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