Tissue Components Flashcards
What are the four major tissue types?
Epithelial, connective, muscle, nervous
What are the three germ layers of the embryonic tissue
Endoderm (innermost), mesoderm, ectoderm (outermost)
What does the endoderm eventually develop into?
The lining of the digestive tract and organs like the pancreas and liver
What does the mesoderm develop into?
Tissues like muscle, bone, and blood vessels
What does the ectoderm form?
Skin and neuroectoderm
Is epithelial tissue highly vascularized or mostly composed of cells?
Mostly cells
What are the 3 surfaces of epithelial cells?
Free (exposed to air/liquid), lateral, and basal (what cells adhering to)
What is the name of the most common basal layer?
Basement membrane
Why do epithelial cells need specialized cell contacts?
They hold the cells together and keep them from falling apart (important because cells avascular)
What is the role of the basement membrane in the kidney nephron?
A filter
Besides attachment, what is a function of the basement membrane?
Guides cell migration during tissue repair
What is an example of cells that don’t have a basement membrane associated with them?
Epithelial cells in liver lining bile caniliculis
What are five functions of the epithelial tissue?
protecting underlying structures, acting as barriers, permitting passage of substances (selective permeability), secreting substances, absorbing substances
Explain the classification “pseudostratified”
When there appears to be multiple layers of cells (as in stratified), but all the cells actually connect to the basement membrane (as in simple)
What are the main functions of simple epithelium?
Diffusion of gases, filtration, secretion, absorption, movement
Why are simple epithelium cells not suited as well to protection?
They have only a single layer of cells, and so are not much of a barrier, especially if damaged
Where are some places where simply squamous epithelium found?
lining of blood/lymphatic vessels, alveoli of lungs, loop of Henle in kidney tubules, lining of serous membrane
Where are some places where simple cuboidal epithelium found?
kidney tubules, glands/ducts, choroid plexus (brain), lining of terminal bronchioles (lungs)
Which simple epithelium types are often associated with cillia and in some cases microvilli?
Simple cuboidal and simple columnar
Where are simple columnar epithelial cells normally found?
Glands/ducts, bronchioles (lungs), stomach, intestines, gallbladder, vile ducts, ventricles in brain
What is the main function of stratified squamous epithelium?
Protection
What is the difference between keratinized and nonkeratinized cells?
Keratinized cells are basically dead cells (have lost most organelles and nucleus), while nonkeratinized are still alive and metabolically active
What is the difference between cillia and microvilli?
Microvilli are merely present to increase surface area, while cillia can move and help remove debris or keep liquid flowing
Where is stratified squamous epithelium commonly found?
Places subject to abrasion or friction (mouth, skin, esophagus, anus, vagina, cornea)
What are the main functions of stratified cuboidal epithelial cells?
Absorption/secretion
Where is stratified columnar epithelium commonly found?
Mammary gland duct, larynx, part of male urethra
Where is pseudostratified epithelium normally found and what are its main functions?
Lining of nasal cavity, sinuses, auditory tubes, pharynx, trachea, bronchi (lungs); synthesize/secrete mucus, move mucus/fluid containing foreign particles over free surface and out of passages
Pseudostratified columnar epithelium almost always associated with _____
cillia
What organ is lined with transitional epithelium?
Bladder
What is unique about transitional epithelium?
It is stratified with cells that are able to change shape to account for increasing volume
What are stereocillia?
Elongated microvilli for sensing/absorption
Desmosomes are commonly found in places subjected to _______
stress
Desmosomes contain especially adhesive ______
glycoproteins
In what cells are desmosomes commonly found?
Striated squamous epithelium (of skin)
What are hemidesmosomes anchored with?
Glycoproteins
Tight junctions are usually found closer to which face of the cell?
Free surface or apical
What are the two zones of tight junctions?
Zonula adherens and zonula occludens
Which tight junction zone covers all part of the cell membrane?
Zonula occludens
What are the two types of glands?
Endocrine and exocrine
What are the three methods of secretion in ducts?
Merocrine, apocrine, holocrine
