Lecture E2, 6/4 & 6/5 notes

Study Guide

1. Key Terminology and Prefixes

• Cytology: Study of cells 

• Innervation: The nerve that supplies (innervates) a muscle 

• Polarity: Having two opposite poles; in epithelial cells, refers to distinct apical and basal surfaces 

• Prefixes and Roots:

  • A-/An-: Without, lack of (e.g., “avascular” means lacking blood vessels) 

  • BV’s (Vaso-): Refers to blood vessels (arteries, veins, capillaries) 

  • Meso-: Middle 

  • Endo-: Inside 

  • Uni- / Multi-: One / many 

  • AA’s: Amino acids; building blocks of proteins 

  • –blast / –cyte: “Blasts” are immature, active cells (e.g., fibroblasts) and “cytes” are mature, less active cells (e.g., fibrocytes) 

2. Overview of Tissues

• Definition: Collections of specialized cells and cell products performing specific functions; combinations of tissues form organs and organ systems 

• Four Major Tissue Types (Chapter 4 Learning Outcome 4-1) 

  1. Epithelial Tissue

     • Covers exposed surfaces, lines internal passageways, forms glands

     • Functions: physical protection, control of permeability, sensation, specialized secretions 

  2. Connective Tissue

     • Fills internal spaces, provides structural support, transports materials, stores energy, defends against microorganisms 

  3. Muscle Tissue

     • Specialized for contraction; includes skeletal, cardiac, and smooth muscle 

  4. Nervous Tissue

     • Conducts electrical impulses; composed of neurons and neuroglia 

3. Epithelial Tissue

3.1. General Characteristics

• Polarity:

  • Apical surface: Facing lumen or external environment; may have microvilli (increase surface area for absorption) or cilia (move fluids)

  • Basal surface: Attached to basement membrane (comprised of basal lamina + reticular lamina)

• Cellularity: Closely packed cells with minimal extracellular matrix; intercellular connections (cell junctions) maintain integrity:

  • Tight junctions: Prevent passage of water and solutes between cells; located near apical surface 

  • Gap junctions: Allow rapid communication via connexons (embedded proteins) permitting small molecules/ions to pass 

  • Desmosomes: CAMs and proteoglycans link adjacent cells, allowing bending/twisting; hemidesmosomesattach cells to basement membrane 

• Attachment: Cells sit on a basement membrane with:

  • Basal lamina (closest to epithelium; secreted by epithelial cells)

  • Reticular lamina (deeper; secreted by underlying connective tissue) 

• Avascularity: No blood vessels; obtains nutrients via diffusion from underlying connective tissue

• Regeneration: Stem cells near the basement membrane continually divide to replace lost cells

3.2. Classification by Cell Shape (Chapter 4 Learning Outcome 4-3)

1. Squamous (thin, flat)

2. Cuboidal (square)

3. Columnar (tall, rectangular)

3.3. Classification by Number of Layers

• Simple epithelium: Single cell layer – for absorption, secretion, diffusion

• Stratified epithelium: Multiple layers – for protection against mechanical or chemical stresses

3.4. Specific Epithelia and Locations

• Simple Squamous Epithelium

  • Locations: Alveoli of lungs; lining of heart and blood vessels (endothelium); lining of body cavities (mesothelium)

  • Functions: Reduces friction; controls vessel permeability; performs absorption and secretion

• Stratified Squamous Epithelium

  • Locations: Surface of skin (keratinized); lining of mouth, throat, esophagus, rectum, anus, and vagina (nonkeratinized)

  • Functions: Provides protection against abrasion, pathogens, and chemical attack

• Simple Cuboidal Epithelium

  • Locations: Glands and ducts; portions of kidney tubules; thyroid gland

  • Functions: Limited protection; secretion; absorption

• Stratified Cuboidal Epithelium (rare)

