Histology block 2

What is a tissue?

An aggregation of cells and extracellular substances

What are the 3 main types of epithelia?

-Lining epithelia

-Glandular epithelia

-special epithelia

What is lining epithelia?

Epithelia that form sheets that cover body surfaces or line luminal organs,tubular structures and body cavities

What is glandular epithelia?

Epithelia with specialized cells that synthesize,store and release various products

What is special epithelia?

Epithelia containing nerve endings

Where is special epithelia found?

Skin,ears and on tounge

What is the origin/Histogenesis of epithelia?

Epithelium arises from all 3 germ layers (ectoderm,mesoderm and endoderm)

What epithelium arises from ectoderm?

Epidermis of skin

what epithelium arises from mesoderm?

Mesothelium and endothelium

What epithelium arises from endoderm?

Lining and glands of GI tract,lining of respirtory system, and the urinary bladder

What are 7 functions of epithelial tissues?

-Protection

-friction reduction

-cleaning

-diffusion

-absorption

-secretion

-sensation

Epithelium is a tissue with ___ cellular density and very little ____ _____

high

intercellular substance

Describe lining epithelium

-avascular

-few nerve endings

What is ex of tissue with low cellular density?

connective tissue

What does it mean that epithelial cells are polarized?

They have an apical surface,lateral surfaces and basal surface

Where are epithelial cells anchored?

to the basal lamina

What use to stain basement membrane?

PAS

What provides epitheliums cohesiveness?

Cell junctions

What form epitheliums cell junctions?

Transmembrane glycoproteins (E-cadherins)

What are the 4 types of intracellular junctions in epithelium and their location?

Tight junctions-lateral side

Desmosomes-lateral side

Gap junctions-lateral side

hemidesmosome-basal side

tight junction function?

impermeable

desmosome function?

anchor adjacent cells like velcro

gap junction function?

communication

What are the 2 subtypes of squamous epithelium?

non-karatinized and keratinized

what are the 2 types of glands?

exocrine and endocrine

To determine epithelial cell shape what look at?

Top layer when stratified

Describe pseudostratified epithelium?

all cells touch basement membrane but nuclei arent all on same level

What are 3 common locations for simple squamous epithelium?

-Mesothelium

-Endothelium

-Alveolar walls

What are 4 ex of simple cuboidal epithelium?

-lining ducts of glands

-choroid plexus of brain

-follicles of thyroid

-lens of eye

What is 5 examples of simple columnar epithelium?

-luminal surfae of stomach

-luminal surface of small and large intesitne

-luminal surface of gall bladder

-lining uterus

-lining uterine tube

What do psudostratified epithelium usually posses?

cilia or stereocilia

What is 4 examples of where find pseudostratified epithelium?

-nasal cavity

-upper respiratory tract

-epididymis

-ductus defrens

How to tell if cell is karatinized?

cells on surface lost their nuclei

What alos call transitional epithelium?

urothelium

What is special about transitional epithelium superficial cells?

have specialized plasma membrane providing an osmotic barrier

How does transitional epithelium differ when bladder full vs empty?

full the transitional epithelium is stretched and when empty transitional epithelium looks thicker

What direction does epithelium repair in?

bottom to top

What cells form new epithelial cells? where located?

stem cells

-located in basal cell layer

What are the 4 criteria of classification for grandular epithelia?

-number of cells in gland (uni vs multicellular)

-shape of duct and adenomeres

-type of product

-mode of secretion

what call a gland secretory unit?

an adenomere

Where are unicellular glands found?

epithelial lining of intestine and respiratory tract

whats an example of a unicellular gland?

goblet cell

What used to stain mucinogen granules blue in goblet cells?

alcian blue

What are the 2 types of multicellular glands?

-exocrine

-endocrine

What is main difference between exocrine and endocrine glands?

endocrine-use no duct by secrete into blood

exocrine-use duct to secrete onto body surface or internal cavity

What are the 2 types of ducts?describe

-simple:one opening

-compound:many branches

What are the 3 types of adenomeres? describe

-tubular:straight or coiled tube

-acinar: pie shaped with small lumen

-alveolar:cricular with large luminal space

What is a myoepithelial cell?

contractile cells associated with salivary,mammary and sweat glands

What call the collection of secretory units and ducts of a compound gland?

parenchyma

What do CT elements comprise in compound gland?

stroma

Large glands are divided into ___

lobes

Lobes are subdivided into ____

lobules

Lobule with multiple adenomeres drains into which type of duct?

intralobular duct

Where do interlobular ducts arise from and where do they lead to?

