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Study Guide: Integumentary and Skeletal Systems (Chapters 4 & 5)

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Integumentary System

Functions of the Integumentary System

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

  • Regulation of Body Temperature: Sweat glands and blood vessels help maintain homeostasis.

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

  • Excretion: Removes waste products through sweat.

  • Synthesis of Vitamin D: UV light triggers vitamin D production in the skin.

Types of Tissues in Skin Layers

  • Epidermis: Composed of stratified squamous epithelium.

  • Dermis: Made of dense irregular connective tissue containing collagen and elastic fibers.

  • Hypodermis (Subcutaneous Layer): Consists of adipose tissue and loose connective tissue.

Layers and Structures of the Skin

  • Epidermis (from superficial to deep):

    1. Stratum corneum

    2. Stratum lucidum (only in thick skin)

    3. Stratum granulosum

    4. Stratum spinosum

    5. Stratum basale

  • Dermis:

    1. Papillary layer (superficial, areolar connective tissue)

    2. Reticular layer (deep, dense irregular connective tissue)

Body Membranes: Structure and Location

  • Cutaneous membrane: The skin; covers the body surface.

  • Mucous membranes: Line body cavities open to the exterior (e.g., digestive, respiratory tracts).

  • Serous membranes: Line closed ventral body cavities (e.g., peritoneum, pleura, pericardium).

  • Synovial membranes: Line joint cavities; secrete synovial fluid.

Proteins Produced by Skin Cells

  • Keratinocytes: Produce keratin, a tough, water-resistant protein.

  • Melanocytes: Produce melanin, a pigment that protects against UV radiation.

  • Response to UV Radiation: Melanocytes increase melanin production, leading to tanning and enhanced protection.

Glands of the Skin

  • Exocrine glands: Secrete products into ducts (e.g., sweat, sebaceous glands).

  • Endocrine glands: Secrete hormones directly into the bloodstream.

  • Eccrine glands: Produce watery sweat for thermoregulation; found throughout the body.

  • Apocrine glands: Found in axillary and genital areas; produce thicker secretion; become active at puberty.

  • Sebaceous glands: Secrete sebum (oil) into hair follicles; lubricates and waterproofs skin and hair.

Burns: Classification and Symptoms

Degree

Symptoms

Layers Damaged

First-degree

Redness, pain, no blisters

Epidermis only

Second-degree

Redness, pain, blisters

Epidermis and part of dermis

Third-degree

No pain (nerves destroyed), white/charred appearance

All skin layers

Skin Cancer Types

Type

Description

Basal cell carcinoma

Most common, least malignant; arises from stratum basale

Squamous cell carcinoma

Arises from stratum spinosum; can metastasize

Malignant melanoma

Most dangerous; arises from melanocytes

  • ABCDE of Malignant Melanoma:

    • Asymmetry

    • Border irregularity

    • Color variation

    • Diameter > 6 mm

    • Evolving (changing in size, shape, or color)

Skeletal System

Functions of the Skeletal System

  • Support for the body

  • Protection of internal organs

  • Movement (leverage for muscles)

  • Mineral storage (calcium, phosphate)

  • Blood cell production (hematopoiesis in red marrow)

  • Fat storage (yellow marrow)

Bone Cells and Their Functions

Cell Type

Function

Osteoblasts

Build bone matrix (bone-forming cells)

Osteocytes

Maintain bone tissue

Osteoclasts

Break down bone matrix (bone-resorbing cells)

Osteon Structure

  • Osteon (Haversian system): Structural unit of compact bone.

  • Consists of concentric lamellae (rings of bone matrix) around a central (Haversian) canal containing blood vessels and nerves.

  • Lacunae (spaces) house osteocytes; canaliculi connect lacunae for nutrient/waste exchange.

Long Bone Anatomy

  • Diaphysis: Shaft of the bone; contains medullary cavity (yellow marrow in adults).

  • Epiphyses: Ends of the bone; contain spongy bone and red marrow.

  • Epiphyseal plate: Growth plate made of cartilage; site of bone lengthening in children.

  • Epiphyseal line: Remnant of the plate in adults; indicates bone has stopped growing.

  • Periosteum: Outer membrane; contains osteoblasts and osteoclasts.

  • Endosteum: Inner membrane lining the medullary cavity.

Bone Classification by Shape

Type

Description

Example

Long bones

Longer than wide

Femur, humerus

Short bones

Cube-shaped

Carpals, tarsals

Flat bones

Thin, flat, often curved

Sternum, skull bones

Irregular bones

Complex shapes

Vertebrae, pelvis

Bone Marrow

  • Red marrow: Site of blood cell formation; found in spongy bone of flat bones and epiphyses of long bones.

  • Yellow marrow: Stores fat; found in medullary cavity of long bones in adults.

Ossification (Osteogenesis)

  • Process of bone formation.

  • Embryonic precursors: Hyaline cartilage (endochondral ossification) or fibrous membranes (intramembranous ossification).

Bone Growth and Remodeling

  • Stimulated by mechanical stress (exercise), hormones (growth hormone, sex hormones), and dietary factors (calcium, vitamin D).

  • Remodeling: Continuous process of bone resorption and formation.

Hormones Affecting Bone

  • Growth hormone: Stimulates bone growth.

  • Sex hormones (estrogen, testosterone): Promote growth and closure of epiphyseal plates.

  • Parathyroid hormone (PTH): Increases blood calcium by stimulating osteoclasts.

  • Calcitonin: Lowers blood calcium by inhibiting osteoclasts.

Bone Repair Steps

  1. Hematoma formation (blood clot at fracture site)

  2. Fibrocartilaginous callus formation

  3. Bony callus formation

  4. Bone remodeling

Bone Fracture Classification

  • Simple (closed): Bone does not penetrate skin.

  • Compound (open): Bone penetrates skin.

  • Other types: comminuted, spiral, greenstick, etc.

Axial vs. Appendicular Skeleton

Division

Components

Axial

Skull, vertebral column, rib cage, sternum

Appendicular

Limbs, pectoral girdle, pelvic girdle

Vertebral Regions

Region

Number of Bones

Cervical

7

Thoracic

12

Lumbar

5

Sacrum

5 (fused)

Coccyx

4 (fused)

Specific Bones

  • Sternum: Covers and protects the heart; made of manubrium, body, and xiphoid process (3 fused bones).

  • Pelvis: Made of ilium, ischium, and pubis (3 fused bones).

  • Upper arm bone: Humerus.

Joints (Articulations)

  • Definition: Site where two or more bones meet.

  • Classification by movement:

    • Synarthroses: Immovable (e.g., skull sutures)

    • Amphiarthroses: Slightly movable (e.g., intervertebral discs)

    • Diarthroses: Freely movable (e.g., synovial joints)

  • Types of Synovial Joints: Plane, hinge, pivot, condyloid, saddle, ball-and-socket

  • Examples:

    • Elbow: Hinge joint

    • Hip: Ball-and-socket joint

    • Shoulder: Ball-and-socket joint

    • Wrist: Condyloid joint

Additional info:

  • Some details (e.g., specific diagrams or labeling) are not included due to the absence of images in the source material.

  • Tables and lists have been expanded for clarity and completeness.

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