Skeletal System (KT) Flashcards
What are the 2 divisions of the skeletal system?
- Axial
2. Appendicular
What components make up the axial skeleton?
Head, center of body, skull, ribs, vertebral column
What components make up the appendicular skeleton?
Movements, limbs, pelvis
2 types of bone tissue
- Compact
2. Spongy
How much percent of total body mass are the bones?
20%
Components of the skeletal system? (4)
- Cartilage
- Bone
- Tendons
- Ligaments
Functions of skeletal system? (5)
- Protection
- Support (rigid support)
- Movement (bones act as levers)
- Storage (Ca, P, and fat)
- Blood cell production
Cartilage cells are called…
Chondrocytes
Where are chondrocytes found…?
Chondrocytes are found in compartments called lacunae
What is the extracellular matrix of cartilage?
- Collagen and elastic fibers
- Ground substance of chondroitin sulfates
Does cartilage have arteries, veins, or lymphocytes?
No.
- That’s why it heals slowly- because not a lot of nutrients getting in
What types of cartilage are there…? (3)
- Hyaline
- Elastic
- Fibrocartilage
Cartilage that…
- is the most common
- weakest concerning tensile strength
- found in places that can be compressed
- lack fibers
Hyaline Cartilage
Hyaline Cartilage Structure (3)
- Chondrocytes
- Chondroitin
- Some collagen
Location of Hyaline Cartilage (5)
- Embryonic Skeleton
- Articular surfaces
- Respiratory passages
- Nasal Septum
- Between ribs and sternum
Cartilage that…
- is elastic yet still needs compression
- flexible, maintains shape but recoils and pushes back
- Ex. nose, ear, epiglottis
Elastic Cartilage
Elastic Cartilage Structure (3)
- Chondrocytes
- Chondroitin Sulfate
- Densely packed elastic fibers
Locations of Elastic Cartilage
- nose,
- ear
- epiglottis
Cartilage that…
- is very strong
- need tensile resistance AND compression resistance
Fibrocartilage
Structure of Fibrocartilage (3)
- Chondrocytes
- Chondrotin Sulfate
- Densely packed collagen fibers
Location of Fibrocartilage (3)
- Intervertebral Disc
- Pubic Symphysis
- Articular Cartilage in Knee
Fibrous connective tissue that surrounds cartilage
Perichondrium
What does perichondrium provide…? (2)
- Support & Protection
2. New Chondrocytes
Locations of Perichondrium (2)
- Hyaline Cartilage
2. Elastic Cartilage
Where is perichondrium absent from…? (2)
- Articular surfaces
2. Fibrocartilage
How many layers does the perichondrium have?
2
What are the layers of the perichondrium?
- Outer
2. Inner
Binds cartilage to adjacent tissues; provides support and protection
Outer layer of perichondrium
Layer for growth and maintenance
Inner layer
- Have cartilage, it expands outward by growing from its own ledge
- this is facilitated by the perichondrium
Appositional Growth
Appositional Growth Steps (6)
- Starts in the Perichondrium
- Mesenchymal (stem) cells at periphery form in inner layer of perichondrium
- Mesenchyme move toward the matrix to become chondrogenic cells
- Chondrogenic cells aggregate and become chondroblasts
- Chondroblasts secrete ,matrix and force cells apart
- Chondroblasts become enclosed in matrix and become chondrocytes
Is Appositional Growth a Fast or a Slow Process?
Slow- because there is no blood supply, oxygen, and glucose
- Internal cartilage growth
- Chondrocytes are enclosed in matrix and divide
- As they move apart, the matrix forms between them
Interstitial Growth
Characteristics of Osseous Tissue (3)
- Supportive CT
- Contains specialized cells
- Solid extracellular matrix
Solid Extracellular Matrix
fibrous
-Osteoid
What components make up the osteoid? (2)
- Organic Portion
2. Protein fibers
Ground Substance of Osseous Tissue
- Ca salts (forms mineralized salts
- water
- Mesenchyme bone cell
- Predecessor to osteoblasts
- Play a role in initial bone growth and fracture repair
Osteoprogenitor
Bone cell that…
- Is derived from osteogenic cells
- secrete osteoid
- common in growing bone
- predecessor to osteocytes
- Increased osteoblast activity=stronger bone
Osteoblasts
Bone cells that... -Are mature cells -Exist within matrix -Maintain Ca and PO4 homeostasis -
Osteocytes
Bone cells that…
- involved in the breakdown of bone
- very large
- increased osteoclast activity –> weaker bone
Osteoclast
How are osteoclasts formed?
