Podcast
Questions and Answers
What is the main function of cartilage in movable joints?
What is the main function of cartilage in movable joints?
Which type of cartilage is characterized by a high concentration of elastin, allowing for flexibility?
Which type of cartilage is characterized by a high concentration of elastin, allowing for flexibility?
Which characteristic is NOT associated with cartilage?
Which characteristic is NOT associated with cartilage?
What is the role of glucosaminoglycans (GAGs) in cartilage?
What is the role of glucosaminoglycans (GAGs) in cartilage?
Signup and view all the answers
What provides nourishment to avascular cartilage?
What provides nourishment to avascular cartilage?
Signup and view all the answers
What component is primarily responsible for the hardness and resistance of bone during calcification?
What component is primarily responsible for the hardness and resistance of bone during calcification?
Signup and view all the answers
Which statement about flat bones is correct?
Which statement about flat bones is correct?
Signup and view all the answers
What type of cartilage is present in the epiphyseal growth plate in children?
What type of cartilage is present in the epiphyseal growth plate in children?
Signup and view all the answers
Which of the following is NOT a way to classify bones based on shape?
Which of the following is NOT a way to classify bones based on shape?
Signup and view all the answers
Which description accurately characterizes the periosteum?
Which description accurately characterizes the periosteum?
Signup and view all the answers
What is the main function of osteoprogenitor cells in the osteogenic layer of the compact bone?
What is the main function of osteoprogenitor cells in the osteogenic layer of the compact bone?
Signup and view all the answers
Which of the following bone markings serves as sites for muscle and ligament attachment?
Which of the following bone markings serves as sites for muscle and ligament attachment?
Signup and view all the answers
What structural feature of the compact bone helps resist twisting forces?
What structural feature of the compact bone helps resist twisting forces?
Signup and view all the answers
Which type of bone is characterized by being composed of regular parallel bands of collagen arranged in sheets?
Which type of bone is characterized by being composed of regular parallel bands of collagen arranged in sheets?
Signup and view all the answers
What describes the composition of short bones such as the wrist and ankle bones?
What describes the composition of short bones such as the wrist and ankle bones?
Signup and view all the answers
Which statement accurately describes the role of osteoblasts in bone tissue?
Which statement accurately describes the role of osteoblasts in bone tissue?
Signup and view all the answers
What is the primary function of fibrocartilage in the human body?
What is the primary function of fibrocartilage in the human body?
Signup and view all the answers
What distinguishes interstitial growth from appositional growth in cartilage?
What distinguishes interstitial growth from appositional growth in cartilage?
Signup and view all the answers
Which type of cartilage is primarily responsible for maintaining the structure of the respiratory tract?
Which type of cartilage is primarily responsible for maintaining the structure of the respiratory tract?
Signup and view all the answers
How does parathyroid hormone affect osteoclast activity?
How does parathyroid hormone affect osteoclast activity?
Signup and view all the answers
Which component primarily makes up the extracellular matrix of bone?
Which component primarily makes up the extracellular matrix of bone?
Signup and view all the answers
Which condition is characterized by defective osteoclasts resulting in abnormally dense bones?
Which condition is characterized by defective osteoclasts resulting in abnormally dense bones?
Signup and view all the answers
At what stage of life does cartilage growth typically cease?
At what stage of life does cartilage growth typically cease?
Signup and view all the answers
What is primarily responsible for the hardness of bones?
What is primarily responsible for the hardness of bones?
Signup and view all the answers
What characterizes intramembranous ossification?
What characterizes intramembranous ossification?
Signup and view all the answers
What is the primary role of osteoclasts in bone maintenance?
What is the primary role of osteoclasts in bone maintenance?
Signup and view all the answers
At what stage does endochondral ossification primarily start during development?
At what stage does endochondral ossification primarily start during development?
Signup and view all the answers
Which hormone decreases blood calcium levels?
Which hormone decreases blood calcium levels?
