The study of the tissues of the body Lab 3 – Histology The study of the tissues of the body Expanded Studies

The science of Anatomy

What is a tissue? Two or more cells that share a common Structure Function Embryological origin

Examples of Tissues MACRO MICRO Blood: Fat:

Examples of Tissues MACRO MICRO Epidermis: (Stratified squamous) Cartilage: (Hyaline)

Examples of Tissues MACRO MICRO Cerebral cortex: (Nervous) Skeletal Muscle: Tendon: (Dense irregular)

Understand an organ by understanding the tissue it is composed of Goal:

There are four tissue categories: Epithelial Tissue Connective Tissue Nerve Tissue Muscle Tissue Histology is the study of tissues.

All 4 tissue types working together to make an organ: Example: lining support, bind, protect movement Connective Epithelial communication

In today’s lab, we’ll concentrate on these two: Epithelial tissue & Connective tissue lining support, bind, protect Connective Epithelial

Epithelial vs. Connective Tissue How can you tell which are Epithelial and which are Connective tissue?

Epithelial tissue is composed of closely packed cells, Connective tissue is composed of a few cells surrounded by lots of extracellular matrix (fibers, fluid, minerals, etc.) Ep;ithelial Tissue Connective Tissue

Questions to ask for identifying tissues Epithelial tissue Connective tissue

Which are Epithelial and which are Connective tissue?

Objective 1: Epithelial Tissues

EPITHELIAL TISSUES - Locations Look for the edge Outer lining covering the body surfaces and organs Inner linings of body cavities and organs

EPITHELIAL TISSUES - Functions Diffusion Filtration Secretion Absorption Protection

EPITHELIAL TISSUES - Examples Edge (apical layer) Lung alveoli (diffusion) Epidermis (protection) Renal tubule (filtration) Small intestine (secretion, absorptoin) Edge

Epithelial tissues come in 3 shapes: Which shape is best suited for secretion &/or absorption? Which shape is best suited for lining a tube? Which shape is best suited for filtration? Columnar “Column-like” Cuboidal “Cubish” Squamous “Flat”

Epithelial tissues come various layers: Single layer = Simple 2 or more layers = Stratified

Putting it all together: To classify an epithelium state the number of layers then cell shape.

Knowing the function and location of each tissue type will help you make sense of them and aid in memorization.

Some specializations: Cilia (i.e. cells lining the trachea) Microvilli (i.e. cells lining the intestines)

Epithelial tissue is connected to the underlying Connective tissue via an extracellular matrix called basement membrane

A type of extracellular matrix Basement Membrane A type of extracellular matrix Collagen (protein fibers) Nidogen a binding glycoprotein Perlecan a GAG proteoglycan Laminin The cell adhesion molecule Integrins Adhesion receptors of cells Epithelium Read the explanation here: http://www.steve.gb.com/science/extracellular_matrix.html

Types of Simple Epithelia Look for the nuclei

Simple Squamous Epithelia Look for a flattened nucleus Nucleus Cytoplasm Frog skin Basement Membrane Cytoplasm Nucleus Tunica interna (blood vessel) Basement Membrane

Simple Cuboidal Epithelia Look for a rounded nucleus Nucleus Cytoplasm Basement Membrane Renal (kidney) duct

Simple Columnar Epithelia Look for an oval nucleus Cytoplasm Nucleus Intestine Basement Membrane

Pseudostratified Columnar Epithelia * Cells have a tapered appearance Goblet Cells Cytoplasm Nuclei Trachea Basement Membrane

Identify this tissue type (both are the same) Simple Squamous Epithelia Lung alveoli Renal corpuscle

Renal (kidney) tubules Identify these Epithelial Tissues Simple Columnar Gall bladder Simple Cuboidal Renal (kidney) tubules

Pseudostratified Columnar Identify these Epithelial Tissues Pseudostratified Columnar Trachea Simple Columnar Intestines

Identify these Epithelial Tissues Simple Squamous Simple Cuboidal

Types of Stratified Epithelia Named according to the shape of the apical layer of cells

Lining esophagus, mouth & vagina Stratified Squamous Epithelia Lining esophagus, mouth & vagina Keratinized: Epidermis (Skin) Apical Cells Basal Cells Esophagus Basement Membrane

(Ducts of large glands = sweat & mammary) Stratified Cuboidal Epithelia RARE Apical Cells Basement Membrane Lumen Basal Cells Testis (Ducts of large glands = sweat & mammary)

Small amounts in pharynx, male urethra & glandular duct linings Stratified Columnar Epithelia RARE Basement Membrane Basal Cells Apical Cells Small amounts in pharynx, male urethra & glandular duct linings

Lines bladder, ureters, part of urethra, uterus Transitional Epithelia Lines bladder, ureters, part of urethra, uterus Apical Cells Basal Cells Large cells w/ Large round nuclei “plumpy” appearance Apical cells larger than basal cells Basement Membrane

Identify the Epithelial Tissues Stratified Cuboidal Simple Cuboidal

Identify the Epithelial Tissues Transitional Stratified Squamous

Pseudostratified Columnar Identify the Epithelial Tissues Pseudostratified Columnar Stratified Columnar Tapering of cells Nuclei uneven

Identify the Epithelial Tissues Simple Squamous Stratified Cuboidal

Pseudostratified Columnar Identify the Epithelial Tissues Simple Columnar Pseudostratified Columnar

Identify the Epithelial Tissues Transitional Transitional

REVIEW

Objective 2: Connective Tissues

CONNECTIVE TISSUES – Locations Most abundant tissue Found everywhere except for body surfaces What type of tissue is found on body surfaces?

