Tissues and Integumentary Systems

Tissues Overview

  • Tissues are groups of cells organized in layers for specific body functions.

  • Organization hierarchy: atoms → molecules → macromolecules → cells → tissues.

Major Tissue Types

  • Epithelial Tissue:

    • Functions: protection, secretion, absorption, excretion.

    • Characteristics: avascular, tightly packed, capable of rapid division.

    • Types: squamous, cuboidal, columnar, transitional.

  • Connective Tissue:

    • Functions: binding, support, protection, fat storage, blood cell production.

    • Organized with an abundant extracellular matrix; vascularity varies.

    • Types: loose (areolar, adipose, reticular), dense (regular, irregular), specialized (cartilage, bone, blood).

  • Muscle Tissue:

    • Types: skeletal (voluntary), smooth (involuntary, found in walls of organs), cardiac (involuntary, heart).

  • Nervous Tissue:

    • Functions: impulse conduction for coordination and sensory reception.

    • Composed of neurons and glial cells.

Integumentary System

  • Composed of the skin and accessory structures (hair, nails, glands).

  • Functions: homeostasis, protection, temperature regulation, sensation, excretion.

  • Skin Layers:

    • Epidermis: outer layer, stratified squamous epithelium, avascular.

    • Dermis: inner layer with connective tissue, blood vessels, hair follicles, glands.

    • Subcutaneous Layer (Hypodermis): connective tissue connecting skin to underlying tissues.

Epidermis Structure

  • Contains layers: stratum basale, stratum spinosum, stratum granulosum, stratum corneum (outermost), and stratum lucidum (only in thick skin).

  • Contains melanocytes that produce melanin (skin color, UV protection).

Accessory Structures

  • Hair: found all over except palms/soles; composed of dead keratinized cells.

  • Nails: protective covering with nail plate, nail bed, and lanula.

  • Glands:

    • Sebaceous: associated with hair follicles, secretes sebum.

    • Sweat Glands: eccrine (temperature regulation) and apocrine (response to stress).

Healing Processes

  • Healing initiates with inflammation (redness, heat, swelling, pain).

  • Superficial cuts heal via epithelial cell reproduction; deeper wounds require more involved processes including blood clotting and collagen deposition.