Anatomy and Physiology Ch. 7 - Skeletal System

bones are ________________.

bones are ________________.

multifunctional

bone functions

support/protect softer tissues, points of attachment for muscles, blood production, store inorganic salts

bones are classified by __________.

shape

what are the classifications of bones?

long, short, flat, irregular

long bones

long longitudinal axes and expanded ends

what is an example of a long bone?

femur, forearm

short bones

equal in length and width

what are examples of short bones?

wrist and ankle bones

sesamoid bone

short bones that form within tendons ex: patella

flat bones

platelike structures with broad surfaces

what are examples of flat bones?

ribs, scapulae, sternum, parts of skull

irregular bones

variety of shapes, most are connected to other bones

what are examples of irregular bones?

vertebrae and facial bones

parts of long bone

epiphysis, diaphysis, compact bone, spongy bone, articular cartilage, periosteum, endosteum, medullary cavity, trabeculae, marrow

epiphysis

expanded end of long bone; articulates another bone, proximal and distal ends

articular cartilage

hyaline cartilage that covers end of epiphysis

diaphysis

bone shaft

metaphysis

widened part of bone between diaphysis and epiphysis

periosteum

vascular covering of dense connective tissue that encloses entire bone; helps form and repair bone tissue

compact bone

tightly packed tissue, continuous ECM with no gaps, makes up wall of diaphysis

spongy bone

branching bony plates called trabeculae, spaces help reduce weight of bone, makes up most epiphyses

trabeculae

branching bony plates that make up spongy bone

spongy bone is found in regions that are prone to _______________.

compression

medullary cavity

tube with hollow chamber of compact bone in diaphysis of long bone; continuous with some spaces of spongy bone

endosteum

thin membrane of bone forming cells that line medullary cavity and spaces within spongy bone

marrow

specialized soft connective tissue that fills spongy bone spaces and medullary cavity

yellow marrow

soft, fatty material found in the medullary cavity of long bones; stores fat

red marrow

location of blood cell formation; usually found near epiphysis in long bones

bone cells are called ___________.

osteocytes

lacunae

small cavities in bone that contain osteocytes

canaliculi

channels that connect lacunae; allows neighboring osteocytes to exchange substances with each other

ECM of bone tissues is composed of __________ and ___________.

collagen and inorganic salts

haversian canal

central canal in compact bone containing blood vessels and nerves; forms shape of osteon

volkmans canal

horizontal canals between osteons; contain a nerve and a blood vessel

collagen gives bones _________ and resilience.

strength

inorganic salts make bones resistant to ___________.

crushing

why do osteons run longitudinally with the axis of a bone?

it allows the bone to bear weight and resist compression

compact bone is made of many _________ together.

osteons

compact bone diagram

do spongy bone cells surround the haversian canal?

no

spongy bone cells are in the ________________.

trabeculae

how do spongy bone cells receive nutrients?

from the diffusion of nutrients through the canaliculi

spongy bone diagram

ossification

formation of bone

intramembranous bones

sheet like layers of connective tissue

when do parts of the skeletal system begin to develop in fetuses?

during the first few weeks of pregnancy

what are the 2 types of bone formation?

intramembranous and endochondral

intramembranous ossification

- bones develop as sheet like layers of connective tissue

- produces broad/flat bones

what are examples of bones that go through intramembranous ossification?

skull bones (not mandible, clavicles, sternum, facial bones

endochondral ossification

- bones develop from hyaline cartilage

- occurs in most bones of the skeleton

intramembranous ossification replaces _____________________________.

embryonic connective tissue

process of intramembranous ossification

- mesenchymal cells in primitive tissue differentiate into osteoblasts

- once osteoblasts are completely surrounded by matrix, they are called osteocytes in lacunae

- mesenchyme on outside forms periosteum

mesencyme

embryonic connective tissue

process of endochondral ossification

- begins as hyaline cartilage

- chondrocytes in large, lacunae grows

- matrix breaks down, chondrocytes die

- osteoblasts invade and deposit bone matrix

- osteoblasts from spongy then compact bone

- osteoblasts are called osteocytes once in matrix

primary ossification center

center of diaphysis where bone tissue first starts to replace cartilage

examples of endochondral bones

Femur, humerus, radius, tibia, phalanges, vertebrae

secondary ossification center

area of epiphyses; spongy bone forms later in development

epiphyseal plate

a band of cartilage that remains between the two ossification centers; remains as spongy bone is deposited into the diaphysis and epiphysis

when does a fetus begin to show development of intramembranous and endochondral bones?

at 14 weeks

osteogenesis imperfecta

hereditary disease that involves a collagen defect; bones are extremely brittle

the epiphyseal plate is also called the ______________.

growth plate

in long growing long bones, the growth plate separates the diaphysis from the ___________.

epiphysis

metaphysis

growth zone between the epiphysis and the diaphysis during development of a long bone

there are ___ layers of the epiphyseal plate.

4

what are the 4 layers of the epiphyseal plate?

resting zone, proliferating zone, hypertrophic zone, calcified zone

zone of resting cartilage

- nearest the epiphysis and contains randomly arranged chondrocytes that do not divide rapidly

- anchors epiphyseal plate to tissue of epiphysis

zone of proliferating cartilage

- rows of young cells undergoing mitosis; rapid cell division

- cartilaginous plate thickens as new cells grow and ECM forms

zone of hypertrophic cartilage

- consists of large, maturing chondrocytes arranged in columns

- thickens epiphyseal plate and lengthens bone

- osteoblasts secrete calcium salts to calcify the matrix

zone of calcified cartilage

thin layer of dead cartilage cells and calcified matrix

at the growth plate, osteoclasts break down ________________.

calcified matrix

osteoblasts invade the epiphyseal plate and deposit _________ tissue in place of calcified cartilage.

bone

how does bone thicken?

deposition of compact bone on outside

when does bone remodeling occur?

throughout life

bone resorption

removal of bone by osteoclasts

bone deposition

formation of bone by osteoblasts

where does bone resorption and bone deposition occur?

surfaces of endosteum and periosteum

bone remodeling is not ____________ and depends on bone type.

uniform

bone remodeling is tightly ___________.

regulated

what percent of bone tissue is replaced per year?

10-20%

what factors effect bone development, repair, and growth?

nutrition, sunlight exposure, hormonal secretions, physical exercise

vitamin D role in bones

calcium absorption; deficiency causes rickets (children) and osteomalacia (adults)

vitamin A role in bones

osteoblast and osteoclast activity; deficiency hinders bone development

vitamin C role in bones

collagen synthesis; deficiency causes slender and fragile bones

proteins role in bones

make up large percentage of bones

collagen makes up ______ percent of bones.

90

growth hormone role in bones

stimulates cartilage cell division in epiphyseal plates

growth hormone is secreted by the __________ gland.

pituitary

pituitary dwarfism

insufficient production of growth hormone in children

pituitary giantism

hypersecretion of growth hormone in childhood

acromegaly

enlargement of the extremities in adults

thyroid gland role in bone

- secretes thyroxine (T4) hormone

- stimulates osteoblasts

parathyroid gland role in bone

- secretes parathyroid hormone

- stimulates osteoclasts

sex hormones role in bones

- promote bone formation at puberty

- stimulate ossification of epiphyseal plates to stop bone lengthening

fractures are classified by

cause and nature of break

fracture classifications by cause

traumatic and spontaneous/pathologic

traumatic fractures

caused by injury

pathologic/spontaneous fractures

caused by disease

fracture classifications by break

simple and compound

simple fractures

fracture protected by uninjured skin

compound fractures

bone penetrates skin and is exposed through outside