Chapter 6 A&P

Open fracture

skin is broken and bone ends may stick out of skin; obvious wound

Closed fracture

skin is not broken

hyperglycemia

a calcium excess in the blood

Osteoporosis

a sufficient enough decrease in bone mass with porous and fragile bones leading to major problems

Articular cartilage

a thin layer of hyaline cartilage remains on the surface of the epiphysis

Osteoclasts

(breaking bone down) bone carving cells; absorb and remove bone matrix

Endochondral ossification

(long bone) bone replaces existing hyaline cartilage, then bone growth occurs through interstitial growth(length) and appositional growth(width)

Healing Fractures

1. hematoma formation 2. soft callus formation 3. hard callus formation 4. bone remodeling

Classifications of bones

Adult skeleton typically contains 206 major bones Bones are classified according to shape and structure

Osteocytes have two major functions

Bone remodeling and repairing damage bone

Calcium phosphate interacts with

Calcium hydroxide to form crystals of hydroxyapatite

2 forms of ossification

Endochondral and intramembranous

Structure of long bone

Diaphysis(shaft)- long, main portion of the bone Compact bone- walls; solid forms sturdy protective layer Medullary cavity- a hallow space within the diaphysis has yellow bone marrow

Projections for forming joints

Head Neck-connection between epiphysis/diaphysis Facet- small flat articular surface Condyle- smooth rounded articular process(knuckle) Trochlea- smooth grooved articular process shaped like a pulley

Bone shapes

Long bones-longer than they are wide(humerus) Short bones-cubed shape & consist of spongy bone(wrist/ankles) Flat bones- usually thin and flat, some are curved(ribs) Sesamoid bones-usually small round and flat develop within tendons near joints of knee(patella) Sutural bones- small, flat, irregularly shaped bones found between flat bones of the skull Irregular bones- bones that don't fall in any of the categories, have complex shapes(vertebrae/pelvic)

Canaliculi

Many routes for nutrients and oxygen to reach the osteocytes and for the removal of waste

Effects of nutrition on bone

Minerals, Vitamins D3, C, A, K

Structures of compact bone

Osteon- Concentric Lamellae- ring like layers of calcified matrix Central Canal- house of blood vessels and nerves supplying osteon Lacunae- spaces in matrix that house osteocytes Canaliculi- passageways connecting lacunae with one another and with the central canal

Collagen Fibers

Provide bone with strength, tolerate twisting, bending and tension(pulling)

Openings

Sinus- chamber within a bone Foramens- hole or rounded passageway for blood vessels/nerves Fissure- deep furrow, cleft or slit Meatus- a large passageway(canal) Canal- duct/channel

Bone is connective tissue made up of

Specialized cells Protein fibers Ground substance

Depressions

Sulcus- narrow grooves(blood vessels/nerves) Fossa- shallow depression(form articulation sites/joints)

skeletal system functions

Support-provides the body's framework Mineral and Lipid storage- bones produce calcium and phosphorous Blood cell production- red blood cells, white blood cells and platelets are all formed by bone Protection- the skull and ribs protect the organs Leverage- bones serve as levers that muscles pull on for movement

Displaced fracture

The portions of bone are out of anatomical alignment

Projections where muscles, tendons and ligaments attach

Trochanter- large, rough projection Crest- prominent ridge(pelvic bones) Spine- pointed process(hip bones) Line- low ridge Tubercle- small rounded projection(humerus) Tuberosity- rough projection(humerus)

hypoclycemia

a calcium deficiency in the blood

Calcitriol

absorbs calcium

Bone deposition

addition of minerals and collagen fibers to bone by osteoblasts

Sex hormones (estrogen and testosterone)

begin being released at puberty

Osteoblast cells

bone building cells, produce bone matrix through osteogenesis

Spiral fracture

bone has been twisted apart

greenstick fracture

bone is bent on one side, having an incomplete fracture on the other

Osteoid

bone matrix without calcium salts; has not yet become calcififed

Lacunae

cavity or depression within the bone matrix

Yellow bone marrow

composed of adipose, reserves energy

Bone remodeling

continual process of recycling and renewing bone matrix

Bone remodeling

continuous dissolving of bone matrix and depositing of new matrix

Calcification

deposition of calcium(into the bone)salts into the framework of collagen fibers, crystallization of the mineral salts and hardening of the tissue

