Chapter 4: Histology: Study of Tissues – Flashcards
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4 tissue types
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epithelial, connective, muscular, nervous
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epithelial
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covering
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connective
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support
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muscular
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movement, contraction
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nervous
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control, quick responses
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tissue
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a group of similar cells that are specialized to perform a function
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epithelial tissue
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covers or lines body surfaces, form a boundary, one or more layers of a cell with a free surface, open space on outside of the free surface
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2 types of epithelial tissues
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membranes and secretions
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membranes
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covering and lining epithelial tissue
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secretions
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glandular epithelial tissue
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functions of epithelial cells
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protection, absorption, filtration, secretion, excretion, sensory reception
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special characteristics of epithelial cells (7)
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polarity, apical surfaces, epithelial cells connections, connective tissue support, avascular, innervation, and regeneration
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polarity of epithelial cells
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all epithelial cells have an apical (free, top) surface exposed to the exterior or a body cavity. Also they have a basal side(back, lower attached)
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apical surfaces of epithelial cells
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may have microvilli that can increase surface area and increase absorption. Some have cilia that beat (respiratory tract) Also their usually is a basal lamin (basal sheet) consisting of secreted proteins that as a support platform and as a filter for nutrients
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how are epithelial cells connected?
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tight junctions and desmosomes which prevents loss of nutrients to the outside world
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are epithelial cells avascular?
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No they contain no blood supply and must get supplied by diffusion through the basement membrane
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are epithelial cells innervated?
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Yes epithelial cells contain nerve endings that help regulate the cell
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regeneration of epithelial cells
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Highly regenative. Skin and intestinal epithelial mucosa have some of the highest regenerative capacities of any cells in the body
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What are the two parts needed to classify a epithelial cell?
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simple or complex and the type of cells (descriptive) ex. simple cuboidal epithelium
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simple squamous epithelium
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single layer, flat (scale-like) and thin cells without much cytoplasm
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functions of simple squamous epithelium
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found where diffusion and filtration are the most critical functions. EX. walls of blood vessels, capillaries (endothelial cells (cells that develop new blood vessels) and lung alveoli (air sacs)
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special example of simple squamous epithelium
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endotheliam cells, these cells comprise the inner (endo) covering of blood vessels and the heart. they have tight junctions but can contract and retract.
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mesothelium
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simple squamous cell, is the epithelium found in serous membranes (fluid-filled membranes that seperate body cavities)
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simple cuboidal epithelium
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are as tall as they are wide (square shaped)
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functions of simple cuboidal epithelium
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secretion and absorption (like sponges)
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examples of simple cuboidal epithelium
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lines the kidney tubules and salivary glands
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simple columnar epithelium
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single layer, column-shaped (longer than wide)
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functions of simple columnar epithelium
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also secretion and absorption
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examples of simple columnar epithelium
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lining of the stomach and intestines and has microvilli (small hairs) to increase surface are and Goblet cells that secrete mucus (thick protective fluid) also cells may be ciliated
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pseudostratified columnar epithelium
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single layer, but may appear to be multilayered since the cells vary in height and the nuclei are not all aligned (like in simple columnar) only the tallest cells reach the surface. many have cilia and goblet cells (mucus secretion)
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goblet cells
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is a single cell that secretes mucin, a protein that converts mucus in the presence of water. mucus forms a slimy surface on the upper respiratory and gastrointestinal tracts.
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microvilli
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small hairs-help inrease surface area
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ciliated
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identical in structure to flagella, beat in rhythmic waves, moving liquids
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functions of pseudostratified columnar epithelium
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line respiratory tract, and comprise the mucociliary elevator
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mucociliary elevator
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pseudostratified columnar epithelial cells that protect the lower respiratory tract from infections by trapping microorganisms particles in mucus and the cilia beat to move these foreign molecules and infecious agents up and out
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stratified squamous epithelium
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most common types of epithelium, cells reproduce in layer closest to basement membrane (deeper layer) it is thick and works well for protection, and there are 2 types of stratified squamous epithelium
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two types of stratified squamous epithelium
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keratinized, nonkeratinized
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keratinized
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one of the two types of stratified squamous epithelium. has a protein that makes the cell water-proof and provides a tough coating. the skin is an example of this. the outer layer of the skin (epidermis) is a tough coating of dead cells
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nonkeratinized
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is the other type of stratified squamous epithelium, much moister than the other, and lines the mouth, throat (larynx), vagina and anal canal.
