Histology Exam 1

The basement membrane is composed of multiple layers secreted by epithelia cells:

-Lamina densa -Lamina lucidae (lamina rarae) -Made of type IV collagen (creates mesh framework), glycoproteins (laminin attaches to integrin membrane proteins to anchor epithelia), proteoglycans like heparan sulfate (cross link laminins to collagen to increase structural integrity) -Reticular fibers secreted by connective tissue not epithelium stain with silver stain (argyrophilic)

Pseudostratified columnar epithelium

-Looks multilayered; but only 1 layer as all cells contact basement membrane. -Nuclei found throughout several layers -Has cilia and goblet cells -Secretes and moves mucus -Respiratory tract and portions of male urethra

transitional epithelium

-Multilayered epithelium. surface cells that change from rounded to flat when stretched -allows for filling of urinary tract -lines ureter and bladder -Binucleated cells may be seen

Keratinized stratified squamous

-Multiple cell layers with cells becoming flat and scaly toward surface -Epidermis of skin; palms and soles heavily keratinized -Major role in protection

Non-keratinized stratified squamous

-Same as keratinized epithelium without the surface layer of dead cells -Tongue, oral mucosa, esophagus, and vagina -Resists abrasion and penetration of pathogens

Simple Cuboidal epithelium

-Single layer of square or round cells. Functions in absorption and secretion, mucus production, and movement. This tissue can be found in liver, thyroid, mammary, and salivary glands, bronchioles, and kidney tubules

Simple Columnar epithelium

-Single row of tall, narrow cells. -Oval nuclei in basal 2/3 of cell. -+/- cilia, +/- goblet cells. Functions in absorption and secretion; secretion of mucus This tissue can be found in lining GI tract, uterus, kidney, and uterine tubes.

simple squamous epithelium

-Single row of thin cells -Diffusion or transport of substances -Secretes serous fluid This tissue can be found in: alveoli, glomeruli, endothelium and serosa.

Stratified cuboidal epithelium

-Two or more cell layers; surface cells square or round -Secretes sweat; sperm production and ovarian hormone production found in sweat gland ducts; ovarian follicles and seminiferous tubules.

Stratified Columnar epithelium

-Very rare -Protects and secretes -Found sometimes in areas of transition > parts of male urethra and vas deferens; anus between simple columnar of colon and stratified squamous of the rest of the anal epithelium

in its role as an interface tissue, Epithelium has many functions including:

1. Protection for underlying tissues from radiation, desiccation, toxins, and physical trauma. 2. Absorption of substances in the digestive tract lining with distinct modifications. 3. Regulation and excretion of chemicals between the underlying tissues and the body cavity. 4.The secretion of hormones into the blood vascular system. The secretion of sweat, mucus, enzymes, and other products that are delivered by ducts come from the glandular epithelium. 5. The detection of sensation.

Mucus is lightly stained using

H&E because the hydrophilic mucin washes away

Organs are composed of

Parenchyma (the functional tissue) and Stroma (the supporting/structural tissue).

Cilia and Flagella

Similar internal structure. internal structure: Axoneme -9 pairs of microtubules in a circular array with another pair in the middle (9+2 array) -Microtubules around periphery are connected by dynein arms (motor proteins) -Nexin proteins cross link microtubules providing structural support -The arrangement of the axoneme allow bending and movement of the cilia and flagella -Axoneme is continuous with microtubules inside cell-this attachment site of the cilium or flagella is the basal body Basal bodies consists of triplets of microtubules.

Epithelium tissue consists of

a sheet of closely adhered polyhedral cells, one or more cell layers thick, and very little extracellular matrix.

microvilli are common in

absorptive cells (e.g. digestive tract)

Microvilli contains

actin filaments attaching internal structure of microvillus to the cytoskeleton of the cell

Epithelium is derived from

all three primary germ layers of the embryo.

goblet cell is an example of

an exocrine gland producing and secreting mucus onto a body surface. Paraticularly common in the digestive and respiratory tracks where mucus provides protection and lubrication.

some surface epithelial cells have specializations of their

apical cell membrane

Stereocillia are

apical extension of membrane for absorption or specialized for sensation-found in male repro track or inner ear

region facing the body surface or lumen is the

apical pole

cuboidal cells

are cube-ish shaped about as tall as they are wide. They absorb nutrients and produce secretions like sweat. their nucleus is pretty circular.

