Biol 2401 Ch 5

Tissues are

Groups of similar cells and extracellular material with a common function.

What are the 4 types of tissue?

Epithelial, connective, muscle, nervous.

Characteristics of Epithelial cells

Composed of one or more layers of tightly packed cells, contains little to no extracellular matrix, covers body surfaces, lines cavities and forms majority of glands.

Cellularity of Epithelium

Composed almost entirely of tightly packed cells.

Apical Surface of epithelium

Exposed to external environment or internal body space, microvilli or cilia.

Basal Surface of epithelium

Epithelium attached to connective tissue.

Avascularity of Epithelium

Lacks blood vessels, nutrients obtained across apical surfacr of from basal surface.

Innervation of Epithelium

Richly innervated, lots of nerves and receptors.

Regeneration of Epithelium

High regeneration capacity, continual replacement of lost cells.

Physical Protection of Epithelium

Protects from dehydration, abrasion and destruction.

Permeability of Epithelium

Selective permeability, allows passage for some substances while preventing passage of others.

Secretion of Epithelium

Some cells are specialized to secrete sensations.

Simple Epithelium

One cell layer thick, all cells contact basement membrane.

Function of Simple Epithelium

Filtration, absorption, or secretion.

Stratified Epithelium

2 or more layers of epithelial cells. Only basal layer is in contact with basement membrane, in areas subjected to mechanical stress.

Pseudostratified Epithelium

Appears layered, all cells contact basement membrane, but may not reach apical surface.

Squamous Cell Shape

Flat, wide and irregular in shape.

Squamous Nucleus shape

Flat

Cuboidal Cell Shape

About as tall as they are wide.

Cuboidal Nucleus shape

Spherical and in center of cell.

Columnar Cell Shape

Slender and taller than they are wide.

Columnar Nucleus shape

Oval shape, oriented lengthwise in basal region.

Transitional Cell Shape

Changes shape depending on the stretch of epithelium.

Simple Squamous Epithelium

Single layer, spherical to oval nucleus, thinnest barrier, allows for rapid movement of molecules across the membrane.

Simple Squamous Epithelium Location

Lines air sacs of lungs (alveoli), vessel walls (endothelium), and serous membrane (mesothelium).

Simple Cuboidal Epithelium

Single layer of uniformly shaped cells, about as tall as they are wide, centrally located spherical nucleus.

Simple Cuboidal Epithelium Function

Absorption and secretion, ideal for structural components of glands.

Simple Cuboidal Epithelium Location

Located in kidney tubules, thyroid gland follicles, surface of ovary; secretory regions and ducts of most glands.

Simple Columnar Epithelium

Single layer of cells, taller than they are wide, oval nucleus lengthwise in basal region ideal for secretory and absorptive functions.

Non-ciliated Simple Columnar Epithelium

Contains microvilli, unicellular glands (goblet cells) that secrete glycoproteins.

Non-Ciliated Simple Columnar epithelium location

Lines most of digestive tract from stomach to anal canal, including the stomach, small intestine and large intestine.

Ciliated Simple Columnar Epithelium

Cilia project from apical surface, moves mucus along, goblet cells are interspersed.

Ciliated Simple Columnar Epithelium Location

Lines bronchioles and uterine tubes which help to move oocyte from ovary to uterus.

Pseudostratified Columnar Epithelium

Appears as multiple cell layers, not really stratified, all cells are in direct contact with basement membrane, nuclei scattered at different distances, not all cells reach apical surface.

Ciliated Pseudostratified Columnar Epithelium

Contains cilia on apical surface, goblet cells secrete mucin, traps foreign particles moved by cilia.

Ciliated Pseudostratified Columnar Epithelium Location

Located in large passageways of respiratory system, nasal cavity, part of pharynx, part of larynx, trachea and bronchi.

Non-ciliated Pseudostratified Columnar Epithelium

Rare, lacks cilia and goblet cells, has protective functions.

Non-Ciliated Pseudostratified Columnar Epithelium Location

Located in male urethra and epididymis.

Stratified Squamous Epithelium

Multiple cell layers, only the deepest layer in contact with basement membrane, Basal layers (bottom) cuboidal, apical with squamous.

Stratified Squamous Epithelium Function

Protects against abrasion and friction, stem cells in basal layer continuously divide to replace lost cells at surface.

Keratinized Stratified Squamous Epithelium

Superficial layer of dead cells, cells lack nucleus and are filled with keratin.

Keratinized Stratified Squamous Epithelium Function and Location

Found in epidermis, protect underlying tissue from abrasion.

Non-Keratinized Stratified Squamous Epithelium

All cells alive and kept moist with secretions (saliva and mucus), lack keratin, microscopically visible cell nuclei.

Non-Keratinized Stratified Squamous Epithelium Location

Lines the oral cavity, part of pharynx, esophagus, vagina and anus.

Stratified Cuboidal Epithelium

Rare, two or more layers of cells, columnar at apical surface, protects and secretes.

