Exam 1: Ch.1 Epithelium and Epithelial Glands Flashcards
What are the four basic types of tissues?
- Epithelial
- Connective
- Nervous
- Muscle
What are the three general functions of epithelium?
- Absorption
- Secretion
- Provide a barrier
What are the three specialized functions of epithelium?
- Transport molecules across epithelium
- Selective Permeability = Prevent transport of materials across epi.
- Sensory (ex: taste buds, retina in eye)
What are the 5 basic characteristics of epithelium?
- Cells are adjacent to each other
- Ass. with a complete or partial basement membrane
- Avascular, obtain nutrients by diffusion
- Ass. with vascular CT
- Cells are held together by cell junctions
What are the two parts of a complete basement membrane and what cells are they produced by?
- basal lamina – produced by epithelium cells
2. reticular lamina – produced by fibroblasts in the CT
What does a partial basement membrane include?
basal lamina ONLY
What are the 4 functions of the basement membrane?
- provides a surface for epithelial cell attachment
- molecular filter–very limited
- limits stretch
- directs migration of cells (i.e. during wound healing)
What are the two functions of the CT that epithelium is associated with?
- provides nutrition
2. source of defensive cells (macrophages, neutrophils, etc.)
What are the four types of Cell Junctions?
- Zonula Occludens = tight junctions
- Zonula Adherens = adhesion belt
- Macula Adherens = desmosome
- Gap junctions
What are the junctions that involve the sharing of intrinsic membrane proteins between adjacent cells?
Zonula Occludens = tight junctions
What are the two functions of Zonula Occludens (tight junctions)?
- provides strong attachment
2. prevents the passage of materials between cells
Zonula Adherens (adhesion belt) are regions consisting of what two things?
- cadherins (linkage proteins) b/w cells
2. marginal bands (microfilaments) that attach cytoskeleton to the cell membrane at these areas
What are the two functions of Zonula Adherens (adhesion belts)?
- strong attachment
2. provide cell structural stability
What is the function of Macula aherens (desmosomes)?
provides strong attachment
Gap junctions are ___ connexins (proteins) arranged in an cylinder. The size of the openings can be controlled by the cell. A _____ = 1 complete structure.
six; connexon
What are the two functions of gap junctions?
- strong attachment
2. transport materials b/w cells
List in order from the free cell surface and deep, the Junctional Complex.
- Zonula Occludens
- Zonula Adherens
- Macula Adherens
What help to connect epithelial cells to the basal lamina?
Hemidesmosomes, (essentially, half a desmosome)
What are Focal Point Contacts?
integrin (a transmembrane protein of the cell membrane) binds to structural CT glycoproteins and also connects to cytoskeleton
What two junctions hold the epithelium to the basement membrane and CT below?
- hemidesmosomes
2. Focal Point Contacts
What autoimmune skin disease causes large blistering lesion that burst, but do heal? The cause is due to antibodies binding to parts of hemidesmosomes
Bullous Pemphigoid
What autoimmune skin disease causes skin blistering that does not heal easily and usually has excessive bleeding, and can be fatal? Cause is antibodies binding to parts of desmosomes.
Pemphigus Vulgaris
What is an acute bacterial infection of the SI that is caused by toxins disrupting proteins in the zonula occludens?
Cholera; allows losee of water and electrolytes form CT below epithelium
What are the 4 types of Simple Epithelium?
- Simple Squamous
- Simple Cuboidal
- Simple Columnar
- Ciliated Pseudostratified Columnar Epithelium (Respiratory Epithelium)
~single cell thick
What are the three functions of Simple Squamous epithelium?
- living filter
- provide a barrier
- secretion
What are example locations of Simple Squamous epithelium? (3)
- lung
- parietal layer of Bowman’s capsule in kidney
- serosa on outside of organs
Describe the appearance of simple squamous epithelium.
a single layer of flattened cells
Describe the appearance of simple cuboidal epithelium.
single layer of cube shaped cells
What are the 3 functions of simple cuboidal epithelium?
- absorption
- secretion
- provide a barrier
Where is simple cuboidal epithelium found? (3)
- exocrine ducts
- thyroid follicular cells
- kidney tubules
Describe the appearance of simple columnar epithelium.
single layer of cells that have height
What re the three functions of simple columnar epithelium?
