Skeletal System Flashcards
Skeletal System Functions
Support, protection, leverage, mineral storage, blood cell production
Axial Skeleton
Consists of skull, hyoid, sternum, rib cage, vertebral column, sacrum, and coccyx
Appendicular Skeleton
Includes bones of the limbs and the pectoral and pelvic girdles
Flat Bones
Thin, parallel surfaces; form roof of skull, sternum, ribs, and scapulae
Sutural Bones
Small, irregularly shaped bones between flat bones of the skull
Long Bones
Relatively long and slender; located in arm, forearm, thigh, lower leg, palms, soles, fingers, and toes
Irregular Bones
Complex shapes with short, flat, notched, or ridged surfaces
Sesamoid Bones
Small, flat bones shaped like sesame seeds; develop inside tendons near joints
Short Bones
Small and boxy; examples include wrist (carpals) and ankle (tarsals) bones
Diaphysis
Long tubular shaft of a long bone; primarily made of compact bone
Epiphyses
Ends of bones composed primarily of spongy bone with red bone marrow filling the spaces
Metaphysis
Narrow zone connecting diaphysis to epiphyses; contains the growth plate
Medullary Cavity
Cavity within the shaft of a long bone where bone marrow is located
Periosteum
Outermost covering of bone made primarily of dense irregular tissue
Nutrient Foramen
Tunnel penetrating the diaphysis to provide access for blood vessels into the bone
Nutrient Artery
Transports oxygenated, nutrient-rich blood to the bone
Nutrient Vein
Transports deoxygenated, waste-laden blood from the bone
Metaphyseal Artery
Carries blood to and from the area of the metaphysis and to the epiphysis
Articular Cartilage
Covers portions of the epiphysis that articulate with other bones; avascular, hyaline cartilage
Fissure
Narrow, slit-like opening or elongated cleft in a bone
Foramen
Round or oval opening through a bone
Canal or Meatus
Large passageway through a bone
Sulcus or Groove
Furrow or narrow trough in a bone
Sinus
Chamber within a bone filled with air and lined with a mucous membrane
Tuberosity
Large, round or rough projection that may cover a broad area
Crest
Narrow ridge of bone; usually prominent
Osteon
Basic structural and functional unit of bone consisting of bone cells organized around a central canal
Central Canal
Also known as the Haversian canal; runs parallel to the axis of bone and is located in the middle of each osteon
Perforating Canals
Passageways that extend perpendicular to the axis of the bone and connect the central canals of adjacent osteons
Lamellae
Nested, concentric rings of matrix surrounding the central canal
Circumferential Lamellae
Specialized lamellae found at the outer and inner surfaces of bone, covered by periosteum and endosteum
Lacunae
Open spaces trapping mature bone cells (osteocytes) within the bone matrix; each lacuna contains only one osteocyte
Osteocytes
Mature bone cells maintaining protein and mineral content of surrounding matrix; secrete chemicals to dissolve adjacent matrix and participate in bone repair.
Canaliculi
Narrow crevices penetrating the lamellae, connecting the lacunae to the central canal; processes of osteocytes extend into canaliculi.
Osteoblasts
Immature bone cells on bone surface; produce new bone matrix in osteogenesis; develop from osteoprogenitor cells and release organic components.
Osteoprogenitor cells
Mesenchymal stem cells within periosteum and endosteum; divide to produce daughter cells that differentiate into osteoblasts, important in osteocyte formation.
Osteoclasts
Giant bone-digesting cells removing and recycling bone matrix; derived from stem cells producing phagocytic white blood cells, important in bone remodeling.
Organic Osteoid
Contributes roughly 1/3 of bone weight; consists of collagen fibers that are strong, flexible, and contribute to the bone’s resistance to bending.
Inorganic Hydroxyapatites
Constitute almost 2/3 of bone weight; mineral salts, primarily calcium phosphate, interacting with other calcium salts and ions to form strong, flexible crystals
Endochondral Ossification
Formation of most bones using a hyaline cartilage model; involves cavitation of hyaline shaft, invasion of internal cavities, formation of medullary cavity, and formation of epiphyses.