Squamous cells

are flat their name means, "scale" and they look kind of squished including their darkly stained nucleus. They have fast absorption and diffusion making thin membranes.

-Once electron microscopy was developed it was discovered that stereocillia

are not in fact, cilia at all. They are more similar to microvilli because they have an actin attachment.

columnar cells

are tall and thick and look like columns, and they cushion underlying tissues. Their nuclei also are stretched into an ellipse. They absorb nutrients and produce secretions as well.

Basement membrane functions in:

attachment, filtration, selective transport of substances from connective tissue to epithelia, and to provide structural support and scaffolding for repair.

all epithelial tissues are

avascular -- meaning not associated with or supplied by blood vessels.

epithelia are polar the region in contact with the basement membrane is the

basal pole

Compound glands

branched ducts

-Microvilli in small intestine referred to as the

brush border (bristles of a toothbrush/hair brush)

epithelial cells are closely adhered to the

connective tissue beneath.

Epithelium is the tissue type that

covers and lines body surfaces. Also secretion, absorption, excretion, filtration, sensation, and contraction/expression

Proper Epithelial Tissue

covers and lines your outer and inner body

enteroendocrine cells are also found in the

digestive tract, secret their chemical products into a blood capillary rather than a body surface.

Exocrine glands of the epithelial tissue have a

duct leading to a free surface

Tubuloacinar glands

elongated and then rounded or bulbous at ends (e.g salivary glands)

tubular

elongated secretory protein

The hormone thyroxin for example is secreted by an

endocrine gland--your thyroid and it needs to be distributed throughout the entire body that it can stimulate the metabolism in all your cells.

glandular epithelium forms two different kinds of glands your

endocrine glands, and exocrine glands

Epithelia tissue forms boundaries between different

environments and nearly all substances must pass through the epithelium.

your glands are also made up largely of

epithelial tissue making epithelial play a big role in facilitating all of your secretions -- from sweat and mucus, to hormones and enzymes.

The four basic tissue types

epithelial, connective, muscle, and nervous

since endocrine glands lose their connection to the body surface they are considered

epithelioid, rather than strictly epithelial.

There are eight basic types of

epithelium tissues, six of them are identified based on both the number of cells and their shape; two of them are named by the type of (squamous) found in them.

Microvilli

extensions of the plasma membrane that increase surface area of cell.

many cilia are motile they tend to be numerous and short-moving the

extracellular fluid outside of the cell rather than cell itself

Cilia tend to be shorter than

flagella

The epithelium cells that are selectively permeable allow

for some level of absorption, filtration, and excretion of substances Example: the tissue lining your small intestines is what allows you to absorb nutrients through diffusion and active transport.

Glandular Epithelium tissue

forms glands and secretes hormones and other substances.

Exocrine or endocrine are

glands derived from epithelia tissue

Mucus

glycosylated protein product, often referred to as mucin.

Unicellular glands are

goblet cells and enteroendocrine cells

PAS staining properties of the basement membrane are due to the basement membrane having a

high glycoprotein content.

Endocrine glands secrete

hormones right into your bloodstream or to nearby cells

flagella are rare in the

human body compared to cilia

Basement membrane

layer between epithelium and the underlying connective tissue. -Anchors the epithelium

another way to classify epithelium tissue other than its shape is its

layering

stratified cuboidal epithelium tissue would have

layers of cube-shaped cells, like the lining of the ducts that leak sweat and spit.

when examining epithelia under the microscope you must find it since epithelia is found

lining body surfaces, you should look for free surface. this can be on the edge of a tissue or even within tissues or organs (i.e, lining a gland, duct, or lumen of a tubular structure.)

sterocilia are

longer than microvilli and may branch

the only flagellated cell in the human body is the

male sperm

Exocrine glands modes of secretion

merocrine, apocrine, holocrine

almost all cells have primary cilium involved in

monitoring of the extra cellular environment

Pseudostratified epithelium has

mostly just one later but the cells can be different shapes and sizes and the nuclei can be at lots of different levels so it looks sort of messy and multilayered even though it really isnt.

flagella drives movement of the whole cell (swims) rather than just

movement of fluid outside of the cell

After mucus secretion,

mucin absorbs water and forms mucus.

