Chapter 5: The Integumentary System

Functions of the Skin

• Protection: Acts as a barrier against mechanical injury, pathogens, and harmful substances.

• Thermoregulation: Regulates body temperature through sweat production and blood flow.

• Sensation: Contains sensory receptors for touch, pain, temperature, and pressure.

• Metabolic Functions: Synthesizes vitamin D when exposed to UV light.

• Excretion: Eliminates small amounts of waste products through sweat.

• Blood Reservoir: Stores up to 5% of the body’s blood volume.

Skin Color & Markings

• Normal Coloration: Determined by melanin, carotene, and hemoglobin.

• Abnormal Coloration:

  • Pallor: Pale skin due to anemia or shock.

  • Cyanosis: Bluish tint from low oxygen levels.

  • Jaundice: Yellowing from bilirubin accumulation (liver dysfunction).

  • Erythema: Redness from increased blood flow (inflammation, fever).

  • Bruising: Black-and-blue marks from blood escaping vessels.

Structure of the Skin

• Layers of the Epidermis (from superficial to deep):

  • Stratum Corneum: Dead, keratinized cells; provides protection.

  • Stratum Lucidum: Present only in thick skin (palms, soles).

  • Stratum Granulosum: Keratinization begins here.

  • Stratum Spinosum: Several layers of keratinocytes; contains dendritic cells.

  • Stratum Basale: Deepest layer; site of mitosis and new cell generation.

• Cell Types in the Epidermis:

  • Keratinocytes: Produce keratin; most abundant.

  • Melanocytes: Produce melanin pigment.

  • Langerhans (Dendritic) Cells: Immune defense.

  • Merkel Cells: Sensory receptors for touch.

• Layers of the Dermis:

  • Papillary Layer: Areolar connective tissue; forms dermal papillae.

  • Reticular Layer: Dense irregular connective tissue; provides strength and elasticity.

• Anchoring Structure: The basement membrane (basal lamina) anchors the epidermis to the dermis.

Organs of the Skin

• Hair and Hair Follicles:

  • Parts of a Hair: Shaft (above skin), root (within follicle), bulb (base of follicle).

  • Hair Follicle: Surrounds the root; contains the hair matrix (growth zone).

• Glands of the Skin:

  • Sebaceous (Oil) Glands: Secrete sebum; lubricates skin and hair; found everywhere except palms and soles.

  • Sudoriferous (Sweat) Glands:

    • Eccrine Glands: Widely distributed; thermoregulation.

    • Apocrine Glands: Axillary and genital areas; produce odoriferous sweat.

  • Ceruminous Glands: External ear canal; produce earwax.

  • Mammary Glands: Modified sweat glands; produce milk.

Burns

• Degrees of Burns:

  • First-degree: Epidermis only; redness, pain (e.g., sunburn).

  • Second-degree: Epidermis and part of dermis; blisters, severe pain.

  • Third-degree: Full thickness (epidermis, dermis, possibly deeper); no pain (nerves destroyed), risk of fluid loss and infection.

• Causes: Heat, chemicals, electricity, radiation.

• Complications: Dehydration, infection, electrolyte imbalance, shock.

Skin Cancer

• Types:

  • Basal Cell Carcinoma: Most common, least malignant.

  • Squamous Cell Carcinoma: Arises from keratinocytes; can metastasize.

  • Melanoma: Most deadly; arises from melanocytes.

• Most Common: Basal cell carcinoma.

• Most Deadly: Melanoma.

Chapter 6: Bones and Skeletal Tissue

Functions of Bone Tissue

• Support: Framework for the body.

• Protection: Shields vital organs (e.g., skull, rib cage).

• Movement: Levers for muscles.

• Mineral Storage: Reservoir for calcium and phosphate.

• Blood Cell Formation: Hematopoiesis in red marrow.

• Triglyceride Storage: Yellow marrow stores fat.

Bone Histology

• Bone Cells:

  • Osteoblasts: Build bone matrix; found on bone surfaces.

  • Osteoclasts: Break down bone matrix; large, multinucleated.

  • Osteocytes: Mature bone cells; maintain matrix; found in lacunae.

  • Osteoprogenitor Cells: Stem cells; differentiate into osteoblasts.

• Bone Matrix: Composed of collagen fibers (organic) and hydroxyapatite (inorganic).

• Osteon (Haversian System): Structural unit of compact bone; concentric lamellae around a central canal.

• Trabeculae: Lattice-like network in spongy bone; spaces filled with marrow.

• Arrangement in Osteon: Osteocytes in lacunae between lamellae; central canal contains blood vessels and nerves.

Effects of Stress on Spongy Bone

• Physical activity and load cause trabeculae to align along lines of stress, increasing bone strength.

Bone Development

• Intramembranous Ossification: Forms flat bones (e.g., skull, clavicle) from mesenchymal tissue.

• Endochondral Ossification: Forms most bones; bone develops from hyaline cartilage.

