Fun. I - Epithelial Tissue

What are the 4 major types of Tissues?

- Epithelial

- Connective

- Muscular

- Nervous

What are the 4 essential processes for generation of a Multicellular Organism?

- Proliferation

- Specialization

- Interaction

- Movement

Histogenesis

Development of Tissues

Histogenesis begins at ____.

gastrulation

Gastrulation

The process in which a gastrula develops from a blastula by the inward migration of cells

What are the 3 specialized layers of the Gastrula?

- Ectoderm

- Mesoderm

- Endoderm

Ectoderm

Outermost Layer

- Neural Tissue

- Epidermis

Mesoderm

Middle Layer

- Connective Tissue

- Muscle

- Heart

Endoderm

Innermost Layer

- Lungs

- GI Tract

- Liver

- Pancreas

Epithelial Tissue

Sheets of cells covering all body surfaces/cavities

Connective Tissue

Collection of supporting cells and ECM that aid structure of other tissue

Tissue is basically a collection of ____ and ____.

cells/ECM

Muscle Tissue

Contractile cells that are responsible for movement

What are the 3 types of Muscle Tissue?

- Skeletal

- Cardiac

- Smooth

Skeletal Muscle

Striated and voluntary muscle attached to bone

Cardiac Muscle

Striated and involuntary muscle found in the wall of the Heart

Smooth Muscle

Non-Striated and involuntary muscle

Nervous Tissue

Receives, transmits, and integrates info to control and coordinate activities of the body

What are the 2 divisions of the Nervous System?

- CNS

- PNS

CNS

Central Nervous System

- Brain and Spinal Cord

PNS

Peripheral Nervous System

- Sensory and Motor Neurons

Light Microscopy

Any kind of microscope that uses visible light to observe specimens

Basic Steps of Tissue Preparation

(1) Fixation

(2) Dehydration

(3) Clearing

(4) Sectioning

(5) Staining

What are the 3 Stains used for Tissue Preparation?

- Hematoxylin (H)

- Eosin (E)

- Periodic Acid Schiff (PAS)

Hematoxylin (H)

Basic dye that stains basophilic structures blue/purple

Eosin (E)

Acidic dye that stains acidophilic structures red/pink

Periodic Acid Schiff (PAS)

Stains carbohydrates pink/red

The ____ is highly acidic, so it would be considered basophilic. This would require Hematoxylin for staining.

nucleus

Immunofluorescence

Use of antibodies tagged with fluorescent dye to identify the presence of a particular disease causing microbe

Basal Lamina

Thin extracellular layer that lies underneath epithelial cells and separates them from other tissues (typically connective tissue)

Cellular Junctions

Transmembrane proteins that bind cells together or to the ECM

Transmembrane Adhesion Proteins

Proteins that span the cellular membrane and link the cytoskeleton to extracellular structures

What are the 4 major Cell Adhesion Molecules?

- Cadherins

- Integrins

- Selectins

- Ig-Superfamily

Cadherins

Calcium-Dependent glycoproteins that hold similar cells together

Integrins

Transmembrane protein that interconnects the ECM and cytoskeleton of a cell

Selectins

Transmembrane protein that binds carbohydrates on other cell surfaces

Selectins and Integrins play an important role in ____.

White Blood Cell Migration

White Blood Cell Migration

(1) Selectin-Dependent Adhesion and Rolling

(2) Adhesion and Emigration of WBC across barrier via Integrins

What are the 4 types of Junctions?

- Tight

- Anchoring

- Channel-Forming

- Cell-Matrix Anchoring

What are the 7 functions of the Epithelia?

- Protection: Epidermis

- Absorption: Digestive Tract

- Secretion: Glands

- Excretion: Kidneys

- Lubrication

- Sensory

- Reproduction: Sperm

The Epithelia is vascular (T/F)

False; Avascular

Cells are normally polarized. What does that mean?

Components of the cell are asymmetrically distributed, creating "poles"

Apical Domain

The exposed free surface of a polarized epithelial cell. Typically have cilia/microvilli.

Basolateral Domain

The surface region of a polarized epithelial cell that is in contact with adjacent cells or the ECM

Functions of the Basal Lamina

- Binds Epithelia to the Connective Tissue

- Permits movement of nutrients into blood

- Filtration

What are the 2 major components of the Basal Lamina?

