VS

Chapter 4 - Skin and Body Membranes PowerPoint

Chapter 4: Skin and Body Membranes

Overview

  • Introduction to body membranes and their significance

  • Division into major categories to understand their structure and function

Body Membranes

Functions

  • Cover body surfaces

  • Line body cavities

  • Form protective sheets around organs

  • Classified based on tissue types

Major Categories

  • Epithelial Membranes

    • Cutaneous membranes

    • Mucous membranes

    • Serous membranes

  • Connective Tissue Membranes

    • Synovial membranes

Epithelial Membranes

General Information

  • Simple organs also called covering and lining membranes

  • Composed of both epithelial and connective tissue layers

Types of Epithelial Membranes

  1. Cutaneous Membrane (Skin)

    • Dry membrane; outermost protective boundary

    • Composed of:

      • Epidermis: keratinized stratified squamous epithelium

      • Dermis: mostly dense, fibrous connective tissue

  2. Mucous Membranes (Mucosae)

    • Moist membranes lining cavities open to exterior

    • Secretes protective mucus; adapted for absorption or secretion

    • Composed of:

      • Varies in epithelium type based on location

      • Loose connective tissue (lamina propria)

  3. Serous Membranes (Serosae)

    • Line closed compartments in the ventral body cavity

    • Occur in pairs (visceral and parietal layers) with serous fluid in between

    • Composed of simple squamous epithelium and areolar connective tissue

    • Key examples:

      • Peritoneum: covers abdominal organs

      • Pleurae: surrounds lungs

      • Pericardia: surrounds the heart

Connective Tissue Membranes

  • Synovial Membranes

    • Consist solely of loose areolar connective tissue

    • Lines fibrous capsules surrounding joints

    • Secretes lubricating fluid for cushioning and movement

Integumentary System

Components

  • Skin (cutaneous membrane)

  • Skin appendages:

    • Sweat glands

    • Oil glands

    • Hair

    • Nails

Functions of the Integumentary System

  1. Insulation and cushioning of organs

  2. Protection against:

    • Mechanical damage (bumps and cuts)

    • Chemical damage (acids and bases)

    • Thermal damage (heat or cold)

    • Ultraviolet radiation

    • Microbes (bacteria)

    • Water loss

  3. Regulation of heat loss controlled by the nervous system

  4. Mini-excretory system for waste removal (urea, salts, water)

  5. Synthesis of vitamin D

  6. Creation of a protective acid mantle via secretions

Detailed Function Breakdown (Table 4.1)

  1. Mechanical Damage: Keratinized physical barrier with pain receptors

  2. Chemical Damage: Keratinized layers and pain receptors protect against irritants

  3. Microbial Damage: Unbroken surface plus acid mantle inhibit pathogen penetration

  4. Ultraviolet Radiation: Melanin produced by melanocytes provides protective effect

  5. Thermal Damage: Nerve receptors alert to temperature extremes

  6. Heat Regulation: Can increase or decrease blood flow through capiliary beds

  7. Waste Excretion: Via perspiration

  8. Vitamin D Synthesis: From cholesterol compounds with sunlight exposure

Structure of the Skin

General Overview

  • Made of two main tissue types: epidermis and dermis

  • Subcutaneous tissue (hypodermis) beneath skin; anchors skin to organs (not part of integumentary system)

  • Composed primarily of adipose tissue for shock absorption and insulation

Epidermis

  1. Outer Layer: Stratified squamous epithelium

  2. Keratinocytes: Produce keratin, which toughens the skin

  3. Layer Composition:

    • Five strata: basale, spinosum, granulosum, lucidum (only in thick skin), corneum

Specific Stratum Details

  • Stratum Basale: Deepest layer; cell proliferation

  • Stratum Spinosum: Flatter, keratinized cells

  • Stratum Granulosum: Contains dying cells; keratin production

  • Stratum Lucidum: Present in thick skin only; high keratin content

  • Stratum Corneum: Outermost layer; dead, keratin-filled cells prevent water loss

Key Epidermal Cells

  • Melanin: Produced by melanocytes (color range yellow to brown to black)

  • Epidermal Dendritic Cells: Immune response activation

  • Merkel Cells: Touch perception

Dermis

  • Comprised of connective tissue; divided into two regions:

    1. Papillary Layer: Upper layer with projections (dermal papillae) containing capillaries and receptors

    2. Reticular Layer: Deeper layer, providing structure with dense connective tissue and inclusions (glands, pressure receptors)

Skin Color

Influencing Pigments

  1. Melanin: Yellow to black pigments

  2. Carotene: Orange-yellow pigment [ also found in some vegetables]

  3. Hemoglobin: Red pigment from blood cells

  4. ctl ;blue pigment that can give skin a bluish tint, particularly in areas where blood vessels are close to the surface.

Abnormal Skin Colorations

  • Erythema: Redness due to various factors (embarrassment, fever)

  • Pallor: Blanching due to stress or poor circulation

  • Jaundice: Yellowing indicating liver issues [ first nail bends and then the eyes}

  • Bruises: Hematomas indicated by black/blue marks

Appendages of the Skin

Types of Glands

  1. Sebaceous Glands: Produce sebum; provide moisture and antibacterial properties

  2. Sweat Glands: Two types—eccrine and apocrine

    • Eccrine: Most numerous, regulate temperature through sweat acidic sweat

    • Apocrine: Found in certain body areas; become active at puberty

Hair Characteristics

  • Composed of hard keratin; pigmentation from melanocytes

  • Produced in hair follicles; growth occurs at the hair bulb in the stratum basale

  • arrector pili muscle -

Nail Structure

  • Heavily keratinized, protecting digits and providing function

  • Growth occurs in the nail matrix; nails lack pigment

Homeostatic Imbalances of Skin

Common Infections and Disorders

  1. Fungal Infections: Athlete’s foot [ tinea pedis]

  2. Bacterial Infections: Boils, impetigo

  3. Skin Conditions: Psoriasis

  4. cold sores [ fever blisters] caused by HPV are viral infections that can cause painful sores on the lips and around the mouth, often triggered by stress or illness.

Burns Classification

  • Severity influences treatment:

    • First-degree: Affects epidermis, red and swollen

    • Second-degree: Blistered, involves dermis, painful and red

    • Third-degree: Destroys dermis and epidermis burned area is painless [ gray black or white]

    • Fourth-degree: Extends to deeper tissues, requires surgical intervention [ may require amputation] appears dry

Skin Cancer Types

most common

  1. Basal Cell Carcinoma: Least malignant [most common] appear shiny dome - shaped nodules

  2. Squamous Cell Carcinoma: Can metastasize [uv exposure]

  3. Malignant Melanoma: Most severe; detects using ABCDE rule [most deadly skin cancers]

Developmental Aspects of Skin

  • Changes throughout life:

    • Lanugo covers fetuses; oily covering (vernix) at birth downy hair

    • Aging leads to thinner, less elastic skin; increased risk of cancer and hair loss

    • milia small white spots

    • in youth skin is thick and wall hydrated 

      blading and alopecia