A&P @ LCC by Dr. Prince

Ch 4 Tissues
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Tissue: The Living Fabric

Epithelial Tissue

Dr. F. Prince

Objectives For Today

The student will be able to list several structural and functional characteristics of epithelial tissue

The student will be able to name, classify, and describe the various types of epithelia and their function

The student will be able to define gland and differentiate between exocrine and endocrine glands

The student will know how exocrine glands are classified structurally and functionally

The student will be able to describe the structure and function of cutaneous, mucous, and serous membranes

Key Concepts:

The cells of most animals interact at three levels of organization: tissues, organs and organ systems

Four types of tissues are seen in most animals: epithelial, connective, muscle and nervous tissues

Cells engage in metabolic activities

Key Concepts:

The body’s internal environment consists of fluids outside of cells

Stability in the internal environment is maintained by cells, tissues, organs and organ systems

Homeostasis is the stable environment maintained for normal operation of an organism

Introduction

What is a tissue ?

A tissue s a group of similar cells that usually have a similar embryological origin and are specialized for a particular function.

What gives each tissue its specific characteristics ?

The nature of the extracellular material, the cells, and the connections between the cells influence the structure and properties of the tissue

Types of Tissues

There are four types of tissues that make up your body.

Epithelial tissue or "covering tissue". It covers body surfaces, lines hollow organs, body cavities and ducts. Epithelia also form glands

Connective tissue supports, protects, binds organs, stores energy as fat, and provides immunity

Muscle tissue that is responsible for movement and generation of force

Nervous tissue initiates and transmits action potentials (nerve impulses) and is involved in the coordination of body activities

The Origin of the Tissues Three Primary Tissues

All tissues develop from one or more of the three primary germ layers

Ectoderm

Skin’s outer layer

Nervous system

Mesoderm

Muscles

Bones

Circulatory, reproductive, urinary systems

Endoderm

Lining of digestive tract and organs

Extracellular Materials

The extracellular substance is all the material that is located outside of the cells.

Interstitial or intercellular fluid is the fluid that fills the microscopic spaces between cells.

The extracellular fluid found in blood it is called plasma.

It provides a medium for dissolving and mixing solutes, transporting substances and carrying out chemical reactions

The extracellular substance of connective tissue is called matrix. It contains protein fibers embedded in a ground substance that may be fluid, gel, or solid.

Cell Junctions
Cell-to-Cell Contacts

A cell junction is a point of contact between adjacent plasma membranes.

Types of cell junctions:
Tight junctions

Tight junctions form fluid tight seals between cells Prevent leaks between cells

They are common among epithelial cells that line the stomach, intestines and urinary bladder

Cell Junctions

Anchoring junctions fasten cells to one another or to the extracellular material "Cement cells together"Are common in tissues subjected to friction and stretching such as the outer layer of the skin, muscle of the heart, neck of the uterus, and lining of the gastrointestinal tract

Include the following:

Desmosomes

hemidesmosomes

adherens junctions

Cell Junctions

Communicating junctions allow for rapid spread of action potentials from one cell to the next are found in some parts of the nervous system, the muscle of the heart and gastrointestinal tract

Help cells communicate

Intercellular connections

Connection of cytoplasm

The microscopic structure that functions as a communicating junction is the gap junction

Objective

The student will be able to list several structural and functional characteristics of epithelial tissue

Epithelial Tissues

General Features: Covering and Glandular

Closely packed cells with little extracellular material

Cells are arranged in sheets, single or multiple layers

Cells have an apical or free surface that faces a fluid or the environment and a basal surface

Attached to a basement membrane

Abundant cell junctions are present

Are avascular

Have a nerve supply

Have a high mitotic rate

Are derived from all three primary germ layers

Epithelial Tissues
Covering and Lining Epithelium

The arrangement of covering and lining epithelium reflects its location and function

Classification of epithelium is determined by the number of layers and cell shape

Layers are:

simple (one layer)

stratified (several layers) Functions in protection

pseudostratified

Cell shapes:

squamous (flat)

cuboidal (cube-like)

columnar (rectangular)

transitional (variable)

Objective

The student will be able to name, classify, and describe the various types of epithelia and their function

Covering and Lining Epithelium

Simple squamous epithelium – Single layer of flat, scale like cells. It is adapted for diffusion and filtration. Parts of body that are subject to little wear and tear like lungs and kidneys. Special types Endothelium and Mesothelium.

