Chapter 4: Tissues

Dense irregular connective tissues

-Description: Primary irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. -Function: Withstands tension exerted in many directions; provides structural strength -Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract

Dense regular connective tissues

-Description: Primary parallel collagen fibers, a few elastic; major cell type is the fibrolast. -Function: attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. -Location: Tendons, most ligaments, aponeuroses.

Steps of Tissue repair

1) Inflammation sets the stage (may lead to regeneration, fibrosis, or both) 2) Organization restores the blood supply 3)Regeneration and fibrosis effect permanent repair

Structural elements of connective tissue

Connective tissues have three main elements: ground substance, fibers, and cells. Together ground substance and fibers make up the extracellular matrix

adipocytes

Defending agaisnt infection (via the activity of white blood cells and macrophages)

ground substance

The unstructured material that fills the space between the cells and contains the fibers.

unicellular exocrine glands

mucous cells and goblet cells. They are sprinkled in the epithelial linings of the intestinal and respiratory tracts amid columnar cells with other functions. In humans, all such glands produce mucin, a complex glycoprotein that dissolves in water when secreted. Once dissolved, mucin forms mucus, a slimy coating that protects and lubricates surfaces. In goblet cells the cuplike accumulation of mucin distends the top of the cell, making the cells look like a glass with a stem.

pleurae

cover the lungs and line the chest wall

Elastic cartilage

nearly identical to hyaline cartilage . Found where strength and exceptional sretchability are needed, elastic cartilage forms skeletons of the external ear and epiglottis.

artifacts

preserved tissue we see under the microscope has been exposed to many procedures that alter its original condition and introduce minor distortions.

Mucous membrane

line all body cavities that open to the outside of the body, such as the hollow organs of the digestive, respiratory, and urogential tracts. They are often adapted for absorption and secretion. Although many mucosae secret mucus, this is not a requirement. They are "wet" or moist membranes, bathed by mucus or in the case of urinary mucosa, urine.

elastic fibers

long, thin, elastic fibers form branching networks in the extracellular matrix. The fibers contain a rubberlike protein, elastin, that allows them to stretch and recoil like rubber bands.

Chondrocytes

mature cartilage cells, are typically found in small groups within cavities called lacunae

white blood cells

(neutrophils, eosinophils, lymphocytes) and other cell types that are concerned with tissue response to injury.

nervous tissue

A body tissue that carries electrical messages back and forth between the brain and other parts of the body.

muscle tissue

A body tissue that contracts or shortens, making body parts move.

Connective tissue

A body tissue that provides support for the body and connects all of its parts

neurons

A nerve cell; the basic building block of the nervous system.

desmosomes

Anchoring junctions that prevents cells subjected to mechanical stress from being pulled apart; button like thickenings of adjacent plasma membranes connected by fine protein filaments

reticular lamina

layer of extracellular material containing a fine network of collagen protein fibers that "belongs to" the underlying connective tissue.

Cardiac muscle

Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs). As it contrasts, it propels blood into the circulation; involuntary control.

Common Characteristics of connective tissue

Common origin Degrees of Vascularity Extracellular matrix

glandular epithelium

Composed of cells that are specialized to produce and secrete substances. Glands are classfied according to two sets of traits: edocrine or exocrine

multicellular exocrine glands

Composed of many cells. Example are sweat glands, salivary glands, ect. It is simple and compound.

Areolar connective Tissue

Description: Gel-like matrix with all three fiber types, cells; fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina proporia of mucous membranes; packages organs; surrounds capillares.

Connective tissue proper: loose connective tissue, areolar

Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body; e.g, forms lamina propria of mucous membranes; packages organs; surrounds capillaries.

Connective tissue proper: loose connective tissue, reticular

Description: Loose network of reticular fibers in a gel-like ground substance; reticular cells lie on a network. Function: Fibers from a soft internal skeleton (stroma) that supports other cell types including white blood cells, and macrophages. Location: Lymphoid organs (lymph nodes, bone marrow, and spleen)

Connective tissue proper: loose connective tissue, adipose

Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells have nucleus pushed to the side by large fat droplet. Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Location: Under skin in subcutaneous tissue around kidneys and eyeballs; within abdomen; in breasts

peritoneum

Double-layered membrane surrounding the abdominal organs

pericardium

Double-layered membrane surrounding the heart.

Skeletal Muscle

Long, cylindrical, multinucleate cells; obvious striations. Voluntary movement; locomotion; manipulation of the environemnt; facial expression; voluntary control.