- absorption
- secretion
- provides a barrier
What are some examples of where simple columnar epithelium is found? (4)
- stomach
- SI
- gallbadder
- larger exocrine ducts
Describe the appearance of ciliated pseudostratified columnar epithelium?
= respiratory epithelium
- contains 3 cell types of various height (therefore appear to be stratified, but still considered simple)
What is the function of respiratory epithelium (ciliated pseudostratified columnar epithelium)?
to catch and move something over the surface
What are the three cell types found in respiratory epithelium (ciliated pseudostratified columnar epithelium)?
- Goblet cells
- Ciliated Columnar cells
- Basal cells
What are Goblet cells?
(in respiratory epithelium)
- modified columnar cell
What is the function of goblet cells in respiratory epithelium?
to produce mucin
What are ciliated columnar cells?
(in respiratory epithelium)
columnar cells that contain cilia
How are cilia anchored in ciliated columnar cells of respiratory epithelium?
anchored in the apex of the cell by basal bodies
What is the function of ciliated columnar cells of respiratory epithelium?
to move mucus over the surface
In respiratory epithelium, what are short pyramidal shaped cells that do not reach the surface? What is there function?
Basal cells; to be the stem cell for this type of epithelium
What are the four surface specialization of simple epithelium?
- Microvilli
- stereocilia
- cilia
- glycocalyx
What is another term for brush border or a striated border surface specializaton?
microvilli
What is the function of microvilli?
to increase surface area to increase absorption
Where are microvilli found?
- kidney tubule cells
- small intestine
What are extremely long microvilli that are non-motile and quite rigid with actin core?
stereocilia; fewere than microvilli and not related to true cilia
What is the function of stereocilia?
to increase surface area
What are example locations of stereocilia?
- epididymis
- chochlear hair cells
Describe cilia.
thin apical hair-like extensions of cytoskeleton
part of respiratory epithelium
What is the function of cilia?
to move something over a surface
What are example locations of cilia?
- trachea
- oviduct
What are two points about cells with cilia we should know?
- cells have many mitochondria
2. basal bodies block free surface = so NO absorption or secretion
What is a surface of glycoproteins and carbohydrates that covers some epithelium called? What produces it?
glycocalyx (produced by epithelial cells)
What are the two main functions of glycocalyx?
- protection
- cell recognition
(other fxns– cell adhesion; hold enzymes)
Give two examples of where glycocalyx is located?
- stomach
- SI
What are the 5 types of stratified epithelium?
- Stratified squamous
- Keratinized Stratified Squamous
- Stratified Cuboidal
- Stratified Columnar
- Transitional (Urinary) = Urothelium
Describe stratified epithelium.
epithelium that is two or more cell layers thick; all kinds have a protective function
What locations can stratified squamous epithelium be found? (4)
- esophagus
- oral cavity
- tongue
- vagina
What type of epithelium have multiple layers of cells and the superficial layer of cells are flat and alive?
stratified squamous
What is the function of stratified squamous epithelium?
protection from abrasion in moist env.
What are the two limitations of stratified squamous epithelium?
- no protection from drying (therefore cells need to be in cell env.)
- limited thickness, so protection is limited
What are multiple layers of cells that also tend to flatten basal to superficial layer, and covered by nonliving layer of keratin?
Keratinized stratified squamous
Where is Keratinized stratified squamous located and what is their function?
skin; fxn = protection in a dry env.
What are the 5 possible players of the Keratinized Stratified squamous epithelium (skin)? deepest to superficial
- stratum basale (germinativum)
- stratum spinosum
- stratum granulosum
- stratum lucidum (only in thick skin)
- stratum corneum
Which layer of the skin is 1-2 layers of keratinocytes that are mitotic and closest to the dermis?
stratum basale (germinativum)
Which layer of the skin has multiple layers of “spiny shaped” keratinocytes that produce keratin?
stratum spinosum
Which layer of the skin contains the uppermost 2-5 layers of flattened living keratinocytes that contain flattened, condensed keratohyaline granules and secrete lipids?
stratum granulosum
Which layer of the skin is only found in thick skin, is a thin layer of recently dead or dying keratinocytes?
stratum lucidum (no nucleus or organelles)
Which layer of the skin contains dead cells, keratin and lipids?
stratum corneum
What are the 3 functions of the stratum corneum?