Intramembranous ossification

development of bone from directly from mesenchyme and fibrous connective tissue(produces flat bones)

Pott's fracture

distal end of tibia and fibula(common sports injury)

Periosteum

fibrous superficial layer of compact bone that covers all bones except within joint cavities

Interstitial lamellae

fill spaces between osteons

Osteogenesis

formation of bone

Hydroxyapatite

is the hardening of the bone and gives strength but they are also inflexible and brittle

Epiphyseal line

is where bone stops growing(usually after puberty)

Circumferential lamellae

lamellae arranged around the entire outer and inner circumference of the shaft of a long bone

Endosteum

lines the medullary cavity , active during bone growth, repair and remodeling

Spongy bone

loosely organized, very porous osseous tissue; highly vascularized and contains red bone marrow; surrounding harder compact bone

Trabeculae

making spongy bone ideal for resisting forces from many directions and filled with red bone marrow

Osteocytes

mature bone cells developed from osteoblasts (bone remodeling, repairing and must abundant)

Endosteum

membranous lining of the medullary cavity where bone growth, repair and remodeling occur

Medullary cavity

minimizes the weight of the bone

Calcium phosphate

most abundant mineral salt found in bone

Canaliculi

narrow passageways/channels within the bone matrix, support cell to cell communication between osteocytes and provide passage way for exchange nutrients and waste in the blood

Metaphysis

narrow region connecting the diaphysis to the epiphysis

Vitamin K

needed for the synthesis of bones proteins

Vitamin C

needed primarily for the synthesis of collagen(citrus=orange)

99%

of the body's calcium is in bones serving as a large calcium reserve

4 main types of bone cells

osteogenic cells, osteoblasts, osteocytes, osteoclasts

Bone surface markings

projections, openings, depressions, projections where muscles, tendons and ligaments attach

Compact bone functions

protect, support and resist stress produced by weight and movement

Spongy bones function

provides some support much lighter(less dense) reduces the weight of the skeleton but weaker than the compact bone

Epiphysis

proximal and distal ends of the bone

Growth hormone

released by the pituitary gland

Calcitonin

released by the thyroid gland in response to high blood calcium level Functions: to decrease blood calcium levels by increasing osteoblast activity

parathyroid hormone (PTH)

released from the parathyroid glands in response to low blood calcium levels Functions: to increase blood calcium levels by increasing osteoclast activity and resorption of calcium from bone

Bone resorption

removal of minerals and collagen fibers from bone by osteoclasts(release calcium in the blood)

Parathyroid Hormone

secreted by the parathyroid glands when blood calcium is low

Calcitonin

secreted by the thyroid when blood calcium is high (reduces calcitriol secretion by the kidneys, decreasing calcium absorption by intestines)

Metaphysis

separates the epiphysis and diaphysis, bone will continue to grow in length though interstitial growth

Red bone marrow

site of blood cell formation

Thyroxine

stimulates cell metabolism and increases the rate of osteoblast activity

Vitamin A

stimulates osteoblast activity(critical for bone growth)

Projections

tendons and ligaments attach and where bones articulate Process-projection/bump Ramus-part of a bone that forms an angle with the rest of the structure

Osteolysis

the breakdown of the mineral matrix of bone that is part of the normal development

Osteopenia

the normal thinning of bone as we age due to decreased osteoblast activity (begins in 30s-40s)

Ossification(osteogenesis)

the process of bone formation

Effects on exercise of bone

the turnover and recycling of minerals give each bone the ability to adapt to new stresses

Perfoating (Sharpeys Fibers)

thick bundles of collagen fibers that extend from the periosteum to the extracellular matrix of the outer circumferential lamellae connecting them

Articular cartilage(forms joints)

thin layer of hyaline cartilage

Periosteum

tough connective tissue sheath and its associated blood supply that surrounds the bone surface wherever it is no covered by articular cartilage

Osteogenic cells

unspecialized bone stem cells derived from mesenchyme; divide and differentiate into osteoblasts -found in endosteum, periosteum and central canals -assist in fracture repair by getting rise to new osteoblasts

Repairing damaged bone

upon release from lacunae, can convert to less specialized cells(osteoblasts.osteogenic cells) and assist in bone repair