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statified cuboidal epithelium
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rare, and only seen in sweat and mammary glands (usually a bilayer)
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stratified columnar epithelium
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rare and seen in the pharynx, male urethra and some gland ducts
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transitional epithelium
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allows for expansion of a lining because the basal layers are cuboidal or columnar and the apical cells shrink in layers and flatten out (the dome-like cells start to loo like squamous cells) as the organ stretches
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functions of transitional epithelium
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permeability barrier that can expand
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example of transitional epithelium
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urinary bladder
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gland
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one or more cell that synthesize and secrete a substance
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secretion
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is the substance that is actually secreted outside the cell
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two types of glands
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endocrine, exocrine
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endocrine glands (endo means inside)
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secretes into bloodstream, ductless (lose their ducts)
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exocrine glands (exo means outside, through a duct)
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secrete into ducts
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example of a unicellular exocrine gland
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goblet cell (shaped like a goblet)
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what are the 2 basic parts of multicellular glands?
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a multicellular duct, a secretory ascinus (berry shapped cells)
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simple exocrine glands have...
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unbranched ducts
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compound glands have...
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branched ducts
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4 types of glands
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tubular, alveolar, tubuloalveolar, ascinar
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tubular
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shaped like a tube
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alveolar
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shaped like a flask (literally hollow cavity)
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tubuloalveolar
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shaped like a tube and a flask
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ascinar
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berry-like
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3 modes of secretion from glands
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merocrine, holocrine, apocrine
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merocrine
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glands secrete by exocytosis without any loss of cells/cell portions. most common type of gland, includes most sweat and salivary glands
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holocrine
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(whole) glands secrete entire cells with the fluid ex. sebaceous glands (secrete oil/wax in skin)
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apocrine
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glands secrete the top of the cell with the secretion
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most abundant tissue by weight in body...
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connective
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the four classes of connective tissue?
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connective tissue proper (includind adipose, and fibrous tissue), cartilage, bones and blood cells
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four main functions of connective tissue
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binding and support (bones, cartilage), protection (bones, cartilage and fat), insulation (fat), transport (blood).
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properties of connective tissue
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derived from mesenchyme, vascularity (from poor (cartilage) to good (bone), consist of mostly extracellular matrix
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composition of extracellular matrix
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ground substance, fibers, cells
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ground substance
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fills the space between cells, composed of fluid, cell adhesion proteins and proteoglycans . the cell adhesion proteins allows for the attachment of cells to the extracellular matrix
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proteoglycans
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consists of negatively charges glycosaminoglycans attached to a protein core. the more GAG's the the more water is trapped and the stickyer the ground substance becomes
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3 types of fibers
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collagen, elastic, reticular
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collagen
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fiber, one of the most abundant body proteins, is secreted into the extracellular space and assembles in fibrils, and then into thick fibers spontaneously. Very strong, but little stretch. ex. tendons on ends of muscles show up as white fibers
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elastic
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fiber, thin and more branched then the former. contains a substance that allows stretch to the fibers. Have less strength the former. Found in the skin, vocal cords, and in the lungs. have a more yellow appearance
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reticular
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fiber, very thin containing both of the other two types of fibers that branch extensively, in a network that surround blood vessels or attach a collagen fiber to a site. most common at the interface of collagen fibers and epithelial tissue, allow for greater flexibility than collagen fibers.
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blasts
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these more immature cells build matrix
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fibroblasts
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build connective tissue
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chondroblasts
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build cartilage
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osteoblasts
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build bone
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hematopoietic
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stem cells that make blood cells
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cytes
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maintain (live-in) matrix, matured blast cells, reside in matrix
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clasts
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break down matrix (osteo___)
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connective tissue
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has living cells surrounded by matrix, all types of a common embryonic origin. comes from mesenchyme which comes from mesoderm (primary germ cell layer)
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what are the 2 types of connective tissue proper
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loose and dense
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what are the 3 types of loose connective tissue
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areolar, adipose, and reticulat
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what are the 3 types of dense connective tissue
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dense regular, dense irregular and elastic
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areolar connective tissue
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most common connective tissue in body, is loose tissue with spaces in between the fibers and fibroblast cells. Primary function, to wrap and cushion the organs, prevent infections, (macrophages are present in this tissue), and to hold fluid. Called the universal packing, is present in all mucous membranes.
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adipose connective tissue
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similar to areolar, but with more fat cells which occupy more of the space. Nucleus typically pushed to the side. mostly found subcutananeous, in the central areas and in the omentum. Serves as a storage area for energy and nutrients. Highly vascularized, brown fat has higher amounts of mitochondria than white fat.
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reticular connective tissue
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similar to areolar but fibers are the smaller and thinner. Found in immune sites, especially the bone marrow, spleen, and in lymph nodes. Forms stroma(bed) that helps nourish the immune cells.