Stratified Cuboidal Epithelium Location

Found in large ducts of salivary glands, parts of male urethra, and conjunctiva covering eye.

Transitional Epithelium

In relaxed state, basal cells are cuboidal or polyhedral, apical cells are large and rounded. Stretched state, apical cells are flattened. Binucleated cells allow for stretching as bladder fills.

Transitional Epithelium Location

Lining of urinary bladder, ureters and part of urethra.

Glands

Individual cells or multicellular organs composed of epithelial tissue, endocrine or exocrine.

Endocrine Glands

Lack ducts, release hormones into blood.

Exocrine Glands

Invaginated epithelium in connective tissue, connected with epithelial surface by duct.

Exocrine Gland examples

Sweat glands, mammary glands, salivary glands.

Unicellular Exocrine Glands

Do not contain a duct, located close to epithelium surface, most common type is goblet cells.

Multicellular Exocrine Glands

Numerous cells, includes acini, ducts transport secretions to epithelial surface, surrounded by fibrous capsules.

Acini are

Cell clusters that oroduce secretions.

Extension of capsules

Septa, partition gland into lobes.

Simple glands

A single unbranched duct.

Compound glands

Branched ducts.

Tubular glands

Secretory portion and duct are same diameter.

Acinar Glands

Secretory portion forms expanded sac.

Tubuloacinar glands

Both tubules and acini.

Merocrine glands

Package secretions into vesicles, released by exocytosis. Examples are salivary glands.

Apocrine glands

Apical membrane pinches off and becomes secretion. Examples are mammary and ceruminous glands.

Holocrine glands

Ruptured cell becomes secretion. Example, sebaceous glands.

3 Basic Components of Connective Tissue

Cells, Protein Fibers and Ground Substance

Resident Cells

Stationary cells housed in CT. Support, maintain and repair extracellular matrix.

Examples of Resident Cells

Fibroblasts, adipocytes, mesenchymal cells, and fixed macrophages.

Fibroblasts

Most abundant cells in CT, flat cells with tapered ends, produce fibers and ground substance of extracellular matrix.

Adipocytes

Appear in small clusters in some types of CT aka fat cells.

Adipose Connective tissue

Dominant area of large clusters.

Mesenchymal cells

Embryonic stem cells, divide to replace damaged cells.

Fixed Macrophages

Relatively large, irregular shaped cells. Derived from monocytes (WBC), dispersed throughout matrix and phagocytize damaged cells or pathogens.

Wandering cells

Continuously move throughout CT, components of the immune system, repair matrix and protect body from harmful agents.

Types of wandering cells

Mast cells, plasma cells, free macrophages, neutrophils and T Lymphocytes.

Mast cells

Small, mobile cells close to blood vessels, secrete heparin to inhibit blood clotting, secrete histamine to dilate blood vessels.

Plasma Cells

Form when B lymphocytes are activated when exposed to foreign material, also produce antibodies..

Free Macrophages

Mobile, phagocytic cells, function like fixed macrophages but are able to move.

Neutrophils

Phagocytizes bacteria.

T-Lymphocytes

Leukocyte that attacks foreign material.

Collagen Fibers

Unbranched, “cable-like”, long fibers, numerous in tendons and ligaments.

Reticular Fibers

Similar to collagen fibers but thinner. Abundant in stoma of some organs (lymph nodes).

Elastic Fibers

Contain protein elastin, stretch and recoil easily, found in skin and walls of arteries.

Ground Substance

Noncellular material produced by CT cells. Viscous, semi-solid and solid materials.

Ground Substance+ Protein Fibers=

Extracellular matrix.

Glycosaminoglycans (GAGs)

Large molecule in ground substance, charge attracts Cations, water follows.

Proteoglycans

Found with GAG linked to a protein.

Glycoproteins

Proteins with carbohydrate attached, bond CT cells and fibers to ground substance.

Scurvy is caused by

Vitamin C deficiency.

Functions of CT

Physical protection, support and structural framework, binding of structures, storage, transport and immune protection.

Mesenchyme

Source of all other CT cells, adult CT often has mesenchymal stem cells.

Mucous Connective Tissue is found in

Umbilical cord only.

Marfan Syndrome causes

Skeletal, cardiovascular and visual abnormalities.

Symptoms of Marfan Syndrome

Abnormally long fingers, toes, and limbs, malformation of thoracic cage and vertebral column, easily dislocate joints, weakness and abnormalities of aorta.

Loose CT

Fewer cells and protein fibers than dense CT, sparse protein fibers and irregularly arranged, abundant ground system.

3 Types of loose CT

Areolar, adipose, reticular.

Areolar CT

Loose organization of collagen and elastic fibers, highly vascularized, contained all fixed and wandering cells, ground substance is viscous.

Areolar CT is found

In the papillary layer of dermis, subcutaneous layer and surrounding organs, nerve and muscle cells, and blood vessels.

Adipose CT

Composed of adipocytes, referred to as fat.

White Adipose

Stores energy, cushions, and acts as an insulator.