Cartilage and Skeleton Flashcards
Components of the Skeleton
Components
• Bones
- Adult has ~206
- Hard, calcified matrix
- Calcium reservoir
• Cartilage
-Provides flexibility
• Nerves
• Blood vessels
• Epithelial tissue
What are Chondroblasts?
Chondroblasts
-Secrete collagen & elastic fibers for support
Are there blood vessels or nerves within cartilage?
No blood vessels or nerves within cartilage
What are the types of cartilage?
• There are 3 types of cartilage:
1. Hyaline
2. Elastic
3. Fibrocartilage
Components of Hyaline Cartilage
• Most abundant
• Mostly collagen fibers
• Firm matrix cushions and resists compression
Where is Hyaline Cartilage found?
• Cartilages in the nose
• Articular cartilage of a joint
- ( the smooth, white tissue that covers the ends of bones where they come together to form joints)
• Costal Cartilage
- (serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax)
• Thyroid Cartilage
• Cricoid Cartilage
- (the ring-shaped cartilage of the larynx.)
• Trachea
Components of Elastic Cartilage
Elastic Cartilage
• Mostly elastic fibers, some collagen
• Able to withstand repeated bending
Locations of Elastic Cartilage
Locations:
• Epiglottis
• Pinna (outer ear)
Components of Fibrocartilage
• Higher concentration of collagen fibers than hyaline; no elastic fibers
• Strong! Resists tension and absorbs compressive forces
Locations of Fibrocartilage
Locations:
• Intervertebral discs
- (lies between adjacent vertebrae in the vertebral column.)
• Menisci
- (protect and cushion the joint surface and bone ends)
• Pubic symphysis
- (joint sandwiched between your left pelvic bone and your right pelvic bone.)
What is Cauliflower Ear?
• A blow to the ear can result in the perichondrium separating from the deeper elastic cartilage resulting in a hematoma and swelling
Functions associated with skeleton
• Support
- Framework and support for soft tissues
• Movement
-Works with muscular system to move body
• Protection
- Of the brain, spinal cord, organs of thorax
• Mineral reservoir
- Calcium and phosphates stored in matrix
• Hemopoiesis
-Houses red bone marrow, which produces new blood cells
• Energy storage
-Fat is stored in yellow bone marrow
• Endocrine
-Osteoblasts secrete hormone (osteocalcin) that helps regulate blood sugar levels
Types of Bone (not shape)
• Spongy bone
-Loosely organized rods of bone called trabeculae
-Found in epiphyses of long bones, interior of flat, short, or irregular bones
• Compact bone
-Lines outer surface of bones
What is Spongy Bone Better for?
Spongy bone is better for:
• Resisting forces from multiple directions
• Forming a lighter skeleton
What is Compact Bone better for?
Compact bone is better for:
• Resisting forces from one direction
• Storage of minerals in the matrix
Structure of Spongy Bone
Made of rods of bone called trabeculae
• Are formed in response to stress placed on the bone
• Trabeculae are lined with endosteum
• Trabeculae contain osteocytes
• Spaces contain red bone marrow
Structure of Compact Bone
Made of repeating structural units called osteons
• Are long, cylindrical structures
• Run parallel to long axis of bone
What is the osteon, in compact bone?
The osteon
• Made of concentric circles called lamellae
• Lacunae are between adjacent lamellae
- Osteocytes live in lacunae
• Lacunae are connected by little canals called canaliculi
- Canaliculi allow movement of nutrients and communication between osteocytes
What is the Haversian/central Canal? (compact bone)
• In the center of the lamellae is a central canal (= Haversian canal)
- Contains blood vessels and nerves
- Perforating canals are how blood vessels reach the central canals
Can Red Blood Cells pass through canaliculi ? (compact bone)
• Red blood cells are too large to pass through canaliculi
• Nutrients must diffuse to osteocytes through canaliculi
- This limits the size of the osteon
Other types of lamellae (compact bone)
• Interstitial lamellae
- Remnants of old osteons
• Circumferential lamellae
- Rings around the circumference of the diaphysis
What direction do adjacent lamellae run?
• Collagen fibers in adjacent lamellae run perpendicular to one another
- This increases strength
Types of bone shapes?
