Kinesiology Exam 3 WVU

5 functions of the skeleton

support body weight, movement, protects critical structures/organs, store minerals, blood cell production

What are the contents of bones?

minerals (calcium carbonate+calcium phosphate), collagen, and water

% water in bones

25-30%

What are the characteristics of collagen?

soft squishy ORGANIC material that provides flexibility, deformation, and tensile strength

What is tensile strength?

ability to resist a stretching force

What are the characteristics of the skeletal portion of bones (calcium carbonate+calcium phosphate)?

provide stiffness and compressive strength

What are the two MINERAL parts of the bone?

calcium carbonate and calcium phosphate

What is stiffness?

ratio of stress to strain (force divided by deformation)

What is compressive strength

ability to resist pressing or squeezing forces

What are the 2 classifications of bone?

cortical (compact bone) and trabecular (cancellous bone)

What are the characteristics of a cortical bone?

dense layer of OUTSIDE bone, typically on long bones, white/shiny

What are the characteristics of a trabecular bone?

Spongy bone with an ORGANIZED honeycomb like structure (organized by stress of the mechanical axis)

What is the purpose of trabecular bone?

shock absorption and allows for a high strength to weight ratio

Trabecular bone is arranged based on...

the forces on the body

What type of bone tissue can withstand more stress and less strain?

cortical

What type of bone tissue can withstand more strain and less stress?

trabecular

What is stress?

the amount of force or loading on a tissue/area

What is strain?

amount of deformation divided by the original length of the structure

How many bones are in the human body?

206

How many bones involve movement in the body?

177

What are the axial bones?

skull, spinal column, sternum, and ribs

What are the appendicular bones?

upper/lower extremities, pelvis, and scapula

What are the 4 types of bones?

long, short, flat, irregular

What are the characteristics of a long bone?

the shaft (diaphysis) is cortical bone and the ends (epiphyses) are trabecular bones

What are the characteristics of a short bone?

small, cube of cortical bone filled with trabecular bone

What are the characteristics of a flat bone?

flat, plate-like

What determines the type of bone?

structure and function

What is the function of a long bone?

lever for movement

What bones are long bones?

clavicle, humerus, radius, ulna, metacarpals, phalanges, femur, tibia, fibula, metatarsals

What is the function of short bones?

shock absorption

What bones are short bones?

tarsals, calcaneus, carpals

What are the functions of flat bones?

protecting internal organs, and provide a surface for muscle attachment

What type of bone is red bone marrow harvested out of?

flat bones

What bones are flat bones?

superior/posterior portion of the skull, ribs, ilium, and scapula

What is the function of irregular bones?

their function is unique to the structure

What bones are irregular bones?

facial bones, maxilla, mandible, vertebrae, sacrum, coccyx, patella, sesamoid

What is the mechanical axis?

a straight lone that connects midpoints of 2 joints

anisotropic

different mechanical properties in response to loads from different directions

Bones strongest in resisting compression are weakest in resisting what force?

shear force

3 types of bones cells

osteoblasts, osteoclasts, and osteocytes

Which type of bone cells slows with age?

osteoblasts

What is the function of an osteoblast?

bone building cells (Blast, Builder)

What are the 2 receptors for osteoblasts and what causes them to increase?

mechanoreceptors (increase in response to force) and estrogen receptors (increase in response to estrogen)

What is the function of an osteoclast?

Bone clearer cells (Clast, Clearer)

What types of bone cell works throughout the lifetime?

osteoclasts

What is an osteocyte?

