CC Skeletal System 2

What are the steps to long bone growth?

1. Cartilage on the side of the epiphyseal plate closest to the epiphysis is relatively inactive

2. cartilage abutting the shaft of the bone organizes into a pattern that allows, fast efficient growth

3. cells of the epiphyseal plate proximal to the resting cartilage form three functionally different zones

zone where cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis

growth zone

zone where older cells enlarge, the matrix becomes calcified, cartilage cells die, and the matrix begins to deteriorate

transformation zone

zone where new bone formation occurs

osteogenic zone

how does a bone grow longer?

cartilage continually grows and is replaced by bone

how does bone remodeling occur?

bone is resorbed and added by appositional growth

adjacent osteoblasts and osteoclasts deposit and resorb bone at periosteal and endosteal surfaces

remodeling units

gives rise to embryonic mesenchymal cells, which produce membranes and cartilages that form the embryonic skeleton

mesoderm

what part of a long bone is not well ossified at birth

epiphyses

By age ______________ nearly all bones are completely ossified

25

when does bone mass begin decreasing

the 4th decade of life

what determines the tendency to accumulate bone mass early in life and the risk for osteoporosis later in life

a gene that codes for Vitamin D docking

modulates the activity of growth hormone

thyroid hormone

the pituitary gland produces this hormone that simulates epiphyseal plate activity

growth hormone

hormones that initially promote adolescent growth spurts, cause masculinization and feminization of specific parts of the skeleton, later induce epiphyseal plate closure, ending longitudinal bone growth

estrogen and testosterone

occurs where bone is injured or added strength is needed

bone deposition

requires a diet rich in protein, vitamins C, A, D, calcium, phosphorus, magnesium, and manganese

bone deposition

unmineralized band of bone matrix

osteoid seam

abrupt transition zone between the osteoid seam and the older mineralized bone

calcification front

accomplished by osteoclasts and osteoclast secretion of lysosome enzymes that digest organic matrix and acids that convert calcium salts into soluble forms

bone resorption

dissolved matrix is transcytosed across the osteoclast's cell where it is scripted into the interstitial fluid and then into the blood

bone resorption

What are 5 things we need ionic calcium for in the body?

1. transmission of nerve impulses

2. muscle contraction

3. blood coagulation

4. secretion by glands and nerve cells

5. cell division

What are the two control loops that regulate bone remodeling?

1. hormonal mechanism maintains calcium homeostasis in the blood

2. mechanical and gravitational forces acting on the skeleton

What are the steps of the Hormonal Mechanism that maintains calcium levels in the blood?

1. Rising blood Ca++ levels trigger the thyroid gland to release calcitonin

2. calcitonin stimulates calcium salt deposit in bone by osteoclasts

3. Falling blood Ca++ levels signs the parathyroid glands to release parathyroid hormone

4. Parathyroid hormone signals osteoclasts to degrade bone matrix and release Ca++ into the blood

a bone grows or remodels in response to the forces or demands placed upon it

Wolff's Law

What are two responses to Mechanical Stress?

1. Trabeculae form along lines of stress

2. Large, bony projections occur where heavy, active muscles attach

Imbalance where bones are inadequately mineralized causing weekend and softened bones, the main symptom is pain when weight is put on the affected bone, caused by insufficient calcium in the diet, or by vitamin D deficiency

osteomalacia

group of diseases in which bone reabsorption outpaces bone deposit, spongy bone of the spine is most vulnerable, occurs most often in postmenopausal women, bones become so fragile that sneezing or stepping off a curb can cause fractures

osteoporosis

what are the treatments for osteoporosis?

1. Calcium and Vitamin D supplements

2. Increased weight bearing exercises

3. Hormone replacement therapy

4. natural progesterone cream

5. statins increase bone mineral density

rounded projection of a bone

tuberosity

narrow, prominent ridge of a bone

crest

large, blunt, irregular surface

trochanter

what is the only bone where you can find a trochanter

femur

narrow ridge of bone

line

small rounded projection of bone

tubercle

raised area above a condyle

epicondyle

sharp, slender projection of a bone

spine

any bony prominence

process

bony expansion carried on a narrow neck

head

smooth, nearly flat articular surface

facet

rounded articular projection

condyle

armlike bar of bone

ramus

canal-like passageway

meatus

cavity within a bone

sinus

shallow, basin-like depression

fossa

furrow

groove

narrow, slit-like opening

fissure

round or oval opening through a bone

foramen

weakest parts of the skeleton

articulations

site where two or more bones meat

articulations

what are the functions of joints

1. give the skeleton mobility

2. Hold the skeleton together

Skeletal division composed of eighty bones divided into three regions

axial skeleton

the body's most complex bony structure, formed by the cranium and facial bones

the skull

tiny irregular shaped bones that may appear within skull sutures

wormian bones

not actually part of the skull, but lies just inferior to the mandible in the anterior neck

hyoid

only bone of the body that does not articulate directly with another bone

hyoid bone

attachment point for neck muscles that raise and lower the larynx during swallowing and speech

hyoid bone

formed from 26 irregular bone connected in such a way that a flexible curved structure results

vertebral column

7 bones of the neck

cervical vertebrae

12 bones of the torso

thoracic vertebrae

5 bones of the lower back

lumbar vertebrae

bone inferior to the lumbar vertebrae that articulates with the hip bones

sacrum

parts of the vertebral column that have posterior concave curvatures

cervical and lumbar vertebrae

parts of the vertebral column that have posterior convex curvatures

thoracic and sacral

what are three examples of abnormal spine curvatures

1. scoliosis

2. lordosis

3. kyphosis

continuous bands down the front and back of the spine from the neck to the sacrum

anterior and posterior longitudinal ligaments

ligaments that connect adjoining vertebrae together

short ligaments

cushion-like pads that are composed of two parts

intervertebral disks

inner gelatinous nucleus that gives the disc its elasticity and compressibility

Nucleus pulposus

surrounds the nucleus pulpous with a collar composed of collagen and fibrocartilage

Annulus fibrosus

What are the four functions of the Bony Thorax?

1. forms a protective cage around the heart, lungs, and great blood vessels

2. supports the shoulder girdles and upper limbs

3. provides attachment for many neck, back, chest and shoulder muscles

4. uses intercostal muscles to lift and depress the thorax during breathing

made up of the bones of the limbs and their girdles

appendicular skeleton

attach the upper limbs to the body trunk

pectoral girdles

secures the lower limbs

pelvic girdle

consist of the anterior clavicles and the posterior scapulae, attach upper limbs to the axial skeleton in a manner that allows for maximum movement, provide attachment points for muscles that move the upper limbs

pectoral girdles

consists of the arm, forearm, and hand

upper limb

What are the eight carpal bones

1. scaphoid

2. lunate

3. triquetral

4. pisiform

5. trapezium

6. trapezoid

7. capitate

8. hamate

what are the three segments of the lower limb

1. thigh

2. leg

3. foot

carry the weight of the erect body and are subjected to exceptional forces when you jump or run

lower limb