Unit 3 - Skeletal System

Collagen fiber function

Promote tissue flexibility; affords great strength

Adipose tissue function

Serve as energy reserve; support

Which tissues relate to the skeletal system

1. Connective 2. Muscular

Endochondral Ossification sequence of events

1. Development of cartilage model 2. Growth of cartilage model 3. Development of primary ossification center 4. Development of medullary (narrow) cavity 5. Development of secondary ossification centers 6. Formation of articular cartilage and epiphyseal plate

Intramembranous ossification sequence of events

1. Development of ossification center 2. Calcification 3. Formation of trabeculae 4. Development of periosteum

Three types of cartilage

1. Hyaline 2. Fibrocartilage 3. Elastic

When does bone formation occur (should be 4)

1. Initial formation of bones in embryo and fetus 2. Growth of bones during infancy, childhood, and adolescense 3. Bone Remodeling 4. Repairing fractures throughout life.

Two methods of ossification

1. Intramembranous ossification 2. Endochondral ossification

Factors that control bone growth, bone remodeling, and repairment of fractured bones

1. Minerals (need adequate amounts of Ca, P, Mg) 2. Vitamins (A, C, D) 3. Hormones (hGH, IGF, insulin, thyroid hormone, parathyroid, calcitonin) (hGH creates dwarfism or gigantism if its under secreted or over secreted) 4. Stress (heavily stressed bones are thicker: unstressed bones are weak)

4 types of fractures

1. Partial 2. Complete 3. Closed(Simple) 4. Open(Compound)

Functions of bone tissue

1. Support soft tissue 2. Protects delicate structures 3. Works with skeletal system to generate movement 4. Mineral storage 5. RBM storage 6. Triglyceride storage

At what age does your bone stop growing in length

18-25

Bones store ___% of the body's calcium

99%

Complete fracture

A break across a bone; broken into two or more pieces

What is ground substance

A medium between blood and cells that supports and binds cell

Bone formation

Addition of minerals and collagen fibers to bone by osteoblasts

What types of cells are found in bone tissue

Adipocytes, mast cells, fibroblasts, microphage (fat cells), and plasma cells

Partial fracture

An incomplete break across the bone, a crack

Fracture

Any break in a bone

Assistance in movement (function of bone)

Attachment of bone to muscle, muscles contract and pulls on the bone

Are tendons vascular or avascular?

Avascular

Is cartilage vascular or avascular

Avascular

Examples of serious bone health risks

Bedridden or paralyzed patients Weightlessness environment (space)

What happens if there is excessive loss of calcium or tissue

Bone is weakened, it becomes overly flexible and vulnerable to a fracture

Formation of Trabeculae (Intramembranous ossification step)

Bone matrix forms, develops into trabeculae. Connective tissue near blood vessels in trabeculae differentiate into Red Blood Marrow.

Development of secondary ossification center (Endochondral Ossification step)

Branch of epiphyseal artery enters epiphyses, secondary ossification centers develop around birth time, spongy bone remains in interior of epiphyses. No medullary cavities formed. Proceeds outward from center of epiphyses toward bone surface.

Effect of low blood calcium level

Breathing may cease

Function of bone in calcium homeostasis in blood calcium levels

Buffer blood calcium level, releasing Ca+2 to blood when blood calcium levels fall, depositing Ca+2 back when blood levels rise

Blood clotting requires

Ca+2

Enzymes require what as a cofactor

Ca+2

Nerve cell functions depend on the right levels of

Ca+2

What other hormone is involved in calcium homeostasis; what produces this hormone

Calcitonin (CT); thyroid gland

Growth of cartilage model (Endochondral Ossification step)

Chondroblasts become chondrocytes, cartilage model grows, cells grow, some cells burst or lose contents. pH of surrounding matrix change that triggers calcification. Other cells die and lacunae form and slowly merge into cavities

What type of ground substance is found in bone tissue

Chondroitin sulfate

Types of fibers found in bone/skeletal muscle tissue

Collagen, elastic, and reticular fibers

Fibrocartilage: consists of, lacks, properties, and location

Consists of: chondrocytes scattered among bundles of collagen fibers Lacks: Perichondrium Properties: strength and rigidity Location: discs between vertebrae, pads of knees

Elastic cartilage: consists of, properties, and location

Consists of: chondrocytes within thread like network of elastic fibers Properties: Strength and elasticity, maintains shape of structures Locations: auricle of external ear, epiglottis and part of larynx, auditory canal

Hyaline Cartilage: consists of, properties, and location

Consists of: resilient gel as its ground substance, appears as bluish-white shiny substance Properties: Compressible, flexible, insensitive Locations: ribs to sternum, supporting larynx, trachea, and bronchia; bone ends at synovial joints; part of large septum

Cartilage consists of

Dense network of collagen fibers

How is cartilage different from other types of connective tissue

Doesn't have blood supply or nerves, secretes antiangiogenic factors

When does ossification begin

During the 6th week of embryonic development and follows one of two patterns

What appears when your bone stops growing in length

Epiphyseal line

Reticular connective tissue function

Filters and removes worn-out blood cells; forms scaffolding for bone marrow

Muscular tissue

Generates the physical force to move body structures

Synovial Membrane

Flat sheets of pliable tissue that line the cavities of some joints

Hemopoiesis

Formation of blood cells

What happens if too much mineral is deposited

Formation of thick bumps, spurs, which interfere with joint movements

Intramembranous ossification

Forms flat bones of skull, facial bones, mandible, and clavicle. It replaces soft spot on fetal skull

Closed (simple) fracture

Fracture that does not penetrate the skin

Open (compound) fracture

Fracture that does penetrate the skin

Support (function of bone)

Framework of the body, supports soft tissue, provides points of attachment for skeletal muscles and tendons

What is the texture of the extracellular matrix of bone

Hard and not pliable

What does vascular mean

Having a rich blood supply

Effect of high blood calcium level

Heart may stop

Connective tissue consists of

Highly vascular cells and extracellular matrix-has nerve cells

Formation of articular cartilage and epiphyseal plate (Endochondral Ossification step)

Hyaline cartilage covering epiphysis becomes articular cartilage. Prior to adulthood hyaline cartilage remains between diaphysis and epiphyses as epiphyseal plate = lengthwise growth of bones. Growth stops between ages 18-25, cartilage replaced by bone = epiphyseal line.