A mature bone cell (an osteoblast that was buried)

What is osteogenesis?

the process of bone development (done by 25)

What is bone remodeling?

the process of removing old bone tissue and depositing the new

What are osteogenesis and bone remodeling affected by?

age, mechanical environment, injury, and hormones

What is the epiphyseal plate?

its a growth plate

What cell is highly concentrated in the epiphyseal plate?

osteoblast

What is the last bone to grow?

clavicle

What type of bone are epiphyseal plates in?

long bones

During childhood and adolescence what part of the bone lengthens the bone?

epiphyseal plate

What is a chondroblast?

cartilage building cells (epiphyseal plate)

what part of the bone does the osteoblast live in?

the periosteum

what part of the bone does the osteoclast live in?

endosteum

Growing bones widen as they length with the help of what cells?

osteoblast adding external surface to the diaphysis (bone deposition), osteoclast removing internal surface of the diaphysis (bone resorption)

What is appositional growth

growing a bone by adding the bone tissue to the surface

What age do your bones stop growing?

25

osteoclasts carve out trabecular bone from solid cortical bone based on what?

force (from childhood)

How often does the skeleton replace itself?

every 2 years

What is Wolff's Law?

Bone strength increases and decreases depending of forces increasing or decreasing

What is bone hypertrophy?

increase in bone mass resulting from a predominance of osteoblast activity

What is bone atrophy?

decrease in bone mass resulting from a predominance of osteoclast activity

What is the function of osteocytes?

monitors the health of the bone

What is the process of osteoclasts degrading a bone?

crawls along surface and secretes hydrochloric acid (dissolves calcium carbonate/phosphate), then lysosomal enzyme (breaks down the collagen) then blood washes the waste away

Is osteoporosis more common in men or women?

women

What causes osteoporosis?

there is more osteoclast than osteoblast activity making bone porous and brittle

osteopenia

1.0-2.5 STD below a normal 25 yr old

What can reduce the negative effects of osteoporosis/osteopenia?

good nutrition and regular exercise

What are bisphononates?

medication that inhibits the digestion of bone by encouraging osteoclast to undergo cell death (apoptosis) which results in slowing bone loss... (used for osteopenia)

What is T score?

how you compare to a 25 year old

What is a Z score?

how you compare to someone your own age

What is the T score for osteoporosis?

<-2.5

What is the T score for osteopenia?

<-1

What does DXA measure?

bone density

What does DXA stand for?

Dual Energy Xray Absorptiometry

Type 1: post-menopausal osteoporosis

Occurs in the first 15 years after menopause

less osteoblasts due to lack of estrogen

Affects 40% of women after age 50

Type 2: Age-associated Osteoporosis

Affects most women and men after age 70

After age 60, 90% of all fractures are associated with OP

What are the 4 most common sites of osteoporosis fractures?

proximal humerus, vertebrae, distal radius hip

What is the most common site of an osteoporotic fracture?

spine/vertebrae

Can medications be bad for bones?

yes

What percent of bone mineral density do you lose in space every month?

1-2%

Why haven't we gone to mars?

bone density loss and radiation

Why is the old model for the Female Athlete Triad wrong?

it stated that eating disorders amenorrhea and osteoporosis all correlate but really amenorrhea and osteoporosis don't have correlation

What is the real Female Athlete Triad?

Not eating enough -> low body fat -> low estrogen = amenorrhea or osteoporosis

What is amenorrhea?

irregular periods

Where is estrogen stored?

in fat or yellow bone marrow

What group of people can be cured of osteoporosis? and how?

young women, using estrogen based birth control

Why can't you give post menopausal women birth control to cure osteoporosis?

cancer risk

What is a fracture?

disruption or break in the continuity of bone

What is a stress fracture?

fracture resulting from repeated loading of relatively low magnitude

What is a stress reaction?

progressive bone pathology associated with repeated loading (swelling/elevated temperature)

What is a precursor to stress fracture?

stress reaction

What is a comminuted fracture?

bone fragments into three or more pieces

How are comminuted fractures caused?

extreme trauma and common in aged people w/ brittle bones

What is a compression fracture?

bone is crushed, trabecular scaffolding collapses, very common in the elderly

How are compression fractures caused?

extreme falls/truama

What is a spiral fracture?

ragged break caused by excessive torsion