Bone Tissue and the skeloton objectives

central canal

middle circle of compact bone

Location, appearance and main function of compact bone

-Found beneath the periosteum of all bones and makes up the bulk of diaphyses of long bone. -Provides protection and support. -Resists the stress produced by weight/movement -Composed of repeating structural units called osteons. each osteon consists of lamellae around the central canal. between the lamellae there is lacunae which contain osteocytes. Which radiate canaliculi

What are the unique features of intramembranous and endochondral processes? and what do they share in common?

-IM replaces mesenchyme, EC replaces hyaline cartilage -osteogenic cells transform into osteoblasts

Location, appearance and main function of spongy bone

-Located in the interior of a bone -makes up most interior bone tissue of short, flat, sesmoid and irregularly shaped bones. -in long bones form the core of epiphyses beneath compact bone -provides nourishment to cells ( osteocytes) - does not contain osteons -located in the interior of a bone -the trabeculae are filled with red bone marrow

Describe the processes of endochondral ossification

-mesenchyme cells turn to chondroblasts - chondroblasts secrete cartilage matrix -perichindrium forms down a catilage model -more cartilage matrix the more the bone grows -nutrient artey penetrates perichondrium increasing nutrient avalibility to the cells -causes osteogenic cells to form into osteoblasts -osteoblasts secrete osteoid -secrete under perichondrium and forms thin shell of compact bone called bone collar -perichondrium turns into periosteum -color deprives cells of nutrients -capilaries grow into cartilage and deliver osteoblasts -primary ossification center is formed -ossification center is where bone tissue replace cartilage -osteoblasts deposit bone matrix -trabecuale are built

Describe the processes of intramembranous ossification

-occurs on fibrous connective tissue -ossification center forms when mesenchyme cells change to osteogenic cells and then osteoblasts -osteoblasts secrete osteoid -osteoblasts become osteocytes -calcium and mineral salts get layed down hardening the matrix -bone matrix develops trabeculae, fuse to form spongy bone - red bone marrow is in the trabeculae - periosteum forms - outer layer spongy turns to compact

What are the cell types in bone?

1. Osteogenic cells 2. Osteoblasts 3. Osteoclasts 4. Osteocytes

Major function of osteogenic cells

Adult stem cells that become osteoblasts

Describe the remodeling of bone

Bone remodeling is the ongoing replacement of old bone tissue by new bone tissue. It involves bone resorption, the removal of minerals and collagen fibers from bone by osteoclasts, and bone deposition, the addition of minerals and collagen fibers done by osteoclasts. Thus, bone resorption results in the destruction of bone extracellular matrix while bone deposition results in the formation of bone extracellular matrix.

Describe the relationship between exercise and bone tissue

Exercise stimulate bone growth. when placed under stress, bone tissue becomes stronger through increases deposition of mineral salts and production of collagen fibers by osteoblasts

Identify the two most abundant components of the ground substance of bone

Hydroxyapatite- 85% Calcium Carbonate- !0%

The effects of parathyroid hormone on calcium homeostasis in the body

Icreases blood Ca2+ level.

Identify the two types of bony tissue

Inner Spongy and outer compact

Describe the process of bone growth both in lenght

Involves 2 major events. (1) interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate. (2) replacement of cartilage on the diaphyseal side of the epiphyseal plate with bone by endochondral ossification. The activity of the epiphyseal plate is the only way the diaphysis can increase in length. - the epiphyseal plate has the 4 zones.. they push the top of the bone up and the bottom z line turns into calcified bone. epiphyseal plate turns into line when growth is done.

Red arrow- Lacuna Green line- Lamellae

Label

Red bone marrow Marrow cavity Yellow bone marrow Periosteum Nutrient foramen Epiphyseal line Articular Cartilage Right side: Epiphysis Diaphysis

Label

Define osseous tissue

Osseous tissue is another name for bone. It contains an abundant extracellular matrix that surrounds widely seperated cells

Describe the process of bone growth in diameter

Ridges in perosteum groove for periosteal blood vessels periosteal ridges fuse, forming an endosteum- lined tunnel Osteoblasts in endosteum build new concentric lamellae inward toward cennter of tunnel, forming new osteon Bone grows outward as osteoblasts in periodteum build new circumferential lamellae - repeats and build new ridges that fold over blood vessels

Classify bones according to their shapes and recognize an example for each (6)

Short-carpals or tarsals Long- Femur or ulna Flat- Scapula or cranial Irregular- facial bones sutural- between flat bones of the skull sesmoid- develop inside tendons near joints of knees, hands and feet.

nutrient foramen

a hole in compact bone. nutrient artery and vein pass through it

epiphyseal plate

a layer of hyaline cartilage in the metaphysis of a growing bone that consists of 4 zones

endosteum

a thin membrane that lines the medullary cavity

circumferential lamellae

arranged around the entire outer and inner circumference of the shaft of a long bone

Major function of osteoblasts

bone-building cells, ( produce matrix, until there is no more room and so turns into osteocyte)

Major function of osteoclasts

bone-dissolving cells found on the bone surface. secrete enzymes, break down bone.

perforating canals

canals that go horizontal in the bone. blood vessels, nerves,from periosteum penetrate compact bone through these

concentric lamellae

circular plates of mineralized extracellular matrix of increasing diameter- surrounding network of blood vessels

Define osteoporosis

condition where bone resorption outplaces bone deposition

yellow bone marrow

consist mainly of adipose cells which store triglycerides

The effects of Calcitonin on calcium homeostasis in the body

decreases blood Ca++ level

epiphyseal line

epiphyseal plate fades leaving bone structure

medullary cavity

hollow, cylindrical space with in the diaphysis that contains fatty yellow bone marrow and blood vessels in adults

The effects of Calcitrol ( vitamin D) on calcium homeostasis in the body

increases blood Ca++ level

Pink arrow- Trabeculae Yellow arrow- Perforating Canal Blue arrow- Central Canal Purple line- Haversion system Red line- Lamellae

label Components of bone

trabeculae

lamellae that are arranged in an irregular pattern of thin columns

Major function of osteocytes

mature bone cells. may build or absorb bone in helping maintain the homeostasis of bone density and blood calcium concentrations

red bone marrow

produces red blood cells, white blood cells, and platelets

Epiphysis

proximal and distal ends of the bone

canaliculi

radiating in all directions from the lacunae are tiny?

osteons

repeating structural units

lacunae

small spaces

Describe the function of the skeletal system

support protection assistance in movement blood cell reproduction triglyceride storage mineral homeostasis

Diaphysis

the bones shaft or body

articular cartilage

thin layer of hyaline cartilage covering the part of the epiphysis where bone forms articulation joint with another bone

periosteum

tough connective tissue sheath and its associated blood supply that surrounds the bone surface where it is not covered by articular cartilage