- Laminin

- Type IV Collagen

Laminin

Protein in the basement membrane to which integrins from cells attach

What is the difference in Basal Lamina and Basement Membrane?

The Basal Lamina is the protein portion of the Basement Membrane. The Basement Membrane also includes ECM.

2 Epithelial Layers can be fused to a Basal Lamina (T/F)

True; Used mainly for exchange and filtering like in the Lungs and Kidneys

Apical Modifications of Epithelia

- Microvilli

- Stereocilia (Stereovilli)

- Motile Cilia

Basolateral Modifications of Epithelia

Basal/Lateral Folds

What are the 5 Classes of Junctions?

- Tight Junctions

- Adherens

- Desmosomes

- Gap Junctions

- Hemidesmosomes

Tight Junctions

Transmembrane proteins that seal adjacent cells together

What are the 2 main Transmembrane Proteins that make up Tight Junctions?

- Occludin

- Claudin

Paracellular Transport

Transport of materials through the interstitial space without interactions with the cytoplasm or cell membrane

Occurs through Tight Junctions

Adherens

Joins intracellular actin-filaments between cells

Desmosomes

Cell-Cell Anchoring junctions via intermediate filaments

Gap Junctions

Provide cytoplasmic channels between adjacent animal cells via connexins

Hemidesmosomes

Attach epithelial cells to the basement membrane via intermediate filaments

Junctional Complex

Collective term for...

- Tight Junctions

- Adherens

- Desmosomes

Microvilli

Projections of actin-microfilaments that increase the cell's surface area

Stereocilia (Stereovilli)

Longer microvilli projections of actin-microfilaments that increase the cell's surface area

Limited to inner ear and male reproductive tract

Motile Cilia

Projections of microtubules that "beat" to move fluid/cells

Motile Cilia are made up of ____.

axonemes

Axoneme

- Structure found in cilia and flagella that are responsible for motion

- Composed of two central microtubules surrounded by nine doublet microtubules (9 + 2 arrangement).

Basal/Lateral Folds

Increase surface area of basal/lateral regions

Epithelia shape is defined by the innermost layer (T/F)

False; Outermost

Simple Squamous Epithelia

Important for absorption and diffusion

- Blood Vessels

- Alveoli

- Kidneys

Simple Cuboidal Epithelia

Important for secretion and absorption

- Exocrine Ducts

- Kidneys

Simple Columnar Epithelia

Important for absorption and secretion

- GI Lining

Pseudostratified Epithelia

Appear to have multiple layers due to difference in cell height, but are only 1 layer

- Trachea/Bronchioles

- Male Reproductive Tract

PCCE

Pseudostratified Ciliated Columnar Epithelium

Stratified Squamous Epithelia

Important for protection against mechanical stress

- Skin

- Oral Cavity/Esophagus

- Vagina

Stratified Squamous Epithelia can be ____ or ____.

keratinized/non-keratinized

Stratified Cuboidal Epithelia

Important for secretion

- Sweat Ducts

- Mammary Ducts

Stratified Columnar Epithelia

Important for secretion

- Exocrine Glands

Transitional Epithelia

Cell Shape and Layering varies with stretching; Can appear squamous or cuboidal

Transitional Epithelia is found only in the ____.

urinary tract

What are the 2 types of Epithelial Glands?

- Exocrine

- Endocrine

What are the 2 portions of a Gland?

- Duct

- Secretory

Exocrine Gland Development

Invagination of Epithelial Cells

Endocrine Gland Development

(1) Invagination of Epithelial Cells

(2) Duct "disappears" and the secretory portion is isolated from surface layer

(3) Epithelial Cells become vascularized and secrete products into the blood

All glands are derived from and are lined with ____.

epithelia

Exocrine Glands are based on what 3 Characteristics?

- Structure

- Secretory Products

- Mechanism of Secretion

Exocrine Gland structure is typically either ____ or ____.

tubular/acinar

Tubular Exocrine Gland

Acinar Exocrine Gland

Exocrine Glands products can be considered ____ or ____.

serous/mucous

Epithelium Renewal

Occurs at different rates depending on the tissue

- Division occurs at the basal lamina

- Capable of rapid repair

Carcinoma

Malignant tumor that occurs in epithelial tissue

Adenocarcinoma

Malignant tumor that originates from glandular epithelial tissue

Collagen IX and XII are proteins important in basement membrane binding (T/F)

True