what is? hematopoiesis
DESCRIPTION
What is? Hematopoiesis. Bone Formation. Fetal INTRAMEMBRANOUS OSSIFICATION ENDOCHONDRAL OSSIFICATION From birth to young adult APPOSITIONAL (flat, short, irregular bones) Increase diameter for ALL bones INTERSTITIAL (EPIPHYSEAL PLATE) Increase length. SKELETAL TISSUES CHAPTER 7. - PowerPoint PPT PresentationTRANSCRIPT
What is?
Hematopoiesis
Bone Formation• Fetal
– INTRAMEMBRANOUS OSSIFICATION– ENDOCHONDRAL OSSIFICATION
• From birth to young adult– APPOSITIONAL (flat, short, irregular
bones)• Increase diameter for ALL bones
– INTERSTITIAL (EPIPHYSEAL PLATE)• Increase length
SKELETAL TISSUESCHAPTER 7
By John McGillSupplement Outlines: Beth WyattOriginal PowerPoint: Jack Bagwell
INTRODUCTION TO THE SKELETAL SYSTEM
STRUCTURE
• Organs: Bones• Related Tissues: Cartilage and Ligaments
PRIMARY FUNCTION
• Support
PRIMARY TISSUES OF THE SKELETAL SYSTEM• BONE TISSUE• CARTILAGE
• These are both Connective Tissues
MACROSCOPIC STRUCTURE:
Long Bones• DIAPHYSIS
– Shaft– Composed of Compact
Bone• EPIPHYSES
– Both Ends Composed of Cancellous Bone
• ARTICULAR CARTILAGE– “Joining Cartilage”– Covers Epiphyses (Thin
Layer)– Provides Cushioning at
Joints
MACROSCOPIC STRUCTURE: Long Bones
PERIOSTEUM
• Bone’s Covering• White• Thin but Tough• “Welded” to Underlying Bone• Contains Blood Vessels
MEDULLARY (MARROW) CAVITY• Space Within the Diaphysis• Contains Bone Marrow
ENDOSTEUM
• Lines the Medullary Cavity• Thin
MACROSCOPIC STRUCTURE:
SHORT, FLAT, IRREGULAR BONES
• “spongy bone”
Inner Portion: Cancellous Bone
• dense and solid
Surfaces: Compact Bone
Periosteum Present
MICROSCOPIC STRUCTURE OF BONE: COMPACT
BONE: • HAVERSIAN
SYSTEMS (OSTEONS)– Microscopically,
Compact Bone is Composed of Haversian Systems
– Haversian Systems: Microscopic Structural Units of Compact Bone
Microscopic structure - Haversian SystemHaversian system (osteon)- consists of the canal and surrounding structures
Lamellae – concentric layers of calcified matrix
Lacunae – “little lakes”; where the bone cells live
Canaliculi – very small canals that radiate from the lacunae; carry nutrients
Haversian canal – central canal which carries blood vessels
FUNCTION OF HAVERSIAN SYSTEMS
• Blood Supply to Compact Bone• Periosteum Haversian Canals Canalculi
Lacunae
BONE (MICROSCOPIC VIEW)
canaliculi osteocyte in lacunae
Haversian canal
ossified matrix (lamellae)
CANCELLOUS BONE: TRABECULAE
• Trabeculae: Needlelike Pieces of Bone (Surround Spaces)
• Contains Osteocytes• How Cancellous Bone Gets Its Blood Supply:
– Periosteum Bone Marrow Openings in Trabeculae
BONE TISSUE isOSSEOUS TISSUE
COMPONENTS: MATRIX, PROTEIN FIBERS, CELLS• Typical Connective Tissue
COMPOSITION OF BONE MATRIX• INORGANIC COMPONENTS
• Minerals (Esp. Ca and Phosphate)• Forms hydroxyapatite
• Gives Matrix Hardness and Strength• ORGANIC COMPONENTS
• Complex Mixture of Carbohydrates and Proteins• Gives Matrix Strength
• PROTEIN FIBERS: COLLAGENOUS
Types of BONE CELLS• OSTEOBLASTS
– Bone-Forming Cells– Location: Periosteum (Primarily)
• OSTEOCLASTS– Bone-Destroying Cells– Location: Endosteum (Primarily)
• OSTEOCYTES– Bone Cells (Mature Osteoblasts)– Locations:
• 1) Compact Bone: Lacunae• 2) Cancellous Bone: Trabeculae
BONE MARROW is MYELOID TISSUETissue Type: Connective Tissue• Reticular
LOCATIONS
• Long Bones: • Medullary Cavity• Epiphyses: • Spaces in Cancellous
Bone• Short, Flat, Irregular Bones: • Spaces in Cancellous Bone
Myeloid tissue is a biologic tissue with the ability to perform hematopoiesis.