CONNECTIVE TISSUES – Functions Bind Support Protect Insulate Transport

CONNECTIVE TISSUES – Examples Areolar (bind, support) Dense Irregular (bind, support, protect) Hyaline cartilage (support, protect) Bone (support, protect) Adipose (fat) (protect, insulate) Blood (transport)

Connective tissue has: Cells Fibers Ground substance Areolar connective tissue The prototype of connective tissues: Other connective tissues contain variations in the amount or type of cells, ground subtance &/or fibers as found in areolar connective tissue

Recall Connective tissue is relatively cell poor Contains many different cell types Fibroblast Adipocytes Mast cells Macrophage

Cell types Fibroblasts (cytes)*- secret /maintain ground substance (connective tissue proper) Chondroblasts (cytes)*- secret /maintain ground substance (cartilage) Mast cells – secret histamine, heparin Macrophages – phagocytes Adipocytes – fat storage Blasts secrete ground substance Cytes maintain ground substance

Ground substance Fibers Interstitial fluid Proteoglycans – viscosity Collagen fibers Elastic fibers Reticular fibers Thick Thin Hard to stain

“St. Ives® combines essential collagen & elastin, the proteins found in young, healthy skin, …”

Classes of Connective Tissue

Mesenchyme embryologic connective tissue Note star-shaped cells ground substance cells fibers

Connective Tissues Proper Loose Connective Dense Connective Areolar Dense Regular Adipose Dense Irregular Reticular

Loose Connective Tissue Areolar connective tissue Binds other tissues together, wraps organs & vessels, underlies epithelia, forms lamina propria cells collagen fibers ground substance elastic fibers

Loose Connective Tissue Adiopse tissue extracellular matrix Adipocytes (vacuoles) adipocyte nucleus Hypodermis; Omentum; Breasts; around kidneys, eyeballs, heart, lymph nodes

Loose Connective Tissue Reticular tissue Lymph nodes, Spleen, Bone marrow mast cell reticular cell reticular fibers

Dense Connective Tissue Dense regular Tendons, most Ligaments, Aponeuroses

Dense Connective Tissue Dense Irregular Dermis (skin), Submucosa (GI tract), Fibrous capsules of organs & joints collagen fibers

Cartilage

Hyaline Cartilage matrix lacuna chondrocytes Costal cartilage (ribs), Trachea & Bronchi, Larynx, Nose, Articular cartilage (joints) matrix lacuna chondrocytes

External ear (pinna), Epiglottis Elastic Cartilage External ear (pinna), Epiglottis elastic fibers chondrocyte in a lacuna

Intervertebral discs, Pubic symphysis, Knee joint discs Fibrocartilage Intervertebral discs, Pubic symphysis, Knee joint discs collagen fibers chondrocytes in lacuna

Tissue Comparisons Areolar Mesenchyme Reticular

Tissue Comparisons Adipose Elastic Carilage Hyaline Cartilage

Tissue Comparisons Dense Regular Fibrocartilage Dense Irregular

What questions do you need to ask to identify a connective tissue and in what order?

Clinical Significance: CELLULITIS An acute inflammation of the connective tissue of the skin (dermis and hypodermis), caused by a bacterial infection, most commonly Streptococcus pyogenes and occasionally Staphylococcus aureus. The skin tissues in the infected area become red, hot, swollen and painful. Cellulitis can have serious consequences because of its potential to spread through the lymphatic system and into the bloodstream (bacteremia). http://www.supplementnews.org/cellulitis/

ACUTE CELLULITIS Adipose neutrophils Dense Irregular Notice the infiltration of neutrophils (white blood cells) into the dense irregular and adipose tissues of the skin.

Objective 3: Membranes

Membranes are simple organs composed of 2 tissues: Epithelium Connective Tissue

Types of Membranes Mucous Serous Cutaneous = Moist lining of body cavities exposed to the exterior Serous = Pleura, Pericardium, Peritoneum Cutaneous = Skin

Serous Membrane Parietal peritoneum Parietal pleura Visceral pericardium Visceral pericardium

Serous Membrane Serous Membrane Simple squamous ET Areolar CT simple squamous epithelium areolar connective tissue Simple squamous ET Areolar CT

Moist lining of body cavities exposed to the exterior Mucous Membrane Moist lining of body cavities exposed to the exterior Mucosa of nasal cavity Esophagus lining Trachea Mucosa of lung bronchi Mucosa of digestive tract Mucosa of urogenital tract

Which type of epithelium is shown here? Mucous Membrane stratified squamous, pseudostratified columnar, or simple columnar epithelium areolar connective tissue (lamina propria) Which type of epithelium is shown here?

Mucous Membrane Esophagus Identify the epithelial tissue Lamina propria Lamina propria Identify the epithelial tissue Stratified squamous ET lamina propia

Mucous Membrane Trachea Identify the epithelial tissue Pseudostratified columnar ET Identify the epithelial tissue Lamina propria lamina propia

Mucous Membrane Intestine Lamina propria

On the Practical: Identify the epithelial tissues Identify the connective tissues Identify the mucous membranes Identify labeled components of each