Integumentary System Quiz

Integumentary System

• The integumentary system includes skin, hair, fingernails, and glands (sweat and oil).
• It acts as a protective layer, regulating body temperature, and excreting waste.
• It's the first barrier, preventing harmful substances from entering and retaining beneficial ones (e.g., water).

Functions of Skin

• Protects the body.
• Synthesizes vitamin D with UV light.
• Regulates body temperature.
• Helps excrete wastes via sweat.
• Provides sensory reception (through nerve endings).

Epithelium: Layers and Cells

• The epidermis has layers: stratum corneum, stratum granulosum, stratum spinosum, stratum basale.
• Key cell types include keratinocytes, Langerhans' cells, melanocytes, and Merkel cells.
• Keratinocytes are dead, flat cells filled with keratin. Glycolipids make the skin waterproof.
• Stratum granulosum cells are flattened with deteriorating organelles; their cytoplasm contains granules.
• Stratum spinosum cells have thick bundles of pre-keratin.
• Stratum basale is actively dividing stem cells; some newly formed cells move to more superficial layers.

Dermis

• Strong, flexible connective tissue.
• Contains fibroblasts, macrophages, mast cells, and white blood cells (WBCs).
• Fiber types include collagen (strength), elastic (stretch), and reticular (network).
• Crucial for temperature regulation (via blood vessels).
• Two layers: papillary (areolar connective tissue, containing dermal papillae) and reticular (network of collagen and reticular fibers).

Skin Appendages

• Derived from epidermis but extend into the dermis.
• Include hair follicles, sebaceous (oil) glands, sweat (sudoiferous) glands, and nails.

Nails

• Composed of hard keratin.
• Similar to hooves and claws.
• Grow from the nail matrix.

Hair and Hair Follicles

• Derived from epidermis and dermis.
• Present everywhere except palms, soles, nipples, and parts of genitalia.
• Arrector pili ("arrector hair") is smooth muscle.
• Hair is made up of three layers: cuticle, cortex, and medulla.

Hair Functions and Structure

• Hair provides warmth (less so in humans).
• Has tactile sensory functions.
• Protects the scalp.
• Composed of hard keratin.
• Has three concentric layers (cuticle, cortex, medulla).

Hair Types

• Vellus (fine, short hairs)
• Intermediate hairs
• Terminal hairs (longer, courser hairs)

Hair Growth

• Averages about 2mm per week.
• Has active growth phase followed by a resting phase.

Hair Loss

• Thinning/loss is often age-related.
• Male pattern baldness is a specific type.

Sebaceous Glands

• Present throughout the body except palms and soles.
• Produce sebum by holocrine secretion.
• Sebum is an oily substance that lubricates and conditions the skin.

Sweat Glands

• Located throughout the skin surface.
• Prevent overheating.
• Humans secrete 500-12,000 ml of sweat per day, mainly water.
• Different types: eccrine and apocrine.

Types of Sweat Glands

• Eccrine: most abundant, for thermoregulation.
• Apocrine: located in axillary, anal, and genital areas; ducts open into hair follicles, and secrete organic molecules that decompose to cause odor.

Disorders of the Integumentary System

• Burns: (threat to life, catastrophic loss of fluids) First-degree (redness,e.g., sunburns), Second-degree (blistering), Third-degree(destroys skin layers).
• Infections (Direct Contact, Vector borne).
• Wounds
• Skin cancer:
  • Benign-warts
  • Malignant- Melanoma (recognition: ABCD – Asymmetry, Borders, Color, Diameter).

Immune System

• A functional system, not an organ system.
• Components: skin, lining of mucus membranes, secretions, blood cells, vasculature, bone marrow, liver (makes complement proteins), lymphatic system, lymphoid organs, and resident immune cells.
• Two major types: innate and adaptive.
• Innate (first line of defense): no time lag, not antigen-specific, no memory.
• Adaptive (second line of defense): Has lag period, antigen-specific, memory component.
• Key players:
  • Cytotoxic lymphocytes.
  • Phagocytic cells (e.g., neutrophils, macrophages).
  • Natural killer (NK) cells.
  • Antimicrobial proteins (e.g., interferons, complement).
  • Inflammatory response.

Innate Immunity - Internal Defenses

• Cellular Components: neutrophils, monocytes/macrophages, NK cells, TLRs.
• Extracellular components: Cytokines, Complement, Coagulation proteins.

Phagocytosis

• Neutrophils and Macrophages ingest and destroy microbes within the body.
• The process involves several steps.

Cytokines

• Small secreted proteins by immune system cells that help regulate cell behaviour.
• Involved in innate and adaptive immunity.
• Examples of types: interferons, interleukins, and tumor necrosis factor (TNF).

Interferons

• Signaling proteins secreted by virus-infected cells.
• Warn neighbouring cells of viral threats.
• Function by producing anti-viral proteins.

Interleukins

• Proteins secreted by immune cells in response to infection.
• Primarily secreted by lymphocytes and macrophages.
• Function by boosting the immune response or modulating other immune cells.

Complement System

• A group of plasma proteins that work together in the immune response.
• Acts as an opsonin (enhances phagocytosis), directly lyses pathogens, and promotes inflammation.

Coagulation Proteins

• A pathway that stops bleeding through blood clot formation.
• Involves platelets and coagulation factors, and vitamin K.

Antibodies

• Secreted by plasma cells (B lymphocytes).
• Essential components of the adaptive immune system, binding to unique antigens with high specificity.
• Structural components include two identical heavy chains and two identical light chains forming Y-shaped proteins.

Antibody Functions (Fab and Fc regions)

• Fab: antigen-binding variable fragment.
• Fc: constant fragment; binds to cell receptors.
• Antibodies exist in both soluble (secreted) and membrane-bound forms.

Specific Response (Adaptive Immunity)

• Involves lymphocytes (B and T cells) and plasma cells (for antibody production).
• Crucial for vaccinations and immune responses against known threats or antigens.

Test your knowledge of the integumentary system, focusing on the structure and functions of skin and hair. This quiz covers various topics including sebaceous glands, hair growth, and skin pigmentation. Challenge yourself and learn more about the complexities of skin anatomy!