LESSON 4: TISSUES Flashcards
group of cells with similar structure and function
tissues
study of tissues
histology
A physician who examine cells and tissue
pathologist
a physician who examines cells and tissues to help other physicians make accurate diagnoses.
pathologist
One of the principal functions of a pathologist is to
examine tissues for any changes that might indicate disease
types of tissues
epithelial
connective
muscular
nervous
Cell Junctions
tight junctions
adherens junctions
desmosome
hemidesmosome
gap junction
consist of weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells
They inhibit the passage of substances between cells and prevent the contents of these organs from leaking into the blood or surrounding tissues.
tight junctions
bind adjacent cells together
ex. intestines
tight junctions
mechanical links that bind cells
Desmosomes: (cadherins)
Help epithelial surfaces resist separation during contractile activities
Adherens: (cadherins)
bind cells to the basement membrane
Hemidesmosomes: (integrins)
- small channels that allow molecules to pass between cells
- allow cells to communicate
- most common
Gap junctions: (connexins)
- covers body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands.
- allows the body to interact with both its internal and external environments.
epithelial tissue
- Cover and line body surfaces
- Often form sheets with one free surface, the apical surface, and an anchored surface, the basement membrane
- Avascular (no blood supply)
- Regenerate easily if well nourished
Hallmarks of epithelial tissues:
Classification of Epithelium Based on Cell Layers (Arrangement of Layers)
Simple epithelium
stratified epithelium
pseudostratified epithelium
- Consists of only a single layer of cells; Secretion, absorption
Simple Epithelium
consists of more than one layer of epithelial cells, with some cells sitting on top of others.
Stratified Epithelium
Appeared to be 2 or more layers of cells, some are tall and others are short
Pseudostratified Epithelium
Classification of Epithelium Based on Idealized Shapes (Cell shapes)
Squamous
Cuboidal
Columnar
flat or scalelike; rapid passage of substances
squamous cells
cube-shaped; may have microvilli; secretion and absorption
cuboidal cells
tall and thin, cell tends to be taller than they are wide; secretion and absorption; protect underlying tissues
columnar cells
change shape, from squamous to cuboidal and back, as organs such as the urinary bladder stretch (distend) to a larger size and then collapse to a smaller size
transitional cells
Major Types of Epithelial Tissues
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple columnar epithelium
- Pseudostratified epithelium
- Stratified squamous epithelium
- Stratified cuboidal epithelium
- Stratified columnar epithelium
- Transitional epithelium
- single layer of flat cells that resembles a tiled floor when viewed from apical surface; centrally located nucleus that is flattened and oval or spherical in shape
simple squamous epithelium
- lines the cardiovascular and lymphatic system (heart, blood vessels, lymphatic vessels), where it is known as _________ and forms the epithelial layer of serous membranes where it is called ________
endothelium
mesothelium
simple squamous epithelium
FUNCTION:
- presents at sites of filtration (such as blood filtration in kidneys) or diffusion (such as diffusion of oxygen into blood vessels of lungs) and at site of secretion in serous membrane
- not found in body areas subject to mechanical stress (wear and tear)
simple squamous epithelium
- single layer of cube-shaped cells; some cells have microvilli (kidney tubules) or cilia (terminal bronchioles of the lungs)
- secretion and absorption by cells of the kidney tubules; secretion by cells of glands and choroid plexuses; movement of particles embedded in mucus out of the terminal bronchioles by ciliated cells
location: kidney tubules, glands and their ducts, choroid plexuses of the brain, lining of terminal bronchioles of the lungs, and surfaces of the ovaries
simple cuboidal epithelium
single layer of tall, narrow cells; some cells have cilia (bronchioles of lungs, auditory tubes, uterine tubes, and uterus) or microvilli (intestines)
simple columnar epithelium
movement of particles out of the bronchioles of the lungs by ciliated cells; partially responsible for the movement of oocytes through the uterine tubes by ciliated cells; secretion by cells of the glands, the stomach, and the intestine; absorption by cells of the intestine
location: glands and some ducts, bronchioles of lungs, auditory tubes, uterus, uterine tubes, stomach, intestines, gallbladder, bile ducts, and ventricles of the brain
simple columnar epithelium
single layer of cells; some cells are tall and thin and reach the free surface, and others do not; the nuclei of these cells are at different levels and appear stratified; the cells are almost always ciliated and are associated with goblet cells that secrete mucus onto the free surface
pseudostratified columnar epithelium
synthesize and secrete mucus onto the free surface and move mucus (of fluid) that contains foreign particles over the surface of the free surface and from passages
location: lining of nasal cavity, nasal sinuses, auditory tubes, pharynx, trachea, and bronchi of lungs
pseudostratified columnar epithelium