Tissue Flashcards
group of cells with similar structure and function
Tissue
study of tissues
Histology
- a physician who examine cells and tissue
- A ______ (____- = disease) is a physician who examines cells and tissues to help other physicians make accurate diagnoses. One of the principal functions of a pathologist is to examine tissues for any changes that might indicate disease
Pathologist
TYPES OF TISSUE
Epithelial
Connective
Muscular
Nervous
Cell junction (types/parts)
Tight junctions
Desmosomes
Adherens
Hemidesmosomes
Gap 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.
EPITHELIAL TISSUE
- allows the body to interact with both its internal and external environments.
EPITHELIAL TISSUE
Hallmarks of epithelial tissues:
- 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
Epithelial tissue is arranged in two general patterns in the body:
1) covering and lining various surfaces and (2) forming the secreting portions of glands.
Functions of Epithelial Tissue
PROTECTS
SECRETES (mucus, hormones, and enzymes)
ABSORBS (nutrients in the gastrointestinal tract)
EXCRETES (various substances in the urinary tract)
Classification of Epithelium Based on Cell 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
Squamous
Cuboidal
Columnar
Transitional
cells are flat or scalelike; rapid passage of substances
Squamous
are cube-shaped; may have microvilli; secretion and absorption
Cuboidal
are 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
Single layer of flat, often hexagonal cell; the nuclei appear as bumps when viewed in cross section because the cells are so flat.
SIMPLE SQUAMOUS
Function: Diffusion, filtration, some secretion, and some protection against friction
SIMPLE SQUAMOUS
Location: Lining of blood vessels and the heart, lymphatic vessels, alveoli of the lungs, portions of kidney tubules, lining of serous membranes of body cavities
SIMPLE SQUAMOUS
Single layer of cube-shaped cells; some cells have microvilli (kidney tubules) or cilia (terminal bronchioles of the lungs)
SIMPLE CUBOIDAL
Function: 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
SIMPLE CUBOIDAL
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
Single layer of tall, narrow cells; some cells have cilia (bronchioles of lungs, auditory tubes, uterine tubes, and uterus) or microvilli (intestines)
SIMPLE COLUMNAR
Function: 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
SIMPLE COLUMNAR
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
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
Function: Synthesize and secrete mucus onto the free surface and move mucus (or fluid) that contains foreign particles over the surface of the free surface and from passages
PSEUDOSTRATIFIED COLUMNAR
Location: Lining of nasal cavity, nasal sinuses, auditory tubes, pharynx, trachea, and bronchi of lungs
PSEUDOSTRATIFIED COLUMNAR
Several layers of cells that are cuboidal in the basal layer and progressively flattened toward the surface; the epithelium can be nonkeratinized (moist) or keratinized; in nonkeratinized stratified squamous epithelium, the surface cells retain a nucleus and cytoplasm; in keratinized stratified epithelium, the cytoplasm of cells at the surface is replaced by a protein called keratin, and the cells are dead
STRATIFIED SQUAMOUS
Function: Protects against abrasion, forms a barrier against infection, and reduces loss of water from the body
STRATIFIED SQUAMOUS
Location: Keratinized-outer layer of the skin; nonkeratinized-mouth, throat, larynx, esophagus, anus, vagina, inferior urethra, and corneas
STRATIFIED SQUAMOUS
-consists of more than one layer of cuboidal epithelial cells.
- This epithelial type is relatively rare and is found in sweat gland ducts, ovarian follicular cells, and the salivary glands.
- It functions in absorption, secretion, and protection.
STRATIFIED CUBOIDAL EPITHELIUM
- consists of more than one layer of epithelial cells, but only the surface cells are columnar
STRATIFIED COLUMNAR EPITHELIUM
Stratified cells that appear cuboidal when the organ or tube is not stretched and squamous when the organ or tube is stretched by fluid
TRANSITIONAL EPITHELIUM
Function: Accommodates fluctuations in the volume of fluid in an organ or a tube, protects against the caustic effects of urine
TRANSITIONAL EPITHELIUM
Location: Lining of urinary bladder, ureters, and superior urethra
TRANSITIONAL EPITHELIUM
Two major gland types develop from epithelial sheets
Endocrine glands
Exocrine glands
- Ductless; secretions (hormones) diffuse into blood vessels
- Examples: thyroid, adrenals, and pituitary
Endocrine glands
- Secretions empty through ducts to the epithelial surface
- Include sweat and oil glands, liver, and pancreas (both internal and external)
Exocrine glands