Collagen fibers

Long, thin, elastic fibers form branching network in the extracellular matrix

endocrine glands

Glands of the endocrine system that release hormones into the bloodstream. Eventually lose their ducts, and are often called ductless glands. Endocrine glands are structurally diverse, so one description does not fit all.

Fibroblasts

Holding body fluids (the ground substance's role)

Connective tissue

It is the most abundant and widely distributed tissue in the body. There are 4 main classes of connective tissue and several subclasses. These are 1) connective tissue proper 2) cartilage 3) bone, and 4) muscle. They have three main elements: ground substance, fibers, and cells. Together ground substance and fibers make up the extracellular matrix.

stratified columnar epithelia

Lining of stomach, intestine, uterine tubes, gallblader, uterine tubes, and collecting ducts of kindneys. Protection, secretion, absorption

Tight junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

Modes of secretion

Multicellular exocrine glands secrete their products in different ways, so they can also be described functionally as merocrine, holocrine, or apocrine glands.

Smooth muscle

Muscle tissue found in the walls of hollow organs, e.g., blood vessels, the digestive tract, the uterus, etc. It is controlled involuntarily (automatic nervous system) and are spindle shaped. No striations and cells are arranged closely to form sheets.

Primary germ layers

One of the first events of embryonic development is the formation of the three primary germ layers, which lie one atop of the other like a pancake. From superficial to deep, these layers are ectoderm, mesoderm, and endoderm.

Osseous tissue

Osseaous tissue has an exceptional ability to support and protect body structures. Bones of the skeleton also provide cavities for storing fat and synthesizing blood cells.

transitional epithlium

Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on the degree of organ stretch. Stretches readily, permits stored urine to distend urinary organ. Location: Lines the ureters, bladder, and part of the urethra.

pseudostratified columnar epithelium

Single layer of cells of differing heights; some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia. It secretes substances, particularly mucus; propulsion of mucus by ciliary action. The non-ciliated type in male's sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachae, most of the upper repiratory tract.

Simple squamous epithelium

Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. Located in the kidney glomeruli, air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae). Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.

Regeneration

The ability to regrow a missing part of the body

basal surface

The bottom layer of epithelial tissue that attaches to the basement membrane

intercalated discs

The cell-to-cell contacts of the cardiac muscle fibers are called

serous membrane

The epithelial membrane that lines the closed ventral cavities of the body; makes up the pleura and pericardium

Simple cuboidal epithelium

consists of a single layer of cells as tall as they are wide.

Cartilage

They are three varieties of cartilage: hyaline cartilage, elastic cartilage, and fibrocartilage. Each dominated by a particular fiber type. stand up to both tension and compression. Lacks nerve fibers and is avascular. It recieves its nutrients by diffusion from blood vessels located in the connective tissue layer (perichondrium) surrounding it. The movement of tissue fluid in its matrix enables cartilage to rebound after being compressed and helps to nourish the cartilage cells.

lamina propria

This layer of the GI tract is composed of areolar connective tissue containing blood and lymph vessels. The capillaries that nourish the epithelium and absorb digested nutrients lie in the ________.

Connective tissue fibers

Three types of fibers are found in connective tissue matrix: collagen, elastic, and reticular fibers.

Transmission Electron Microscopy

Tissue sections are "stained" with heavy metal salts. These metals deflect electrons in the beam to different extents, providing contrast.

Connective tissue cells

a primary tissue; form and function vary extensively. Functions include support, storage and protection.

inflammatory response

a relatively nonspecific reaction that develops quickly wherever the tissues are injured.

Epthelial tissue

a sheet of cell that covers a body surface or lines a body cavity

epithelial tissue

a sheet of cells that covers a body surface or lines a body cavity . (epithe=line, covering) Two forms occur: Covering and lining epithelium, forms the outer layer of the skin. Glandular epthelium: which fashions the glands of the body.

simple columnar epithelium

a single layer tall, closely packed cells, aligned like soldiers in a row. Lines the digestive tract from the stomach to the rectum

Merocrine glands

a term used to classify exocrine glands and their secretions in the study of histology. A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and thence onto a bodily surface or into the lumen.

endothelium

a type of epithelium that lines the interior surface of blood vessels and lymphatic vessels, forming an interface between circulating blood or lymph in the lumen and the rest of the vessel wall.