Simple cuboidal epithelium – Single layer of cube-shaped cells. Adapted for secretion and absorption. Found in kidney tubules.

Simple columnar nonciliated epithelium – Single layer of nonciliated rectangular cells. Functions in secretion of mucus (goblet cells) and in absorption. Found in GI tract containing microvilli.

Simple columnar ciliated epithelium – Single layer of ciliated rectangular cells. Moves fluids or particles by ciliary action. Upper respiratory tract, uterine tubes and paranasal sinuses and central canal of spinal cord.

Stratified squamous epithelium keratinized – Several layers of cells but the top layer is flat, it performs a protective function. Outer layer of skin, keratin a protein makes it waterproof and resistant to friction.

Covering and Lining Epithelium

Stratified squamous epithelium nonkeratinized – Several layers of cells but the top layer is flat and performs a protective function. Lines the mouth, esophagus, epiglottis, vagina and tongue.

Stratified cuboidal epithelium – Several layers of cells but top layer is cube-shaped. Protects and secretes. Ducts of sweat glands and parts of the male urethra.

Stratified columnar epithelium – Several layers of cells but the top layer is rectangular. Protects and secretes. Male urethra and exretory ducts of some glands.

Transitional epithelium – Several layers of cells whose appearance is variable. Capable of stretching so permits distention of an organ. Urinary bladder and portions of ureters and urethra.

Pseudostratified columnar epithelium – Has ONLY ONE layer but gives the appearance of many. Secretion and movement of mucus by ciliary action. A variety with goblet cells lines most of the upper respiratory tract.

Epithelial Tissues

Functions of epithelial tissue:

Protection

Filtration

Lubrication

Secretion

Digestion

Absorption

Transportation

Excretion

Sensory reception

Reproduction

Simple columnar nonciliated epithelium

Simple columnar nonciliated epithelium

Pseudostratified columnar epithelium

Simple cuboidal epithelium

Simple columnar ciliated epithelium

Objective

The student will be able to define gland and differentiate between exocrine and endocrine glands

The student will know how exocrine glands are classified structurally and functionally

Glandular Epithelium

A gland is a single cell(unicellular) or a mass (multicellular) of epithelial cells adapted for secretion.

Endocrine glands are ductless; their products (hormones) enter the extacellular fluid and diffuse into the blood (Form the endocrine system)

Exocrine glands secrete their products into ducts that empty at the surface of covering and lining epithelium or onto a free surface.

The functional classification of exocrine glands is based on how the secretion is released from the cell:

Holocrine glands accumulate the product and when the cell dies it and its product are discharged

Merocrine glands discharge their products by exocytosis

Apocrine glands accumulate the product at the apical surface of the cell and that portion is pinches off

Glandular Epithelium

Exocrine

Mucus

Saliva

Earwax

Milk

Oil

Digestive enzymes

Endocrine

Secrete hormones

Objective

The student will be able to describe the structure and function of cutaneous, mucous, and serous membranes

Membranes

An epithelial membrane is a combination of an epithelial layer and an underlying connective tissue

Mucous membranes line cavities that open to the exterior

Serous membranes lines a body cavity that does not open to the exterior

Cutaneous membrane is the skin

Synovial membranes line joint cavities, bursae and tendon sheaths

In Conclusion

A tissue is a group of cells that perform a common function

Tissues, organs, and organ systems work together to maintain homeostasis

 

In Conclusion

Epithelial tissues cover external body surfaces and line internal cavities

Connective tissues support, connect, strengthen, protect, and insulate other tissues

Muscle tissues are contractile and move the body or parts of it

Nervous tissue integrates and responds to stimuli about internal and external conditions

Objectives For Today
Outcomes

The student will be able to list several structural and functional characteristics of epithelial tissue

The student will be able to name, classify, and describe the various types of epithelia and their function

The student will be able to define gland and differentiate between exocrine and endocrine glands

The student will know how exocrine glands are classified structurally and functionally

The student will be able to describe the structure and function of cutaneous, mucous, and serous membranes

Review of Last Class Objectives

Structural and functional characteristics of epithelial tissue

Name, classify, and describe the various types of epithelia and their function

Define gland and differentiate between exocrine and endocrine glands

Exocrine gland classification structurally and functionally

Describe the structure and function of cutaneous, mucous, and serous membranes

Tissue: The Living Fabric

Connective Tissue

Dr. F. Prince

Objectives for Today

The student will be able to indicate the common characteristics of connective tissue.

