epithelial tissue - glands Flashcards
what is a tissue
an aggregation of cells and an extracellular matrix that has a common origin in the development of an individual
what is an intercellular substance
cumulative product of the activity of cells of the tissue
what are postcellular structures
derivatives of cells which have lost major signs and characteristics of cells
what are symplasts
results of cell fusion with loss of their borders and formation uniform cytoplasm mass in which their are nuclei
what are syncytium
result of incomplete cytotomia at cell division
what is epithelial tissue
covers body surfaces and organs, lines body cavities
what is connective tissue
binds and supports body parts
what is muscular tissue
contracts producing movement
what is nervous tissue
responds to stimuli and transmits nerve impulses
where is epithelial tissue found
- covering and lining type
- glandular tissue
- some sensory organs
what is the function of epithelial tissue
- protection
- absorption
- filtration/ excretion
- secretion
- transport
- resorption
- covering
what are the morphological features of epithelial tissue
- cells closely packed together
- intracellular substance minimum
- rest on basement membrane
- no blood vessels - avascular
- intercellular junctions
- high regeneration ability
- exhibit functional and morphologic polarity
- cytoskeleton contain cytokeratin intermediate fibres
what are the 3 surfaces (domains) of epithelial tissue
- apical
- basal
- lateral
what does apical domain do
structure surface modifications to carry out specific functions
what modifications do the apical domain do
microvilli - cytoplasmic processes containing core actin filaments
stereocilia - branched and longer than microvilli
cilia - cytoplasmic processes containing bundles of microtubules
what is the base of microvilli made from
actin microfilaments coupled with villin
what are microvilli covered by
layer of glycoproteins and glycolipids (glycocalyx) - some contain digestive enzymes
where are microvillous boarders found
- small intestine
- gallbladder
- proximal cavity of nephron
where are stereocilia found
testicular duct, initial part of seminal duct, hair cells of inner ears
where are cilia / kinocilia found
pseudostratified columnar epithelium of the nasal cavity,
trachea and bronchi, simple columnar epithelium of the fallopian
tube, efferent ductules of testis
what is the structure of cillia
axoneme and basal body
what are basal striations
numerous infoldinfgs of the basolateral membrane
aligned with numerous mitochondria
radiate towards the nucleus
what is basal lamina
product of epithelial cells containing collagen (IV), glycoproteins and proteoglycans
what is the clear and dense layer of basal lamina
clear - inner lamina Lucida
dense - outer lamina densa
what is reticular lamina
product of subepithelial CT cells
consists of mainly reticular, type 3 collagen fibres
what are the functions of the basement membrane
- mechanical reinforcement using hemidesmosomes
- selective barrier
- prevents spread of epithelial tumour cells into connective tissue
how does the basement barrier become a selective barrier
- filtration of blood in renal glomeruli
- alveolocapillary membrane in lungs
- blood brain barrier
what is an adhesive/ anchoring junction
tie adjacent cells mechanically together
what are the subtypes of adhesive cell junctions
- demosome
- adhesive belt
- fascia adherens/ adhesive strips
- hemidesmosomes
what are occluding/ tight/ zonula occludens junctions
seal adjacent cell membranes with each other to
create barrier for movement of material through
interval between the cells.
what are gap junctions/ communicating junctions
permit transport of substances across cells
what are covering epithelia classified according to
- number of layers
- shape of cell in the surface layer
what is simple epithelia
one layer
what is stratified epithelia
more than one layer
what is squamous epithelia
flattened shape
what is cuboidal epithelia
cube shape
what is columnar epithelia
column like
what are the types of simple epithelial
- squamous
- cuboidal
- columnar
- pseudostrified
what are the subtypes of simple squamous epithelium
- endothelium - blood vessels
- mesothelium - body cavities
what is the functions of simple squamous
- diffusion
- filtration or secretion
where is simple cuboidal epithelium found
- glands and ducts
- wells of kidney tubules
- covers the ovaries
what is the function of simple cuboidal epithelial
recreation and absorption
what is simple columnar epithelium
- tall cells
- often contain microvilli
where is simple columnar epithelium found
lines digestive tract - large and small intestine and stomach
what is the function of simple columnar epithelium
secretion and absorption
what is pseudostratified columnar ciliated epithelium
- single layer
- all cells rest on basement
- nuclei appear at different layers
where is pseudostratified columnar ciliated epithelium found
- respiratory tract
- male and female reproductive tract
what is the function of pseudostratified columnar ciliated epithelium
- absorption
- secretion
- filtration
what are the 3 main types of stratified epithelium
- keratinased
- non-keratinased
- transitional
what are the subgroups of non-keratinised epithelial tissue
- squamos
- cuboidal
- columnar
what is Stratified squamous keratinased
- multiple laters of cells
- cells at apical surface are flattened and dead
- keratin has very good protective properties
what is the location and function of Stratified squamous keratinased
- protection
- epidermis of the skin
what is Stratified squamous non-keratinised
- multiple layers of cells
- cells at the apical surface are flattened but without keratinisation are still alive
what is the location and function of Stratified squamous non-keratinised
- oral cavity
- esophagus
- cornea
- vagina
- protection
where is Transitional epithelium (urothelium) found and what is its function
- lines organs of urinary tract - ureter and urinary bladder
- stretching and the ability to return to normal shape
what is stratified cuboidal epithelium
- two layers of cuboidal cells
- protection
what is stratified columnar epithelium
- surface cells are columnar but cells underneath vary in size
- protection
what are exocrine glands
secrete their products via ducts onto apical surface
what are endocrine glands
release secretion directly into lymph or blood vessels, have no ducts
what is the secretory cycle
1) phase of absorption - substrates come from blood through plasmeolemma of basal pole of glandular cell
2) phase of synthesis - processes of formation new product
3) phase of accumulation of the synthesised product - increase of maintenance of secretary granules
4) phase of extrusion of secretion - exocytosis of secrete
what is merocrine
during secretion no part of the cell is lost, only sectors product is expelled via exocytosis
what is apocrine
synthesise secretory product and accumulate in apical portion, cells are shed off
what is holocrine
while discharging secretions, entire cell disintegrated and undergoes programmed cell death on maturation
what are the parts of exocrine glands
- secretory portion
- duct
what are unicellular glands
goblet cells, mucus secreting cells
what are multicellular glands
consist of many cells
what are mucous glands
contain mucous secreting cells
- lingual and goblet cells
what are serous glands
contain only serous cells
- parotid gland and pancreas
what are mixed glands
contain both mucous and serous secretion
- submandibular and sublingual salivary glands
what is a simple exocrine gland
1 duct
what is a complex exocrine gland
more than 1 duct
what are the simple types of exocrine glands
- tubular
- coiled tubular
- branched alveolar
what are the types of compound glands
- tubular
- alveolar
what are unbranched exocrine glands
1 secretory portion connected with 1 duct
what are branched exocrine glands
1 duct connected with several secretory proteins
what are the shapes of secretory portions of exocrine glands
- tubular
- alveolar
- tubulo-alveolar
why does metaplasia happen
adaptive response to stress, chronic inflammation or other abnormal stimuli
what is metaplasia
reversible conversion of one mature epithelial cell type to another mature epithelial cell type
what is the most common form of epithelial metaplasia
columnar to squamous and occurs in glandular epithelium
what is an adenoma
benign tumour of epithelial tissue within glandular origin