Where does endochondral ossification occur

Hyaline cartilage that develop from mesenchyme

Development of primary ossification center (Endochondral Ossification step)

Inward from external surface of bone, nutrient artery penetrates perichondrium stimulating osteogenic cells to differentiate into osteoblasts. Perichondrium starts to form bone now known as periosteum. Periosteum capillaries grow into disintegrating calcified cartilage. Primary ossification center forms bone tissue that replaces cartilage. Osteoblasts deposit bone matrix forming spongy bone trabeculae. Osteoblasts break down trabeculae at bone ends leaving a cavity, medullary cavity fills with red blood marrow.

Synovial Membrane location, type, and function

Location: joint area of bones Types: Areolar connective tissue adipose tissue and collagen fiber Function: secretes synovial fluid from synoviocytes that lubricates the end of a bone as the move at the joint, nourishes cartilage, removes microbes and debris from joints

Development of ossification center (Intramembranous ossification step)

Mesenchymal cells cluster and differentiate into osteogenic cells and then into osteoblasts, which secrete organic extracellular matrix of bone until trapped/surrounded

Development of cartilage model (Endochondral Ossification step)

Mesenchymal cells crowd into shape of future bone develop into chondroblasts that secrete cartilage matrix. Consists of hyaline cartilage. Perichondrium develops around cartilage model.

Where does intramembranous ossification occur?

Mesenchyme arranged in sheet layers

Development of Periosteum (Intramembranous Ossification step)

Mesenchyme condenses at periphery and develops into periosteum. Thin layer of compact bone replaces surface layer of spongy bone.

What is the embryonic skeleton composed of?

Mesenchyme shaped like bones, sites/templates where ossification occur

Bone Growth in length

New chondrocytes are formed on epiphyseal side of plate, old chondrocytes and diaphyseal side are replaced by bone thus thickness of epiphyseal plate remains constant but on diaphyseal side it increase.

Do all types of connective tissue have nerves? If some do not, name them

No; cartilage and tendons

Growth in thickness

On surface, cells in the perichondrium differentiate into osteoblasts, lamella are added to the surface of the boe, new osteons of compact bone tissue.

Bone remodeling

Ongoing replacement of old bone tissue by new bone tissue

Types of bone tissue

Osseous tissue Periosteum Red/Yellow Blood Marrow Endosteum

Main component of compact bone

Osteon of Haversion system

What hormone regulates Ca+2; what produces this hormone

Parathyroid hormones; parathyroid gland

What surrounds the surface of cartilage

Perichondrium (dense irregular connective tissue)

Cell junctions

Point of contact between plasma membranes of tissue cells

Development of medullary cavity (Endochondral Ossification step)

Primary ossification center grows towards ends of bone. Osteoclasts break down some of the newly formed spongy bone trabeculae. Activity leaves a cavity, medullary, in the diaphysis. Diaphysis is replaced by compact bone.

Tissue Repair

Process that replaces worn out, damaged, or dead cells

Blood cell production (function of bone)

Produces red and white blood cells and platelets in connective tissue and developing bones

Protection (function of bone)

Protect brain, spinal cord, and vital organs

Connective tissue

Protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity

Extracellular matrix consists of

Protein fibers and ground substance

Elastic fiber function

Provide elasticity for parts of body that are easily and constantly stretched

Dense regular connective tissue function

Provides strong attachment between structures

Reticular fiber function

Provides support and strength; forms stroma and basement membrane

Resorption

Removal of minerals and collagen fibers from bone by osteoclasts; results in destruction of bone extracellular matrix

Endochondral Ossification

Replacement of cartilage by bone; most bone if formed this way

Calcification (Intramembranous Ossification step)

Secretion of extracellular matrix stops. Osteocytes lie in lacunae and extend narrow cytoplasmic processes into canaliculi. Calcium and other mineral salts are deposited. Extracellular matrix calcifies.

What type of muscular tissue if found in bone

Skeletal muscle tissue

Fiber function

Strength and support

Functions of Bone and the Skeletal System

Support, protection, assistance in movement, mineral homeostasis, blood cell production, triglyceride storage

Ossification

The process of bone formation, located in loose fibrous connective tissue membranes and pieces of hyaline cartilage, shaped like bones in embryonic skeletons

Main component of spongy bone

Trabeculae

How does calcium become available to other tissues

When it is broken down during remodeling

Triglyceride storage (function of bone)

Yellow marrow contains adipose tissue that stores triglycerides to be used as energy; found in adults as red blood cells turn into yellow blood cells as you age

Bone connective tissue has a continuous capacity for renewal because it has an

ample blood supply

Cartilage resilience is due to

chondroitin sulfate

Cartilage strength is due to

collagen fibers

Male skeletal bones are_____ than female skeletal bones

larger

Where does ossification occur

loose fibrous connective tissue membranes and pieces of hyaline cartilage shaped like little bones in embryonic skeleton

Cartilage does not have a continuous capacity for renewal because of

poor blood supply

Dense irregular connective tissue function

provides pulling strength

Lacunae

small cavities in bone that contain osteocytes

Mineral Homeostasis (function of bone)

stores calcium and phosphorus--minerals are released into the blood when needed