BME 260 Final Exam Bio

bone cells osteocyte

mature bone cells that make up the majority of the bone cell population

a single osteocyte occupies a

lacuna (a pocket surrounded by two different layers of bone matrix termed lamellae)

osteocytes do not

divide

narrow passageways, termed canaliculi, penetrate through the

lamellae, connecting lacunae providing a communication pathway between osteocytes

cytoplasmic extensions of osteocytes fill the canaliculi

osteocytes maintain the

protein/mineral content of surrounding bone matrix and play a role in bone repair

bone cells- osteoblast

produce new bone matrix in a process termed ossification or osteogenesis

the matrix that is produced by osteoblasts is not

crystalized by calcium or other minerals upon release

at this point, the bone matrix is termed osteoid

osteoblasts release a significant amount of

calcium, above its solubility limit, to help initiate calcium deposition within osteoid

osteoblasts differentiate into

osteocytes if they become completely surrounded by bone matrix

bone cells- osteoprogenitor cell

bone contains small numbers of these mesenchymal cells

osteoprogenitor cell differentiates into

osteoblasts

osteoprogenitor cell play an important role in

fracture healing responses

osteoprogenitor cells are found on

all exterior surfaces of bone (ex. facing the marrow cavity and the outer surface of a long bone)

bone cells- osteoclast

cells that absorb and remove bone matrix

very large cells that are multinucleated

osteoclasts are more

similar to macrophages than other bone cells

osteoclasts secrete these to dissolve the matrix and release the minerals found in the bone matrix

acids and proteolytic enzymes

this process is termed osteolysis (or resorption)

in living bone, osteoblasts and osteoclasts are both

active; the balance of these two processes determine if new bone is formed, old bone is removed or there is no net change

the functional unit of compact bone is the

osteon (or Haversian canal system)

osteocytes are arranged in

concentric circles surrounding a central canal, which contains blood vessels (normally a capillary and a small venule)

these lamellae form a bulls-eye like pattern

perforating canals (volkmann canals) are

the passageways for blood vessels to enter the bone

in spongy bone

the lamellae are not arranged in the osteon structure

thin trabecular divide and converge in a

seemingly “random” pattern

spongy bone is typically found where

stresses arise from multiple directions

the role of spongy bone is to

reorient those stresses to a more uniform direction (compact bone handles the stresses in a more uniform direction)

red bone marrow is found between

trabeculae of long bones; some spongy bone may contain yellow bone marrow

the epiphysis (which is composed of spongy bone)

transfer forces from many directions to the diaphysis

the compact bone must withstand both

tensile and compressive forces if the load is off-center

assuming a non-rigid body

wolff’s law tries to quantify the

loading condition on bone and the remodeling of the bone (ex. a tennis player will have different bone mechanical properties in their playing arm vs. their non playing arm)

axial skeleton

composed of 80 bones

skull

8 cranial bones + 14 facial bones

6 auditory bones + the hyoid bone

vertebral column

24 vertebrate +sacrum +coccyx

thoracic cage

24 ribs + sternum

axial skeleton protects

the brain, spinal cord, and thoracic/abdominal organs

extensive surface for muscle attachment

helps with respiration

stabilize the appendicular skeleton

vertebrae

7 cervical vertebrae (compose the neck)

12 thoracic vertebrae (articulates with the ribs)

5 lumbar vertebrae (strength and articulates with the sacrum)

sacrum, composed of fused sacral vertebrae-begin to fuse after puberty

coccyx, composed of ~4 fused coccygeal vertebrae-begin to fuse around age of 25

cervical vertebrae

the atlas (C1) holds up the head and axis (C2) which provides a pivot for the head

lumbar vertebrae

largest of the vertebrae, withstand a significant portion of the weight

sacrum

protects reproductive, digestive, and urinary organs

coccyx

attachment site for multiple muscles/ligaments

appendicular skeleton

composed of 126 bones

pectoral girdle

2 clavicles + 2 scapula

upper limbs

60; humerus, radius, ulna, carpal bones, metacarpal bones, phalanges

pelvic girdle

2 hip bones

lower limbs

60; femur, tibia, fibula, patella, tarsal bones, metatarsals bones, phalanges

the appendicular skeleton allows you to

manipulate the/interact with the environment

pectoral girdle helps

to anchor the arms to the axial skeleton, attachment site of muscle that wrap the upper arms and back

upper limb adapted for

manipulation/interaction with the environment

pelvic girdle attach to

lower limbs, involved in weight bearing

lower limb transfer

of weight to the ground and motion

movement can only occur at

joints (or articulations)

joints are the locations where

two (or more) bones meet

remember bones are relatively inflexible

the stricture of the joint determines

the type and amount of movement that may take place

the need for mobility at a joint is balanced by the strength of the joint

strong joints are typically

inflexible-the joints between the vertebrae

highly mobile joints tend to be

weak-the shoulder joint

joint categories

synarthrosis, amphiarthrosis, diarthrosis

synarthrosis

immovable joint, typically fibrous or cartilaginous, bones may fuse over time

amphiarthrosis

slightly movable joint, can be fibrous or cartilaginous

diarthrosis

freely movable joint (synovial joint), these joints are sub-divided by range of motions that are allowed

the articulation between the superior and inferior articular processes of adjacent vertebrae are

gliding joints that permit small movements

small flexion movements and rotation movement are allowed at these joints

vertebrae are separated by small cushions of

fibrocartilage termed intervertebral discs

the exception to this are the vertebrae that compose the sacrum/coccyx and the join between the atlas and axis