BONE MARROW TYPES: RED MARROW
• DESCRIPTION/FUNCTIONS– Red in Color Because
Functions in Hematopoiesis• LOCATIONS
– Children: All Bones Contain Red Marrow
– Adults: Certain Bones Contain Red Marrow• Flat Bones of the Skull• Sternum, Ribs, Vertebrae• Pelvic Bones• Epiphyses of Humerus and Femur
BONE MARROW TYPES: YELLOW MARROW
• DESCRIPTION/FUNCTIONS– Yellow in Color
Because Contains Largely Adipose Tissue
– Yellow Marrow Was Once Red Marrow, Now Yellow B/C
– It No Longer Functions in Hematopoiesis
• LOCATIONS– Most Bones in Adults
Contain Yellow Marrow
Functions of Bones• Support
– support the weight of the rest of the body• Protection
– protect the delicate body parts• Movement
– muscles attach to bone and allow movement• Mineral storage
– calcium, phosphorous, and other minerals are stored in the bone
• Hematopoiesis– red marrow plays an important role in the
formation of red blood cells, some flat bones also play a role here
Fetal Bone FormationOsteogenesis
• The cartilaginous skeleton is changed to bone in one of two ways:– Intramembranous ossification– Endochondral ossification
#1. INTRAMEMBRANOUS
OSSIFICATION
• How Bones Form in the Fetus– DEFINITION
• “Within Membrane Bone Formation”
• Method by Which Flat Bones Form
• MECHANISM– Connective Tissue Membrane – Cells Develop Into Osteoblasts – Secrete Organic Matrix and
Collagenous Fibers– Calcification Occurs
• Intramembranous bone formation in a fetal pig skull.
• Flat bones of the skull develop by IO.
• Embryonic mesenchyme cells form a membrane (Mes) &
• differentiate into osteoblasts that• form bony spicules or cancellous
bone (CsB). • Eventually osteonsform.
#2. ENDOCHONDRAL OSSIFICATION• ENDOCHONDRAL OSSIFICATION
– DEFINITION• “Within Cartilage Bone
Formation”• Method by Which Most
Bones Form– MECHANISM
• Cartilage Model • Periosteum Forms • Cells Develop Into
Osteoblasts • Secrete Organic Matrix
and Collagenous Fibers• Calcification Occurs
– *Note: In Both Types of Ossification: • Osteoclasts Resorb
Bone • Forms Medullary Cavity,
Spaces in Cancellous Bone
• Embryonal hyaline cartilage is model for bone formation.
• Osteoblasts begin to calcify the cartilage
• Osteoblasts and osteoclasts are constantly reshaping the bone
• Epiphyseal plate is site of continued bone growth; indicates the bone is not yet mature.
Bone Growth - Animation
• http://www.anatomy.gla.ac.uk/fab/tutorial/generic/bonet.html
FETAL SKELETON
BONE GROWTH AND RESORPTION• How Bones Increase in Size after Birth
– FLAT BONES (Also Short, Irregular Bones) grow by APPOSITIONAL GROWTH
– Growth By Adding to the Surfaces– LONG BONES grow in length by EPIPHYSEAL
PLATE• Epiphyseal Plate: Layer of Hyaline Cartilage That
Lies B/T Epiphyses and Diaphysis• Didn’t Ossify During the Fetal Period (Purpose: To
Allow Bone Growth in Length)• Epiphyseal Plate 1) Thickens and 2) Ossifies
Repeatedly• When Growth in Length is Complete, Cells in EP
Stop Mitosis and the Entire Plate Ossifies, What Remains is Epiphyseal Line
EPIPHYSEAL PLATE
Epiphyseal PlateThe epiphyseal plate allows for growth in bones.