Intramembranous Ossification
Formation of bones without a cartilage model; involves formation of bone matrix within fibrous membrane, formation of woven bone and periosteum, and formation of compact bone plate.
Longitudinal Growth
Process involving the formation of tall columns at the epiphyseal plate by hyaline cartilage cells, leading to lengthening of long bones; eventually replaced by bone, stopping growth in height.
Appositional Growth
Process involving differentiation of osteoprogenitor cells into osteoblasts beneath the periosteum, forming new osteons on the external bone surface, contributing to bone width.
Appositional growth
Increase in bone diameter through the addition of bone to the outer surface
Medullary cavity
Cavity within the bone that enlarges as the bone diameter increases
Fractures
Repair of cracked or broken bones
Hematoma formation
Formation of a large blood clot in the initial stage of bone fracture repair
Fibrocartilage callus formation
Process involving capillary growth, invasion by phagocytic cells, and migration of fibroblasts and osteoblasts to the fracture site
Bony callus formation
Process where fibrocartilaginous callus material calcifies into a bony callus
Fracture classification
Categorization based on skin penetration, orientation of the break, and position of bone ends after the fracture
Calcium and Vitamin D
Essential nutrients for bone health, obtained from diet and critical for calcium absorption
Vitamin K
Supports bone mineralization and may have a synergistic role with vitamin D in bone growth regulation
Growth Hormone
Synthesized in the pituitary, controls bone growth, triggers chondrocyte proliferation, increases calcium retention, and stimulates osteoblastic activity
Thyroxine
Secreted by the thyroid gland, promotes osteoblastic activity and bone synthesis
Sex Hormones
Estrogen and Testosterone promote osteoblastic activity, bone matrix production, and are responsible for the growth spurt during adolescence
Calcitriol
Active form of vitamin D, stimulates calcium and phosphate absorption from the digestive tract
Calcium Homeostasis
Interactions of the Skeletal System and Other Organ Systems, involving bone deposition, resorption, and hormonal control
Remodeling
Constant process of bone deposition and resorption regulated by osteoblasts and osteoclasts
Parathyroid hormone (PTH)
Secreted when blood calcium levels are too low, enhances calcium absorption and reabsorption
Calcitonin
Secreted when blood calcium levels are too high, inhibits osteoclasts and calcium absorption
pituitary growth failure
(dwarfism) results from inadequate production of growth hormone which leads to reduced epiphyseal cartilage activity and abnormally short bones, can be treated with synthetic growth hormone
comminuted fracture
bone fragments into many pieces
compression fracture
bone is crushed from upward and downward forces
depressed fracture
broken bone is pressed inward (skull)
spiral fracture
raged break as a result of excessive twisting of the bone
epiphyseal fracture
break occurring along the epiphyseal plate
greenstick fracture
bone breaks incompletely
colle’s
distal part of the radius breaks
pott’s
malleolus of tibia and fibula break
Achondroplasia
results from abnormal hyaline cartilage development. Because hyaline cartilage forms the model for long bone formation, the individual will have short, stocky limbs but the torso and head are of normal size
Marfan syndrome
very tall with long, slender limbs due to excessive cartilage formation at the epiphyseal plates. Other defects in the structure of connective tissues commonly cause life-threatening cardiovascular problems
gigantism
results from an overproduction of growth hormone before puberty. Puberty is often delayed. The most common cause is a pituitary tumor which may be treated by surgery, radiation, or drugs that suppress the release of growth hormone
acromegaly
result from too much growth hormone after the epiphyseal plates close so that the bones do not grow longer but instead get thicker (especially the bones of the face, hands, and jaw). This leads to changes in their physical appearance.
Fibrodysplasia ossificans progressiva
a rare gene mutation that causes the deposition of bone around skeletal muscles and the normally soft tissues of the body. There is no effective treatment for this painful and debilitating condition, and patients seldom survive into their 40’s.
paget’s disease
overactive osteoclasts cause pores and weakening of the long bones leading to bending/bowing. Osteoblasts try to compensate for the overactive osteoclasts, but the bone laid down is weak and brittle and prone to fractures.