• Long bone
• Short bone
• Flat bone
• Irregular bone
Examples of each type of bone
• Long bone
- Ulna / radius (forearm)
- the femur (thigh bone)
- humerus (upper arm)
• Short bone
- Talus (ankle)
- Capitate (carpal) bone (wrist)
• Flat bone
- Scapula (shoulder blade)
- Sternum (chest)
• Irregular bone
- Sphenoid bone (base of cranium)
- Vertebra (backbone)
Structure of Long Bone
• Epiphyses
• Diaphysis
• Connective tissue membranes
What is Epiphyses?
Epiphyses
• Spongy bone surrounded by compact bone
• Red bone marrow is found between trabeculae
• Epiphyseal line/plate separates epiphysis from diaphysis
• Articular cartilage covers articulating surface
What is the Diaphysis?
Diaphysis
• Medullary cavity
• Adults: is filled with yellow marrow (adipocytes)
• Children: is filled with red bone marrow (hemopoiesis)
• Switches to yellow bone marrow between ages 8-18
What is the Connective tissue membranes?
Connective tissue membranes
• Periosteum surrounds outer compact bone (except where articular cartilage is present)
- Made of dense irregular CT
- Perforating fibers attach periosteum to
bone (Very strong)
- Is osteogenic where touches compact
bone –> osteoclasts and osteoblasts are
deep to the periosteum and actively
remodel the bone
What is the Endosteum?
Endosteum lines inner surfaces (including trabeculae)
• Thinner dense CT
• Osteogenic (bone forming)
• Osteoblasts and osteoclasts are located under endosteum
What is the Arterial Supply to Long Bones?
Nutrient arteries
• Pierce periosteum to supply bone with blood
• Perforating arteries (inside perforating canals) connect with arteries in central canal
- Nutrients travel to osteoclasts via canaliculi
What is the Epiphyseal plate?
Epiphyseal plate = growth plate; site of active growth in long bone
What is the Epiphyseal line?
Epiphyseal line = growth plate becomes ossified; growth in length is complete
Layers for Bone formation
Epiphysis
- Resting (quiescent) zone
- Proliferation (growth zone)
- Hypertrophic zone
- Calcification zone
- Ossification
Diaphysis
What happens in Proliferation zone?
Cartilage cells undergo mitosis
What happens in Hypertrophic zone?
Older cartilage cells enlarge
What happens in calcification zone?
Matrix becomes calcified: cartilage cells die; matrix deteriorating
What happens in Ossification zone?
New bone formation is occuring
What is Intramembranous Ossification
Intramembranous ossification
• Connective tissue membranes are replaced by bone
• Most of skull and clavicle form this way
• Fontanels are remnants of CT membrane
How do osteoblasts become osteocytes?
Osteoblasts produce the matrix; once trapped by matrix are called osteocytes
Steps of Intramembranous Ossification
- Ossification centers develop in fibrous CT
- Organic component (osteoid, contains collagen) is secreted then is calcified
- Immature bone (=woven bone made of trabeculae) is formed
- Woven bone is remodeled into compact bone (externally) and spongy bone (internally)
What is Endochondral ossification?
Endochondral ossification
• Hyaline cartilage serves as a template
• Most bones of skeleton form this way
-Lower part of skull down (except clavicles)
• Epiphyseal plate is a remnant of hyaline skeleton
What is Remodeling?
Remodeling
• Occurs under periosteum andendosteum
• Continues throughout a lifetime; based on need of blood calcium levels
• Osteoclasts secrete HCl which dissolves and releases minerals from matrix
• Osteoblasts lay down organic osteoid which fills with minerals
Steps of Bone Fracture Healing
- A hematoma forms
- Fibrocartilaginous callus forms
- Bony callus forms
- Bone remodeling occurs
What is Osteoporosis?
Osteoporotic: pits on surface of bone indicate where osteoclasts have broken down the matrix
• Osteoclasts outpace osteoblasts
What is Osteomalacia?
Osteomalacia
• Called rickets in children
• Characterized in children as bowed long bones
• Bone matrix not properly mineralized
• Often a result of a nutritional or UV deficiency resulting in not enough calcium added to matrix
• Reason why vitamin D is added to milk
