Week 3- Tissues Flashcards
Name the 4 primary types of tissues.
Epithelial tissue- covers and lines
Connective tissue- provides support
Muscle tissue - enables movement
Nervous tissue- controls work
What are the vital functions of epithelial tissue?
- protects, lines and covers
- filters biochemical substances
- absorbes nutrients
- provides sensory input
- manufactures secretions
- manufactures excretions
Define “avascular” and discuss how it relates to to the epithelium and wound healing.
Avascular means it lacks blood vessels and capillaries, thus it is harder for inflammation to take place which results in a slower healing process.
Describe the basement membrane and its function.
- foundation of the epithelial cell
- non-living meshwork of fibers
- cements the epithelial cell to underlying connective tissue
- strength and elasticity help prevent the cell from being torn off by intraluminal pressures such as stretching or erosion caused by the rubbing of luminal material.
Define and give the function of cilia
-hair like structures found on the free surface of some cells, usually in the respiratory and urogential tracts.
-an electrical potential moves through junctional complexes connecting adjacent cells.
movement occurs in co-ordinated “beats” which enable the efficient transport of material.
-help propel mucus and debris away from the lungs and towards the mouth in the trachea
-in the opening of the oviduct they are called the infundibulum. encourage newly expelled ova into the oviducts.
Define and give the function of microvilli.
-finger-like projections on the luminal surface of the cell. surface is called the “brush border”
-increases the surface area bout 20 times , thereby increasing the absorptive ability of the cell.
usually occur on cells involved in absorption or secretion.
-commonly found in the intestinal and urinary tracts.
Define and give the function of Keratin.
- protective, water-proof substance that fills epithelial cells of the skin.
- accumulation occurs as cells mature and move from basal layer to superficial layer of the integument.
- aids in preventing desiccation.
What is the effect of Parvovirus on the intestinal epithelium?
The virus attacks and kills the epithelial tissue that helps absorb nutrient molecules from the lumen of the gut and it sloughs off in sheets. animals develop diarrhea, vomit and can become severely dehydrated in a short time. The sudden loss of the epithelial tissue causes bleeding into the intestine, which creates a distincly foul-smelling hemorrhagic diarrhea.
Define and give examples of simple squamous epithelium.
- cells are delicate, thin, flat & smooth
- often found in the lining surfaces involved in the passage of either gas or liquid. (ex. inner lining of the lung or filtration membranes of the kidneys.)
- occurs only in protected regions of the body
- given special names depending on where they are located in the body,
- called the misothelium in the lining of the chest (pleural), around the heart (cardinal) and abdominal (peritoneal) cavities.
- endothelium lines blood and lymphatic vessels.
Define and give examples of simple cuboidal epithelium.
- composed of a single layer of cubical cells.
- round, dark staining nuclei align in a a single row (resembles a string of pearls)
- occurs in sheltered regions of the body.
- involved in absorption and secretion.
- can be smooth or covered in microvilli.
- importent to endocrine and exocrine tissue.
- found on the surface of ovaries, in the secretory portions of glands like the thyroid, in the lining of the ducts of the liver, pancreas, kidney, and salivary glands
Define and give examples of simple columnar epithelium.
- elongated and closely packed together.
- makes epithelia relatively thick and more protective than other simple epithelium.
- nuclei are aligned in a row at the base of the cell, near the basement membrane.
- line the length of the gastrointestinal tract from the stomach to the rectum.
- associated with absorption and secretion.
- found in many excretory ducts as well as in the digestive tract.
- absorptive cells blanketed in microvilli
- goblet cells manufacture and store lubricating mucus.
- simple ciliated columnar epithelia: apical surfaces are covered with cilia. line uterine tubes and respiratory tracts.
Define and give examples of stratified squamous epithelium.
- consists of various cell layers.
- base is formed by cuboidal cells, attached to the basement membrane.
- continually dividing to keep up with cell loss.
- as cuboidal cells mature, they are progressively pushed to the surface away from the nutrient sources provided by the underlying connective tissue.
- cells loose their cytoplasm and nuclei and take on squamous shape.
- cells on the outer surface are continually being worn away or sheared off
- replaced at an equal rate by cells from deeper layers.
- occurs in regions of the body that are subject to mechanical and chemical stress (lining of the mouth, esophagus, vagina, and rectum)
Define and give examples of stratified cuboidal epithelium.
- generally occurs as two layers of cuboidal cells.
- found primarily along large excretory ducts, such as those of sweat glands, mammary glands and salivary glands.
- important in protecting the delicate tissues in deeper layers.
Define and give examples of transitional epithelium.
- -forms a leak-proof membrane that prevents diffusion.
- has the ability to stretch
- appearance varies depending on how much it is stretched.
- relaxed, it is thick, multilayered and has round, domelike cells on the luminal surface.
- stretched, it may becomes half as thick, and the apical cells become flattened and squamous.
- found in the regions of the body that are required to expand and contract as part of their normal function.
ex: urinary bladder, ureters, urethra, and calyxes of the kidney.
endocrine glands
-do not have ducts or tubules
-secretions are distributed throughout the body
-produce and secrete regulatory chemicals (hormones) into the bloodstream or the lymphatic stream.
-part of the endocrine system
ex: pituitary gland in the brain
adrenal gland near the kidney
exocrine glands
- can be multicellular or unicellular
- always possess ducts except goblet cell
- more common than endocrine glands
- -discharge secretions via their ducts directly into nearby areas where they may cover cell surfaces or empty into body cavities.
- secretions act locally and do not normally enter the circulation.
- ex: sweat, musk, hepatoid, salivary glands, in the pancreas and liver
serous glands
produce watery secretions that have a high concentration of enzymes.
mucous glands
produce thick, viscous secretions, composed of glycoproteins.
extracellular matrix
the nonliving substance found between cells that provides support and nourishment.
extracellular fibers
the fibers of connective tissues located outside the cells that perform a variety of functions depending on the degree of their elasticity or concentration
ground substance
the shapeless, viscous matrix present in connective tissue in which cells receive nutrients and void waste products.
-also helps protect the boy from infectious agents by acting as a barrier.
