Adv Human Anatomy and Histology (OPTO5233) Midterm 1

most common stain used in histology and pathology

hematoxylin/haematoxylin and eosin stain

hematoxylin staining pattern

stains cell nuclei blue

also stains rough ER, ribosomes, collagen, myelin, elastic fibers, and acid mucins

eosin staining pattern

stains cytoplasm pink

also stains collagen

hydrophobic structures in stains tend to remain?

clear

structures rich in lipids

epithelial tissues

sheets of cells lining internal or external surfaces of the body

form interface between biological compartments

rapid renewal

two types of epithelia

surface epithelia and solid organs

functions of epithelial tissues

barrier/protection

absorption/diffusion

transport across epithelial layers

synthesis and secretion

apical/basal domains are a part of what basic characteristic of epithelia

polarity

apical surface

exposed to outside

basal side attaches to?

attached to underlying basement membrane

lateral surfaces are attached to ?

other epithelial cells

Basement membrane characteristics

thin sheet-like ECM

attaching/anchoring epithelial and endothelial cells to underlying connective tissue

bi-layered

thickness and permeabiltity of BM depends on

location and function of surface epithelia

presence/absence of disease

epithelial cells depend on diffusion from

supporting tissues

blood vessels never transverse the BM

keratins basic characteristics

expressed solely by epithelial cells

intermediate filament proteins

make up cytoskeleton of epithelial cells

anchor desmosomes and hemidesmosomes

basic properties of epithelial cells (STAR)

cover/line body surfaces, cavities, and tubes

polarized cells

have a basement membrane

express the intermediate filament keratin

have specialized cell-cell junctions

simple epithelia

1 layer of cells

involved in diffusion, absorption and/or secretion, provides no support to abrasion

stratified epithelia

two or more layers of cells

protective function

squamous cells

thin, flat cells that look like fish scales

cuboidal cells

square from the side

polygonal from the top

nucleus in the center of the cell

columnar cells

tall from the side

polygonal from the top

nuclei are located towards the base of the cell

can present microvilli or cilia

simple squamous epithelium morphology

single layer with little cytoplasm

tightly packed, interdigitations

simple squamous epithelium function

fluid transport

nutrient exchange

gaseous exchange

simple squamous epithelium location

lining of blood and lymph conduits

pulmonary alveoli

body cavity membranes

kidney

simple cuboidal epithelium morphology

single layer

square from the side

polygon from the top

centrally located nucleus

simple cuboidal epithelium function

secretion and absorption

simple cuboidal epithelium location

kidney tubules

mammary tubules

sweat gland ducts

simple columnar epithelium morphology

single layer

rectangular from the side

polygon from the top

variable height based on metabolic rate

nuclei often aligned

simple columnar epithelium function

absorption and secretion

simple columnar epithelium location

small intestine

large intestine

gall bladder

stomach

simple columnar epithelium with cilia

simple columnar and apical cilia

conduction/transport, absorption, and secretory

female reproductive tract and bronchi/bronchioles

ONLY IN COLUMNAR

stratified squamous epithelium morphology

flattened superficial cells

+/- keratinization

stratified squamous epithelium function

protection

resistance to friction/forces

SSK impermeable and extra protection

stratified squamous epithelium location

mouth (SSNK) may have areas with SSK

esophagus (SSNK)

cornea (SSNK)

vagina (SSNK)

epidermis (SSNK)

stratified cuboidal epithelium morphology

multi-layered cuboidal

stratified cuboidal epithelium function

transport

absorption/secretion

stratified cuboidal epithelium location

salivary glands

sweat glands

Pseudostratified Columnar Epithelium morphology

pseudo-multilayered and columnar-shaped

nuclei not aligned

typically ciliated

pseudostratified columnar epithelium function

conduction

protection

secretion

pseudostratified columnar epithelium location

respiratory tract

transitional epithelium morphology

stratified

cuboidal (non-distended) to squamous (distended)

superficial layer of cells are large and rounded, may have 2 nuclei

transitional epithelium function

protection - waterproof

distention - expansive

transitional epithelium location

urinary tract

endothelium

simple squamous epithelial like cells

single layer of flattened cells

attached to a basement membrane

corneal endothelium

hexagonal shaped from the top

transport of nutrients into avascular cornea

two cornea layers consist of what type of cells

top layer of stratified squamous

bottom layer of simple squamous

bullous keratopathy

corneal clouding due to edema in the stroma of the cornea

loss of transparency

edema in bullous keratopathy is due to the failure of which corneal layer

endothelium fails to maintain the normally dehydrated state of the cornea

bullous keratopathy treatment

topical dehydrating agents

IOP lowering agents

occasional short-term use of therapeutic soft CLs

corneal transplantation (curative)