  • Locations: Some sweat gland ducts; mammary gland ducts

  • Functions: Protection; secretion; absorption

• Transitional Epithelium

  • Locations: Urinary bladder; renal pelvis; ureters

  • Functions: Tolerates repeated stretching without damage; appearance changes with stretching

• Simple Columnar Epithelium

  • Locations: Lining of stomach, small intestine, large intestine, gallbladder, uterine tubes, collecting ducts of kidneys

  • Functions: Protection; secretion; absorption; often has microvilli to increase surface area

• Pseudostratified Ciliated Columnar Epithelium

  • Locations: Lining of nasal cavity, trachea, bronchi; portions of male reproductive tract

  • Functions: Protection; secretion; moves mucus with cilia

• Stratified Columnar Epithelium (rare)

  • Locations: Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts, urethra

  • Functions: Protection

3.5. Glandular Epithelium

• Glands: Collections of epithelial cells that produce secretions (Chapter 4 Learning Outcome 4-3)

  • Endocrine glands: No ducts; release hormones directly into bloodstream

  • Exocrine glands: Have ducts; discharge secretions onto epithelial surfaces

• Methods of Secretion (Chapter 4 Learning Outcome 4-3)

  1. Merocrine: Secretions released by exocytosis (e.g., merocrine sweat glands)

  2. Apocrine: Released by shedding cytoplasm (e.g., mammary glands)

  3. Holocrine: Entire cell bursts, releasing contents (e.g., sebaceous glands); cells replaced by stem cells

• Glands Classification by Structure

  • Unicellular: Goblet cells (secrete mucin → mucus)

  • Multicellular Exocrine Glands:

    • Simple (undivided) Duct vs. Compound (branched) Duct

    • Tubular vs. Alveolar/Acinar secretory portions

    • Examples:

      • Simple tubular (intestinal glands)

      • Simple coiled tubular (merocrine sweat glands)

      • Simple branched tubular (gastric glands)

      • Simple alveolar (developmental stage; not in adults)

      • Simple branched alveolar (sebaceous glands)

      • Compound tubular (mucous glands in mouth; bulbo-urethral glands; seminiferous tubules)

      • Compound alveolar (mammary glands)

      • Compound tubulo-alveolar (salivary glands; respiratory tract glands; pancreas)

4. Connective Tissue

4.1. General Components and Functions (Chapter 4 Learning Outcome 4-4)

• Components:

  • Specialized cells (e.g., fibroblasts, adipocytes, macrophages, mast cells, lymphocytes)

  • Extracellular protein fibers (collagen, reticular, elastic)

  • Ground substance: Fluid/glycoprotein mixture filling spaces between cells; matrix = fibers + ground substance

• Functions:

  • Establish structural framework for body

  • Transport fluids and dissolved materials

  • Protect delicate organs

  • Support, surround, and interconnect other tissues

  • Store energy reserves (especially triglycerides)

  • Defend body from invading microorganisms

4.2. Categories of Connective Tissues (Chapter 4 Learning Outcome 4-4)

1. Connective Tissue Proper: Connect and protect (loose and dense types)

2. Fluid Connective Tissues: Transport (blood and lymph)

3. Supporting Connective Tissues: Structural strength (cartilage and bone)

4.3. Connective Tissue Proper (Chapter 4 Learning Outcome 4-5)

• Loose Connective Tissue (more ground substance, fewer fibers)

  • Areolar Tissue

    • Locations: Within/deep to dermis; covered by epithelial lining of digestive, respiratory, urinary tracts; between muscles; around joints, blood vessels, nerves

    • Functions: Cushions organs; provides support but permits independent movement; phagocytic cells provide defense

  • Adipose Tissue

    • White Fat: Most common; stores fat, absorbs shock, insulates to slow heat loss

    • Locations: Deep to skin (sides, buttocks, breasts); around eyes and kidneys

    • Brown Fat: Found in infants/young children; more vascular; adipocytes have many mitochondria to generate heat

