Bone Physiology and Pathology Quiz

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Questions and Answers

Which type of bone is characterized as immature and irregular typically found in the fetus?

Lamellar bone

Compact bone

Spongy bone

Woven bone (correct)

What is the role of osteoclasts in bone physiology?

To provide tensile strength to bones

To form new bone through mineralization

To resorb bone tissue (correct)

To produce osteoid

Which structure in the bone is responsible for housing blood vessels and nerves?

Lacunae

Epiphyseal line

Volkmann’s canal (correct)

Osteon

Which statement best describes the process of ossification?

The method of transforming cartilage into bone Signup and view all the answers

Which type of bone is known for its highly organized structure and is chiefly involved in providing strength?

Lamellar bone Signup and view all the answers

Which histopathological feature is characterized by central fibrinoid necrosis surrounded by palisading macrophages?

Rheumatoid nodules Signup and view all the answers

What is a common extra-articular manifestation of rheumatoid arthritis?

Anemia Signup and view all the answers

Which feature is NOT typically associated with rheumatoid arthritis?

Degenerative cartilage degeneration Signup and view all the answers

What is the minimum number of clinical features required for a diagnosis of rheumatoid arthritis?

4 Signup and view all the answers

Which of the following is commonly found within the proliferative synovitis seen in rheumatoid arthritis?

Plasma cells and macrophages Signup and view all the answers

What is the most common type of osteoporosis?

Primary osteoporosis Signup and view all the answers

Which of the following is a characteristic of osteomalacia?

Inadequate mineralization of bone matrix Signup and view all the answers

What dietary intake is associated with the prevention of primary osteoporosis?

800mg of calcium per day Signup and view all the answers

What effect does corticosteroid use have on bone health?

Inhibits osteoblastic activity Signup and view all the answers

What role does parathyroid hormone play in hyperparathyroidism?

Stimulates osteoclastic activity and increases calcium levels in blood Signup and view all the answers

Which of the following conditions can lead to secondary osteoporosis?

Celiac disease Signup and view all the answers

What is a primary cause of osteoarthritis?

Defect in cartilage Signup and view all the answers

Which of the following is a complication associated with osteomyelitis?

Septicemia Signup and view all the answers

What is a common sign of osteoporosis in vertebrae?

Compression fractures Signup and view all the answers

What is a characteristic feature of rickets seen in children?

Open epiphyseal plates Signup and view all the answers

Which joints are most commonly affected by osteoarthritis?

Knees and hips Signup and view all the answers

What type of organisms are primarily responsible for osteomyelitis?

Bacteria Signup and view all the answers

What is a potential consequence of chronic osteomyelitis?

Chronic inflammation Signup and view all the answers

What is the most common clinical feature of arthritis?

Deformity Signup and view all the answers

Which of the following factors is NOT associated with secondary osteoarthritis?

Young age Signup and view all the answers

What structural change is characteristic of osteoarthritis?

Narrowing of joint space Signup and view all the answers

What condition is characterized by the deposition of calcium pyrophosphate crystals in cartilage and juxta-articular tissues?

Chondrocalcinosis Signup and view all the answers

Which type of CPPD is specifically associated with elderly men and presents as pseudo gout?

Type A Signup and view all the answers

What is the primary genetic inheritance pattern associated with Duchenne muscular dystrophy?

X-linked recessive Signup and view all the answers

Which symptom is commonly observed in boys with Duchenne muscular dystrophy before the age of 5?

Waddling gait Signup and view all the answers

What is the major pathological finding in Duchenne muscular dystrophy after one year of age?

Pseudohypertrophy due to adipose tissue Signup and view all the answers

What is the role of dystrophin testing in diagnosing Duchenne muscular dystrophy?

To evaluate muscle biopsy samples Signup and view all the answers

Why might negative results in serum creatine kinase tests not exclude the carrier state of Duchenne muscular dystrophy?

The test may not detect mild cases Signup and view all the answers

By what age do most boys with Duchenne muscular dystrophy require a wheelchair?