Fat cells

adipose tissue is made of

basal lamina

adjacent to the basal surface of an epithelium is a thin supporting sheet

Mircroscopy

allows us to study tissue structure. Before a specimen can be viewed through a microscope, it must be fixed (preserved) and then cut into sections (slices) thin enough to transmit light or electrons. Finally, the specimen must be stained to enhance contrast. Stains are used in light microscopy that contain negatively charged molecule (acidic stains) or positively charged molecules (basic stains) that bind within the tissue to macromolecules of opposite charges. Different parts of cells and tissues take up different dyes, distinguishing different anatomical structures.

apical surface

an upper free surface exposed to the body exterior or the cavity of an internal organ

Cuboidal cells

are boxlike, approximately as tall as they are wide.

Squamous cells

are flattened and scale-like

Tissues

are groups of cells that are similar in structure and perform a common or related function. Four primary tissue types interweave to form the "fabric" of the body. These basic tissues are epithelial, connective, muscle, and nervous tissue.

Electron-microscope images

are in shades of gray because color is a property color is a property of light, not of electron waves, but the image may be artificially colored to enhance contrast. Another kind of electron microscopy, scanning electron microscopy (SEM), provides three dimensional pictures of an unsectioned tissue surface.

Multicellular exocrine glands structural classification

are structurally more complex

columnar cells

are tall and column shaped.

hormones

chemicals that they secrete by exocytosis directly into the extracellular space.

Stratified epithelia

composed of two or more cell layers stacked on top of each other, are common in high abrasion areas where protection is important, such as the skin surface of the lining of the mouth.

Simple epithelia

consists of a single cell layer

microvili

fingerlike extensions of the plasma membrane increase the membrane surface area

Reticular connective tissue

found around the kidney, the spleen, and lymph nodes, as well as in bone marrow.[4] The liver however have a meshwork of reticular fibers, not to be mixed with reticular connective tissue. Form a soft skeleton (stroma) to support the lymphoid organs (lymph node stromal cells, red bone marrow, and spleen). Adipose tissue is held together by reticular fibers.

stratified epithelia

found covering the exterior body surfaces and lining portions of the body tracts where friction phenomena occur. A multilayered epithelium allows deeper cells to replace the more superficial cells as they are damaged or cast off from the epithelial free surface. Although most prevalent in the skin and portions of the digestive and reproductive tract, stratified epithelia can be found in some large ducts and tubules.

mesenchyme

has a fluid ground substance containing fine sparse fibers and star-shaped mesenchymal cells.

Fibrocartilage

is intermediate between hyaline cartilage and dense regular connective tissues. Its rows of chondrocytes (a cartilage feauture) alternate with rows of thick collagen fibers.

stratified cuboidal epithelia

is quite rare in the body, mostly found in the ducts of some of the larger glands (sweat glands, mammary glands).

Hyaline Cartilage

is the most abundant cartilage in the body. Although it contains large numbers of collagen fibers, they are not apparent and the matrix appears glassy. exists on the ventral ends of ribs; in the larynx, trachea, and bronchi; and on the articular surface of bones.

stratified squamous epithelia

its free surface cells are squamous, and cells of the deeper layers are cuboidal or columnar. This epithelium is found in areas subjected to wear and tear, and its surface cells are constantly being rubbed away and replaced by division of its basal cell. Location: Non-keratinized types form moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.

Macrophages

large, irregularly shaped cells that avidly devour a broad variety of foreign materials, ranging from foreign molecules to entire bacteria to dust particles.

basement membrane

reinforces the epithelial sheet, helping it resist the stretching and tearing, and defines the epithelial boundary.

Regenerative capacity of different Tissues

the ability of an organism to regrow certain parts of the body

goblet cells

the cuplike accumulation of mucin distends to the top of the cell

Mesothlium

the epithelium that lines the pleurae, peritoneum, and pericardium.

Blood

the fluid within the vessels, is the most atypical connective tissue. Functions as the transport vehicle for the cardiovascular system, carrying nutrients, wastes, respiratory gases, and many other substances throughout the body.

histology

the study of tissues

Muscle fibers

threadlike structures that are held together by connective tissues

Mast cells

typically cluster along blood vessels. These oval cells detect foreign microorganisms and initiate local inflammatory responses against them. Mast cell cytoplasm contains secretory granules with chemicals that mediate inflammation, especially in severe allergies. These chemicals include : Heparin, Histamine, Protease, other enzymes.

Cutaneous membrane

your skin. an organ consisting of keratinized stratified squamous epithelium (epidermis) firmly attached to a thick layer of connective tissue (dermis). Unlike other epithelial membrane, the cutaneous membrane is exposed to the air and is a dry membrane.