased

A
  1. Ca levels increase
  2. chemoreceptors detect the increase in Ca
  3. the thyroid gland secretes calcitonin into the blood and kidneys excrete Ca
  4. calcitonin inhibits osteoclast bone resorption
  5. Ca levels decrease
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15
Q

what is wolff’s law

A

a bone grows or remodels wherever it needs to in order t compensate for the stresses placed on it

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16
Q

what is a bone stress

A

gravity (weight), muscle pull

17
Q

what is the function of a joint

A

to connect bones together

18
Q

what are the 3 types of joints

A

fibrous, cartilaginous, synovial

19
Q

what are fibrous joints

A

bones connected by collagen fibers

20
Q

what is the function for fibrous joints

A

allows for very little or no movement

21
Q

what are cartilaginous joints

A

bones connected my cartilage

22
Q

what is the function of cartilaginous joints

A

provides little or no movement

23
Q

what is a synovial joint

A

a joint with a cavity that separates connected bones, the cavity is filled with synovial fluid, most joints in the body are synovial joints

24
Q

what is the function of a synovial joint

A

allows for lots of movement

25
Q

what are the 6 structural features of a synovial joint, explain each one

A
  1. cartilage: on the ends of the 2 bones where they come in contact
  2. joint capsule: covering where 2 bones meet , made of fibrous connective tissue, keeps bones from separating, lined with synovial membrane
  3. synovial fluid: lubricates to reduce cartilage degradation from friction
  4. joint cavity: holds synovial fluid
  5. ligament: attaches bone to bone
  6. nerves + blood vessels: nerves monitor pain and stretch and blood vessels nourish the synovial membrane
26
Q

what is a synovial membrane

A

what secretes the synovial fluid

27
Q

what is a bursae

A

flat bags made of synovial membrane, contains synovial fluid, the function is to reduce friction

28
Q

what is a tendon sheath

A

like a bursae but wrapped around a tendon, contains synovial fluid, the function is to reduce friction

29
Q

what is a tendon

A

attaches muscle to bone