Signup and view all the answers
What primarily occurs at the epiphyseal growth plates during adolescence?
What primarily occurs at the epiphyseal growth plates during adolescence?
Signup and view all the answers
The term 'chondro' in medical terminology primarily refers to which type of tissue?
The term 'chondro' in medical terminology primarily refers to which type of tissue?
Signup and view all the answers
What is the role of the periosteum during bone development?
What is the role of the periosteum during bone development?
Signup and view all the answers
What type of bone formation occurs through endochondral ossification?
What type of bone formation occurs through endochondral ossification?
Signup and view all the answers
What tissue is primarily responsible for the formation of bone?
What tissue is primarily responsible for the formation of bone?
Signup and view all the answers
Study Notes
Cartilage
- A specialized form of connective tissue with a firm extracellular matrix
- Able to withstand mechanical stress without permanent distortion
- Provides support for soft tissues and acts as a shock absorber due to its resilience
- Plays a crucial role in movable joints, providing a smooth and lubricated surface for sliding movements
- Guides the development and growth of long bones
- Contains high concentrations of Glucosaminoglycans (GAGs) & proteoglycans that interact with collagen and elastic fibers
- The extracellular matrix composition and cells determine the three types of cartilage: hyaline, elastic, and fibrocartilage
- Chondrocytes are responsible for producing and maintaining the extracellular matrix components
- Chondrocytes reside in matrix cavities called lacunae
- All cartilage types contain collagen, hyaluronic acid, proteoglycans, and glycoproteins
- Hyaline cartilage is the most common type and contains collagen type II
- Elastic cartilage contains elastin, providing pliability and distensibility
- Fibrocartilage possesses a dense network of coarse type I collagen fibers, making it suitable for regions subjected to pulling forces
- Cartilage is avascular, relying on diffusion from the perichondrium and synovial fluid in areas lacking perichondrium
- Perichondrium is a dense connective sheath surrounding cartilage
- Chondrocytes exhibit low metabolic activity
- Cartilage lacks lymphatics and nerves, but they are present in the perichondrium
- Fibrocartilage resists compression and tension
- Fibrocartilage consists of rows of thick collagen fibers alternating with rows of chondrocytes (in matrix)
- Examples include knee menisci and the annulus fibrosus of intervertebral discs
Growth Of Cartilage
- Appositional growth: "Growth from outside"
- Chondroblasts in the perichondrium (external covering of cartilage) secrete matrix
- Interstitial growth: "Growth from within"
- Chondrocytes within the cartilage divide and secrete new matrix
- Cartilage growth ceases in late teens (chondrocytes stop dividing)
- Regenerates poorly in adults
Bone
- A specialized connective tissue composed of cells and a predominantly collagenous extracellular matrix called osteoid, which becomes mineralized by the deposition of calcium hydroxyapatite
Functions of Bone
- Support
- Movement: muscles attach by tendons and use bones as levers to move the body
- Protection: skull protects the brain, vertebrae protect the spinal cord, rib cage protects thoracic organs
- Mineral storage: stores calcium and phosphate, which are released as ions into the blood as needed
- Blood cell formation and energy storage: bone marrow produces red blood cells and stores fat
Bone Cells
- Osteoblasts: synthesize osteoid and mediate its mineralization, found on bone surfaces
- Osteocytes: inactive osteoblasts trapped within formed bone in cavities called lacunae between bone matrix layers (lamellae), with cytoplasmic extensions into small canaliculi between lamellae
- Osteoclasts: phagocytic multinucleated cells that erode bone and are essential for resorption, remodeling, and refashioning of bone, found in depressions or cavities known as Howship's lacunae
- Osteoclastic activity is regulated by hormones and signaling factors
- Osteoclasts respond to parathyroid hormone and calcitonin
- Parathyroid hormone stimulates osteoclastic resorption and calcium ion release from the bone