By 13 years of age Signup and view all the answers

Study Notes

Musculoskeletal System

The musculoskeletal system provides form, support, stability, and movement to the body.
Composed of: bones, muscles, cartilage, tendons, ligaments, joints, and connective tissue.

Bone

Dynamic tissue with osteoblasts (forming bone) and osteoclasts (resorbing bone).
Osteoblasts produce osteoid, a protein matrix composed of type 1 collagen.
Calcium and phosphate are incorporated into the matrix, forming calcium hydroxyapatite, which gives bone its hardness.
Bone anatomy consists of:
- Diaphysis: shaft of the bone
- Metaphysis: wider portion at the end of the diaphysis
- Epiphysis: end of the bone, further divided into proximal and distal epiphyses
- Epiphyseal line: growth plate between the epiphysis and metaphysis
- Periosteum: outer covering of bone
- Compact (cortical) bone: dense outer layer
- Spongy bone: inner layer with trabeculae
- Articular cartilage: smooth surface covering the joint ends
- Medullary cavity: central space within the bone
- Marrow: tissue within the medullary cavity (red marrow produces blood cells)

Types of Bone Tissue

Woven bone: irregular, immature bone found in the fetus and during fracture repair
Lamellar bone: regular, mature bone found in adults, further divided into:
- Circumferential lamellae: outer layers
- Concentric lamellae: layers arranged around a central haversian canal
- Interstitial lamellae: remnants of old osteons
- Trabecular lamellae: found in spongy bone
Compact and spongy bone are both lamellar bone.
Bone formation can be endochondral (cartilage template) or intramembranous (directly from mesenchymal tissue).

Bone Growth Plate

Located at the epiphyseal line.
Responsible for longitudinal bone growth.
Composed of zones of proliferating chondrocytes (cartilage cells).

Osteoporosis

Reduction in bone mass per unit of bone volume.
Metabolic bone disease with normal mineral to matrix ratio.
Primary osteoporosis: most common, uncertain etiology, common in postmenopausal women and elderly.
- Affects peak bone mass, involves estrogen decline, and aging.
- Calcium intake (800mg/day), exercise, and environmental factors like smoking (decreases estrogen) are important.
Secondary osteoporosis: caused by other conditions, including:
- Corticosteroids: inhibit osteoblastic activity and impair vitamin D's role in calcium absorption.
- Hematologic malignancies: can impact bone mass
- Malabsorption: GI and liver diseases
- Alcoholism: inhibits osteoblasts and reduces calcium absorption

Osteoporosis Manifestations

Osteopenia: decrease in bone thickness, especially cortical bone.
Reduction in the number and size of trabeculae, the thin, bony struts within spongy bone.
Fractures can be the first sign, particularly compression fractures of vertebrae.

Osteomalacia and Rickets

Inadequate mineralization of the newly formed bone matrix.
Osteomalacia: in adults
Rickets: in children, affecting the open epiphyseal plates and cartilage.
Characterized by:
- Beaded appearance of costochondral junctions (where ribs meet cartilage)
- Pectus carinatum (pigeon chest)
- Dental abnormalities
Caused by:
- Vitamin D deficiency
- Phosphate deficiency
- Defects in mineralization process

Osteomalacia and Rickets Manifestations

Osteopenia
Exaggeration of osteoid seams (unmineralized bone matrix)
Poorly localized pain, often in the femoral neck, pubic ramus, spine, and ribs

Hyperparathyroidism

Excess parathyroid hormone (PTH) due to:
- Parathyroid adenoma (tumor)
- Parathyroid hyperplasia (overgrowth of glands)
- Parathyroid malignancy (rare)
PTH causes:
- Increased phosphate excretion in urine and stimulation of osteoclastic activity, leading to hypercalcemia (high blood calcium).
- Increased tubular reabsorption of calcium and excretion of phosphate.
- Increased intestinal calcium absorption.

