Integumentary System: Skin and Body Membranes

Study Notes

Integumentary System Overview

Integument: Latin origin meaning "to cover," signifies an outer protective layer found in plants and animals, such as skin and shells.
Skin: External covering of vertebrates, composed of three main layers; vital for protection and sensory functions.

Body Membranes

Structure: Thin, sheet-like formations.
Functions:
- Provide coverage and protection to body surfaces.
- Line body cavities.
- Encase hollow organs (digestive, reproductive, respiratory) and anchor them to other structures.
- Secrete lubricating fluids to minimize friction between organs.
Types of Body Membranes:
- Epithelial Membranes
- Cutaneous Membrane (skin)
- Connective Tissue Membrane

Cutaneous Membrane Types

Serous Membranes: Protect organs and reduce friction; consist of visceral (covers organs) and parietal layers (lines body cavities).
- Pleura: Thoracic cavity membrane.
- Peritoneum: Abdominal cavity membrane.
Mucous Membranes: Line surfaces opening to the exterior; secrete mucus.
Connective Tissue Membrane: Lacks epithelial tissue; secretes synovial fluid to reduce friction in joint areas.

Skin Functions

Serves as a barrier against pathogens, UV light, chemicals, and physical injuries.
Regulates body temperature.
Functions as a sensory organ detecting touch, pressure, pain, and temperature.
Involved in metabolic processes, notably vitamin D synthesis.

Skin Structure

Three Layers:
- Epidermis: Outermost, thinnest layer with tightly packed cells; contains five strata:
  - Stratum corneum: Dry, dead keratin-filled cells.
  - Stratum germinativum/basale: Cells undergoing mitosis, replenishing epidermis.
  - Specialized Cells:
    - Melanocytes: Produce melanin for UV protection.
    - Keratinocytes: Create keratin for resistance against abrasion.
    - Langerhans Cells: Play a role in immune response.
- Dermis: Deep, thick layer composed of connective tissue; loosely packed structure provides strength.
- Hypodermis: Primarily adipose tissue; functions in insulation and shock absorption; contains collagen and elastin fibers.

Specialized Structures in Dermis

Hair follicle: Extension of epidermal cells forming a tube.
Hair bulb: Base of the hair follicle.
Hair papilla: Supportive cluster of living cells.
Root and Shaft: Root hidden in follicle; shaft is visible.
Arrector pili: Smooth muscle causing hair to stand up (goosebumps).
Sebaceous Glands: Produce sebum; linked to hair follicles; contribute to acne.
Sudoriferous Glands: Sweat glands; two types:
- Eccrine: Widespread, produces watery sweat.
- Apocrine: Located in armpits and genital areas, secretes a thicker fluid.
Sensory Receptors:
- Pacinian Corpuscle: Responds to deep pressure.
- Meissner’s Corpuscle: Detects light touch.
- Free Nerve Endings: Respond to pain and temperature.

Skin Injuries and Diseases

Burns: Skin damage from heat, chemicals, or radiation; can disrupt infection control and fluid balance.
- First Degree: Affects only the epidermis.
- Second Degree: Involves epidermis and upper dermis layers; characterized by blisters.

Description

Learn about the outer protective layer of an animal, including the definition and functions of the integument and skin. This quiz covers the basics of the integumentary system, perfect for biology students. Test your knowledge and understanding of this essential body system.