The student will be able to list and describe the structural elements of connective tissue.

The student will be able to describe the types of connective tissue found in the body and indicate their characteristic functions.

Connective Tissue

General Features of Connective Tissue:

Connective tissue is the most abundant tissue in the body

Consists of three basic elements

cells

ground substance

fibers

(ground substance and fibers combine to form the Matrix)

Matrix is abundant with relatively few cells

Do not occur on free surfaces

Has a nerve supply (except for cartilage)

Is highly vascular (except for cartilage)

Matrix may be fluid, semifluid, gelatinous,fibrous, or calcified, is secreted by the connective tissue cells and determines the tissue’s qualities

Cells of Connective Tissue

Cells of connective tissue are derived from mesenchyme

Immature cells have names that end in -blast and produce most of the matrix

Mature cells have names that end in -cyte and are responsible for maintaining the matrix

Some cell types are:

fiblroblasts

macrophages

plasma cells

mast cells

adipocytes

leukocytes

Connective Tissue Fibers

Fibers in the matrix provide strength and support for tissues

Collagen fibers are very tough and resistant to stretching

Elastic fibers provide strength and stretching capacity

Reticular fibers consisting of collagen and glycoprotein provide support form the basement membranes and the stroma of soft organs

Ground Substance of Connective Tissue

The ground substance and fibers, deposited in the space between the cells, comprise the matrix of the connective tissue

The function of the ground substance is that is supports, binds and provides a medium for the exchange of materials between the blood and cells, and is active in influencing cell functions

Embryonic Connective Tissue

Mesenchyme is found almost exclusively in the embryo and is the tissue from which all other connective tissues arise

Wharton’s jelly is mucous connective tissue found in the umbilical cord of the fetus

Mature Connective Tissue

It exists in the newborn and it’s cells have differentiated from mesenchyme and does not change after birth

Types

Loose connective tissue

Areolar connective tissue

Adipose tissue

Reticular connective tissue

Dense connective tissue

Dense regular connective tissue

Dense irregular connective tissue

Elastic connective tissue

 

 

 

 

 

Cartilage / Bone / Blood Connective Tissue

Cartilage has a jelly like matrix (chondroitin sulfate) collagenous and elastic fibers and chondrocytes it it surrounded by perichondrium

Cartilage has no blood vessels or nerves

Types of cartilage

Hyaline cartilage -most abundant, fine collagen fibers

Fibrocartilage -bundles of collagen in its matrix

Elastic cartilage thread-like network of elastic fibers in the matrix

Bone consists of matrix containing mineral salts and collagenous fibers and osteocytes it is surrounded by the periosteum

Blood consists of a liquid matrix called plasma and formed elements such as RBC, WBC and thrombocytes

Cartilage

Cartilage is surrounded by perichondrium

It has no blood vessels or nerves

Three major types of cartilage:

Hyaline cartilage is the most abundant type and has fine collagen fibers

Fibrocartilage contains bundles of collagen in its matrix

Elastic cartilage contains a thread lid network of elastic fibers within the matrix (epiglottis, Eustachian tubes, external ear).

Muscle Tissue

Skeletal

Attached to bones

Striated

Voluntary

Smooth

Internal organs

Involuntary

Cardiac

Heart

Involuntary

Special end junctions

Nervous Tissue

Neurons

Excitable cells

Neuroglia

Protect and support neurons

Stimulation

Electrical charges

Neuron stimulate or inhibit adjacent neurons or other cells

In Conclusion

Connective tissues support, connect, strengthen, protect, and insulate other tissues

Muscle tissues are contractile and move the body or parts of it

Nervous tissue integrates and responds to stimuli about internal and external conditions

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