Anatomy and Physiology Chapter 6 (e2)

Ossification

(Osteogenesis) Formation of bone by osteoblasts. Occurs by appositional growth on the surface of pre-existing bone or cartilage. -ex; Bone matrix produced by the osteoblasts covers the older bone surface and surounds the osteoblasts and cell bodies. Results in New layer of bone

Perichondrium

-Double-layered sheath of dense irregular connective tissue (containing fibroblasts) that surrounds elastic and most hyaline cartilage. Protect inner more delicate layers (containing chondroblasts) Provides nourishment to cartilage's chondrocytes.

Trabeculae

-Latticework of thin plates of bone, filled with bone marrow and blood vessels. Oriented along lines of stress to provide structural strength.

Hyaline Cartilage

-Most common cartilage, is the precursor for most bones in the body. -Bone lengthening and bone repair. -Consists of specialized cells: - chondroblasts>chondrocyte>lacuna

Ruffled border

-Reabsorption-specific area of membrane -ATP powered H+ pumps created acidic environment The side of the osteoclasts facing the bone surface. Several deep infoldings of the plasma membrane which increases surface area and resorption

Bone repair

1) Hematoma formation 2) Fibrocartilagenous callus formation (osteoblasts, fibroblasts, collagen) 3) Bony callus formation. Its a combination of endochondral and intermemranous bone formation, with coordinated remodeling and resorption. -calluses become ossified to be woven bone. -woven bone replaced by compact bone

What percent organic is mature bone?

35%

What percent of inorganic material is mature bone?

65%

Periosteum

A dense membrane composed of fibrous connective tissue that closely wraps (invests) all bone, except that of the articulating surfaces in joints, which are covered by a synovial membrane.

epiphyseal plate

A thin wall of cartilage separating the primary and secondary marrow cavities at one or both ends of the bone. Comes from the cartilage model. Serves as growth zone for bone elongation

After an osteoblast is surrounded by bone matrix this is what is is referred too

An Osteocyte

Integrin

Anchor the cell(osteoclast) to the extracellular matrix b) sense mechanical forces at anchoring points

Lacunae

Another word for "lake" contains osteocyte in its fluid.

Yellow Marrow

Appears after birth, mostly adipose tissue. Consists of fat.

Osteoblasts

Bone Forming cells. -extensive endoplasmic reticulum, many ribosomes. -Produce collagen and proteoglycans which are packaged and shipped into vesicles by Golgi Apparatus and released from cells by exocytosis. -Also release Matrix Vesicles -Ossification

The Four Components of the Skeletal System

Bones, cartilage, tendons, ligaments.

What are the spaces occupied by osteocyte cell processes?

Canaliculi

Bone Reabsorption Process

Carried out by mature osteoclasts. 1. Osteoclast must access bone 2. Form attachment via interactions w cell surface proteins called "Integrins" 3. Podosomes develop and seal in osteoclast below forming a "Ruffled Border"

Interstitial Growth

Cartilage Growth -chondrocytes within the tissue divide and add more matrix between the existing cells.

Appositional Growth

Cartilage growth -chondroblasts in perichondrium add new cartilage to the outside edge of the existing cartilage. -Chondroblasts lay down new matrix and add new chondrocytes to the outside of the tissue.

Chondroblasts

Cartilage producing cell. -Specialized cell that produces matrix surrounding themselves, and after they are fully encased, they become (???-cytes).

Lacuna

Cavities containing osteocytes, arranged in concentric rings called lamellae, around the central canal. -Within matrix, containing collagen(strength) and proteogylcans(trap water for resilience)

Organic Material In Bone

Consists of 35% of total bone. -Primarily collagen and proteoglycans. -Flexible strength in bone(Steel bars)

Inorganic Material in Bone

Consists of 65% of total bone. -Primarily a type of calcium phosphate crystal called Hydroxyapetite. CA10(PO4)6(OH)2 -Brittle, weight bearing strength(Concrete)

Endosteum

Contains osteoprogenitor cells, osteoblasts, and osteocytes used for bone growth, repair, and remodelling -Lines cavities inside of bones.

Articular cartilage

Covers the ends of bone, protection during movement and cushions jars and blows to the joint. -No perichondrium, blood vessels, or nerves.

Remodeling

Coverts woven bone to lamellar bone and allows bone to change shape, repair, regulate.

Epiphyses

Ends of long bone (contains red marrow).

Which type of cartilage is most associated with bone?

Hyaline

Three Types of Cartilage

Hyaline cartilage, Fibrocartilage, elastic cartilage.

What are the spaces occupied by osteocyte cell bodies?

Lacunae

Woven bone is remodeled into what?

Lamellar bone

Connect Bone to Bone

Ligaments

Canaliculi

Little canals; spaces that are occupied by osteocyte cell process's . How osteocytes retrieve nutrients

What bones have an outer covering made of compact bone surrounding spongy bone?

Long, Short and Irregular

Bone Shapes

Long, flat, short, irregular

Osteoclasts

Massive, multinucleated Bone-Destroying cells, formed in red bone marrow/ macrophage. -Break down bone matrix for remodeling and for the release of calcium and phosphorus to be used by metabolic processes.

