Concentration Guide for Chapters 4 and 5 (OpenStax)

Topic Concentration Guide for Chapters 4 and 5 (OpenStax)

Chapter 4: Tissue Types

Common Characteristics of Tissues

• Epithelial Tissues: Tightly packed cells, avascular (lack blood vessels), regenerate quickly, and serve functions including protection, absorption, and secretion.

• Connective Tissues: Develop from mesenchyme, primarily involved in supporting and binding other tissues, and vary widely in structure and function.

• Muscle Tissues: Specialized for contraction, responsible for movement, includes skeletal, cardiac, and smooth muscle.

• Nervous Tissue: Composed of neurons and glial cells, responsible for transmitting electrical impulses and supporting neural function.

Skin Cancer Dynamics

• Skin cancers develop rapidly due to:

  • High proliferation rate of epithelial cells in the epidermis.

  • Ability for cells to quickly invade surrounding tissues and spread through lymphatic and blood systems.

Connective Tissue Healing Rates

• Variability in healing rates among connective tissues:

  • Tissues like bone heal quickly due to high vascularity.

  • Cartilage heals slowly due to limited blood supply.

Junctions and Their Functions

• Gap Junctions: Allow for intercellular communication via ions and small molecules. Essential for electrical signal transmission in cardiac and smooth muscle.

• Desmosomes: Connect adjacent cells mechanically, providing structural support, especially in tissues subjected to stress.

• Tight Junctions: Create barriers between cells, regulating the passage of substances between the epithelium and underlying tissues.

Endocrine vs. Exocrine Glands

• Endocrine Glands: Secrete hormones directly into the bloodstream (e.g., thyroid gland).

• Exocrine Glands: Secrete substances through ducts to the epithelial surface (e.g., sweat glands, salivary glands).

Specific Epithelial Tissues

• Simple Squamous Epithelium: Functions in diffusion and filtration; located in alveoli (lungs) and capillaries.

• Simple Cuboidal Epithelium: Functions in secretion and absorption; found in kidney tubules and glandular ducts.

• Simple Columnar Epithelium: Functions in absorption and secretion of mucus and enzymes; located in the digestive tract.

• Pseudostratified Columnar Epithelium: Functions in secretion and movement of mucus via cilia; typically found in the respiratory tract.

• Transitional Epithelium: Protective, allows stretching; located in the bladder.

• Stratified Squamous Epithelium: Keratinized type protects underlying tissues; found in the skin (the keratin provides protection against abrasion).

Functions and Locations of Connective Tissues

• Mesenchyme: Serves as the embryonic stem cell tissue that develops into all connective tissues.

• Collagen and Elastin: Provide structural support and elasticity to tissues, respectively.

• Cell types:

  • Fibroblasts: Produce fibers and extracellular matrix.

  • Adipocytes: Store energy in the form of fat.

  • Macrophages: Provide immune defense by engulfing pathogens.

  • Mast Cells: Involved in inflammatory responses and release histamine.

  • Melanocytes: Produce melanin for pigment.

• Types of Connective Tissues:

  • Adipose: Energy storage and insulation.

  • Areolar: Supports and binds other tissues; located around organs and under epithelia.

  • Reticular: Provides a supportive framework; found in lymph nodes and the spleen.

  • Dense Regular: Provides strong attachment; tendons and ligaments.

  • Dense Irregular: Provides structural strength to withstand stress; found in dermis of skin.

  • Elastic Connective Tissue: Allows for stretching; found in large arteries and ligaments.

  • Cartilage Types (Hyaline, Fibrocartilage, Elastic): Vary by fiber composition and function, supporting structures.

  • Bone Tissue/Osseous Tissue: Provides structure and support, stores minerals.

Tissue Membranes

• Cutaneous Membrane: Skin, provides protection and sensory reception.

• Serous Membranes: Line closed body cavities, providing lubrication.

• Mucous Membranes: Line openings to the exterior, involved in secretion and absorption.

Chapter 5: Integumentary System Functions

Skin Functions

• Protects against injury, infection, and fluid loss.

• Serves as a barrier to mechanical invasions, supported by structural integrity.

• Acts chemically through the secretion of antimicrobial substances (defensins and dermicidins).

• Maintains homeostasis, especially in temperature regulation.

Skin as a Barrier

• Mechanical Barrier: Physical integrity that helps prevent pathogens from entering the body.

• Chemical Barrier: The skin's normal pH, approximately 4.5-5.5, inhibits bacterial growth; this acidity is due to the secretion of sweat and sebum.

