A&P Skeletal System

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what are the 5 functions of the skeletal system?

support, protection, storage, manufacturing, movement

how does the skeletal system provide support?

bearing the weight of the body

How does the skeletal system provide protection?

encasing essential organs

what is an example of how the skeletal system provides protection?

ribcage protects the heart and lungs from injury

how does the skeletal system provide storage?

stores minerals to be released into the bloodstream, stores fat in yellow bone marrow

how does the skeletal system provide manufacturing?

hematopoiesis

what is hematopoiesis?

production of red and white blood cells from red bone marrow

how does the skeletal system provide movement?

joints provide movement for bones

what structures do the bones provide shape for?

head, face, thorax, limbs 

what do the skull bones protect?

brain, ears, eyes

what do the bones of rib cage and shoulder girdle protect?

heart and lungs

what do the bones of the pelvic girdle protect?

internal reproductive organs and lower abdominal organs

what provides movement

bones and muscles

what are bones made of?

a solid matrix of living cells and fibers surrounded by calcium deposits 

how are bones classified?

by their shape

what are the 5 shapes of bones?

flat bones, irregular bones, long bones, short bones, sesamoid bones

what is an example of a flat bone?

scapula

what is an example of an irregular bone?

vertebrae 

what is an example of a long bone?

femur

what is an example of a short bone?

wrist

what is an example of a sesamoid bone?

patella

what is the shape of long bones?

long and narrow

long bones have _______ ends

expanded

how are short bones shaped?

cubelike: length=width

how are sesamoid (round) bones classified?

included as short bones 

where are sesamoid bones found?

embedded in tendons

how are flat bones shaped?

platelike with broad surfaces

how are irregular bones shaped?

variety of shapes

where are irregular bones found?

connected to other bones

what are the 2 basic regions of a long bone?

diaphysis, epiphyses

what is the diaphysis region of a long bone?

shaft, long part of bone

what is the epiphyses region of a long bone?

ends of bone

what is the layer of internal cartilage between the diaphysis and epiphysis regions of a long bone?

epiphyseal plate (growth plate)

what are the ends if the epiphyses covered with in a long bone?

articular cartilage 

what is the function of articular cartilage?

provides smooth movement of joints and cushion from shock

what is the periosteum of the long bone?

encloses bone; dense connective tissue

where is the compact (cortical) bone found?

wall of diaphysis

what does the spongy (cancellous) bone make up?

epiphyses

what is trabeculae in long bone?

branching bony plates that make up spongy bone

what is the medullary cavity of long bone?

hollow chamber in diaphysis

what does the medullary cavity of long bone contain?

marrow

what is endosteum of long bone?

lines spaces, cavity

what are the kinds of bone marrow?

red or yellow marrow

where is bone marrow found?

lines of medullary cavity, spongy bone spaces

what causes red bone marrow to be replaced with fatty yellow marrow?

age

where are new blood cells produced through hematopoiesis?

within bone marrow

what is the outer layer of bone made of?

periosteum- tough connective tissue

where does muscle attachment and bone repair occur?

periosteum

What layer is underneath the periosteum?

compact bone 

spongy bone is found at the _____ of long bone and beneath ______ bone

ends; compact

what is spongy bone made of?

a lattice of trabeculae

where is trabeculae found?

along lines of stress

what is the function of spongy bone?

perfect resistance from compression

what fills the spaces between the spaces of trabeculae?

marrow or blood vessels

how is compact bone arranged?

cylinders called osteons

how are osteons arranged?

in concentric circles called lamellae

what do the lamellae surround?

central/Haversian canal 

what does the haversion canal contain?

blood vessels and nerves

how are haversion canals connected?

perforating (volkmann’s) canals running perpendicularly

where are osteocytes found?

in lacunae

what do blood vessels provide to bone tissue?

nutrients 

how do osteocytes pass nutrients?

through canaliculi

what are osteocytes?

mature bone cells that make up the majority of bone structure

what is the function of canaliculi?

connect all bone cells, receive nutrients, remove waste

what lines the haversion canals and surfaces of compact and spongy bone?

osteoclasts and osteoblasts 

what is the function of osteoclasts?

break down bone

what is the function of osteoblasts?

produce new bone

what is an embryo’s skeleton made of?

cartilage

what do osteoblasts do in the third month of embryo development?

osteoblasts secrete mineral deposits that replace cartilage. The osteoblasts mature into osteocytes.  

what is ossification?

The process of incorporating calcium and minerals into cartilage to become bone

when does primary ossification occur?

during fetal development

when does secondary ossification occur?

during childhood and adolescence

what happens during intramembranous ossification?

flat skull bones are forming between sheets of primitive connective tissue

what happens during endochondral ossification?

long bones and most of skeleton are forming from hyaline cartilage models. 

what happens to chondrocytes at the epiphyseal plate when a child grows?

tall columns of chondrocytes divide and then deteriorate as the matrix around them calcifies.

what are the cells called after chondrocytes are deteriorated and calcified?

osteoblasts

what do osteoblasts form?

spongy bone 

what is the function of acid secreted by osteoclasts?

enlarge the medullary cavity as bone grows so that more marrow is available for cells.

what percent composition is organic in bone?

35% osteiod

what is osteoid made of?

made of ground substance and collagen

what is the function of organic bone composition?

provides the flexability and tensile strength required to keep bones from breaking

what does a lack of collagen cause?

brittle bone disease

what percent composition of bone is inorganic?

65% mineral salts

what are inorganic crystalline salts made of?

hyrdoxyapatites Ca10(PO4)6(OH)2

what is the function of inorganic bone composition?

provides bone strength and hardness

what does a lack of hydrocyapatites cause?

rickets

what other inorganic salts make up the bone matrix?

magnesium ions, sodium ions, potassium ions, carbonate ions

what condition occurs at the loss of bone mineralization

osteoporosis

what regulates blood calcium levels 

parathyroid hormone and calcitonin

what is a fragility fracture?

fracture that occurs from less than standing height; a sign of low bone density

how does the body maintain an ideal blood calcium level?

bone is created or dissolved

what gland is activated due to low calcium in the blood?

parathyroid gland produces PTH

what gland is activated due to high calcium in the blood?

thyroid gland produces calcitonin 

when does bone remodeling occur?

throughout life

what is bone resorption, and what causes it?

removal of bone, action of osteoclasts

what is bone deposition, and what causes it?

formation of bone, action of osteoblats 

what approximate percentage of the skeleton is replaced each year?

10%-20%

what are the 4 steps of repairing a broken bone?

1. hematoma forms 

2. callus forms 

3. callus ossifies

4. compact bone forms 

what factors affect bone development, growth, and repair?

nutrition, sunlight exposure, hormone levels, and physical exercise

bone is formed as _________ calcifies

cartilage