Lec 2-7 Flashcards
Four types of bone cells
Osteoprogenitors, Osteoblasts, Osteocytes, Osteoclasts
Bone cell growth cycle
Osteoprogenitors > Osteoblasts > Osteocytes
Bone stem cells, and turn into Osteoblasts
Osteoprogenitors
Bone cells that make new bone, and turn into Osteocytes
Osteoblasts
Bone cells that maintain bone
Osteocytes
Bone cells that break down bone, different from other 3 types of cells
Osteoclasts
Two hormones that work in opposition
Parathyroid hormone vs calcitonin
Hormone that raises blood calcium levels, released from parathyroid
Parathyroid hormone (PTH)
Three ways to increase blood calcium levels
absorb in intestines, take out of bones, stop excreting out of kidneys
Two hormones that increase blood calcium levels
Calcitriol and PTH
Calcitriol acts on intestines to
increase Ca2+ absorption from intestines
PTH + Calcitriol work on bones how
increase osteoclastic activity to release Ca2+
PTH and Calcitriol work on kidneys how
decrease Ca2+ excretion in urine
Three ways to lower blood calcium levels
stop absorbing in intestines, stop breaking down bones, increase excretion in kidneys
Hormone that lowers blood calcium levels, released from thyroid gland in response to high blood calcium
Calcitonin
Calcitonin action on intestines
counteracts PTH+calcitriol, stop absorption
Calcitonin action on bones
stops osteoclastic activity
Calcitonin action on kidneys
increases Ca2+ excretion in urine
Glassy-appearing matrix; irregularly arranged chondrocytes in lacunae; usually covered by perichondrium. Provides support; forms most of fetal skeleton.
Hyaline cartilage
Abundant elastic fibers that form weblike mesh; chondrocytes in lacunae; perichondrium present. Maintains shape while permitting extensive flexibility.
Elastic cartilage
Readily visible, numerous parallel collagen fibers; large chondrocytes in lacunae; no perichondrium. Resists compression; acts as shock absorber in some joints.
Fibrocartilage
Catilage located in tip of nose; trachea; most of larynx, costal cartilage; articular ends of long bones; most of fetal skeleton
Hyaline cartilage
Cartilage located in intervertebral discs; pubic symphysis; menisci of knee joints
Fibrocartilage
Cartilage located in external ear; epiglottis of larynx
Elastic cartilage
Bone found on outside of bone, dense, has osteons
compact bone
Bone found on inside of bone, has trabeculae
spongy bone
Functions of bones
structure, protection, movement, storage, production of blood
Production of blood cells, happens in bone marrow
hemopoesis
bone that is longer than wide, eg humerus, ulna, radius, metacarpals, metatarsals, phalanges
long bones
bone that is same length as width, eg carpals, tarsals, patella
short bones
Type of short bone that grows within tendon, eg patella
sesmoid bones
bone that is flattish, eg parietal bones, roof of skull, sternum, ribs
flat bones
bone that doesn’t fall into other categories, eg vertebrae, hip bones, ethmoid, sphenoid
irregular bones
Bone types that lack a medullary cavity, but still have marrow
short, flat, irregular
Small opening or hole in bone that is a entrance for artery, vein, nerve, serve as an entry/exit point for nutrients
nutrient foramen
Bone marrow that makes blood cells
red bone marrow
Fatty tissue that is the product of red marrow degeneration
yellow bone marrow
In case of extreme need, body can turn what marrow into what other marrow
yellow marrow to red marrow
Middle of a long bone, shaft
diaphysis
Cavity inside the disphysis of a long bone
medullary cavity
Bone cavity that contains bone marrow
medullary cavity
Ends of a long bone, proximal and distal
epiphyses (singular epiphysis)
Region of bone between the diaphysis and epiphysis
metaphysis
Site of bone growth (growth plate) in the bone
metaphysis
Name for cartilage layer in metaphysis where bone growth happens in kids
epiphyseal plate
Name for sealed epiphyseal plate in bones, seals when bone stops growing
epiphyseal line
Spongy struts in spongy bones
trabeculae
Connective tissue that wraps the outside of bone
periosteum
Fibers that hold periosteum to bone
perforating fibers
Extension of periosteum connective tissue that connects to muscle
tendon
Connective tissue that line medullary cavity, inner surface of bones
endosteum
Term for growth in bone length
Interstitial growth
Term for growth in bone width
appositional
Two processes for bone formation
intramembraneous ossification, endochondral ossification
Bone formation process specific to long bones
endochondral ossification
Bone formation process for flat bones
intramembraneous ossification
Term for tissue turning into bone
ossification
depositing of calcium salts