(most superficial layer of skin)
- prevents water loss
- provides barrier to microbes
- protects against abrasion
How long is the life cycle of keratinocytes? In what layer can they divide?
~28 day life cycle
- can divide when in stratum basale
- produces keratins/keratohyaline granules
What is produced by keratinocytes and in what layers of the skin?
- produce keratins/keratohyaline granules (in stratum basale, spinosum, and granulosum)
- produced lipids (in stratum granulosum)
What layer of the skin are melanocytes found in? And what is their function?
stratum basale; fxn to protect against UV radiation
How do melaocytes function?
keratinocytes phagocytize the cytoplasmic tips of melanocytes containing melanosomes with melanin
What are three things that influence skin color
- Env. (increase UV, increase melanocytes and melanin)
- Genetics
- Vascularity of dermis
T/F. Melanocyte numbers are about equal in all humans.
True
What genetic factors can influence skin color?
- Eumelanin (darker) or pheomelanin) reddish
- placement of melanin
- destruction rate of melanin by lysosomes
What layer of skin are Langerhan cells in and what are their function?
stratum spinosum; fxn is to recognize and process external foreign antigens; APC (antigen presenting cells)
What layer of the skin are Merkel cells in? What is another name for them?
stratum basale; also called epithelial tactile cells
What is the function of Merkel cells?
provide touch receptors; ass. with free nerve endings
What type of cell increases when one is exposed to UV light repeatedly? What type of cell decreases?
increase in melanocytes
decrease in langerhan cells
Is there a cause for concern with exposure to UV light decrease Langerhan cells?
yes, factor for skin cancer development; Langerhan cells aid in detecting not wanted cells)
What is the appearance of stratified cuboidal epithelium?
- two layers of cells
- basal layer flattened
- superficial layer cuboid in shape
not common
What are two functions of stratified cuboidal?
- increase protection
2. provide a barrier
What type of epithelium is found in larger ducts in sweat glands and in salivary glands?
stratified cuboidal
Describe stratified columnar epithelium.
- two layers of cells
- basal layer flattened/cuboid
- superficial layer is columnar
very rare*
What are three functions of stratified columnar?
- increase protection
- to provide a transition b/w epithelial types
- provide a barrier
What is the least common type of epithelium?
stratified columnar
What type of epithelium is found in large ducts in pancreas, parts of male urethra, and conjunctiva of the eye?
stratified columnar
What is another name(s) for Transitional epithelium? Describe the appearance.
Urinary epithelium or urothelium
multiple layers of cells
Where is transitional epithelium found?
most of urinary tract
What are three functions of Transitional (Urninary, urothelium)?
- provide protection
- to stretch*
- barrier
What are three specializations of Transitional epithelium?
- thin, fenestrated basement membrane
- large, rounded superficial cells
- well-developed zonula occludens
What is a well developed zonula occcludens important in Transitional epithelium?
- need due to fenestrated basement membrane
2. prevents urine/cellular waste from seeping b/w epe. cells
In transitional epithelium, what is an unusual superficial cell feature?
some bi-nucleated superficial cells exist.
Cells in transitional epithelium obtain more oxygen because of what two reasons?
- fenestrated basement membrane
2. when stretched, the diffusion difference is decreased
What disorder has patchy skin lesions, unknown etiology, and inflammation in dermal papillae?
Psoriasis vulgaris
What feature is described as spots with extra pigment, esp in fair skinned ind.? Is there increased melanocytes?
freckles; there is an increase in melanin, WITHOUT an increase in melanocytes
What disorder lacks melanocytes and has an unknown cause?
Vitiligo
What is discoloration due to a proliferation of melanocytes?
mole (naevi)
What occurs in malignant melanoma?
melanocytes become mitotically active and invade dermis; very invasive and metastatic
Tx: surgery and chemotherapy
What is caused by melanocytes failing to produce melanin? What is the MC form?
Albinism
- MC form = tyrosinase is missing from melanocytes (no conversion of tyrosine to melanin)
What are the two MAIN subcategories of epithelial glands?
