Anatomy and Physiology: Bones

What is the bone composed of?

Bone tissue, cartilage, fibrous connective tissue, blood, and nerve tissue

What are the functions of bone?

Support, protection, Movement, MINERAL STORAGE, blood cell formation

What are the 6 different types of bones?

Flat, long, short, sesamoid, irregular, Wormian

Describe the long bone...

Long longitudinal axes (shafts) and expanded ends (heads). Mostly made of compact bone

Describe short bones...

Cube-like, more spongy bone than compact

Describe flat bones...

Usually thin and flattened with a broad surface; spongy bone between two layers of compact bone

Describe irregular bones...

Variety of shapes unlike other bone

Describe sesamoid bone...

Small bones found within tendons; VARIES AMONG INDIVIDUALS

Describe Wormian bones...

AKA sutural bones, tiny bones between major cranial bones; VARY AMONG INDIVIDUALS

What is compact bone?

Dense outer solid layer of bone

What is spongy bone?

AKA cancellous bone, spiky, open faced look from the arrangement of spicules of bone material (trabeculae)

What is trabeculae? What is found in open spaces between it?

Spicules of bony material; Red and yellow bone marrow

What are the three names for the central canal of an osteon?

Haversian canal, osteonic canal, or central canal

What is contained within the central canal?

small blood vessels and nerve fiber

What are the concentric "rings of bone matrix called?

Lamellae

Where are osteocytes found?

Lacunae

What are osteocytes?

Mature bone cell, contains bone matrix

What connects lacunae to each other?

Canaliculi

What are volkmann canals?

Connect blood, and nerve supply of periosteum to various osteons

What are the names fo the 4 structures in a long bone?

Periosteum, endosteum, interstitial lamellae, and circumferential lamellae

What is the membrane that lines the outside of the bone called?

Periosteum

What is the membrane that lines the medullary cavity called?

Endosteum

Whats the name for the layers of bone matrix between osteons?

Interstitial lamellae

What are circumferential lamellae?

Layers of bone between periosteum and endosteum, extends around the shaft

Is bone made up of only organic components?

No, contains inorganic as well

What are the organic components of bone?

Cells and osteoid

What cells are within a bone?

Osteoblasts, osteoclasts, osteocytes

What is the osteoid?

Collagen fibers, proteoglycans, glycoproteins. Provides flexibility and tensile strength

What are the inorganic compounds of bone?

Hydroxyapatites

What causes the bone to be hard?

Hydroxyapatites

Name the parts of a long bone

Epiphysis, articular. cartilage, diaphysis, periosteum, sharpey's fibers, medullary cavity, endosteum

What in the name of the end of a long bone that forms a joint with another bone? What is it made of?

Epiphysis; thin layer of compact bone filled with spongy bone

What is the articular cartilage?

Layer of hyaline cartilage that covers epiphysis; helps prevent friction

What is the shaft of a long bone called?

diaphysis (made of compact bone)

What is the periosteum?

Vascular fibrous tissue surrounding the shaft of the long bone

Where do blood vessels and nerves enter the bone?

Through the periosteum

What are Sharpey's fibers?

ibers of the periosteum that penetrate the bone

What is the tube-like chamber in the diaphysis called? What does it store?

Medullary Cavity; bone marrow

What is the endosteum?

Thin layer of squamous cells lining the medullary cavity

Name the three types of cartilages found in bone.

Hyaline, elastic, fibrocartilage

What is cartilage surrounded by?

Perichondrium (Made of dense irregular connective tissue)

What is the function of the perichondrium?

To prevent outward expansion of cartilage when its' compressed

What is the relationship between the perichondrium and chondrocytes?

Perichondrium is the source of blood vessels from which nutrients enter chondrocytes

What are the cell sin cartilage called?

Chondrocytes (found in lacunae)

What are the two ways cartilage grows?

Appositional and interstitial

What is appositional growth?

Cartilage forming cells in the perichondrium secrete new matrix

What is interstitial growth?

Chondrocytes is lacunae divide and secrete new matrix, expanding cartilage from within

During what stage of life does cartilage growth usually end?

Adolescence

What is osteogenesis or ossification?

Bone tissue formation

When does bone being to grow?

After 8 weeks in the fetus

During fetal development what are bones formed from?

Connective tissue

What are the names of the bones that grow between sheet-like layers of connective tissue?

Intramembranous bones

What are endochondral bones?