Role of Defensins and Dermicidins

• Defensins: Antimicrobial peptides produced by skin cells that fight off bacteria and other pathogens.

• Dermicidins: Another type of antimicrobial peptide that contributes to the skin's defense against pathogens.

Care for Vulnerable Populations

• Special care is necessary when scrubbing the skin of infants and the elderly due to:

  • Fragility of the skin barrier which increases susceptibility to infection.

  • Risk of damaging thin skin, leading to injury or inflammation.

Glandular Functions

• Sebaceous Glands (Oil Glands): Secrete an oily substance (sebum) that lubricates the skin and hair, preventing dryness and protecting against infections.

• Sudoriferous Glands (Sweat Glands): Involved in thermoregulation and waste excretion.

  • Eccrine Sweat Glands: (also known as merocrine glands) They produce a watery secretion primarily for thermoregulation.

  • Apocrine Sweat Glands: Produce a thicker secretion associated with odor, located in areas such as armpits and groin.

Skin Structure and Anatomy

• Fingerprints: Created by dermal papillae, which enhance grip and increase friction on surfaces.

• Layers of Skin:

  • Epidermis: Outer layer made up of stratified squamous epithelium.

  • Dermis: Contains connective tissue and houses glands and hair follicles.

  • Hypodermis: Composed of loose connective and adipose tissue, providing insulation and cushioning.

Sensory Structures in the Skin

• Hair Follicle Receptors: Detect hair movement, sensitive to touch.

• Merkel Disks: Tactile receptors for light touch.

• Ruffini Endings: Respond to skin stretch, providing feedback on pressure.

• Pacinian Corpuscles: Responsive to deep pressure and vibration.

• Meissner's Corpuscles: Sensitive to light touch, located in the dermis.

Thermoregulation

• Heat Elevation Mechanisms: Increased blood flow to the skin and perspiration raise body temperature.

• Cooling Mechanisms: Evaporation of sweat and dilation of blood vessels near the surface facilitate cooling.

Epidermal Layers

• Stratum Lucidum: Present in thick skin, located between the stratum corneum and stratum granulosum, provides an extra layer of protection.

• Pigments:

  • Carotene: Contributes to skin color and is found in yellow/orange vegetables.

  • Hemoglobin: The oxygen-carrying pigment in red blood cells that contributes to skin's pink hue.

  • Melanin: Provides pigmentation and protection against UV radiation.

Skin Disorders

• Vitiligo: Loss of skin pigment resulting in white patches.

• Cyanosis: Blue discoloration indicating hypoxia or lack of oxygen.

• Skin Cancers:

  • Basal Cell Carcinoma: Most common type, arises from the bottom layer of the epidermis.

  • Squamous Cell Carcinoma: Arises from the squamous cells in the epidermis.

  • Melanoma: The most serious form; initiated by melanocytes.

• ABCDs of Melanoma Evaluation:

  • A: Asymmetry

  • B: Border irregularity

  • C: Color variation

  • D: Diameter over 6 mm.

Causes and Effects of Skin Cancer

• Factors contributing to skin cancer include genetic predisposition and excessive UV radiation exposure.

• Dark-skinned individuals have higher melanin levels which provide some protection against UV damage, thus lower incidence of skin cancer compared to fair-skinned individuals.

Functions of Hair and Nails

• Hair: Provides protection, regulates body temperature, and has sensory functions.

• Nails: Protect the distal phalanx and enhance precise movements of the fingers.

Healing and Repair Mechanisms

• Phases of Skin Injury Repair:

  • Inflammatory Phase: Immediate response to injury, characterized by redness and swelling.

  • Proliferative Phase: New tissue formation occurs, including fibroblast activity and collagen deposition.

  • Maturation Phase: Remodeling of the new tissue to restore strength and function.

Burns Classification

• First Degree Burn: Affects only the epidermis, resulting in redness.

• Second Degree Burn: Involves the epidermis and part of the dermis, causing blisters and pain.

• Third Degree Burn: Extends through the dermis to the subcutaneous tissue, potentially resulting in loss of sensation in the injured area.

• Rule of Nines: A method to estimate body surface area affected by burns. Each section of the body represents approximately 9% of total body surface area.

• Critical Burns: Classified as critical if they cover more than 25% of the body for second-degree burns or 10% for third-degree burns, or involve face, hands, or feet.

• Pain in Third-Degree Burns: Initially painless due to nerve ending destruction in the affected area.

• Fluid Loss vs. Infection: Fluid loss is the most pressing concern in severe burns, leading to hypovolemic shock, while infection is also a critical risk due to compromised skin integrity.