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Chapter 6: Cartilage and Bone Tissue

5 types of connective tissue

Blood, Bone, Cartilage, Connective tissue proper (loose CT and Dense CT)

Types of Cartilage

Hyaline, Fibrocartilage, Elastic

Hyaline Cartilage

Most abundant type. Provides support through resillience and flexibility. Found at the end of bones.

EX: trachea, articular cartilage, epiphyseal plate, fetal skeleton, costal cartilage, nose

Fibrocartilage

Contains thinck collagin fibers. Acts as a shock absorber.

EX:Intervertebral disk, menisci of knee, pubic symphasis

Elastic

contains highly branched elastic fibers. Provdes flexibility.

Ex: Epiglottis, auricle of the ear

Charateristics of cartilage

1. semigrid, weaker than bone.
2.Flexible and resillient bc of elastic fibers and water content
3. Avascular
-get nutrients through diffusion

Functions of cartilage

1. support soft tissues
2.articular surface for joints
2. Provide a modle for enchondral bone formation
*Endochondral (within cartilage). "Chon" = w/ cartilage

Strcture fo cartilage

Chondroblast, chondrocytes, extracellular matrix, perichardium

Chondroblast

produce matrix of cartilage

Chondrocytes

marture cartilage cells. Reside in lacunae. Alive, but not doing much.

Extracellular MAtrix (ECM)

any substance produced by cells and excreted to the extracellular space within the tissues, serving as a scaffolding to hold tissues together and helping to determine their characteristics.

Perichardium

made of dense CT. Provides mechanical support and protection.

Bone

1. Osseous CT
2.Clacified ECM (Calcium phosphate

Bone functions

1. support and prtect
2. Movement
-attchment site for muscles
3. hemopoiesis: red bone marrow
-especially in long bones such as the femur
4. Storage of mineral and energy reserves
-calcium phosphate and yellow bone marrow

Bone types

1. Long
2. short
3. Flat
4. Irregular

Long bones

Conatin diaphysis and epiphysis
EX: Humerus, radius, ulna, metacarpals, phalanges, femur, tibia, fibula, metatarsals

Short bones

EX: Carpals, tarsals, sesamoid bone (platella)

Flat Bones

EX: skull, scapulae, sternum, ribs

Irregular bones

EX: vertabrae, sacrum, coccyx, Os, Coxa, Ethmoid, Sphenoid

Structure of long bones Part 1 (See diagram on pg 150 of TB)

1. Compact bone
-superficial bone tissue
2.Spongy Bone
-dense bone tissue
3. Epiphysis
-ends of long bones
4. Diaphysis
-Shaft
5. Metaphysis
-contains the epiphyseal plate
6. Aricular Cartialge
-hyaline cartialge covering the ends of bones within a joint

Structure of long bones Part 2 (See diagram on pg 150 of TB)

7. Medullary Cavity
-contains yellow bone marrow in adults and red in children
8. Endosteum
-layer of cells lining the spongy bone and medullary cavity
9. Periosteum
-dense CT outer covering of the bone
10. perforating fibers
-attach the periosteum to the compact bone
11. nutrient foramen
-conatins nutrient artery

Cells of Bone

1.Osteoprogenitor
2.osteoblast
3.osteocytes
4.osteoclast

Osteoprogenitor (See Pictures on TB pg. 152)

Stem cells derived from the mesenchyme that becomes osteoblast

Osteoblast

Immature osteocytes that BUILD bone by secreting osteoid (organic part of ECM)

Osteocytes

Mature bone cells that maintain bone matrix. Reside in the lacunae

Osteoclast

1. cells that CONSUME bone (bone reabsorption)
2. Phagocytic cells using hydrochloric acid and lysosomes
3.Increase blood Calcium levels

Classification of bone by Histoology

Compact VS Spongy bone

Compact bone

1. AKA cortical bone
2. solid, dense
3. lined by periosteum
4. found in the superficial regions of bone
5. contains osteons

Spongy bone

1. AKA cacellous or trabecular bone
2. porous
3. lined by endosteum
4. Found in deeper regions of the bone

Structure of compact bone Part 1 (see diagrams on TB Pg. 154/156)

1. Osteon (haversian system)
-basic structural and functional unti
2. Central canal (Haversian Canal)
3.Concetric Lamellae
-concetric rings of osseous CT that surround the central canal
4. Osteocytes
-mature bone cells

Structure of compact bone Part 2 (see diagrams on TB Pg. 154/156)

5. Lucanae
-cavities which house osteocytes
6. Canaliculi
-connect neighboring lacunae
-allows nutrients to travel btw the cental canal and the osteocytes
7. Perforating ccanals (Volkmann's canals)
-connect blood and nerve supply to central canal

Structure of spongy Bone (Pic. on TB Pg. 154)

1. Trabeculae
-main structural/ functional component
-form criss crossing bars and plates for strength
2. Parallel Lamellae
3.Osteocytes within lacunae
4.Canaliculi
-provides nutrients to cells through diffusion

Osteogenesis

1.Intermembranous ossification
2. Enchondral ossification

Intermembranous ossification

bone growth wi membrane (mesenchyme)
-forms flat bones of the skull, some facial bones, mandible, and clavical

Enchondral ossification (Diagram on TB Pg. 159)

Bone growth with in cartilage
-turns fetal frmawork of hyaline cartilage into bone
- formation of most bones
-Primary ossification center in diaphysis and secondary in epiphysis

Bone Growth

1. Occurs during childhood and adolesence
2. Intersitial gowth (length) VS. Appositonal Growth (thickening)

Intersitial Growth

Occurs at Epiphysil plates:
1.Chonfroblast neart he epiphysil plate multiply, pushing the epiphysis away from the diaphysis
2. Chondrocytes enlarge; matrix calcifies
3. Chondrocytes die and disentigrate
4. Remodeling by osteoclast

Bone Fractures

1.simple
2.open/compund
3.stress
4.pathologic

Simple fracture

Bone doesn't perice skin

Open/Compound fracture

bone pierces the skin

Stress fracture

thin break from repetitive loads

Patholigic Fracture

Disease weakens the bones

Fracture Repair (Pic TB Pg. 166)

1. Fracture hematoma forms
2. Fibrocartilage (soft) callus forms
3.Hard (bony) callus forms
4. Bone remodeled

Osteomalacia

Called rickets in small children
-Soft bones
-leads to bowed legs

Osteoperosis:

excessive bone reabsorptipon. Aged and post menopause.

Other Bone disorders

-Vitamin D deficency
-Calcium Deficency

Osteitis Deformans

*AKA Paget's disease
*Excessive osteoclast and osteoblast function
*Bone is unstable and Immature
*most common in os coxa, skull, vertebrae, femure, and tibia

What is the function of red bone marrow? Yellow?

Red blood cells, platelets and most white blood cells arise in red marrow; some white blood cells develop in yellow marrow. The color of yellow marrow is due to the much higher number of fat cells. Both types of bone marrow contain numerous blood vessels and capillaries.

In what region of the long bone is the epiphysis plate found?

Metaphysis

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