- Calcitonin inhibits osteoclastic activity
Disorders Of Bone
- Osteopetrosis: defective osteoclasts, resulting in heavy bones
Bone Surfaces
- Both the internal and external surfaces of bones are lined by connective tissue layers: endosteum and periosteum, respectively
- Both contain osteogenic cells
Extracellular Matrix Components
- Organic components: collagen type I, proteoglycans, and several glycoproteins
- Inorganic components: calcium hydroxyapatite, phosphate, bicarbonate, citrate, magnesium, potassium, and sodium ions
- The ions of hydroxyapatite are hydrated, facilitating ion exchange between the mineral and body fluids
- The association of minerals with collagen fibers during calcification gives bone its hardness and resistance
Classification Of Bones
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Pneumatized bones
- Sesamoid bones (included in short bones)
Gross Anatomy of Bones
- Compact bone (cortical): represents about 80% of the total bone mass
- Spongy (cancellous or medullary or trabecular) bone: represents about 20% of the total bone mass
- Expanded ends are called the epiphysis
- The shaft is known as the diaphysis
- At the junction of the diaphysis and epiphysis in long bones is the epiphyseal or growth plate (occupied with hyaline cartilage during the growing stage of life)
- Blood vessels: nutrient arteries and veins pass through nutrient foramen
- Membranes: periosteum and endosteum
Compact Bone
- Consists of osteons (pillars)
- Lamellae: concentric tubes surrounding a Haversian canal
- Haversian canals contain blood vessels and nerves
- Osteocytes reside in lacunae between lamellae
Spongy Bone
- Consists of layers of lamellae and osteocytes
- Osteocytes seem to align along stress lines
Chemical Composition of Bones
- Organic component (35%): cells, matrix of collagen fibers and ground substance, contributing to flexibility and tensile strength
- Inorganic component (65%): primarily calcium phosphate, located in and around collagen fibrils, contributing to bone hardness
- Small amount of water
Bone Development
- Osteogenesis: "formation of bone"
- Occurs from osteoblasts
- Bone tissue first appears in week 8 of embryonic development
- Ossification: "to turn into bone"
- Intramembranous ossification (also called "dermal" since it occurs deep in the dermis): forms directly from mesenchyme, not modeled first in cartilage
- Examples: most skull bones except a few at the base, clavicles, sesamoid bones
- Endochondral ossification: modeled in hyaline cartilage, then replaced by bone tissue
- Examples: all other bones
- Intramembranous ossification (also called "dermal" since it occurs deep in the dermis): forms directly from mesenchyme, not modeled first in cartilage
Intramembranous Ossification
- Forms directly from mesenchyme
- Osteoblasts secrete osteoid, which becomes mineralized, forming bone
Endochondral Ossification
- Modeled in hyaline cartilage, called the cartilage model
- Gradually replaced by bone, beginning late in the second month of development
- Perichondrium is invaded by vessels and becomes periosteum
- Osteoblasts in the periosteum lay down a collar of bone around the diaphysis
- Calcification occurs in the center of the diaphysis
- Primary ossification centers form
- Secondary ossification occurs in epiphyses
- Epiphyseal growth plates close at the end of adolescence, fusing the diaphysis and epiphysis, ending bone lengthening
Factors Regulating Bone Growth
- Vitamin D: increases calcium absorption from the gut
- Parathyroid hormone (PTH): increases blood calcium levels (some from bone)
- Calcitonin: decreases blood calcium levels (opposes PTH)
- Growth hormone and thyroid hormone: modulate bone growth
- Sex hormones: growth spurt at adolescence and closure of epiphyses
Bone Remodeling
- Osteoclasts: responsible for bone resorption
- Osteoblasts: responsible for bone deposition
- Triggers: hormonal (parathyroid hormone) and mechanical stress
- Osteocytes are transformed osteoblasts
Repair Of Bone Fractures
- Simple and compound fractures
- Closed and open reduction
Disorders Of Cartilage And Bone
- Defective collagen: numerous genetic disorders, such as Marfan syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
