Endocrinology and Bone Growth Quiz

Vitamin C Deficiency and Scurvy

• Vitamin C deficiency in children and adults causes scurvy, characterized by ulceration and hemorrhage throughout the body.

Growth Hormone

• Anterior pituitary's growth hormone increases overall tissue and bone growth.
• Excessive growth hormone leads to gigantism.
• Insufficient growth hormone results in dwarfism.

Thyroid Hormone

• Essential for normal tissue growth, including cartilage.
• Deficiency results in smaller individuals.

Estrogen and Testosterone

• Stimulate bone growth and closure of the epiphyseal plate.
• Levels dramatically increase during puberty.

Bone Remodeling

• Continuous process involving osteoclasts removing bone and osteoblasts depositing new bone.
• Responds to calcium ion levels in blood and muscle/gravity pull on skeleton.
• Essential for maintaining bone proportions and strength during growth.
• Leads to thicker bones and projections where muscles attach.

Stages of Bone Remodeling

• Resorption: Osteoclasts remove bone (3-4 weeks).
• Reversal: Mononuclear cells prepare the bone surface for osteoblasts.
• Formation: Osteoblasts build new bone (3-4 months).
• Resting: A prolonged period before a new cycle begins.

Bone Repair

• Bone fractures damage blood vessels, forming a hematoma.
• Blood vessels and cells invade the clot, forming fibrous connective tissue and cartilage to hold bone fragments together.

Fractures

• Incomplete: Fracture traverses part of the bone.
• Complete: Bone separates into at least two fragments.
• Comminuted: Bone breaks into multiple fragments.

Calcium Homeostasis

• Bone is a major calcium storage site.
• Calcium movement into (osteoblasts) and out of (osteoclasts) bone regulates blood calcium levels.
• Balanced osteoblast/osteoclast activity maintains calcium equilibrium.
• Decreased blood calcium stimulates parathyroid hormone (PTH) secretion.
• PTH stimulates osteoclasts, increases kidney reabsorption of calcium, and promotes vitamin D formation for intestinal calcium absorption.
• Increased blood calcium stimulates calcitonin secretion from the thyroid, inhibiting osteoclasts and promoting osteoblast calcium uptake.

Cartilages of the Skeleton

• Hyaline cartilage: Provides sturdy support with flexibility (most skeletal cartilages).
• Elastic cartilage: More flexible than hyaline, tolerates bending (external ear, epiglottis).
• Fibrocartilage: High tensile strength and compression resistance (intervertebral discs, knee joint).

Important Adult Skeletal Cartilages

• Articular cartilages: Cover bone ends at movable joints.
• Costal cartilages: Connect ribs to sternum.
• Nasal cartilages: Support the external nose.
• Intervertebral discs: Separate and cushion vertebrae.

Bone Count

• Newborns: ~350 bones
• Adults: 206 bones

Axial Skeleton

• Skull, vertebral column, and thoracic cage.
• Protects brain, spinal cord, heart, and lungs.

Skull

• Sits atop the vertebral column.
• Cranium (8 bones) & Facial bones (14 bones).
• Bones joined by sutures except for the mandible (movable joint).

Cranium

• Cranial vault (calvaria): Superior, lateral, and posterior skull walls.
• Cranial base: Bottom of the skull.

Cranial Bones

• Frontal bone: Forehead, superior orbit, anterior cranial fossa floor.
• Parietal bones (2): Superior and lateral skull aspects.
  • Temporal bones (2): Inferolateral skull; temples, external auditory meatus, zygomatic process.
• Occipital bone: Posterior skull and base; foramen magnum.
• Sphenoid bone: Keystone bone; articulates with all other cranial bones; parts of eye orbits; sella turcica (pituitary gland location); optic canals; foramen rotundum.

Humerus

• Head separated from shaft by anatomical and surgical neck (fracture site).
• Capitulum (articulates with radius).
• Trochlea (articulates with ulna).

Forearm (Antebrachium)

• Ulna (medial, little finger side); trochlear notch rotates over humerus.
• Radius (lateral, thumb side); head rotates over humerus. Ulna and radius articulate with humerus at the elbow.

Hand (Manus)

• Wrist (8 carpal bones in two rows).
• Proximal row: Scaphoid (boat-shaped), lunate (moon-shaped), triquetrum (three-cornered), pisiform (pea-shaped).
• Distal row: Hamate (hooked process), capitate (head-shaped), trapezoid (4-sided, parallel sides), trapezium (4-sided, no parallel sides).
• Metacarpals (5 bones; palm; form knuckles).
• Phalanges (digits; thumb has 2; fingers have 3).

Types of Body Movement

• Flexion: Decreases joint angle.
• Extension: Increases joint angle.
• Rotation: Movement around a longitudinal axis.
• Abduction: Movement away from midline.
• Adduction: Movement towards midline.
• Circumduction: Combination of flexion, extension, abduction, and adduction.
• Supination: Forearm rotates laterally (palm anterior, radius & ulna parallel).
• Pronation: Forearm rotates medially (palm posterior).
• Opposition: Thumb movement.
• Inversion: Sole turns medially.
• Eversion: Sole turns laterally.
• Dorsiflexion: Lifting foot towards shin.
• Plantar flexion: Depressing the foot.

Test your knowledge on the effects of various hormones on bone growth and development. This quiz covers topics including Vitamin C deficiency, growth hormones, thyroid hormones, and the processes involved in bone remodeling. Challenge yourself and understand how these factors contribute to the overall skeletal health.