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reticulocytes
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specialized fibroblasts present in reticular tissue that release specific growth factors and nourish immune cells
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dense regular connective tissue
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also called fibrous ______, contains wavy, parallel collagen fibers (thick). Very strong, once the waves have been straightened out it cannot stretch. Strong in mainly a single direction. Forms tendons, ligaments, and aponeuroses
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tendon
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attach muscles to bone
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ligaments
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attach bones to bones, usually in joints
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aponeuroses
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flat sheet-like tendons that attach muscles to muscles to form a fascia (bond) that wraps or bundles muscles with nerves and blood vessels.
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dense irregular connective tissue
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has thicker bundles of collagen and are not in the same straight patterns. has more elastic fibers and it is found in skin and the fibrous capsules of joints and organs
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cartilage
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can withstand both stretch and compression and is a great shock absorber. intermediate between connective tissue and bone, no nerve fibers and no vascularization. all nutrients come from diffusion
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chondrocytes
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cells that maintain cartilage, after cartilage is made, chondroblasts turn in to condrocytes that reside in the lacunae (pit or swimming pool) in the cartilage
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3 main types of cartilage
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hyaline, elastic, fibrocartilage
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Hyaline cartilage
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most common type, appears glossy, white/blue. covers the ends of long bones, forms the costal cartilage, the nose, trachea and the larynx. forms the template for the formation of all bones during embryogenesis and development. forms the epiphyseal plate (growth plate of long bones)
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elastic cartilage
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similar to hyaline but contains more elastic fibers. adds increased flexibility. two sites are the external ear, and the epiglottis
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fibrocartilage
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an intermediate structure between cartilage and connective tissue. less rigid matrix than hyaline, found in the disks between the vertebrae and the knee joint, gives these areas additional cushioning from compression
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osseous tissue
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bone, provides the rigid structure needed for support and movement in the body. Similar to cartilage but contains calcium salts and phosphate that hardens the bone. Highly vascularized compared to cartilage
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osteoblasts
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cells that secrete calcium and phosphate to make bone
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osteon
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structural unit of the bone. has a central canal surrounded by rings of bony matrix (lamellae)
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2 types of bone
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cancellous (spongy), compact
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cancellous
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bone has spaces between the trabeculae (tubules of bone)
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compact bone
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solid, no spaces between the layers (lamellae)
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blood
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a connective tissue, is used for transport of respiratory gases, nutrients, wastes products and electrolytes. the cells do not make the matrix (plasma) unlike all other types of connective tissue. stays contained in the vessel
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nervous tissue
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not a connective tissue, found in the brain, spinal cord and peripheral nerves. rapidly control and regulate body functions
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neurons
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cells that can generate and conduct electrical signals that lead to the controlling function of nerves
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neuroglia
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are the support cells for neurons
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muscle tissue
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are contractile tissues that initiate body movements, as it contracts it pulls at the attached bones and causes movement of body parts. myofilaments serve as the contractile element
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3 kinds of muscles
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skeletal, cardiac, smooth
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skeletal muscle
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voluntary muscle, that is striated (regular pattern of light and dark bands) have cells called muscle fibers which contain many nuclei, packaged into sheets that are attached to bones.
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cardiac muscle
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found only in the heart, involuntary and also striated. helps circulate the blood about 60 times per min. only one nucleus per cell had intercalated (alternating layered) disks that allow electrical communication between _______ ______ cells
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smooth muscle
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involuntary, not striated and the individual cells are spindle shaped and uni-nucleated. Found in digestive tract, the blood vessels, and the urinary bladder. Forms the walls of most hollow organs (except heart) it acts to squeeze substances through the organs
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what are the 3 main coverings or membranes?
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cutaneous, mucous, serous
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coverings and membranes
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continuous sheets of at least two tissue types. an epithelium layer bound to connective tissue. this makes membranes simple organs.
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cutaneous membranes
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the skin, actually an organ system consisting of epidermis, and dermis. is exposed to air and pathogens
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epidermis
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dead keratinized stratified squamous epithelium attached to dermis
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dermis
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attached to epidermis, dense irregular connective tissue
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mucous membrane (mucosea)
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lines the body cavities that open to the environment, maintain a moist, wet surface that is bathed in secretion. cover the openings of the digestive react, respiratory tract, and the urogenital tract. either stratified squamous or simple columnar epithelia on the outside and attach to loose connective tissue called the lamina propria, sometimes a layer of smooth muscle underneath the lamina propria.
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serous membranes
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cover the body cavities and organs. allow for smooth movement of organs against one another. composed of simple squamous epithelium (mesothelium) on top of loose connective tissue (areolar)
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mesothelium
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what serous membranes are composed of, secretes a clear fluid that lubricates the surface.
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pleura
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serosa covering the lungs
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pericardium
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serosa covering the heart
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peritoneum
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serosa covering the abdominal cavity
