BIO116 Exam 2 Study Guide: Integumentary and Skeletal Systems

The Integumentary System

Layers of the Cutaneous Membrane

The cutaneous membrane, commonly known as the skin, consists of multiple layers, each with distinct structures and functions.

• Epidermis: The outermost layer composed primarily of keratinized stratified squamous epithelium. It provides a waterproof barrier and creates our skin tone.

• Dermis: Located beneath the epidermis, this layer contains connective tissue, blood vessels, nerve endings, hair follicles, and glands. It supports and nourishes the epidermis.

• Hypodermis (Subcutaneous Layer): Not technically part of the skin, but often discussed with it. This layer consists mainly of adipose tissue and anchors the skin to underlying structures.

Example: The epidermis protects against pathogens, while the dermis provides strength and elasticity due to collagen and elastin fibers.

Accessory Structures of the Integument

Accessory structures are derived from the epidermis and serve various protective and sensory functions.

• Hair: Protects the scalp from UV radiation, provides insulation, and acts as a sensory receptor.

• Nails: Protect the distal phalanges and enhance fine touch sensation.

• Glands:

  • Sebaceous (oil) glands: Secrete sebum to lubricate skin and hair.

  • Sudoriferous (sweat) glands: Regulate body temperature and excrete waste products.

Example: Eccrine sweat glands are distributed throughout the body and play a key role in thermoregulation.

Infectious Skin Diseases and Allergic Reactions

Common skin infections and allergic reactions present with characteristic signs and symptoms.

• Bacterial Infections: Redness, swelling, pus (e.g., impetigo).

• Viral Infections: Vesicular rashes (e.g., herpes simplex).

• Fungal Infections: Itchy, scaly patches (e.g., ringworm).

• Allergic Reactions: Hives, redness, itching (e.g., contact dermatitis).

Example: Allergic contact dermatitis is caused by exposure to allergens like poison ivy.

Burn Classification: Rule of Nines

The rule of nines is used to estimate the percentage of body surface area affected by burns.

• The body is divided into sections, each representing approximately 9% (or multiples thereof) of the total body surface area.

Body Region	% of Total Surface Area
Head and Neck	9%
Each Arm	9%
Each Leg	18%
Anterior Trunk	18%
Posterior Trunk	18%
Perineum	1%

Example: A burn involving the entire right arm and anterior trunk would cover 27% of the body surface area.

Degrees of Burns and Critical Burns

Burns are classified by depth and severity.

• First-degree: Affect only the epidermis; redness and pain (e.g., sunburn).

• Second-degree: Involve epidermis and part of dermis; blisters, swelling, pain.

• Third-degree: Destroy both epidermis and dermis; may appear white, charred, or leathery; often painless due to nerve damage.

Critical burns include:

• Over 25% of body with second-degree burns

• Over 10% of body with third-degree burns

• Third-degree burns on face, hands, feet, or perineum

Types of Skin Cancer

There are three common types of skin cancer, each with distinct characteristics.

Type	Layer Affected	Appearance	Prognosis
Basal Cell Carcinoma	Stratum basale	Pearly, raised nodule	Excellent with treatment
Squamous Cell Carcinoma	Stratum spinosum	Scaly, red papule	Good if caught early
Malignant Melanoma	Melanocytes	Dark, irregular mole	Poor if not detected early

ABCDE Rule for Skin Cancer Diagnosis

The ABCDE rule helps identify suspicious moles or lesions that may indicate melanoma.

• Asymmetry: One half does not match the other.

• Border irregularity: Edges are ragged or blurred.

• Color: Varies in shade or has multiple colors.

• Diameter: Greater than 6 mm (about the size of a pencil eraser).

• Evolving: Changes in size, shape, or color over time.

The Skeletal System

Types of Bone Tissue

Bone tissue is classified into two main types based on structure and function.

• Compact Bone: Dense and solid; forms the outer layer of bones and provides strength for weight bearing.

• Spongy (Cancellous) Bone: Porous and lightweight; found at the ends of long bones and inside flat bones, containing red marrow for blood cell production.

Main Functions of Bones

Bones serve several vital functions in the human body.

• Support: Framework for the body and attachment for muscles.

• Protection: Shields vital organs (e.g., skull protects brain).

