Lecture 3 Histology Flashcards
Name the 4 basic tissue types.
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
Where are epithelial tissues found?
■Barrier/Covers or lines every body surface and all body cavities. External and internal lining of many organs.
■Oral Mucosa (lining of the cheek), Nasal Cavity
What are the functions of epithelial tissue?
■Physical protection- Epidermis, esophagus
■Selective permeability- alveoli of lungs, lining of blood vessels, kidney tubules, intestines
■Secretion - glands, intestines
■Sensation - Epidermis, nerve endings
Describe the special characteristics of epithelial tissue that distinguishes it from other tissue types.
■Cellularity - It’s made up of lots of cells, with very little space between them (extracellular matrix).
■Polarity - Have two sections: a top(apical surface) which is free and unbound, and a bottom(basilar surface) which is bound to the basement membrane.
■Avascularity - No blood flow directly to cells. They get their nutrients from the connective tissue below.
■Innervation - Does contain nerve endings
■Regeneration - Capable of rapid division to replace old or worn out cells
■Attachment- Bound to basement membrane.
■AIR CAP (Avascular, Innervated, Regeneration, Cellularity, Attachment (to basement membrane), Polarity)
Name and describe the types of intercellular junctions found in epithelial tissue.
- Tight Junction - Closely attach adjoining cells and are closest to apical surface. Impermeable
- Adhering Junction - Hold cells together, usually more basal than tight. Like belt around cells.
- Desmosomes - Junctions that are usually found at stress points.
- Hemidesmosomes - half desmosome, hold cell to basement membrane.
- Gap Junction - Connects cytoplasms of two cells, allowing exchange of molecules.
Describe how epithelial tissue is classified according to cell shape and layers.
■Layers •Simple epithelium - has one layer •Stratified epithelium - anything more than one layer ■Shape •Squamous - basic flat cell •Cuboidal - cube like •columnar - column like
What is the basic structure, function, and location of the following epithelial tissue.
Simple squamous
Flat, circular, single line
Diffusion and filtration
Found in the lung air sacs(alveoli), lining of blood vessels and serous membranes.
What is the basic structure, function, and location of the following epithelial tissue.
transitional
Multiple lines of squares on top of each other that can go flat or go back to square shaped
Distention and relaxation of urinary structures
Found in ureters, bladder, and urethra.
What is the basic structure, function, and location of the following epithelial tissue.
simple cuboid
Cube shaped, single line
Absorption and secretion
Found in kidney tubules and glands. (Longer cells provide more room for cellular machinery)
What is the basic structure, function, and location of the following epithelial tissue.
simple columner
Rectangle cube shaped, single line
Absorption, secretion, and movement(if ciliated, which is in the uterine tubes).
Found in stomach, small intestine, and large intestine.
What is the basic structure, function, and location of the following epithelial tissue.
stratified squamous
Multiple lines of flat circles on top of each other
Protection
Found in oral cavity, pharynx, esophagus, vagina, anus, epidermis of skin.
What is the basic structure, function, and location of the following epithelial tissue.
pseudostratified columner
Multiple lines of rectangle cube shapes on top of each other
Protection, Movement(if ciliated)
Found in the respiratory tract.
Explain the basic differences between endocrine glands and exocrine glands.
Endocrine - Ductless, secrete products directly into interstitial fluid and bloodstream. Release hormones wherever they are.
Exocrine - Secrete products through ducts onto an epithelial surface(your face, for example). Acinus is the secretory portion and the Duct is the conducting portion. 3 types of exocrine glands
Describe the three different types of exocrine glands (merocrine, holocrine and apocrine).
- Merocrine - watery sweat, tears, and saliva. Products excreted by secretory vesicles via exocytosis (ie, the cell produces the product then transports it out).
- Holocrine - The entire (holo) cells disintegrate and become the product(ie, oil glands). Multiple branches.
- Apocrine gland - A part of the cell (apo) breaks off and becomes the product. Thick smelly sweat (armpits and other crevice-like areas) and milk.
What are the basic characteristics of connective tissue?
Connective tissue is in some ways opposite of epithelial tissue. Connective tissue has very few SPARSE cells in a large extracellular matrix. It contains protein fibers and ground substance.