Formed by the fusion of many white blood stem cells
Inorganic Materials of Bone Matrix
- 65%
- Brittle Salts
- Na, K, Mg
Organic Materials of Bone Matrix
- Osteoid
- 35%
- Flexible Fibers aka collagen, glycoproteins, and proteoglycans
How are compact bones arranged?
Osteons
How are spongy bones arranged?
Trabeculae
-Communicate through canaliculi that radiate outward and connect one cell to the next cell
Osteocytes
A unit of compact bone
Osteon
Osteons consist of… (2)
- Concentric lamellae of matrix surrounding a central (Haversian) canal
- Contains blood vessels and nerves
How are osteons connected to eachother?
Perforating Canals
Types of Lamellae (3)
- Concentric
- Interstitial
- Circumferential
- Layers of bone surrounding the central canal
- Make up osteons
Concentric Lamellae
- Found between the osteons
- Represents older osteons partially removed during tissue remodeling
Interstitial Lamellae
- Surround the compact bone
- Directly produced from periosteum
Circumferential Lamellae
What does spongy bone contain? (4)
- Trabeculae
- Osteocytes in lacunae
- Canaliculi
- Matrix
(Does NOT contain osteons and central canal)
- Lattice work of thin plates of bone oriented along lines of stress
- Spaces are filled with red marrow where blood cells develop
- Found in ends of long bones and inside flat bones
- Lightens the bone, allows for movement
Trabeculae
- Encloses bone
- Absent at site of attachment of muscles, tendons, ligaments, surfaces covered by articular cartilage
Periosteum
2 Layers of the Periosteum
- Outer Fibrous- gives rise to collagen
2. Inner- for growth of new cells or maintenance
- One cell layer
- Covers all surfaces of spongy bone & medulla
- Cell types are osteogenic, osteoblasts, and osteoclasts
Endosteum
Shaft of long bone
Diaphysis
One end of the long bone
Epiphysis
Growth plate region
Metaphysis
Over joint surfaces… acts as friction and shock absorber
Articular Cartilage
Marrow cavity
Medullary Cavity
2 Types of Bone Marrow
- Red Marrow
2. Yellow Marrow
- Areolar and myeloid tissue
- Produces all types of blood cells
- Located in the medullary cavities of bebes and spongy bone of adults
Red marrow
- Areolar and Adipose CT
- In medullary cavity of long bones
- Energy storage
- Absent in bebes
Yellow marrow
KT
I figured I would put this in here to give you a break from studying and hopefully put a smile on your face! I want you to know that I am very thankful that Janelle introduced me to you in spring semester last year. If it wasn’t for her I would have never met the amazing person you are and I would be short one of my best friends. Well that is all I have right now.
Until next time,
Connor :)
P.S. get back to work now
When does intramembranous ossification begin?
At about 8 weeks in embryo.
When does intramembranous ossification end?
About week 15.
What does intramembranous ossification form? (5)
Cranial flat bones, facial bones, dentary bones, clavicle, and sesmoid bones.
What is the primary ossification center?
Location where bone growth begins.
When does endochondral ossification begin?
7 weeks of embryo.
Does endochondral ossification end?
No, it continues throughout adulthood.
What does endochondral ossification form?
Long bones, most short bones, non-cranial irregular & flat bones, and middle ear ossicles.
This forms the model of future bone?
Hyaline cartilage.
Artery that supplies the periosteum
Periosteal Arteries
- Artery that enters through the nutrient foramen
- Supplies compact bone of diaphysis and yellow marrow
Nutrient arteries
Artery that supplies red marrow and bone tissue of epiphyses and metaphyses
Mataphyseal and Epiphyseal Arteries
Replacing Connective Tissue with bone
Ossification
2 Types of Ossification
- Intramembranous
2. Endochondral
Ossification that goes from…
Mesenchymal cells to spongy bone
Intramembranous
Ossification that goes from… Hyline cartilage to spongy bone
Endochondral
When does intramembranous Ossification occur?
- Begins at about week 8 in embryo
- Mainly finished by week 15
What does Intramembranous Ossification form…? (5)
- Cranial Flat Bones
- Facial Bones
- Dentary Bones
- Clavicle
5t. Sesmoid Bones
What is the primary ossification center of Inframembranous Ossification?
-Location where bone growth begins
What arrange around blood vessels in Intramembranous Ossification?