• Movement: Acts as levers for muscles to produce movement.

• Mineral Storage: Reservoir for calcium and phosphorus.

• Blood Cell Production: Hematopoiesis occurs in red marrow.

• Triglyceride Storage: Yellow marrow stores fat.

Classifications of Bones

Bones are classified by shape and structure.

Classification	Description	Examples
Long Bones	Longer than wide, shaft with heads at both ends	Femur, humerus
Short Bones	Cube-shaped, mostly spongy bone	Carpals, tarsals
Flat Bones	Thin, flattened, usually curved	Sternum, skull bones
Irregular Bones	Complex shapes	Vertebrae, hip bones

Gross Anatomy of a Long Bone

Long bones have distinct anatomical regions.

• Diaphysis: Shaft, composed of compact bone.

• Epiphyses: Ends of the bone, mostly spongy bone.

• Metaphysis: Region between diaphysis and epiphysis; contains growth plate in children.

• Medullary Cavity: Central cavity containing yellow marrow.

• Periosteum: Outer fibrous covering.

• Endosteum: Lining of the medullary cavity.

Microscopic Anatomy of Compact Bone

Compact bone is organized into structural units called osteons (Haversian systems).

• Osteon: Cylindrical structure containing concentric lamellae around a central canal.

• Central (Haversian) Canal: Contains blood vessels and nerves.

• Lacunae: Small spaces housing osteocytes.

• Canaliculi: Tiny channels connecting lacunae for nutrient exchange.

Subdivisions of the Skeletal System

The skeleton is divided into two main parts.

Division	Description	Examples
Axial Skeleton	Central axis of the body	Skull, vertebral column, rib cage
Appendicular Skeleton	Limbs and girdles	Arms, legs, pelvic and pectoral girdles

Example: The femur is part of the appendicular skeleton; the sternum is part of the axial skeleton.

Paranasal Sinuses

Paranasal sinuses are air-filled spaces in the skull that lighten its weight and enhance voice resonance.

• Frontal sinus

• Ethmoid sinus

• Sphenoid sinus

• Maxillary sinus

Vertebral Column Regions and Features

The vertebral column is divided into regions, each with unique vertebrae.

Region	Number of Vertebrae	Unique Features
Cervical	7	Transverse foramina, bifid spinous process
Thoracic	12	Facets for rib articulation, long spinous process
Lumbar	5	Large, robust bodies, short spinous process

Types of Ribs

Ribs are classified based on their attachment to the sternum.

• True Ribs (1-7): Attach directly to the sternum via costal cartilage.

• False Ribs (8-12): Attach indirectly or not at all to the sternum.

• Floating Ribs (11-12): Do not attach to the sternum.

Bones of the Appendicular Skeleton

The appendicular skeleton includes the limbs and girdles.

• Upper Limb: Humerus, radius, ulna, carpals, metacarpals, phalanges

• Lower Limb: Femur, tibia, fibula, tarsals, metatarsals, phalanges

• Carpals: Wrist bones

• Metacarpals: Hand bones

• Tarsals: Ankle bones

• Metatarsals: Foot bones

• Phalanges: Finger and toe bones

Proximal vs. Distal: Proximal refers to closer to the trunk; distal is farther from the trunk.

Os Coxa and Pelvic Differences

The os coxa (hip bone) consists of three fused bones and differs between sexes.

• Ilium

• Ischium

• Pubis

Male Pelvis: Narrower, heavier, heart-shaped inlet. Female Pelvis: Wider, lighter, oval-shaped inlet for childbirth.

Classification of Joints

Joints are classified structurally and functionally.

Structural Classification	Description	Example
Fibrous	Joined by dense connective tissue	Sutures of the skull
Cartilaginous	Joined by cartilage	Intervertebral discs
Synovial	Joint cavity with synovial fluid	Knee, elbow

Functional Classification	Description	Example
Synarthrosis	Immovable	Sutures
Amphiarthrosis	Slightly movable	Pubic symphysis
Diarthrosis	Freely movable	Shoulder joint

Example: The knee is a synovial, diarthrotic joint.

Additional info: Where specific diagrams or images are referenced in the outcomes, students should refer to their textbook or lecture materials for labeled diagrams of bones, sinuses, and joints.