calcification
Steps for intramembraneous ossification
(1) osteoprogenitor cells cause bone to get thicker, (2) calcium is added, (3) hard areas grow together and bone is wrapped in periosteum, (4) outer edges harden
Steps for endochondral ossification
(1) start with hyaline cartilage model, (2) diaphysis outer edge hardens, (3) inner diaphysis hardens, (4) epiphysis starts to harden a little bit (primary ossification center), (4) rest of epiphysis hardens, still a hyaline cartilage growth plate, (5) cartilage grows in length (interstitial growth) a little, hardens a little, grows a little, hardens a little, etc., (6) diaphysis and epiphysis harden together, growth plate seals
Site where bone formation occurs in the epiphyses
primary ossification centers
Bone growth in width, bone hardens, eats away center, repeats process
Appositional growth
How to bones get stronger
under mechanical stress (walking, climbing, etc)
How to bones get weaker
without mechanical stress, sitting, laying
Hormones that affect bone growth
testosterone, growth hormone, thyroid hormone, parathyroid hormone, estrogen
Hormone that makes bones grow thicker
testosterone
Effects of aging on bone
Cells get smaller, fewer, doesn’t work as well, doesn’t repair as well, dies
Normal bone density decrease with age, non-pathological, mitigated with physical movement
osteopenia
Thinning of bone with age that is potentially pathological, more common in females due to menopause
osteoporosis
Complete severing of body part
avulsion fracture
Fracture of the distal end of the radius (fall on outstretched hand)
colles fracture
Bone is splintered
comminuted fracture
Bone is broken in two or more pieces
complete fx
Broken ends of bone protrude through the skin
compound fx
Bone is squished (eg in vertebra during fall)
compression fx
Fractured bone sare out of anatomic alignment
displaced fx
Epiphysis is separated from the diaphysis at the epiphyseal plate
epiphyseal fx
Partial fx with young bones, one side of bone fractures
greenstick fx
Fine crack in bones
hairline fx
Partial fx that extends only part way through the bone
incomplete fx
Fractures that break at an angle
oblique fx
Breaks due to disease
pathological fx
Fx at the distal end of the tibia and fibula
potts fx
Bone does not break through the skin
simple fx
Thin fractures due to repeated microtraumas, eg shin splints
stress fx
Fracture at right angles to bone
transverse fx
Steps in fracture healing
(1) bone breaks, (2) blood clot forms (hematoma), (3) blood clot is replaced by fibrocartilage, (4) fibrocartilage hardens into bone, (5) extra bone dissolves
Blood clot that form in a bone fracture
hematoma
Compact bone is ________ after fracture
thicker
How does bone get its blood supply
Bone highly vascularized, entering from periosteum
osteogenic cells, osteoblasts, osteocytes, and osteoclasts and osteoid
organic components of bone matrix
Approximately one-third of the bone matrix, includes ground substance (composed of proteoglycans and glycoproteins) and collagen fibers, both of which are made and secreted by osteoblasts.
Osteoid
mineral salts, largely calcium phosphates present in the form of tiny, tightly packed crystals in and around the collagen fibers in the extracellular matrix
inorganic components of bone matrix
What vitamins are needed for healthy bone
Calcium and vitamin D
What cells are involved with bone resorption
osteoclasts
Why does bone resorption occur
low blood calcium levels
chronic disease of elderly people characterized by deterioration of bone tissue, especially in the spine, skull, or pelvis, sometimes causing severe pain
Osteitis Deformans
Basic functional and structural unit of mature compact bone
osteon
__________ is oriented parallel to the bone Diaphysis
osteon
production of new bone
osteogenesis
newly formed bone connective tissue is immature & not well organized
woven bone
mesenchyme that still surrounds the woven bone begins to thicken and eventually organizes to form the periosteum
lamellar bone
renewing and reshaping of bone
bone remodeling
long bones of limb stop growing in childhood generally have big head
achondroplastic dwarfism
disease caused by vitamin D deficiency in childhood and characterized by overproduction and deficeint calcification of osteoid tissue
rickets
What contributes to bone strength and flexibility
Calcium
What causes bone mass to decrease
not incorporating mechanical stress (physical activity)
How is vitamin D formed
ultraviolet light converts the precursor molecule in keratinocytes to Vitamin D
How is vitamin D used
regulating levels of minerals such as phosphorus and calcium