  • Reticular Tissue

    • Locations: Liver, kidney, spleen, lymph nodes, bone marrow

    • Functions: Provides supportive framework (stroma) via reticular fibers

• Dense Connective Tissue (more fibers, less ground substance)

  • Dense Regular Connective Tissue

    • Locations: Tendons (muscle → bone), ligaments (bone → bone), aponeuroses (broad tendinous sheets)

    • Functions: Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes positions of bones

  • Dense Irregular Connective Tissue

    • Locations: Capsules around visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis of skin

    • Functions: Resists forces from many directions; helps prevent overexpansion of organs (e.g., urinary bladder)

  • Elastic Tissue

    • Locations: Between vertebrae of spinal column (ligamenta flava, ligamentum nuchae); ligaments supporting penis; ligaments of transitional epithelia; walls of blood vessels

    • Functions: Stabilizes positions of vertebrae and penis; cushions shocks; permits expansion/contraction of organs

4.4. Cells of Connective Tissue Proper (Chapter 4 Learning Outcome 4-5)

• Fibroblasts: Most abundant; secrete proteins and hyaluronan (cellular cement)

• Fibrocytes: Maintain connective tissue fibers

• Adipocytes: Fat cells; store lipid droplet

• Mesenchymal Cells: Stem cells that respond to injury/infection; can differentiate into fibroblasts, macrophages, etc.

• Melanocytes: Synthesize/store melanin (pigment)

• Macrophages: Large phagocytic cells; engulf pathogens and damaged cells (fixed in tissue or free migrating)

• Mast Cells: Stimulate inflammation; release histamine and heparin

• Lymphocytes: Can develop into plasma (B) cells to produce antibodies; circulate throughout body

• Microphages (Neutrophils, Eosinophils): Phagocytic blood cells attracted to sites of injury/infection

4.5. Connective Tissue Fibers (Chapter 4 Learning Outcome 4-5)

• Collagen Fibers: Most common; long, straight, unbranched; strong and flexible; resist force in one direction; abundant in tendons and ligaments

• Reticular Fibers: Form network (stroma); support functional cells (parenchyma) and structures; resist forces in many directions (e.g., liver, spleen)

• Elastic Fibers: Contain elastin; branched, wavy; return to original length after stretching; found in elastic ligaments of vertebrae and vessel walls

5. Fluid Connective Tissues (Chapter 4 Learning Outcome 4-6)

5.1. Blood

• Matrix (Plasma): Watery solution containing proteins, electrolytes, hormones (yellow/golden)

• Formed Elements:

  • Erythrocytes (Red Blood Cells): Transport O₂ (and some CO₂); lack nucleus; ~50% of blood volume

  • Leukocytes (White Blood Cells): Nucleated; defend against infection/disease; two categories:

    • Granulocytes (“BEN is grand”):

      • Basophils: Promote inflammation (release histamine, heparin)

      • Eosinophils: Involved in asthma, allergy, parasite defense

      • Neutrophils: Phagocytic; target bacteria

    • Agranulocytes:

      • Lymphocytes: Viral and cancer response; can become plasma cells producing antibodies

      • Monocytes → Macrophages: Engulf pathogens and debris

  • Platelets (Thrombocytes): Cell fragments involved in blood clotting

5.2. Lymph

• Formation: Derived from interstitial fluid that enters lymphatic vessels

• Function: Monitored by immune system; returned to veins near heart; helps maintain fluid balance

6. Supporting Connective Tissues (Chapter 4 Learning Outcome 4-7)

6.1. Cartilage

• General Features:

  • Matrix is a firm gel containing chondroitin sulfates (polysaccharide derivatives)

  • Cells = chondrocytes, located in lacunae

  • Avascular (chondrocytes produce antiangiogenesis factor to prevent vessel formation)

  • Covered by perichondrium (outer fibrous layer; inner cellular layer for growth/maintenance)

