EXAM 2 JOHN REIDY (SUMMER 8 WEEK)

What are components of the skeletal system?

ligaments, bones, cartilage

Cartilage

It is more flexible than bone.

It is found in the head, arms, legs, and trunk of the body.

It contains cells and a matrix.

Growth from within cartilage is called ______.

interstitial growth

The matrix of bone is solid due to deposition of minerals in the matrix, known as_____

calcification

What is the best description of the skeletal system?

It is composed of dynamic, living tissues.

What type of tissue is cartilage?

connective

functions of cartilage

It supports soft tissues.

It provides a gliding surface at joints.

It provides a model for the formation of bones.

Growth along the periphery of cartilage is called _______growth.

appositional

Functions of bone include ______.

-support

-mineral storage

-blood cell formation

-protection

Another term for calcification is_____

mineralization

Bones provide structural support for the body by serving as a(n)_____ for the entire body.

framework

Bone A, in the picture provided, is classified as a(n) ______ bone.

Long

The elongated cylindrical shaft of a long bone is called its ______.

diaphysis

Which is a function of bone?

Protection of organs

The expanded end of a long bone is called the_____

epiphysis

Which organs are protected by bones?

brain, heart, lungs, reproductive organs

In adults, the remnant of the epiphyseal plate is the

epiphyseal line

Bone B, in the picture provided, is classified as a(n) ______ bone.

irregular

The major weight support of a long bone is provided by the______

diaphysis

What are the basic components of osteology?

bones, cartilage, ligaments/flexible organs

Bones

The rigid organs that form the frame

cartilage

pliable organs

Ligaments

flexible organs that connect Bone-to-Bone/Cartilage

Skeletal system apparent functions

•Acts as anchors and levers

•Forms the frame for the body

•Protects the viscera from injury

skeletal muscle inapparent functions

•Balances acids & bases partiallyin ExtraCellular Fluid (ECF)

•Contains HematoPoietic Tissue, i.e. Blood-Producing Tissue

•Stores energy & mineral reservoirs, e.g. Calcium (Ca2+) & Phosphate

•DeToxifies heavy metals, e.g. Lead (Pb) from ECF

A Skeletal ArcheType exists for all_______

Vertebrates

All Crania of Vertebrates evolved from________

common skeletal units

All Carpi of TetraPods evolved from______

common skeletal units

What does Cartilaginous Tissues consist of?

•Consist of ChondroBlasts that mature into ChondroCytes

•Which are in Lacunae

Produce Extra-Cellular Matrices that appear____and_______

gelatinous and semisolid

Which are AVascular so it repairs poorly

Cartilaginous tissues are made up of_____

•PeriChondrium

•Except Articular Hyaline Cartilages and all of the Fibrous Cartilages

Cartilaginous Tissues 3 major tissue types?

Hyaline Cartilage decreases friction

•Fibrous Cartilage provides durability

•Elastic Cartilage provides elasticity

ChondroGenesis proceeds by___ processes

2

Appositional Growth

•Occurs on their Cartilaginous Surfaces

•Within its PeriChondrium

Interstitial Growth

•Occurs in their Cartilaginous Matrix

•Within its Lacunae

Name the osseous tissues in order from immature to mature.

3.OsteoProGenitors

2.OsteoBlasts

1.OsteoCytes

how does the long bone grow?

What are OsteoProGenitors?

•Appear as squamous Cells

•Are ancestral MultiPotential Stem Cells

•Generate multiple OsteoBlasts

•Developing Humans to produce new Osseous Tissue

•Developed Humans to repair old Osseous Tissue

•Located in EndOsteum & in PeriOsteum

What are OsteoBlasts?

Builders

•Appear as cuboidal Cells

•Are immature “Bone Building” Cells

•Participate in OsteoGenesis

•Produce Osteoid

•Which is a pre-mineralized, gelatinous Matrix

•Secrete Proteins, e.g. Alkaline Phosphatase

•Which will mineralize the gelatinous Osteoid

•Located in EndOsteum & in PeriOsteum

What are OsteoCytes?

•Appear as stellate Cells

•Are mature “Bone Manage” Cells

•Manage organic & inorganic components of its ExtraCellular Matrix (ECM)

•Located in Lacunae separated by Lamellae

•With their processes in Canliculi

What are OsteoClasts?

Bone-recyclers cells

Where are osteoblasts located?

On bone surface, lining bone of resorption canals.

Where are osteocytes located?

Lacunae and canaliculi of bone matrix.

Where are osteoclasts located?

Bone surface, lining bone of resorption canals.

What is the function of osteoblasts?

Deposit bone matrix; initiate mineralization by releasing matrix vesicles.

What is the function of osteocytes?

Maintain bone matrix; secrete mineral-related signals, regulate calcium and phosphate homeostasis.

What is the function of osteoclasts?

Resorb bone by enzymatic hydrolysis of the mineralized bone matrix.

What is the lifespan of an osteoblast?

1-12 days.

What is the lifespan of an osteocyte?

Years (10-20 years).

What is the lifespan of an osteoclast?

3-14 days.

The ECM of Osseous Tissue include two major classes of Components. What are they?