Bones that form as masses of cartilage and are replaced by bone

What forms layers at the site of future bones?

Primitive connective tissue

What are osteoblasts?

Immature bone forming cells

What is an osteocyte?

An osteoblasts that becomes surrounded by the matrix and secluded in lacunae

What cells form the periosteum?

Mesenchymal cells collecting on the outside of bone

What is the name of the process of forming an intramembranous bone by replacing CT?

Intramembranous ossification

What are examples of intramembranous bones?

Flat bones of skull and clavicle

How are endochondral bones formed? What do they develop from?

Endochondral ossification; Hyaline cartilage

What happens when the perichondrium is infiltrated with blood vessels?

Becomes vascularized periosteum, underlying mesenchymal cells become osteoblasts and secrete osteoid forming a bone collar around diaphysis

What happens when chondrocytes in the center of the diaphysis grow rapidly?

Causes the matrix around them to calcify, and the chondrocytes to die

What forms the periosteal bud?

Blood vessels and CT cells invade bone tissue

What are osteoclasts?

Bone-destroying cells

Where is the primary ossification center present?

Diaphysis of a long bone

When bone is being formed on the outside what forms the medullary cavity?

Osteoclasts breaking down bone inside the bone

When do secondary ossification centers develop?

After birth

What is the epiphyseal disk (plate)?

Cartilagenous area left between ossification centers

When does the long bone stop growing?

When ossification centers come together and epiphyseal disk becomes ossified

What is the epiphyseal plate closure?

when epiphysis and diaphysis fuse (18 in girls; 21 in boys)

What influences bone development, growth, and repair?

Nutrition, hormones, exercise, and sunlight

What hormones control growth?

Growth hormone, thyroid hormones, male and female sex hormones

What is growth hormone (GH)?

Secreted from pituitary gland; stimulates epiphyseal plate activity during infancy and childhood

What does hyper secretion cause in adults and children?

Gigantism in child, acromegaly in adults

What does hypo secretion of GH cause?

Dwarfism

What are the thyroid hormones?

From thyroid gland; causes cartilage to be replaced by bone; modulate activity of GH to keep bones in proportion

How do sex hormone regulate growth?

Promote growth spurts; cause masculinization or feminization of skeleton; induce ending of bone growth

What hormones control calcium level in our blood?

Calcitonin and parathyroid hormone

What is calcitonin?

Hormone by thyroid gland; inhibits bone resorption and stimulate calcium deposition into bone matrix (Ca levels too high)

What is parathyroid hormone?

BY parathyroid glands; stimulate osteoclasts to resorb bone (release calcium into blood);

What can happen if calcium levels are too high or low?

Neuromuscular problems. If too high muscles may be non-responsive. If too low muscles are hyper-excitable (occurs a lot in pregnant women)

How much bone is recyclyed every week? When is spongy bone replaced? When is compact bone replaced?

5-7%; 3-4 years; 10 years

Where does bone deposition occur?

where a bone is injured or where added bone strength is needed

What vitamins are best for bone growth and why?

Vitamin A to balance bone resorption; Vitamin C for collagen synthesis; Vitamin D for calcium absorption

What is calcium necessary for?

Nerve impulse transmission, muscle contraction, blood coagulation, secretion by glands and nerve cells, and cell division

What stimulates bone growth and causes bone tissue to thicken and strengthen?

Physical stress

What is it called when bones a thin and weak?

Atrophy

What is Wolff's law?

Bone grows or remodels itself in response to the forces or demands placed on it

What is osteomalacia?

Bones are not mineralized well causing them to be "soft" (ADULTS)

What are rickets?

Bowed legs, deformities of pelvis, skull, and rib cage (CHILDREN)

What causes osteomalacia and rickets?

Insufficient calcium, vitamin D

What is osteoporosis?

Excessive loss of bone and minerals in bones. Bones develop spaces that fill with fatty tissue

What is Paget's disease?

Excessive bone formation and breakdown.

What is the name of a fracture if the bone ends are in normal position?

Non-displaced

What is the fracture called if bones are out of normal position?

Displaced

What is the name of a fracture if bone in not completely broken through?

incomplete

Fracture if bone is broken through?

Complete

Fracture if it is parallel to axis of the bone?

Linear

Fracture is perpendicular to bone's long axis?

Transverse

Fracture when bones do not penetrate skin?

Sinple