Hyperparathyroidism Manifestations

Stones: kidney stones
Bones: brown tumors (bone lesions)
Psychiatric depression
GI tract irregularities

Secondary Hyperparathyroidism

Occurs due to chronic renal failure.
Leads to:
- Decreased filtration of phosphate, causing hyperphosphatemia (high blood phosphate).
- Impaired active vitamin D production.
- Decreased calcium absorption in GI tract, leading to hypocalcemia (low blood calcium).
- Secondary hyperparathyroidism develops as a response to these abnormalities.

Osteomyelitis

Inflammation of bone caused by an infectious organism, often bacteria like:
- Staphylococcus
- Streptococcus
- Escherichia coli
- Neisseria gonorrhea
- Haemophilus influenza
- Salmonella
Infection can occur via:
- Direct penetration: wounds, fractures, surgery
- Hematogenous spread: through the bloodstream (common in metaphyses of long bones, especially the knee, ankle, and hip)

Osteomyelitis Complications

Septicemia: blood poisoning
Acute bacterial arthritis
Pathologic fractures: fractures caused by weakened bone
Squamous cell carcinoma: a type of skin cancer
Amyloidosis: abnormal protein deposits
Chronic osteomyelitis: persistent infection

Joints - Anatomy

Joints are the points where two or more bones meet
Different types of joints with varying degrees of movement
Articular cartilage covers the ends of the bones, providing a smooth surface
Synovial fluid lubricates the joint

Arthritis

Inflammation of joints, a common condition.
Often a site for autoimmune injury due to exposure of heart valves and joints to hidden antigens.
Can be caused by infections and degeneration.
Clinical features:
- Pain caused by inflammation of the capsule, synovium, and periosteum.
- Swelling due to inflammation, effusion (fluid accumulation), and synovial proliferation (growth).
- Restricted movement caused by pain, fluid, synovial swelling, and joint damage.
- Deformity caused by mal-alignment, erosion, and ankylosis (joint fusion).

Osteoarthritis

Most common joint disease, a slow progressive degeneration of articular cartilage.
Affects weight-bearing joints (hips, knees) and fingers.
Primary osteoarthritis: defect in cartilage, not inflammatory.
Secondary osteoarthritis: caused by various factors like trauma, crystal deposits, and infection.
Narrowing of the joint space is a key sign, indicating loss of cartilage.
Increased thickness of subchondral bone: the bone beneath the cartilage becomes thickened (eburnation).
Subchondral cysts: fluid-filled cavities within the bone beneath the cartilage.
Osteophytes: bony growths (bone spurs), also known as Heberden nodes on the fingers.

Osteoarthritis Causes

Primary: intrinsic cartilage defect
Secondary:
- Intra-articular fracture
- Previous infective arthritis
- Rheumatoid arthritis
- Congenital dislocation of hip
- Abnormal stresses (Paget's disease)
- Chronic overuse
- Metabolic and endocrine disorders (hemochromatosis, gout, calcium phosphate deposition)
- Neuropathic disorders (peripheral neuropathy in diabetes mellitus)
- Excess intra-articular corticosteroids

Osteoarthritis Histopathology

Fibrillation: fraying and roughening of the articular cartilage
Loose bodies: pieces of cartilage floating in the joint space
Eburnation: hardened articular bone
Subarticular cyst formation
Rice bodies: small, white, rice-shaped bodies in the joint fluid, comprised of fibrin.
Hyperplastic synovium: thickened synovium
Pannus: a thick, abnormal layer of tissue that can form in the synovium and over the cartilage.
Allison-Ghormley bodies: small, round bodies found in the joint fluid.
Rheumatoid nodules: firm, rubbery lumps that can appear in the skin or other organs.

Rheumatoid Arthritis (RA)

Autoimmune, chronic inflammatory disease.
Inflammation of the synovium (lining of the joint), which eventually destroys cartilage.
Affects small joints, especially in the hands and feet, bilaterally (symmetrically).