Mesenchymal Cells
What kindof protiens are realeased in Intramembranous Ossification?
Morphogenic Proteins
What do mesenchymal cells undergo during intramembranous ossification? (3)
- Become recruited
- Divide
- Differentiate into osteoblasts
Steps of Intramembranous Ossification… (6)
- Osteoblasts then secrete osteoid
- Osteoblasts become isolated and turn into osteocytes
- Produce spicules of bone that interconnect
- Mesenchymal cells at the surface from inner layer of periosteum
- Calcified matrix is degraded by osteoclasts to form spongy bone
- Ended up with spongy bone covered in thin layer of compact bone
In this type of ossification…
- Bone replaces a cartilage model
- Begins at week 7 of embryo
- Continues to adulthood
Endochodral Ossification
What does endochondral ossification from? (4)
- Long Bones
- Most Short Bones
- Non cranial Irregular and flat bones
- Middle ear ossicles
In endochondral ossification, this type of cartilage forms model of future bone…?
Hyaline Cartilage
What happens during endochondral ossification? ()
- Chondrocytes near center hypertrophy
- Matrix reduced to struts
- Chondrocytes deprived of nutrients and die
- Blood vessels grow around and penetrate cartilage
- Cells differenciate into osteoblasts
- Compact bone forms around the diaphysis
- Spongy bone forms in center of model (primary ossification center)
What happens during endochondral ossification? (3)
- Remodeling of the shaft
- Formation of the medullary cavity
- Length increases
What forms at both epiphyses?
Secondary Ossification Centers
and Blood vessels penetrate the ends of the model
How does endochondral ossification end?
- Ends with incomplete ossification of epiphysis
- Some cartilage remains
What 2 kinds of cartilage remain after endochondral ossification?
- Articular Cartilage (contact points of bone)
2. Epiphyseal Plate (growth plate)
Where does bone elongation occur and when does it end?
- Occurs at epiphyseal plate
2. Growth in length continues until 2 ossification centers meet
About the Epiphyseal Plate (3)
- Relative thickness of epiphyseal plate does not change until growth is almost complete, then…
- Cartilage is depleted
- Epiphyseal plate narrows to epiphyseal line
Type of Bone growth that…
- Compact bone deposited beneath periostium
- Bone thickens
- Bone remodeling occurs throughout life (due to osteoclasts and osteoblasts)
Appositional
- Ongoing, since osteoclasts carve out small tunnels and osteoblasts rebuild osteons
- Continual redistribution of bone matrix along lines of mechanical stress
Bone Remodeling
Percentage of remodeling? (3)
- 4% of compact bone remodeled per year
- 20% of spongy bone remodeled per year
- Distal femur is fully remodeled every 4 months
Break in bone
Fractures
2 Types of fractures…
- Closed (simple) break that does not penetrate the skin
2. Open (compound) broken bone that penetrates the skin
How are fractures treated?
Reduction and immobilization
4 Steps of Fracture Repair
- Fracture Hematoma
- Fibrocartilage Callus
- Bony Callus
- Remodel Tissue
Fracture hematoma formation (4)
- Forms within hours of the injury
- A mass of blood
- Swelling and inflammation occur in response to dead bone cells
- Phagocytes and osteoclasts elimate dead cells and broken matrix
Fibrocartilaginous Callus Formation (5)
- A fibrocartilaginous callus consists of a mass bridging the broken ends of the bone
- Fibroblasts in periosteum produce collagen
- Periosteum cells differentiate into chondrocytes
- Results in fibrocartilage
- Takes about 3 weeks
Bony Callus Formation (2)
- Formation of the bony callus occurs as the fibrocartilaginous callus is converted to spongy bone trabeculae
- The bony callus last about 3 to 4 months
- Remaining dead bone fragments are resorbed and compact bone replaces spongy bone
- A well handled fracture is virtually undetectable
Bone Remodeling
Factors Affecting Growth, Repair, and Development (4)
- Nutrition aka Vitamin D
- Sunlight
- Hormones: PTH, calcitonin, GH, thyroid hormone, sex hormones
- Physical Stress
- Abnormal reduction of bone loss
- Loss of estrogen at menopause
- Deficiency of mineral in youth
- Imbalance in activity between osteoblasts and osteoclasts
Osteoporosis
- Fibrous tissue becomes ossified
- Genetic Disorder
- Injury results in inappropriate bone formation
- No treatment
Fibrodysplasia Ossificans Progressiva