Startified epithelium has

multiple layers set on top of each other, like bricks and mortar of a wall

during development both exocrine and endocrine glands are produced by

multiplication of epithelia extending downward to form the gland. the attachment of the gland to the epithelial surface is lost in formation of an endocrine gland but the attachment remains as the duct in an exocrine gland. the duct is typically non-secretory but is used for transportation of the product.

simple glands are

non branching duct, secretory portion can be unbranched, branched, or coiled.

Basal Lamina is

not visible with light microscope, requires electron microscopy to view.

Epithelial tissues nomenclature is based upon the

number of cell layers, the shape of the surface cell, and the presence of any surface specializations.

Simple epithelium has

only one layer of cells

all your epithelial cells are

polar, meaning they have distinct sides. the apical or upper side, is exposed to either the outside of your body or whatever internal cavity its lining. The basal side, or inner surface is tightly attached to the basement membrane, a thin layer of mostly collagen fibers that helps hold the epithelium together and anchors it to the next deeper layer--your connective tissue.

merocrine produce

product and release via exocytosis (e.g. acinar cells of pancreas) sometimes also refered to as eccrine glands.

Apocrine cell produces

product and secrets it by shedding the apical portion of the cell (e.g. mammary glands) Nucleus found in basal half of the cell because this portion of the cell remains behind after secretion.

Holocrine cell fills with

product and whole cell is shed to release products, cell division must replace lost cells (e.g. sebaceous glands of scalp-oil glands)

Endocrine glands of the epithelial tissue secrete their

product into the blood stream and lack a duct.

Epithelial tissue can be broken down into two things, the...

proper epithelium and the glandular epithelium

Epithelial tissue functions to

protect your deeper layers of tissue from injury or infections.

epithelial tissue regenerates really

quickly.

Acinar

rounded sac-like secretory portion

Glands derived from epithelia tissue are primarily responsible for

secretion or excretion

many of these boundaries that epithelium cells form aren't absolute--instead they're

selectively permeable

The basement membrane is visible with the light microscope particularly when

silver impregnation or the PAS (periodic acid schiff stain-stains the carbohydrates) methods are used.

Type of exocrine glands

simple, compound, or the combination of the two--tubuloacinar

Simple squamous epithelium tissue refers to a

single layer of flat, scale-like cells, like lining of the air sacs deep in your lungs.

it takes many layers of the ___ cells to form a tissue thats thick enough to offer protection

squamous

there are three basic shapes of epithelium tissue

squamous, cuboidal, and columnar

Epithelia typically make up part of the

stoma but in the case of glands, epithelia can make up parenchyma.

The epithelial cells are nourished by

substances diffusing from blood vessels in the underlying connective tissue.

some examples of exocrine secretions would be

sweat, saliva, mucus, stomach acid, and milk if your lactating.

Exocrine glands secrete

their juices into tubes or ducts that lead to the outside of the body or the inside of your tube, rather than right into the blood.

Epithelial tissues

this tissue lines and covers and generally organizes your body.

Stratified Squamous epithelium are

tissues formed from multiple layers of cells resting on a basement membrane, with the superficial layer(s) consisting of squamous cells.

simple and compound glands can be classified into two groups

tubular glands and Acinar glands

glands from the epithelia tissue may be

unicellular or more complex multicellular structures with supporting connective tissue

serous

watery unglycosylated protein product. cells have lots of rough ER and Golgi and stain darkly

flagellum is much longer than cilia and moves in a

whip like motion

primary epithelium protects

your whole body, inside and out