specializations of the epithelium

cilia, microvilli, and stereocilia

adhering/communicating junctions

adhering junctions

common cell junctions

tight/occluding junctions

zonular adherens

desmosome

hemidesmosome

communicating junctions

tight junctions

along the apical/luminar border

forms selective barrier; paracellular diffusion

enables epithelium to protect underlying tissues

necessary for polarity

fluorescein staining process

add fluorescein to a healthy ocular surface

wash away excess

add to ocular surface damaged tight junctions

wash away excess; staining remains

adherens and adhering belt

membrane to membrane; epithelial cells to each other at actin cytoskeleton

just below tight junctions

zonula adherens form a continous belt around the cell

strong mechanical adhesion

desmosomes

connect neighboring epithelial cells to each other forming plaques between cells

anchor epithelial cells to intermediate filamentous cytoskeleton - keratin

strong cohesive epithelium; common in more stressful areas

hemidesmosomes

anchor epithelia to the basal lamina of the basement membrane

linked to intermediate filaments (keratin) within the cytoplasm

communicating junctions

gap junctions made of connexins that form a channel between adjacent cells

cell-cell communication and permit small molecules to pass between cells

epithelial basement membrane dystrophy

defective corneal BM / redundant BM

leads to poor epithelial adhesion, epithelial inclusion cysts

thickened BM and redundant epithelium

reccurent corneal erosion

repeated breaks in the corneal epithelium

caused by abnormal adhesion to the underlying basal lamina

ocular pain, blurred vision, tearing, photophobia

etiology of trauma, genetics, and other conditions

tx objectives for RCE

relief of symptoms

epithelial integrity

prevent infection

reduce recurrence - preservative free lubricant

tx options for RCE

hyperosmotics

lubricants

bandage contact lens for wound healing

anterior stromal micropuncture

photoablation (PTK/PRK) for redudant BM

debridement

microvilli

small finger-like projections on the luminal side of epithelia

shorter and narrower than cilia

core contains actin filaments, contractile

rich glycocalyx

microvilli specialization

absorption

brush border of small intestine

increase surface area (30x)

what type of cells in the corneal epithelium contain microvilli and why

superficial cells

increases SA for anchoring of the tear film via rich mucin glycocalyx

corneal hydration

friction prevention btwn eyelid and corneal epithelium

Cilia

long motile hairlike projections

beat in rhythmic pattern

purpose of cilia rhythmic movement

allows for propelling surface mucus, fluids for unidirectional movement

where is cilia found in the body

respiratory tract and female reproductive tract

glands overview

originate from epithelial cells after invagination into the underlying tissue

endocrine and exocrine

exocrine glands

produce secretions that enter ducts and land onto an epithelial surface

eventually break off

endocrine glands

deposit secretions directly into bloodstream

may have mutltiple types of secretion

act on distant targets

thyroid, parathyroid, adrenal, pituitary, gonads, pancreas

exocrine secretion types

merocrine (eccrine)

apocrine

holocrine

merocrine (eccrine) secretion

most common

involves exocytosis; only secretory component is released

mostly protein products

none of cell lost in secretion

apocrine secretion

membrane bound vesicles released apically

usually lipid products

breast and some sweat glands

pinched off secretion with some cell lost

holocrine secretion

disintegration of cells to release lipid products

sebaceous glands mainly

apoptosis leads to contents being released and the entire cell disintegrates

merocrine/eccrine sweat glands

associated with thermoregulation

contains secretory/acinar cells, ductal cells, myoepithelial/basket cells

sweat, salivary, and lacrimal glands

apocrine glands

associated with thermoregulation, scent production, territory marking, sexual attractant

axillary and groin regions and mammary glands

contains secretory/acinar cells, ductal cells, myoepithelial/basket cells

holocrine sebaceous glands

usually associated with hair follicle (1/3 depth)

sebum for waterproofing and lubrication

may be independent of follicle in areas like the eyelids, aerola, labia, and vulva

constant cell proliferation with bursting cells near the top

goblet cells

modified columnar epithelial cells

unicellular

synthesize and secrete mucus

scattered throughout many epithelial tissue linings like the respiratory tract, ocular conjunctiva, digestive tract

protective function

connective tissue

tissue found between and/or surrounding all other tissues

found everywhere in the body; most abundant

connetive tissue characteristics

general structure to tissues and organs

mechanical strength and protection

metabolic support

tissue defense

macrophages and mast cells resident cells

connective tissue examples

dermis and hypodermis of skin

meninges of the brain and spinal cord

organ capsules

skull

blood and lymph

ECM of connective tissue

fibers (elastic and collagenous fibers)

ground substance (gel-like substance, GAGs, PGs)

supporting cells

collagen fibers

tensile strength that provides resistance to tissues

elastic fibers

elasticity that allows distortion of tissues

ground substance

amorphous, gel-like component of ECM

surrounds cells, collagen, and elastic fibers

volume filling that provides cushioning and support

type 1 collagen

most abundant in dermis, ligaments, bone, cornea

type 2 collagen

hyaline cartilage, vitreous humor

type 3 collagen

reticular collagen, forms meshwork in highly cellular organs (liver, spleen, kidney)

type 4 collagen

major component of basement membranes

ehlers danlos syndrome

disorder of fibrillar collagen caused by mutations in collagen genes

joint hypermobility, skin hyperextensibility, tissue fragility

how ehlers danlos affects the eye

corneal thinning due to cornea not being well adapted to pulling forces anymore

unusual corneal curvature

brittle cornea syndrome

high myopia

blue sclera

DE or ptosis

strabismus

conjunctival hemorrhage

elastin

has ability to stretch and return to the original state

thinner fibers and not as strong as collagen

wavelike strands of collagen and elastic fibers

makes tissue flexible and resistant to stretching

marfan syndrome

genetic disorder affecting elastin biosynthesis

tall and thin, long limbs

highly flexible joints and scoliosis

heart issues

marfan syndrome ocular manifestations

lens dislocation due to weakness of ciliary zonules

risk for early glaucoma and early cataracts

high myopia and blurred vision

corneal flatness

main component of ground substance

GAGs

Glycosaminoglycans (GAGs)

linear polysaccharide composed of repeating disaccharide units

some contain sulfate groups

GAGs and water provide

gel-like cushioning due to the ability to hold in water

resident cells in connective tissue

fibroblasts

chondroblasts and chondrocytes

osteoblasts and osteocytes

adipocytes

mast cells and macrophages

immigrant cells in connective tissue

neutrophils, monocytes, lymphocytes