• Types of Cartilage

  1. Hyaline Cartilage

     • Locations: Between rib tips and sternum; covering bone surfaces at synovial joints; supporting larynx, trachea, bronchi; forming part of nasal septum

     • Functions: Provides stiff but somewhat flexible support; reduces friction between bony surfaces

  2. Elastic Cartilage

     • Locations: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx

     • Functions: Provides support but tolerates distortion without damage; returns to original shape

  3. Fibrocartilage

     • Locations: Pads within knee joint; between pubic bones; intervertebral discs

     • Functions: Resists compression; prevents bone-to-bone contact; limits movement

• Cartilage Growth

  • Interstitial Growth: Expansion from within as chondrocytes divide in lacunae and secrete new matrix

  • Appositional Growth: New matrix deposited at perichondrium edge; mesenchymal cells differentiate into chondroblasts that secrete matrix

6.2. Bone (Osseous Tissue)

• General Features:

  • Matrix is calcified (rigid) due to calcium salts; collagen fibers provide flexibility to resist shattering

  • Cells = osteocytes, located in lacunae, arranged around central canals (osteons)

  • Canaliculi: Small channels through matrix allowing exchange with blood

  • Covered by periosteum (fibrous outer layer; cellular inner layer)

• Functions:

  • Provides weight support; resists compression and tension; site of blood cell production in marrow

7. Fasciae and Tissue Membranes (Chapter 4 Learning Outcomes 4-5, 4-8)

7.1. Fasciae

• Superficial Fascia: Separates skin from underlying tissues; composed of areolar tissue and adipose tissue; also called subcutaneous layer or hypodermis

• Deep Fascia: Sheets of dense regular connective tissue; bound to capsules, tendons, ligaments; forms a strong internal framework

• Subserous Fascia: Lies between deep fascia and serous membranes lining body cavities; composed of areolar tissue

7.2. Tissue Membranes

• Mucous Membranes (Mucosae)

  • Locations: Line passageways with external connections (digestive, respiratory, urinary, reproductive tracts)

  • Features: Epithelial surface must be moist (mucous secretion reduces friction, facilitates absorption/secretion); underlying lamina propria = areolar tissue

• Serous Membranes

  • Locations: Line cavities not open to outside (pleura, peritoneum, pericardium)

  • Features: Thin but strong; parietal portion lines cavity; visceral portion (serosa) covers organs; serous fluid reduces friction

• Cutaneous Membrane (Skin)

  • Features: Covers body; thick; relatively waterproof; usually dry; comprised of stratified squamous epithelium (epidermis) and underlying connective tissue (dermis)

• Synovial Membranes

  • Locations: Line synovial joint cavities

  • Features: Produce synovial fluid for lubrication; lack a true epithelium; composed of specialized connective tissue and an incomplete layer of macrophages and fibroblasts

8. Muscle Tissue (Chapter 4 Learning Outcome 4-9)

• General Features: Specialized for contraction; generates tension and produces movement or maintains posture

• Types of Muscle Tissue

  1. Skeletal Muscle

     • Features: Long, cylindrical fibers; striated; multinucleated; voluntary control; cells cannot divide (new fibers produced by myosatellite cells)

     • Functions: Moves or stabilizes skeleton; guards entrances/exits of digestive, respiratory, urinary tracts; generates heat; protects internal organs

  2. Cardiac Muscle

     • Features: Short, branched, striated cells; usually single nucleus; connected by intercalated discs (gap junctions + desmosomes); involuntary control; regulated by pacemaker cells

     • Locations: Heart

     • Functions: Circulates blood; maintains blood pressure

  3. Smooth Muscle

     • Features: Short, spindle-shaped cells; nonstriated; single central nucleus; can divide and regenerate; involuntary control

     • Locations: Walls of blood vessels; digestive, respiratory, urinary, reproductive organs

     • Functions: Moves food, urine, reproductive tract secretions; controls diameter of respiratory passageways and blood vessels