Chondrocyte

Matured type of cartilage cells that grown in the lucuna. Rounded. Surrounded in matrix. (was once a ...blast)

Bone Cells

OsteoBlasts, OsteoCytes, OsteoClasts.

Periosteum components

Outer layer contains blood vessels and nerves. Inner layer contains osteoblasts , osteoclasts, and ostechondral progenitor cells Fibers hold the periosteum, ligaments, and tendons in place

Endochondral Ossificaton

Process of transforming cartilage into bone- hyaline cartilage template forms, osteoblasts migrate in and produce spongy bone (primary ossification center), other osteoblasts produce compact bone beneath the periosteum, osteoclasts break down spongy bone, creates medullary cavity. Doesnt form on articular ends of bones, andd the epiphyseal plate does not ossify

Intramembranous Ossification

Produces the flat bones of the skull and most of the clavicle (collarbone). Such bones develop within a fibrous sheet similar to the dermis of the skin, referred to as dermal bones(8 weeks) Soft Spots! Grown OUT, so outer edges of bone(skull) are weakest.

Compact bone Canals

Provide gasses nutrients, wastes in and out of bone (through caniculi) to osteocytes.

Compact Bone

Provides strength for weight bearing. In long bones, designed for rigidity and attachment of muscles and ligaments, the amount of this bone is greater near the middle of the shaft (body) of the bone, where it is liable to buckle. Living bones have some elasticity (flexibility) and great rigidity (hardness) -Forms osteons -surround central canals -exchange of gasses, nutrients, ect -llamellae form outside of this bone.

Osteogenesis

Second name for ossification. Formation of bone by osteoblasts. Occurs by appositional growth on the surface of pre-existing bone or cartilage. Adds new layers to bones.

Diaphysis

Shaft of long bone

Red Marrow

Sight of blood cell production

Epiphyseal plate

Site if lengthwise bone growth

Fontanels

Soft Spots(INTRAmembranous ossification)

Tendons

Strong bands of connective tissue that connect Muscle to Bone

Ligaments

Strong bands of fibrous connective tissue that connect Bone to Bone.

Functions of the Skeletal System

Support, Protection, Movement, Storage, Blood Cell Production. (SPMSB) "Someone Please Make Special Brownies"

Connect Muscle to Bone

Tendons

The composition of what defines the characteristics of the bone?

The Extracellular Bone Matrix

Bone remodeling

The process of removing old bone and adding new bone (osteoclasts job)

Calcium Homeostasis

The regulation of calcium homeostasis is achieved through the combined interaction of PTH and calcitonin. -small intestine, urine, absorption. -calcitonin reduces blood CA levels by decreasing bone breakdown.

osteon

The unit of combact bone, also called a Haversian system. They are essentially long cylinders of bone; the hollow center is called the central canal, and is where blood vessels, nerves, and lymphatic vessels are found. Compact bone is laid down around the central canal in rings (lamellae).

Stem Cells

The unspecialized cells from which specialized cells develop. Found in blood marrow.

Lamellae Combine to form

Trabeculae, beams of bone that interconnect to for spongy bone's lattice-like shape

Lamellar Bone

a mature bone thats organized into thin sheets or layers called lamellae, which have collagen fivers oriented parallel to each other.

How do bones adjust to stress?

adding new bone by realigning bone through remodeling.

Trabeculae grow by

appositional growth

Bones increase in size only by

appositional growth, the additional growth of new bone to surface of old bone

Osteocytes

become relatively inactive after the stage of being osteoblasts. Dont make near as much bone matrix as they did, but do make enough to maintain bone.

Osteogenesis Imperfecta

brittle bone disorder.

Podosome

integrins group in clusters around an area to form a suction cup-like structure; macrophages and osteoclasts; for osteoclasts, surrounds the cavity in the cell is making in the bone to keep cell there, but also to keep enzymes and acids from escaping area where osteoclast is degrading the bone

Matrix Vesicles

membrane-bound sacs formed when the plasma membrane buds, or protrudes outward, and pinches off. (Bone formation) -created by osteoblasts -Form Hydroxyapetite crystals to plant new "seeds" -Ca2+ & PO4^3-

Calcitonin

reduces blood CA levels by decreasing bone breakdown.(calcium homeostasis)

Medullary cavity

space within the diaphysus, Hollow space within the center of the diaphysis, filled with yellow bone marrow, which is mostly fat cells.

Osteochondral Progenitor Cells

stem cells that can become osteoblasts or chondroblasts. These cells are found in the inner layer of the perichondrium and in connective tissue.

Woven Bone

the collagen fibers are randomly oriented in many directions.First formed during fetal development or during fractures. Osteoclast break this type of bone down to build new matrix.

How do Collagen Fibers of Lamellae lie

they lie parallel to one another, but an angle to the collagen fibers in the adjacent lamellae.

Spongy Bone has

type of bone that has many spaces in between each cell, lattice-like structure