transmembrane proteins that fuse the outer surfaces of adjacent plasma membranes; forms a water tight seal between adjacent epitheleal cells by sealing off passageways between adjacent cells
can form a belt around a cel using plaque, microfilaments, and cadherins; holds epithelial cells together
similar to adherens junctions since they have plaque and cadherens; instead of microfilaments these are connected to intermediate filaments; prevent cells from separating
half-desmosome; transmembrane glycoproteins called integrins replace the cadherins of desmosomes and attch the protein laminin in the basement membrane; anchors an epithelial cell to the basement membrane, rather than attaching cells to each other
transmembrane proteins called connexins that form channels (connexons); connexons in adjacent cells attach each other to form a continuity between the cytosols for transfer of nutrients, cell signals and perhaps wastes
What are the two general types of epithelium?
Covering and lining (also called membrane epithelium); glandular
Are membrane proteins generally the same on the various surfaces of epithelial cells, or are they commonly different for different surfaces of the same cell?
Often there are different membrane proteins on the different surfaces.
What is the function of the basement membrane?
Anchors the basal surface of an epithelium to underlying connective tissue.
Recognize the general functions are performed by epithelial tissue.
Protection, Filtration, Secretion, Absorption, Excretion
What are the different types of epithelium based on number of cell layers?
Simple, Stratified, Pseudostratified
What are the different types of epithelium based on cell shape?
Squamous, Cuboidal, Columnar, Transitional
Where is endothelium found? Of the different types of epithelium based on shape, what is endothelium?
Lines the cavities of the heart, blood vessels, and lymphatic vessels
Secrete to surface or lumen; Typically are multicellular, and have ducts (the only important unicellular exocrine gland in humans is the goblet cell);Sweat, oil, mucus, enzymes
Secrete to extracellular space; Ductless, having lost ducts during development; Diffuse to blood stream; Hormones
Whole cell secreted (mitosis replaces the cells lost); Sebaceous (oil) glands of the skin are the only true example
Apical portion discharged, cell repaired; Only possibility in humans is mammary glands (most histologists classify mammary glands as merocrine); other mammals definitely have apocrine glands
Goblet cells are glandular simple columnar epithelial cells whose sole function is to secrete mucin, which dissolves in water to form mucus. The cells are exocrine, which means they secrete to the lumen (surface). They are single celled. They are found scattered among the epithelial lining of organs, such as the intestinal and respiratory tracts. They are found inside the trachea, bronchus, and larger bronchioles in respiratory tract, small intestines, the colon, and conjunctiva in the upper eyelid.
Recognize the general functions that are performed by connective tissue.
Binds, supports, and strengthens other body tissues (bone, cartilage); Protects and insulates internal organs; Compartmentalizes (fascia) ; Transports (blood) ; Stores energy (adipose tissue); Main source of immune responses
is most common cell in connective tissue. Secretes and maintains the matrix (fibers and ground substance). Typical cell of dense connective tissue.
appear to have a large empty vacuole when prepared for microscopic observation. Signet ring shape. Synthesizes and stores lipid.
Where is the matrix of connective tissue located? Is the matrix cellular or acellular? What are the two general components of the matrix of connective tissue?
The matrix is located between connective tissues' widely spaced cells; Acellular; The main components are ground substance (may be fluid, semifluid, gelatinous, or calcified. Support the cell, binds them together, stores water and provides a transport medium) and fibers (strengthen and support connective tissue)
What is the function of the matrix of connective tissue? (589,613) From what do connective tissue cells arise?
Occupies the spaces between cells and fibers. Provides structural support and integrity for the connective tissue; Connective tissue cells arise from mesenchyme, which is an embryonic connective tissue
From what (immediate) precursor cells are plasma cells derived? What is the main function of plasma cells?
Plasma cells come from B lymphocytes. To secrete protein and antibodies that neutralize foreign substances in the body.
Where in mast cells are histamines located? What is the function of histamines?
They are stored in the granules of the mast cell; Histamines dilate small blood vessels as part of the body's inflammatory response.
Where in mast cells is heparin located? What is the function of heparin?
It is stored in the granules of the mast cell; Heparin is an anticoagulant
What are the functions of the matrix of connective tissue?
Occupies the spaces between cells and fibers; Provides structural support and integrity for the connective tissue
What range of physical characteristics may be presented by the matrix of connective tissue?
Ground substance, which may be fluid, semifluid, gelatinous, or calcified, and consists of large molecules of hydrated, amorphous material ; Protein fibers
Recognize the names of polysaccharides that comprise the ground substance. What is the collective name given to these polysaccharides?
Hyaluronic Acid; Chondroitin Sulfate; Dermatan Sulfate;Keratan Sulfate; Collective name is glycoaminoglycans (GAGs)
What is the overall function of hyaluronic acid in connective tissue?
Binds cells together, lubricates joints, and helps maintain the shape of eyeballs (vitreous)
What are the three types of fibers found in connective tissue?
Chondroitin sulfate; Dermatan Sulfate; Keratan Sulfate; Fibronectin
What are the three types of fibers found in connective tissue?
Collagen Fibers; Elastic Fibers; Reticular Fibers
Compare and contrast the strength of collagen fibers along the length of their axis versus transverse to their axis.
Like a rope bundle:
•Inelastic along the length of fibers. (like rope: If force is too great the rope will fray)
•Tensile Strength is greater than steel(pressure would be on transverse axis)
What are the two general types of connective tissue?
Embryonic Connective Tissue
Mature Connective Tissue
Contrast, compare, and distinguish pleuripotent cells from totipotent cells with regard to: range of cell types each may eventually become or give rise to, temporal appearance during development.
o Give rise to all other specific connective tissue
o Located along developing cones of the embryo and under the skin
• Totipotent Cells-
o First cell to form after fertilization
o Gives rise to pleuipotent Cells
o have total cell potential
Where is mucous connective tissue found? What is its function?
•Found in umbilical cord of fetus; Resists compression