9. Nervous Tissue (Chapter 4 Learning Outcome 4-10)

• General Features: Specialized for conducting electrical impulses; concentrated in brain and spinal cord; contains neurons and neuroglia (supporting cells)

• Neurons

  • Cell Body: Contains nucleus and nucleolus; integrates signals

  • Dendrites: Short branches that receive incoming signals

  • Axon (Nerve Fiber): Long extension that carries outgoing electrical signals to target cells

• Neuroglia (Supporting Cells)

  • Maintain physical structure of nervous tissue

  • Repair tissue framework after injury

  • Perform phagocytosis

  • Provide nutrients to neurons

  • Regulate composition of interstitial fluid surrounding neurons

10. Tissue Injuries and Repair (Chapter 4 Learning Outcome 4-11)

• Two Stages of Response

  1. Inflammation (Inflammatory Response)

     • Triggers: Trauma (physical injury), infection (pathogen presence)

     • Mediators: Damaged cells release prostaglandins, proteins, K⁺; mast cells activated in connective tissue

     • Process:

       • Mast Cell Activation: Release histamine, heparin, prostaglandins → stimulates inflammation

       • Cardinal Signs of Inflammation: Redness, heat (warmth), swelling (edema), pain, sometimes loss of function

       • Increased Blood Flow: Vasodilation → redness and warmth

       • Increased Vessel Permeability: Plasma diffuses into tissues → swelling; phagocytes activated; toxins/wastes removed via circulation

       • Pain: Nerve endings stimulated by chemical mediators and pressure from edema

  2. Regeneration

     • Epithelia, Connective Tissues (except cartilage), Smooth Muscle: Regenerate well

     • Skeletal Muscle, Cardiac Muscle, Nervous Tissue: Regenerate poorly (cardiac muscle replaced by fibrous tissue through fibrosis)

11. Aging, Regeneration, and Cancer (Chapter 4 Learning Outcome 4-12)

• Aging Effects on Tissue Structure

  • Regeneration: Speed and effectiveness decline with age due to slower repair/maintenance, hormonal changes, reduced physical activity

  • Chemical/Structural Changes: Thinner epithelia; fragile connective tissues; increased bruising; brittle bones; cardiovascular disease; mental deterioration

• Cancer Incidence

  • Increases with age

  • ~25% of people in U.S. develop cancer; second leading cause of death

  • Most cancers caused by chemical exposure/environmental factors (smoking 40% of cases, alcohol, drugs, diet, pollution, radiation; family history, age, lifestyle)

12. Blood Vessels and Related Concepts (From BV.docx)

12.1. Blood Vessel Types

• Arteries: Carry oxygenated blood away from heart to tissues 

• Veins: Return deoxygenated blood back to heart 

• Capillaries: Site of gas exchange (O₂/CO₂) between blood and tissues 

12.2. Connective Tissue Examples

• Dense Regular Connective Tissue: Tendons, ligaments; supports muscles and bones 

• Dense Irregular Connective Tissue: Cushions organs; prevents overexpansion (e.g., dermis, periosteum) 

• Elastic Tissue: Found in blood vessel walls, penis, vertebrae; allows stretch and recoil 

12.3. Vascular Tone Regulation

• Vasodilation: Expansion of blood vessels → increases blood flow 

• Vasoconstriction: Contraction of blood vessels → decreases blood flow 

12.4. Injury and Repair—Specific to BV.docx Content

• Fasciitis: Inflammation of fascia (connective tissue surrounding muscles/organs) 

• Fibrosis: Scarring process replacing normal tissue after extensive injury 

13. Inflammation (From BV.docx)

• Cardinal Signs (aligned with Chapter 4):

  • Pain 

  • Redness 

  • Warmth 

  • Swelling/Edema 

  • Loss of Function 

14. Blood Composition (From BV.docx)

• Plasma: Yellow/golden fluid; contains proteins, electrolytes, hormones 

• Formed Elements:

  • RBCs (Erythrocytes): Transport O₂ 

  • WBCs (Leukocytes): Defense; subdivided into granulocytes (Basophils, Eosinophils, Neutrophils) and agranulocytes (Lymphocytes, Monocytes/Macrophages) 

  • Platelets (Thrombocytes): Involved in clotting 

15. Summary of Key Points from “Notes” (Notes.docx)

• Epithelial Locations (by type):

  • Simple Squamous: Lungs, around heart, kidneys, peritoneum, cornea 

  • Stratified Squamous: Skin; lining of digestive tract; vagina 

  • Simple Cuboidal: Kidney, thyroid 

• Cell Surface Specializations:

  • Microvilli: Short, finger-like projections; increase surface area for absorption 

  • Cilia: Long, hair-like structures; move substances across epithelium (e.g., in trachea) 

• Pharynx: Throat region, connecting nasal and oral cavities to larynx and esophagus 

• Pancreatic Hormones: Insulin, glucagon, somatostatin, pancreatic polypeptide 

• Types of Connective Tissue Cells:

  • Fibroblasts / Fibrocytes: Fiber production and maintenance 

  • Adipocytes: Fat-storing cells 

  • Mesenchymal Cells: Stem cells for connective tissue 

  • Melanocytes: Pigment-producing cells 

  • Macrophages: Phagocytic cells 

  • Mast Cells: Involved in allergic responses; release histamine 

  • Lymphocytes / Plasma (B) Cells: Antibody production; immune function 

• Antigen–Antibody: Interaction underlying immune response 

• BV’s (Arteries, Veins, Capillaries): Vascular system; vaso- prefix refers to vessels 

16. Integration and Exam Preparation Tips

1. Focus on Definitions and Locations:

   • Memorize epithelial tissue classifications by shape and layer, plus their functional locations (e.g., simple squamous in alveoli; stratified columnar in urethra).

   • Recall connective tissue categories (loose vs. dense; proper vs. fluid vs. supporting) and know examples for each.

2. Understand Structures to Functions:

   • Relate microvilli to absorption, cilia to fluid movement, and tight junctions to barrier functions.

   • Connect cartilage types to their mechanical roles (e.g., fibrocartilage resists compression in intervertebral discs).

   • Associate bone structure (osteons, canaliculi) with weight support and nutrient exchange.

3. Clinical Correlates:

   • Link inflammation signs (redness, heat, swelling, pain, loss of function) to underlying vascular changes (vasodilation, increased permeability).

   • Recognize how decreased regenerative capacity with aging leads to thinner epithelia and brittle bones.

   • Recall that fibrosis replaces damaged cardiac muscle post-myocardial infarction, impeding contractility.

4. Blood and Immune Function:

   • Differentiate granulocytes (BEN: Basophils/Inflammation; Eosinophils/Allergy & Parasites; Neutrophils/Bacteria) and agranulocytes (lymphocytes/viral & adaptive immunity; monocytes/macrophages).

   • Understand how platelets contribute to hemostasis and how plasma composition supports transport and homeostasis.

5. Compare Muscle Types:

   • Skeletal: Voluntary, striated, multinucleate – locomotion;

   • Cardiac: Involuntary, striated, branched, intercalated discs – continuous pumping;

   • Smooth: Involuntary, nonstriated, spindle-shaped – moves substances through hollow organs.

6. Membranes and Fasciae:

   • Distinguish mucous (moist lining of tracts) vs. serous (lubricating cavities) vs. cutaneous (skin) vs. synovial (joint lubrication).

   • Recognize fasciae layers: superficial (subcutaneous), deep (dense connective tissue), and subserous (between deep fascia and serous membranes).

7. Review Aging and Cancer Risks:

   • Note that reduced tissue regeneration with age increases susceptibility to injury and disease.

   • Recall environmental factors (smoking, diet, radiation) contribute to ~40% of cancers; incidence rises with age.