RA - Clinical Features

Morning stiffness that lasts at least an hour.
Arthritis in at least 3 joint areas.
Arthritis in the small hand joints.
Symmetrical arthritis.
Rheumatoid nodules.
Positive serum rheumatoid factor (antibody).
Typical radiographic changes
At least 4 of these features are required for diagnosis.

RA Pannus

Hyperplastic and inflamed synovium.
Infiltrates the joint space, destroying cartilage and bone.

Extra-Articular RA

Can affect other parts of the body:
- Rheumatoid nodules: firm, rubbery lumps in the skin, caused by inflammation.
- Vasculitis: inflammation of blood vessels, affecting small arteries, especially those in the fingers.
- Pleuritis: inflammation of the pleura (lining of the lungs).
- Pericarditis: inflammation of the pericardium (lining of the heart).
- Tendonitis: inflammation of tendons.

RA Nodule Microscopic Features

Central fibrinoid necrosis: a central area of dead tissue, often with a granular appearance.
Palisading macrophages: macrophages (immune cells) arranged around the necrotic area.

Joint Involvement in RA

Swan neck deformity: a bending of the finger joint at the middle joint (PIP) and straightening of the end joint (DIP), resulting in a swan-neck shape.

Differentiating RA from Osteoarthritis

Feature	Rheumatoid Arthritis	Osteoarthritis
Age	Young, often 20-40 years of age	Elderly
Joints	Small joints (hands, wrists, feet), symmetrical	Large, weight-bearing joints (hips, knees, spine)
Cause	Autoimmune, chronic inflammation of the synovium	Degenerative disease of cartilage
Cartilage	Eroded by pannus	Gradual breakdown, wear-and-tear

Pseudogout (Calcium Pyrophosphate Deposition Disease - CPPD)

Deposition of calcium pyrophosphate crystals in cartilage and juxta-articular tissues.

Types of CPPD

Type A (Pseudo Gout): primarily affects the knee of elderly men.
Type B (Pseudo Rheumatoid): affects multiple joints, causing polyarthritis, similar to RA.
Type C: Combines features of OA and acute attacks, more common in women.
Type D: Pseudo OA, acute attacks, primarily affect the hands.
Type E: Asymptomatic, without symptoms.
Type F: Pseudoneuropathic, associated with nerve damage, resembling Charcot joint.

CPPD Clinical Features

Often found in patients with hyperparathyroidism.
Frequent in elderly.
Affects joints like the knee.
Characterized by joint swelling and inflammation, commonly triggered by trauma.

CPPD Histopathology

Calcium pyrophosphate crystals present in the cartilage, synovium, and joint fluid.

Muscular Dystrophy

Group of genetic diseases affecting muscle, causing weakness and degeneration.
Duchenne muscular dystrophy (DMD) is the most common type, X-linked recessive.

Duchenne Muscular Dystrophy (DMD)

Affects males primarily because the gene is on the X chromosome.
Onset before age 5: Delayed motor development, waddling gait, difficulty running.
Gower's manoeuvre: using arms to push the body up from a squatting position due to weakness in pelvic girdle muscles.
Wheelchairs needed by 13 years old.
Death from respiratory failure or cardiac arrhythmias in late teens.

DMD Pathological Findings

Hyaline (prenecrotic) and necrotic muscle fibers with initial good regeneration.
Regeneration decreases over time.
Progressive replacement of muscle fibers with adipose and fibrous tissue, causing pseudohypertrophy (muscle feels larger due to fat and connective tissue).

DMD Diagnosis

Dystrophin testing on muscle biopsy (dystrophin is a protein important for muscle function).
Serum creatine kinase estimation: Elevated in carriers, but negative results don't rule out the possibility of being a carrier.

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Description

Test your knowledge on bone physiology, types, and histopathological features with this comprehensive quiz. Explore concepts like ossification, osteoporosis, and conditions such as rheumatoid arthritis. Perfect for students studying anatomy or healthcare professions.