Skeletal System

PPT 1 and 2

Type of cartilage containing no blood vessels or nerves

Skeletal Cartilage

the perichondrium is composed of what type of connective tissue

dense irregular

connective tissue found in skeletal cartilage that resists outward expansion

perichondrium

What are the three types of skeletal cartilage?

1. Hyaline

2. Elastic

3. Fibrocartilage

type of cartilage providing support, flexibility and resilience. Is the most abundant skeletal cartilage.

Hyaline cartilage

type of hyaline cartilage that covers the ends of long bones

articular cartilage

type of Hyaline cartilage that connects the ribs to the sternum

costal cartilage

type of hyaline cartilage that makes up the larynx, and reinforces air passages

respiratory cartilage

type of hyaline cartilage that supports the nose

Nasal Cartilage

type of skeletal cartilage that is similar to hyaline but contains elastic fibers

Elastic Cartilage

type of skeletal cartilage that is found in the external ear and epiglottis

elastic cartilage

type of skeletal cartilage that is highly compressed with great tensile strength, contains collagen fibers

fibrocartilage

type of skeletal cartilage found in the menisci of the knee and in intervertebral discs

fibrocartilage

type of growth that occurs when cells in the perichondrium secrete matrix against the external face of existing cartilage

appositional growth

type of growth where lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within

Interstitial growth

When does calcification of cartilage occur?

1. during normal bone growth

2. during old age

What are the 5 functions of bones?

1. support

2. protection

3. movement

4. storage

5. blood cell formation

Function of bones that has them forming the framework that holds up the body and cradles soft organs

support

function of the bones providing a case for the brain, spinal cord, and vital organs

protection

function of the bones providing levers for muscles

movement

function of the bones that says they act as a reservoir for minerals especially calcium and phosphorus, as well as fats

storage

function of the bones for hematopoiesis that occurs within the marrow cavities

Blood Cell formation

bones of the skull, vertebral column, and rib cage

Axial skeleton

bones of the upper and lower limbs, shoulder, and hip

Appendicular Skeleton

bones that are longer than they are wide

Long Bones

the humerus is an example of what bone shape

Long

type of bone that is cube shaped and found in the wrist and ankle, bones that form within tendons

Short bones

type of bone shape that is thin, flattened, and bit curves

flat bones

what are some examples of flat bones

sternum, and most skull bones

type of bone that have complicated shapes

Irregular bones

what are some examples of irregular bones?

vertebrae and hip bones

what are the two major parts of a long bone

epiphysis and diaphysis

tubular shaft that forms the axis of long bones, composed of compact bone that surrounds the medullary cavity, yellow bone marrow being contained in the medullary cavity

Diaphysis

fat that is contained in the medullary cavity of a bone

yellow bone marrow

expanded ends of a long bone, exterior is compact bone, and the interior is spongy bone, joint surface is covered with articular cartilage

Epiphyses

dense outer layer of a bone is this type of bone

compact bone

honeycomb of trabeculae filled with bone marrow

spongy bone

type of bone marrow found mainly in the medullary cavity of long bones, storing lipids

yellow marrow

type of bone marrow found mainly in spongy bone, forms blood cells

red marrow

double-layered protective membrane, the outer fibrous layer is dense irregular connective tissue, inner osteogenic layer is composed of osteoblasts and osteoclasts, richly supplied with nerve fibers, lymphatic vessels

periosteum

delicate membrane covering internal surfaces of bone

endosteum

type of bones that have no diaphysis or epiphysis, contain bone marrow between trabeculae

short

irregular

flat

mature bone cells

osteocytes

small cavities in bone that contain osteocytes

Lacunae

hairlike canals that connect lacunae to each other and the central canal

Canaliculi

the structural unit of compact bone

Haversian System or osteon

weight bearing, column like matrix tubes composed mainly of collagen

Lamella

central chanel containing blood vessels and nerves

Haversian or central canal

Channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

Volkmann's Canals

bone-forming cells

osteoblasts

mature bone cells

osteocytes

large cells that resorb or break down bone matrix

osteoclasts

unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen

osteoid

make up 65% of bone by mass, mainly calcium phosphate, responsible for bone hardness and its resistance to compression

inorganic composition of bone

the process of bone tissue formation

osteogenesis and ossification

the formation of the bony skeleton in embryos, bone growth until early adulthood, bone thickness, remodeling and repair

osteogenesis and ossification

when does the bony skeleton begin to form

week 8 of embryo development

when bone develops from a fibrous membrane

intramembranous ossification

bone forms by replacing hyaline cartilage

endochondrial ossification

formation of most of the bones of the skull and the clavicles, fibrous connective tissue membranes are formed by mesenchymal cells

intramembranous ossification

What are the stages of intramembranous ossification?

1. An ossification center appears in the fibrous connective tissue membrane

2. Bone matrix is secreted within the fibrous membrane

3. Woven bone and periosteum form

4. Bone collar of compact bone forms and red marrow appears

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