A&P Honors: Ch. 4 — Tissues

What are tissues?

Groups of cells that are similar in structure and perform a common or related function.

What are the 4 primary types of tissues?

Epithelial, connective, muscle, and nervous tissue.

What are the simplified roles of the 4 types of primary tissues?

Epithelial covers, connective supports, muscle tissue moves, and nervous tissue controls.

What is epithelial tissue?

A sheet of cells that covers a body surface or lines a body cavity.

What are the 2 forms of epithelial tissue?

Covering and lining epithelium and glandular epithelium.

What does covering and lining epithelium do?

Forms the outer layer of the skin; dips into and lines the open cavities of the urogenital, digestive, and respiratory systems; and covers the walls and organs of the closed central body cavity.

What does glandular epithelium do?

Fashions the glands of the body.

What are the 6 functions of epithelium?

(1) protection, (2) absorption, (3) filtration, (4) excretion, (5) secretion, and (6) sensory reception.

What are microvilli? What do they do?

They are fingerlike extensions of the plasma membrane. They increase the exposed surface area.

What is the basal lamina?

A thin non-cellular, adhesive, supporting sheet that is adjacent to the basal surface of an epithelium. It consists largely of glycoproteins secreted by the epithelial cells plus some fine collagen fibers.

What is the function of the basal lamina?

Acts as a selective filter than determines which molecules diffusing form the underlying connective tissue are allowed to enter the epithelium. Also acts as scaffolding along which epithelial cells can migrate to repair a wound.

What are the sides of adjacent cells tied together by?

Tight junctions and resmosomes.

What functions do tight junctions have?

They prevent substances from leaking through spaces between cells and that desmosomes keep cells from pulling apart.

What are all epithelial sheets resting upon and supported by?

Connective tissue.

What is a basement membrane?

A membrane that lies in between the epithelial and connective tissues that reinforces the epithelial sheet, helps it resist stretching and tearing, and defines the epithelial boundary.

What are the two layers of the basement membrane?

A basal lamina and a reticular lamina.

What is a reticular lamina? Describe it in proportion to the basal lamina.

Consists of a layer of extracellular material containing a fine network of collagen protein fibers that “belongs to” the underlying CT. Deep to the basal lamina.

What is avascular?

Containing no blood vessels.

What is innervated?

Supplied by nerve fibers.

What is epithelium (using avascular and intervated)? What does his mean about it’s regenerative capacity?

It is avascular and innervated. High regenerative capacity.

How are epithelial cells nourished?

By substances diffusing from blood vessels in the underlying CT.

What happens when epithelial cell’s apical-based polarity and lateral contacts are destroyed?

The beginning of to reproduce rapidly.

What does the first name of an epithelia indicate?

The number of cell layers present.

What are the two epithelia characterized by the number of cell layers?

Simple epithelial and stratified epithelia.

What is simple epithelia? Where is it found?

Consists of a single cell layer. Found where absorption, secretion, and filtration occur and a thin epithelial barrier is desirable.

What is stratified epithelia? Where can this be found?

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

What does stratified mean?

Multi-layered

What does an epithelia’s second name describe?

The shape of its cells.

What are the three common shapes of epithelial cells?

Squamous cells, cuboidal cells, and columnar cells.

What are squamous cells?

Flattened and scale-like.

What are cuboidal cells?

Boxlike, approximately as tall as they are wide.

What are columnar cells?

Tall and column shaped.

Describe simple squamous epithelium.

Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasms; the simplest of the epithelia.

What is the function of simple squamous?

Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.

Where is simple squamous located?

Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; serosae

Describe simple cuboidal epithelium.

Single layer of cube like cells with large, spherical central nuclei.

What is the function of simple cuboidal epithelium?

Secretion and absorption.

Where is the location of simple cuboidal epithelium?

Kidney tubules; ducts and secretory portions of small glands; ovary surfaces.

Describe simple columnar epithelium.

Single layer of tall cells with round to oval nuclei; many cells bear microvilli, some bear cilia; layer may contain mucus-secreting unicellular glands.

What are goblet cells?

Mucus-secreting unicellular glands.

What are the functions of simple columnar epithelium?

Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus by ciliary action.

Where is simple columnar epithelium located?

Nonciliated type lines most of the digestive tract (stomach and small intestine), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions on the uterus.

What do cilia do?

Move materials and substances along cell surface. An ex is sweeping mucus or sweeping fertilized egg in to atrium wall.

Describe 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.

What is the function of pseudostratified columnar epithelium?

Secrete substances, particularly mucus; propulsion of mucus by ciliary action.

Where is pseudostratified columnar epithelium located?

Ciliated variety lines the trachea and most of the upper respiratory tract; no ciliated type in males’ sperm-carrying ducts and ducts of large glands.

Name the two simple squamous epithelia in the body that have special names to reflect their location.

Endothelium and mesothelium

Describe stratified squamous epithelium.

Thick epithelium composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers.

What is the function of stratified squamous?

Protects underlying tissues in areas subjected to abrasion.

Where is stratified squamous located?

Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry epithelium.

Describe transitional epithelium.

Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamous like, depending on degree of organ stretch.

What is the function of transitional epithelium?

Stretches readily, permits stored urine to distend urinary organ.

Where is transitional epithelium located?

Lines the ureters, bladder, and part of the urethra.

What is a gland?

Something that consists of one or more cells that make and secrete a particular product.

Whats a secretion?

An aqueous fluid that usually contains proteins.

What two traits are glands classified according to?

Where they release their product (endocrine, exocrine), and the number of cells (unicellular, multicellular).

Describe the difference between endocrine and exocrine.

Endocrine: internally secreting, ductless, secrete product into fluid surrounding. Exocrine: externally secreting, have duct, opens onto epithelial surface.

What are some secretions secreted by endocrine glands?

Amino acids, proteins, glycoproteins, and steroids.

What are some secretions secreted by exocrine glands?

Sweat, mucous, oil, and salivary glands.

What are some examples of unicellular glands?

Mucous cells and goblet cells.

What are the two basic parts of a multicellular exocrine gland?

AN epithelium-derived duct and a secretory unit (acinus) consisting of secretory cells.

What is the secretory unit in multicellular exocrine glands surrounded by? What other functions does ___ have?

Supportive connective tissue. It supplies it with blood vessels and nerve fibers, and forms a fibrous capsule that extends into the gland and divides it into lobes.

What can multicellular exocrine glands be classified by?

Structure and mode of secretion.

On the basis of their duct structures, multicellular exocrine glands are either:

Simple or compound.

What do simple glands have, what do compound glands have?

Simple: unbranched duct. Compound: branched duct.

What three secretory units are glands further categorized by?

(1) Tubular, (2) alveolar, (3) tubuloalveolar.

Describe tubular secretory units.

If secretory cells form tubes.

Describe alveolar secretory units.

If the secretory cells form small, flasklike sacs.

Describe tubuloalveolar secretory units.

They have both types of secretory units.

What are the ways multicellular exocrine glands secrete their products described functionally as?

Merocrine, holocrine, and apocrine glands.

Describe merocrine glands.

Secrete their products by exocytosis as they are produced.

Describe holocrine glands.

Accumulate their products within them until they contrast, accumulate their products within them until they rupture.

Describe apocrine glands.

Accumulate their products, but only just beneath the free surface.

What is duodenum?

Pancreatic juices carried here to breakdown things in stomach.

List characteristics of CT.

Mesenchyme as their common tissue of origin, varying degrees of vascularity, non living extracellular matrix, consisting of ground substance and fibers.

What are the four main classes of connective tissue?

CT proper, cartilage, bone, and blood.

What’re CT’s 5 major functions?

(1) binding and supporting, (2) protecting, (3) insulating, (4) storing reserve fuel, (5) transporting substances within the body.

What do bone and cartilage do for the body and how?

Support and protect body organs by providing the hard underpinnings of the skeleton.

What does fat do for the body?

Insulates and protects body organs and provides a fuel reserve.

What does blood do for the body?

Transports substances inside the body.

What two characteristics do CT’s share that together set them apart from other primary tissues?

Extracellular matrix and common origin.

What is extracellular matrix?

What connective tissues consist largely of. This separates the living cells of the tissue. This allows connective tissue to bear weight, withstand great tension, and endure abuses, such as physical trauma and abrasion, that no other tissue can tolerate.

What does the matrix determine?

The function

What is common origin?

That all connective tissues arise from mesenchyme (an embryiotic tissue).

What is one noticeable different between different types of CT?

How richly they are supplied by blood vessels.

What are the three main components of CT?

Ground substance, fibers, and cells.

What is ground substance?

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

What are the three components of ground substance?

Interstitial fluid, cell adhesion proteins, and proteogylcans.

What are the three types of fibers found in connective tissue matrix?

Collagen, elastic, and reticular.

Describe collagen fibers.

Constructed of collagen. Collagen molecules are secreted into the extracellular space, where they assemble spontaneously into cross-linked fibrils, which in turn are bundled together into the thick collagen fibers seen with a microscope. Extremely tough and produce high tensile strength to the matrix.

Describe elastic fibers.

Long, thin, elastic fibers that form branching networks in the extracellular matrix. These fibers contain elastin, that allows them to stretch and recoil like its thick, ropeliek collagen fibers become taut.

Describe reticular fibers.

Short, fine fibers made of a different type of collagen than the more common, thicker collagen fibers. They connect to the coarse collagen fibers, but they branch extensively, forming delicate networks that surround small blood vessels and support the soft tissue of organs.

What are the four resident cell types that exist in immature and mature forms?

Fibroblasts, chondroblasts, and osteoblasts.

Describe fibroblasts.

CT proper.

Describe chondroblasts.

Cartilage.

Describe osteoblasts.

Bone.

Describe hematopoietic stem cells.

Blood.

What are the other cell types CT is also home to?

Adipocytes, white blood cells, mast cells, and macrophages.

Describe adipocytes.

Fat cells that store energy as fat.