• Stages of Endochondral Ossification:

  • Bony Collar Formation: Osteoblasts form bone around cartilage model.

  • Primary Ossification Center: Forms in diaphysis; cartilage calcifies and is replaced by bone.

  • Secondary Ossification Centers: Develop in epiphyses after birth.

  • Epiphyseal Plate: Cartilage between primary and secondary centers; site of bone growth.

Bone Growth

• Interstitial Growth: Lengthening of bone at the epiphyseal plate during childhood/adolescence.

• Appositional Growth: Increase in bone diameter by adding new bone to the surface.

• Metaphysis Zones:

  • Reserve Cartilage: Resting chondrocytes.

  • Proliferation: Rapid cell division.

  • Hypertrophy: Enlargement of chondrocytes.

  • Calcification: Matrix becomes calcified; chondrocytes die.

  • Ossification: New bone forms.

BMU (Basic Multicellular Unit)

• Group of osteoclasts and osteoblasts that remodel bone; active for about 3-4 months.

Hormonal Control of Bone Growth

• Calcitriol (Vitamin D): Increases blood calcium by promoting absorption in intestines; stimulates osteoclasts.

• Parathyroid Hormone (PTH): Increases blood calcium by stimulating osteoclasts to resorb bone.

• Calcitonin: Lowers blood calcium by inhibiting osteoclasts and stimulating osteoblasts.

• Estrogen & Testosterone: Promote growth at the epiphyseal plate; closure of plate at puberty ends growth.

Bone Fracture Healing Stages

• Hematoma formation

• Fibrocartilaginous callus formation

• Bony callus formation

• Bone remodeling

Osteoporosis

• Effects: Decreased bone mass and density; increased fracture risk.

• Susceptibility: Most common in postmenopausal women, elderly, and those with low calcium/vitamin D intake.

Chapter 8: Joints (Articulations)

Joint Classifications

• Structural Types:

  • Fibrous Joints: Bones joined by dense connective tissue; immovable (e.g., sutures).

  • Cartilaginous Joints: Bones joined by cartilage; slightly movable (e.g., intervertebral discs).

  • Synovial Joints: Bones separated by a joint cavity filled with synovial fluid; freely movable.

• Functional Types:

  • Synarthroses: Immovable joints.

  • Amphiarthroses: Slightly movable joints.

  • Diarthroses: Freely movable joints.

General Anatomy of Synovial Joints

• Articular cartilage covers bone ends.

• Joint (synovial) cavity contains synovial fluid.

• Articular capsule encloses the cavity; lined by synovial membrane.

• Ligaments reinforce the joint.

• May contain menisci, bursae, and fat pads.

Types of Synovial Joints

• Plane: Gliding movements (e.g., intercarpal joints).

• Hinge: Flexion/extension (e.g., elbow).

• Pivot: Rotation (e.g., proximal radioulnar joint).

• Condyloid: Flexion/extension, abduction/adduction (e.g., wrist).

• Saddle: Similar to condyloid but with greater movement (e.g., thumb).

• Ball-and-Socket: Multiaxial movement (e.g., shoulder, hip).

Directional Terms for Joint Movements

• Flexion: Decreases angle between bones.

• Extension: Increases angle between bones.

• Abduction: Movement away from midline.

• Adduction: Movement toward midline.

• Rotation: Bone turns around its own axis.

• Protraction/Retraction: Anterior/posterior movement (e.g., jaw).

• Elevation/Depression: Lifting/lowering a body part.

Movements at Synovial Joints

• Different joints allow specific movements (e.g., hinge joints allow flexion/extension; ball-and-socket allow all movements).

Range of Motion

• Determined by joint structure, ligaments, and muscle tone.

Levers and Mechanical Advantage

• Bones act as levers; joints are fulcrums.

• Mechanical advantage: When a lever allows a small effort to move a large load.

Arthritis

• Osteoarthritis: Degenerative; wear and tear of articular cartilage.

• Rheumatoid Arthritis: Autoimmune; inflammation of synovial membrane.

Artificial Joints

• Prosthetic replacements for damaged joints (e.g., hip, knee).

Selected Synovial Joints

• Knee: Largest, most complex; ACL surgery repairs torn ligament.

• Hip: Ball-and-socket; hip replacement for severe arthritis or fracture.

• Shoulder, Elbow, Ankle: Each has unique structure and movement capabilities.

Table: Comparison of Joint Types

Key Equations

• Mechanical Advantage (MA) of a Lever:

• Calcium Homeostasis:

Example: A patient with a third-degree burn over 20% of their body is at high risk for dehydration and infection due to the loss of the protective skin barrier and fluid loss from damaged capillaries.

Example: Osteoporosis is most common in postmenopausal women due to decreased estrogen, which normally inhibits bone resorption.

Example: The knee joint is a synovial hinge joint, allowing flexion and extension; ACL surgery is performed to restore stability after ligament injury.

Additional info: Academic context and definitions have been added to expand on the study guide prompts and ensure completeness.