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