Arise from between lobules and lead to a lobar duct

What is the order a secretion goes through when leaving adenomere?

Intralobulr duct to interlobular duct to lobar duct to main duct

What are the 4 classification of ducts according to product? describe each

Serous:watery product that contain enzymes

mucous:slick,viscous secretion

mixed:gland produces both mucus and serous secretion

sebaceous:oily secretion known as sebum

What is a subtype of a serous gland? describe

cerumen:the secretion of a modified sweat gland in the skin of the external ear canal

Are mucinogen granules detectable with routine stains?

no

What is a mixed gland?

Mucous and serous cells sharing a common duct system

What are the 2 classifications of glands based on the mode of secretion?

Exocrine and endocrine

What is endocrine mode of secretion?

secrete hormone directly into blood without duct

What are the 3 modes of exocrine secretion? describe

merocrine:produces product and pushes it out into duct

apocrine: apex of cell buldges off into duct

halocrine:cell dies and becomes the secretion into duct

Does connective tissue have low or high cellular density?

low

What is connective tissue?

Tissue mad eup of few cells with no polarity that are loosely embedded in a complete well vascularized extracellular matrix

What is main cell of connective tissue? shape?

Fibroblast

-spindle

What is the embryological origin of connective tissue?

mesenchyme from mesoderm

What is mesenchyme?

embryonic connective tissue

is blood connective tissue?

yes

is bone connective tissue?

yes

What are 6 functions of connective tissue?

-connect other tissues

-gives form and subdivides organs

-gives physical support to body

-thermoregulation

-nutrition and storage

-defense and repair mechanisms

What are the 3 components of connective tissue?

-cells

-fibers

-extracellular matrix

What fibers found in CT?

-collagen

-elastic

-reticular

-others (fibronectin and laminin)

What are the resident cells of CT?

-fibroblasts

-reticular cells

-adipocytes

-macrophages

-mast cells

what is fibroblast function?

synthesize collagen,elastic and reticular fibers

what are reticular cells?

special fibroblasts that synthesize a a fine type of collagen fiber called reticular fibers that offer scaffolding to parenchyma

what are adipocytes specialized in?

depositing lipids

what are the 2 types adipocytes can be?

unilobular-white fat

multilobular-brown fat

What stain can stain fat?

sudan red

Macrophage function in CT?

Pgagocytosis

what call macrophages in liver?

kuppfer cells

what are mast cells involved in?

inflammation and allergies

what do mast cells granules conatin?

histamine

What are the transient CT cells?

white blood cells

what is the most numerous CT fiber type?

collagen

What color are collagen?

white

What is collagen function?

tensile strength

Where often see lots of collagen fibers?

tendons,t unica albuginea and sclera of eye

What is the most abundant protein in body?

collagen

How is collagen formed?

Fibroblast form inside itself procollagen which is then transported outside of cell and assembled into collagen fibrils

what is an important cofactor in collagen synthesis?

vitamin c

what are the 4 main collagen types? where found and function?

1-skin,bone,dentin,tendons,fibrocatilage; resists tensile force

2-cartilage; resists compression

3-reticular fibers in stroma of expandable organs

4-basal lamina

what happens if collagen isnt properly synthesized?

fragile skin syndromes

what stains to stain elastic fibers?

resorcin-fuchsin

orcein

what color is elastic fibers grossly?

pale yellow

where elastic fibers found?

aorta

lungs

vocal cords

dermis

ear pinna

epiglottis

what stain reticular fibers with?

silver

function of reticular fibers?

scaffolding

what are reticular fibers synthesized by?

reticular cells

liver cells

smooth muscle cells

skeletal muscle cells

What is extracellular matrix of CT made up of?

ground substance

What is ground substance produced by?

resident CT cells