Exam 1: Epithelium Flashcards
Mesothelium develops from
Mesoderm
Endothelium develops from
Endoderm
Epithelium develops from
Ectoderm
3 general functions of epithelium
Absorption
Secretion
Provide barrier
Specialized functions of epithelium
Transport moleclues
Prevent transport (selective permeability)
Sensory
5 basic characteristics
- Cells adjacent
- Basement membrane
- Avascular
- Vascular connective tissue
- Cell junctions
Complete basement membrane parts
Basal lamina
Reticular lamina
Basal lamina produced by
Epithelium
Reticular lamina produced by
Fibroblasts in connective tissue
Partial basement consists of
Basal lamina ONLY
Functions of basement membrane
- Surface for epithelial attachment
- Molecular filter
- Limits stretch
- Directs migration of cells
How do cells obtain nutrition
Diffusion
Functions of vascular connective tissue
Provides nutrition
Source of defensive cells
Zonula occludens AKA
Tight junction
These junctions involve sharing of intrinsic membrane proteins between adjacent cells
Zonula occludens
Examples of interacting proteins
Claudins
Occludins
Tight junctions are always located at
Apex
2 functions of zonula occludens
Provides strong attachment
Prevent passage of materials btw cells
Zonula adherens AKA
Adhesion belt
Zonula adherens are regions consisting of
Cadherins and marginal bands
Marginal bands
Attach cytoskeleton to cell membrane
Cadherins are
Linkage proteins between cells
Two functions of adhesion belts
Strong attachment
Provide cell structural stability
Macula adherens AKA
Desmosome
Functions of macula adherens
Provides strong attachment
3 major parts of desmosome
- Cytoplasmic plaque
- Transmembrane proteins
- Tonofilaments
Gap junctions consists of
6 connexins arranges in a cylinder
The size of the opening of a gap junctions is controlled by
The cell
Connexon
1 complete structure (6 connexins)
2 functions of gap junctions
Strong attachment
Transport materials btw cells
Junctional complex in order starting w/ free surface
Zonula occludens
Zonula adherens
Macula adherens
What structure will help to limit epithelial cell stretch
Basement membrane
What tissue is always associated w/ epithelium
Connective tissue
Cell junction consists of protein plaque, transmembrane proteins and tonofilaments
Macula adherens
Bullous pemphigoid
Autoimmune skin disease
Large blister lesions, DO heal
Cause of bullous pemphigoid
Antibodies to proteins in hemidesmosomes
Pemphigus vulgaris
Autoimmune skin disease
Skin blistering that DO NOT heal
Excessive bleeding likely
Cause of pemphigus vulgaris
Antibodies bind to desmosomes
Cholera
Acute bacterial infection of SI
Cause of cholera
Toxins disrupt zonula occludens
Permit loss of water and electrolytes from CT below epithelium
Simple epithelium
Single cell thick
Squamous
Flat cells
Example locations of simple squamous epi
Lung
Parietal layer Bowman’s capsule in kidney
Serosa on outside of organs
Functions of simple squamous epi
Living filter
Provide barrier
Secretion
Example locations of simple cuboidal epi
Exocrine ducts
Thyroid follicular cells
Prox and distal convoluted kidney tubules
Simple cuboidal epi functions
Absorption
Secretion
Provide barrier
Example locations of simple columnar epi
Stomach
SI
Gallbladder
Larger exocrine ducts
Functions of simple columnar epi
Absorption
Secretion
Provide barrier
Ciliated pseudostratified columnar epi AKA
Respiratory epi
Example locations of respiratory epi
Trachea
Bronchi
Respiratory region of nasal cavity
Function of respiratory epi
Catch and move something over the surface
Goblet cells
Modified columnar cell
Function of Goblet cells
Produce mucus
Cilia is anchored by
Basal bodies
Function of ciliated columnar cells
Move mucus over the surface
Basal cells
Short cells
Do not reach surface
Function of basal cells
To be stem cell
Divide and change into another cell type
Microvilli AKA
Brush border
Striated border
Microvilli
Finger-like projections on apical surface
Inc surface area to inc absorption
Example locations of microvilli
Kidney tubule cells
SI
Stereocilia
Extremely long microvilli
Increase surface area
Stereocilia compared to microvilli
Less motile
Rigid w/ actin core
Example locations of stereocilia
Epididymis
Cochlear hair cells
Cilia
Thin apical hair-like extensions of cytoskeleton
Two points about cells w/ cilia
Cell have many mitochondria
Basal bodies block free surface so there is NO absorption or secretion
Example locations of cilia
Trachea
Oviduct
Glycocalyx
Surface layer of glycoproteins and carbs
Protection and cell recognition
Example locations of glycocalyx
Stomach and SI
Stratified epithelium
Two or more cell layers thick
Named for shape of superficial cells
Example locations Stratified squamous epi
Esophagus
Oral cavity
Tongue
Vagina
Stratified squamous general function