Exocrine and endocrine
What is the method of secretion where the product is released into a duct or directly onto an epithelial surface?
exocrine secretion
Define parenchyma.
components directly involved with the primary function
Ex: biceps brachii- parenchyma = skeletal muscle cells
Define stroma.
components providing mechanical/metabolic support
Ex: biceps brahcii – stroma = CT, nerves, lymphatics, blood vessels
What are the 3 methods of sub-classifying exocrine secretion?
- Morphology
- Method of secretion
- Product secreted
Describe the sub-classification “Morphology” for exocrine secretion.
classifies gland according to shape of secretory units(Tubular vs Acinar) and ducts arrangement (Unbranched vs Branched)
What are the three methods of secretion of exocrine glands?
- Merocrine (=eccrine) MC
- Holocrine
- Apocrine
What is the MC type of exocrine secretion?
Merocrine (eccrine)
How is Merocrine/Eccrine secretion done? Is there damage?
secretion by exocytosis; therefore NO cell damage
no odor either
What are examples of locations of Merocrine/Eccrine secretion?
- goblet cells
- salivary glands
- pancreas
- all sweat glands in CHILDREN
- many adult sweat glands
What type of exocrine secretion is it when the cell mature and dies?
Holocrine
What is the secretory product of holocrine excretion? Is there an odor?
the entire cell with in-tact vaculoes; ass. with an odor
What are examples of locations of Holocrine excretion?
- sebacceous glands
- tarsal (Meibomian) glands of eyelid
If the tarsal (Meibomian) glands of the eyelid are not working properly, what occurs?
dry eye
What type of secretion is it when there is minimal damage to the cell and it is ass. with an odor? What is the secretory product?
Apocrine; secretes some cytoplasm ,membranes and in-tact vacuoles
What are examples of locations of Aopcrine secetion?
- lactating mammary glands
- some adult sweat glands (pubic and axillary*)
- ceruminous glands in external auditory canal
- ciliary (Moll’s) glands in eyelid
What occurs if the ciliary (Moll’s) glands in eyelid become blocked?
stye
What is the smallest division of a gland and is a group of cells surrounding a cavity?
Acinus
What is a small group of serous cells attached to ta mucus acinus?
serous demilune
What are Myoepithelial cells?
contractile cells with epithelial origin
- wrap around acini in some exocrine glands
Where are Myoepithelial cells most commonly found?
- salivary and sweat glands
- lacrimal glands
- lactating mammary glands
What is the function of Myoepithelial cells?
to assist secretion
What are three ways glands can be classified by products secreted?
- Serous Glands
- Mucous Glands
- Mixed Glands
What glands produce proteins and are trapezoid shaped?
serous glands
nucleus round and noticeable, cells pick up stain
What are examples of where serous glands are found?
- pancreas
- parotid gland
- chief cells in stomach
What type of glands produce mucus? Where are they found?
mucous glands
- Goblet cells
- mucous cells in stomach
- minor salivary glands in tongue and palate
What are the characteristics of Mucous glands?
- cells typically stain light
- nucleus is often flat and peripheral
What do Mixed glands produce? Where are they found?
serous and mucus
Sublingual and submandibular salivary glands
What are the characteristics of Mixed glands?
(same as Mucous glands–stain light and nucleus flat and peripheral)
**serous demilunes are possible
T/F. Serous demilunes are not possible.
False–they are possible
What three things regulate Exocrine secretion?
- Myoepithelial cells
- Hormonal
- Blood supply
How will increase/decrease in blood flow affect secretion?
increase blood flow will increase O2 which will increase secretion
decrease blood flow will decrease O2 which will decrease secretion
What is endocrine secretion?
secretory product released into nearby CT for vascular dispersal to target cells/organs
What is the secretory product of endocrine glands commonly referred to as?
hormone
What are the two subtypes of endocrine secretion?
- Paracrine secretion
2. Autocrine secretion
What subtype of endocrine secretion is it when signaling cell is close to target cell so the hormone does NOT enter the blood
Paracrine secretion
What subtype of endocrine secretion is it when signaling cell is its own target?
autocrine secretion
How is the endocrine system regulated?
- Hormonal: pos. and neg. feedback loops
2. ANS