•Organic

•InOrganic

What is the main organic component of bone?

Type I collagenous fibers.

What fraction of the extracellular matrix (ECM) is made up of the organic component?

One-third (⅓) of the ECM.

How does the organic component of bone respond to compression?

It fails under compression.

What types of mechanical stress does the organic component resist?

It resists bending and twisting.

What is the function of the organic component of bone?

Provides durability to bones.

What is OsteoGenesis Imperfecta?

•Caused by a defect in Type I Collagenous Fibers

•So their Bones fail bending & twisting

•Causes “Brittle Bones”

What is the inorganic component of bone?

Hydroxyapatite — crystals of Ca₁₀(PO₄)₆(OH)₂

What is the chemical formula of Hydroxyapatite?

Ca₁₀(PO₄)₆(OH)₂

What fraction of the extracellular matrix (ECM) is made up by the inorganic component?

⅔ of the ECM

How does the inorganic component respond to bending and twisting?

It fails — not resistant to bending or twisting

What kind of force does the inorganic component resist?

Compression

What property does the inorganic component provide to bones?

Rigidity

What is OsteoMalacia?

•Caused by deficiency of Vitamin D that causes deficiency of Calcium

•So their Bones fail compressing

•Causes “Soft Bones”

•If skeletally immature, termed Rickets

What are Osteons?

•AKA Haversian Systems

•functional/structural “Bone Units”

•Contain Central Canals

•Which contain Vein, Artery, & Nerve (VAN)

•Encircled by ConCentric Lamellae

•Interconnected by Connecting Canals

•Which contain Vein, Artery, & Nerve (VAN)

ConCentric Lamellae have Collagenous Fibers that________

•Alternate orientation

•Are helicoidal

•Resist compression/tension

•Resist rotation/separation

Lacunae contain_____

osteocytes

_______contain their processes that allow diffusion of O2, CO2, etc.

Canaliculi

_______connect a Central Canal to its central Lacunae

Canaliculi

What are the Two Types of Osseous Tissue?

osseus and spongy bone

Compact Bone

•external

•Contains dense, numerous Osteons

•Forms external Cortex

Spongy Bone

•internal

•Contains spaces between Trabeculae

•Lines Medullary Cavity & EpiPhyses

Compact Bone consists of three types of Lamellae:

Circumferential Lamellae

Concentric Lamellae

InterStitial Lamellae

Circumferential Lamellae

•covers its surface

•Which surround the Bone

Concentric Lamella

•forms its Osteons

•Which surround the Central Canals

InterStitial Lamellae

Which are between the Osteons

Compact bone forms______

the Cortices of Bones

What isCompact Bone?

•Along external Lines of Stress, Osteons conduct forces, e.g.

•Compression

•Tension

What isSpongy Bone?

•Consists of both columns and plates that form lamellaeted Trabeculae, which

•Line Medullary Cavities

•Support EpiPhyses

•Contains no Osteons

Along internal Lines of Stress, Trabeculae support the_____

cortex

What is the EndOsteum?

•Is an incomplete, single layer

•Participates in OsteoGenesis & Repair

•Lines the Medullary Cavity

What is the edosteum composed of?

•OsteoProGenitors

•OsteoBlasts

•OsteoClasts

What is the PeriOsteum anchored by?

perforating fibers

what does the periosteum consist of?

•superficial Fibrous Layer

•deeper OsteoGenic Layer

What does the periosteum contain?

•OsteoProGenitors, OsteoBlasts, & OsteoClasts

What does the periosteum cover?

external surface of the bone

Except at Articular Surfaces

Where does the periosteum attach to?

Ligaments & Tendons to Bones

The periosteum participates in____

OsteoGenesis & Repair

What does the periosteum provide route for?

•Innervation by the Nervous System

•Vascularization by the Circulatory System

How are Bones innervated?

•Bone Nerves distributed

•in the Central Canals

•regulate flow of Blood

•Bones Nerves distributed

•in the PeriOsteum

•sensitive to pain

EpiPhyseal Vessels

•both Proximal & Distal

•Vascularize the EpiPhyses

MetaPhyseal Vessels

•both Proximal & Distal

•Vascularize the DiaPhyseal Side of MetaPhyses

Diaphyseal/Nutrient Vessel

•Enters the Nutrient Foramen of the DiaPhysis

•Penetrates Cortex to enter Medullary Cavity

PeriOsteal Vessels

•distributed in PeriOsteum

•Vascularize the Circumferential Lamellae

“Red” Marrow

•Consists predominantly of HematoPoietic Tissues

•In immature Humans, is in the Medullary Cavities of all Bones

•In mature Humans, is in theMedullary Cavities of Axial Bones only

“Yellow” Marrow

•Consists predominantly of Adipose Tissue

•In mature Humans, replaces “Red” Marrow in Appendicular Bones only

Three factors effect Ossification

•EndoCrine Signals, i.e. Hormones

•Nutrients

•Vitamins

growth hormone

hormone secreted by anterior pituitary gland that stimulates growth of bones

thyroid hormone

modulates activity of growth hormone, ensuring proper proportions

calcitonin

Lowers blood calcium levels