GROWTH IN DIAMETER – COMBINED ACTION OF OSTEOBLASTS AND OSTEOCLASTS
• Osteoblasts (Periosteum) Build New Bone on the Outer Surface
• Osteoclasts (Endosteum) Destroy Bone from the Inner Surface of the Medullary Cavity (Enlarges Med. Cavity)
• http://www.youtube.com/watch?v=6Cn4uusbGk8
BONE GROWTH AND RESORPTION• BONE GROWTH AND RESORPTION
THROUGHOUT LIFE– Both Growth and Resorption Go On
Throughout Life, But at Different Rates• From Infancy Young Adulthood: Growth
EXCEEDS Resorption (Bones Grow and are Thick)
• During Late 20’s/Early 30’s: Growth EQUALS Resorption (Bones Remain Relatively Constant)
• From Mid 30’s/Early 40’s Old Age: Resorption EXCEEDS Growth (Bones Become Thinner, More Susceptible to Fracture and Disease)
BONE GROWTH AND RESORPTION
• BONES RESPONSE TO STRESS– Bone Stress = Weight Bearing Applied
to Bones– Bone Stress Increases the Activity of the
Osteoblasts (Helps Offset the Effects of Aging on Bones)
REPAIR OF BONE
FRACTURES
• FRACTURE: A Break in the Continuity of Bone
FRACTURE HEALING
• VASCULAR DAMAGE– Damage to Blood
Vessels
FRACTURE HEALING
• FORMATION OF FRACTURE HEMATOMA– Blood Clot Forms in
the Area of the Fracture in Order to Stop Bleeding
FRACTURE HEALING• FORMATION OF
CALLUS TISSUE– Thickened Repair
Tissue That Binds the Ends of the Bones Together (Reason That the Fracture is Aligned and Immobilized)
FRACTURE HEALING
• REPLACEMENT BY BONE– Callus Tissue
Becomes Bone (Action of Osteoblasts), Remodeled by Osteoclasts
Epiphyseal Plate Fracture
CARTILAGE• CHARACTERISTICS
– MATRIX• FIRM/FLEXIBLE GEL
– PROTEIN FIBERS• COLLAGENOUS
– CELLS• CHONDROCYTES• Chondrocytes Lie in
Lacunae– AVASCULAR: Oxygen
and Nutrients by Diffusion
Similarities and Differences
Bone Cartilage
f l
Similarities and Differences
Bone Cartilage
ChondrocytesJoints,avascul
arGel matrix
CollagenGround substance/matrixCellsProtectionConnective tissueMitosis (both grow)Appositional, insterstitialLacunae
CARTILAGE: Types
• Hyaline• Elastic• Fibrocartilage
HYALINE CARTILAGE• Most Abundant and
Common• Shiny• Semitransparent• Locations:
– Articular Cartilage– Costal Cartilages– Cartilage Rings in
Trachea and Bronchi– Tip of Nose
ELASTIC CARTILAGE• Has Fewer Collagenous
Fibers Compared to Hyaline
• In Addition, Contains Elastic Fibers
• Locations: – External Ear– Epiglottis– Eustachian Tube
FIBROCARTILAGE• Cartilage With the
Most Collagenous Fibers
• Locations: – Symphysis Pubis– Intervertebral Disks– Menisci in Knee
GROWTH OF CARTILAGE• INTERSTITIAL (ENDOGENOUS)
GROWTH– DEFINITION: “Growth From Within”– OCCURS WHEN: During Childhood and
Adolescence• APPOSITIONAL (EXOGENOUS)
GROWTH– DEFINITION: “Growth by Adding to the
Surfaces”– OCCURS WHEN: During Adulthood