intervertebral discs have

an outer layer of collagen fibers that attach to the vertebrae

the intervertebral discs outer layer surrounds the

nucleus pulposus, which is a soft gelatinous core-shock absorber

articulations move the nucleus pulposus to allow for a gliding motion

synovial joints

freely moveable and contain a two-layered joint capsule (articular capsule) that surrounds the joint

synovial joints contain

a fibrous capsule to provide a mechanical strength to the capsule

a synovial membrane, which is an incomplete layer of epithelial cells to produce a synovial fluid

under normal conditions bones cannot come in contact with each other in a synovial joint

articular cartilage covers the articulating surfaces

this cartilage contains a large portion of water and is composed of many charged proteins (typically hyaluronan)

cartilage reduces the coefficient of friction between bones and it holds in place the lubricant; synovial fluid

cartilage-cartilage, cartilage-bone and bone-bone should never come into contact with each other

synovial fluid

a clear highly viscous fluid that is similar to interstitial fluid with the addition of proteoglycans and hyaluronan

relatively low amounts on all joints

functions of synovial fluid

lubrication, nutrient distribution, shock absorption

synovial fluid lubrication

cartilage is a sponge for synovial fluid; upon compression this fluid is squirted into the joint space and significantly reduces the friction coefficient

synovial fluid nutrient distribution

cartilage is avascular and the synovial fluid brings nutrients and removes waste from the joint space it is continually circulated through the joint space

synovial fluid shock absorption

synovial fluid cushions joints subjected to compression and due to the high viscosity can dampen sudden high-magnitude impacts (ec. walking)

supporting joint structures

meniscus, fat pads, ligaments, tendons, bursae

meniscus

pad of fibrocartilage located between opposing bones, may help to direct the flow of synovial fluid

fat pads

localized mass of adipose tissue that can protect the articular cartilage-packing material that fills space during articulations

ligaments

support, strengthen and reinforce joints (sprain is a tear of the collagen fibers within a ligament

tendons

not part of the joint, but may limit the motion of the joint as they pass over the joint space

bursae

small, fluid-filled sacs that contain synovial fluid, they form when tendons/ligaments rub against other tissues, can act as a shock absorber

gliding movements

two opposing surfaces slide over each other

angular movements

flexion, extension, abduction, adduction, circumduction, pronation/supination

classification of synovial joints

gliding joint, hinge joint, saddle joint, pivot joint, ball and socket

gliding joint

flattened or slightly curved surfaces that slide across one another, but offer little movement

hinge joint

permit angular motion in a single plane

condylar joint

ellipsoid joints that have an oval articulation nested within a depressed surface, permits biaxial angular motion

saddle joint

concave bone articulating with a convex bone, permits biaxial angular motion

pivot joint

only permits rotation along one direction

ball and socket joint

rounded head of one bone rests within a cup-like depression of a second bone, permits angular rotation circumduction

shoulder joint

permits the greatest range of motion of any joint and it is also the most frequently dislocated

the bones of the pectoral girdle provide some stability, because they project over the joint

is it the skeletal muscles that provide the majority of the stability/strength to the joint

hip joint

relatively stable ball and socket joint that permits extension, flexion, adduction, abduction, circumduction and rotation

the articular capsule of the hip joint is extensive and strong, enclosing both the head and the neck of the femur

much of the strength and stability is provided by the surrounding muscles, which are typically much more extensive than the shoulder joint

also the pelvic girdle for the humeral head

many ligaments also wrap the hip joint

elbow joint

complex hinge joint, involving the articulation of three bones

humeroradial joint is a much smaller joint that helps to support the main joint (strongest)

this joint is very stable because the humerus interlocks with ulna, a thick capsule surrounds the entire joint and there is extensive ligaments that wrap around the joint

knee joint

most complicated

hinge joint

not stable and the contact points are always changing (femur-tibia, femur-tibia, patella-femur)

the articular capsule of the knee is thin and not complete, however extensive ligaments and tendons help to strengthen the joint

kinesiology

breaking down motor movements, determining the nature of each moevemtn

erect posture

human body does not have one single posture because we are a multisegmented organism

has many issues (not a static position, oscillations of the center of gravity is remarkable constant, very strong alignment with the line of gravity and particular anatomical features)

energy costs of erect posture

there appears to be a minimal demand for excess energy to maintain an erect posture as compared with basal energy demands

poor erect posture (either stand stiffly or relaxed) does not have an effect on other organ function

proprioceptors (sense of self) are responsible for most of the movements necessary for the maintenance of erect posture

changes to ones posture can be made with frequent repetition of specific exercises

walking

is a reflexive action;no conscious control is needed

example of translational motion of the body by angular motion of the legs

phases of walking

beginning of restraining phase of one leg overlaps the end of the propulsion phase of the other leg-period of double support (running does not have)

swinging phase like a pendulum, where gravity and momentum of the body provide much of the motion

supporting phase is like an inverted pendulum

motion during the supporting phase is provided by the propulsion of the other leg and the overall momentum of the body

running

there is no period of double support and there is a period of no support

jumping

the amount of energy needed to overcome inertia is intense

functions of blood (which is connective tissue)

transporting dissolved gases, nutrients, hormones and metabolic wastes, regulate pH and composition of interstitial fluid, restricting fluid loss at injury sites, defense against toxins and pathogens, stabilize body temperature

blood functions: regulate the pH and composition of interstitial fluid

diffusion between blood and fluid compartments dictates concentrations

blood functions: restricting fluid loss at injury site

clotting prevents the loss of fluid and cellular matter