Human Anatomy Chapter 6 The Skeletal System 1

Calcium and phosphate

raw materials for calcified ground substance

vitamin A

promotes formation of glycosaminoglycans (protein-carb fibers)

vitamin C

promotes collagen cross-linking adding stiffness

vitamin D

necessary for calcium absorption by small intestine and reduces urinary calcium loss

Calcitonin

secreted by thyroid gland and stimulates osteoblasts in children and pregnant women

Parathyroid hormone

secreted by parathyroid glands and stimulates bone reabsorption to boost level of calcium in blood

acromegaly

features of bones start to get bigger due to adult growth hormone hypersecretion

osteitis deformans

excessive osteoclast proliferation and bone resorption

Lacunae

cavities that house osteocytes

Canaliculi

small canals that connect lacunae

Osteon

-basic unit
-concentric lamellae
-central canal

growth hormone

promotes intestinal absorption of calcium and stimulates growth plates and bone elongation

estrogen and testosterone

stimulate long bone growth during adolescence

Osteopenia

loss of bone

complete fracture

bone is broken into two or more pieces

impacted fracture

one bone fragment is driven into the marrow cavity or spongy bone of the other

Osteoporosis

-bone lose mass and become subject to pathological fractures
-treatment: bis-phosphonates and parathyroid hormone
-Prevention: weight-bearing exercise, adequate calcium and protein

osteosarcoma

bone cancer

Cartilage

embryonic precursor of most bones and covers many joint surfaces

Ligaments

hold bone to bone at joint

Tendons

attach muscle to bone

Functions of the skeleton

support, protection, movement, electrolyte balance, acid-base balance, blood formation

What is bone?

connective tissue with a hard matrix

What are the other tissues present in bone?

blood, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous CT

What are the bone shapes?

long, short, flat, irregular, sesamoid

Flat bones

-thin, often curved

Long bones

-rigid levers for movement
-compact and spongy bone tissue
-two epiphyses at ends of diaphysis
-marrow cavity

Short bones

-glide within joints
-composed of spongy bone sandwiched between plates of compact bone

Irregular bones

complex (weird) shapes

Sesamoid bones

oval, generally within tendon

Epiphysial line

remnant of growth plate

Periosteum

covering of bone

Nutrient foramina (long bone)

tubes/holes in bone for vessel

Endosteum

lining

trabeculae

honey comb like structure

Osteogenic cells

bone stem cells

Osteoblasts

bone forming cells

Osteocytes

mature bone cells, contribute to bone maintenance/homeostasis

Osteoclasts

bone-dissolving macrophages

Bone matrix

1/3 organic (collagen and large protein-carbohydrate complexes), 2/3 inorganic (85% hydroxyapatite, 10% calcium carbonate, and 5% other inorganic minerals)

spongy bone contains

-spicules and trabeculae
-porous appearance where the spaces filled with bone marrow

spicules

rods and spines of bone

bone marrow

A soft tissue inside medullary cavities of long bones, spaces within spongy bone, and large central canals within osteons.

red marrow

hematopoietic tissue, both red and white blood cells are made here

yellow marrow

mainly fat

red marrow location

skull, vertebrae, sternum, ribs, parts of pelvic girdle, and proximal heads of humerus and femur

yellow marrow location

long bones of limbs

ossification

bone formation, begins with mesenchyme

two methods of ossification

intramembranous and endochondral

Intramembranous ossification

-produces flat bones of skull and most of clavicle
-bone develops in a fibrous sheet resembling the dermis

endochondral ossification

-most bones develop this way
-bone develops from hyaline cartilage model

Bone elongation

bones grow longer at epiphysial plates

metaphysis

area of transition from cartilage to bone at each end of marrow cavity

Appositional growth

growth in diameter and thickness

stress fracture

caused by abnormal trauma

pathological fracture

occurs in bone weakened by a disease such as osteoporosis

closed reduction

nonsurgical realignment of broken bone ends and splinting of bone

open reduction

surgical realignment of broken bone ends

closed fracture

broken bone with no open wound

open fracture

skin is broken, bone protrudes through skin or wound extends to fractured bone

nondisplaced fracture

the portions of the bone are still in correct anatomical alignment

displaced fractures

the portions of the bone are out of anatomical alignment

comminuted fracture

bone is broken into three or more pieces

greenstick fracture

bone is bent toward one side and has incomplete fracture on opposite side

hairline fracture

fine crack in which sections of bone remain aligned

depressed fracture

broken portion of bone forms a concavity

linear fracture

fracture parallel to long axis of bone

transverse fracture

fracture perpendicular to long axis of bone

oblique fracture

diagonal fracture, between linear and tranverse

spiral fracture

fracture spirals around axis of long bone as the result of twisting stress