Protection from abrasion in moist environment
Limitations of stratified squamous epi
No protection from drying
Protection is limited
Example location Keratinized stratified squamous
Skin
Function of keratinized strat squamous dpi
Protection in dry environment
Layers in epi of skin
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
3 gen functions of stratum corneum
Prevent water loss
Barrier to microbes
Protects against abrasion
Epi cells types in keratinized strat squamous epi
Keratinocytes
Melanocytes
Langerhans
Merkel
Keratinocytes
Divide in stratum basale
Produce keratins
Produce lipids in stratum granulosum
Melanocytes found in
Stratum basale
General functions of melanocytes
Protect from UV radiation
Determine skin color
Eumelanin
Darker
Pheomelanin
Reddish
Langerhans cells
Antigen presenting cells (APC)
Found in stratum spinosum
Merkel cells found in
Stratum basale
Merkel cells associated w/
Free nerve endings
Touch receptors
Cell type in stratum corneum
none (all dead)
Example locations Stratified cuboidal
Larger ducts in sweat and salivary glands
Strat cuboidal epi functions
Increase protection
Barrier
Example locations Strat columnar epi
Pancreatic ducts
Male urethra
Conjunctiva
Strat columnar epi functions
Increase protection
Transition between epi types
Barrier
Transitional epi AKA
Urothelium
Example locations of transitional epi
Most of urinary tract
Function of transitional epi
Protection
Stretch
Barrier
Specializations of transitional epi
Thin, fenestrated BM
Large, rounded superficial cells
Well-developed zonula occludens
Psoriasis vulgaris appears as
Patchy skin lesions
Psoriasis vulgaris effect in dermal papillae
Inflammation
Psoriasis effect on cell cycle
Keratinocytes life cycle is sped up (~1 week)
Cells accumulate here in psoriasis vulgaris
Stratum corneum
Freckles result from an
Increase in the amount of melanin without an increase in melanocytes
Freckles
Skin spots with extra pigment that fade in the winter and darken with sun exposure
Vitiligo appear as
Patches without melanocytes (lighter than the skin)
Cause of Vitiligo
Unknown but associated with system diseases such as hypothyroidism, hyperthyroidism, diabetes, Addison’s disease, pernicious anemia, and leprosy
Moles (naevi)
Discoloration due to a proliferation of melanocytes
Characteristics of Malignant Melanoma
Occur when melanocytes become mitotically active and invade the dermis. Very invasive and metastatic
Treatment for malignant melanoma
Surgery and chemotherapy
Cause of Albinism
Melanocytes don’t produce melanin
Common form of albinism
The tyrosinase enzyme is missing from the melanocytes
Tyrosinase catalyzes the conversion of tyrosine to melanin
Exocrine secretion
Product is released into a duct or directly onto an epithelial surface
Parenchyma
Parts involved with primary function
Ex: Biceps brachii- skeletal muscle cells
Storms
Parts providing mechanical or metabolic support
Ex: biceps brachii- CT, nerves, lymphatics, and blood vessels
3 methods of exercise exocrine secretion
Merocrine, holocrine, apocrine
Morphology of exocrine secretion
Classifying exocrine glands by the shape of the secretory units and duct arrangement
Merocrine AKA
Eccrine
Merocrine examples
- Goblet cells
- Salivary glands
- Pancreas
- All sweat glands in children
- Many adult sweat glands
Merocrine secretion
Most common method of secretion. No cell damaged with secretion
Examples of holocrine secretion
- Sebaceous glands
2. Tarsal (meibomian) glands of eyelid
Holocrine secretion
Cell matures and dies
The entire cell secretes with in-tact vacuoles
Associated with odor
Apocrine gland examples
- Lactating mammary glands
- Adult pubic and auxiliary sweat glands
- Ceremonious glands in EAC
- Ciliary glands in eyelid
Apocrine gland secretion
Minimal cell damage
Some cytoplasm, membrane, and in-tact vacuoles are secreted
Associated with odor
Acinus
Smallest division of gland
Group of cells surrounding cavity
Serous demilune
Small group of serous cells attached to mucus acinus
Myoepithelial cells
Contractile cells
Wrap around acini
Myoepithelial cell locations
Salivary/sweat glands
Lacrimal glands
Lactating mammary glands
Myoepithelial cell function
Assist secretion
Serous glands produce
Proteins
Examples of serous glands
Pancreas
Parotid gland
Chief cells in stomach
Mucus gland examples
Goblet cells
Cells in stomach
Minor salivary glands
Mucus gland characteristics
Cells stain light
Nucleus flat and peripheral
Mixed glands produce
Serous and mucus
Mixed glands examples
Sublingual and submandibular salivary glands
Mixed glands, ______ are possible
Serous demilunes
Exocrine regulation
Myoepithelial cells
Hormones
Blood supply
Increase blood will _____ O2 which will ______ secretion
Increase; increase
Decrease blood will _____ O2 which will _____ secretion
Decrease; decrease