Chapter 5; Histology Flashcards
(187 cards)
1
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histology (microscopic anatomy)
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study of tissues
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tissue
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group of similar cells
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matrix (extracellular material)
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surrounds the cells and the relative amount of space occupied by the cells and matrix
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ground substance (tissue fluid, ECF, or interstitial fluid)
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clear gel
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primary germ layers
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give rise to all of the body’s mature tissues
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ectoderm
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outer layer that gives rise to the epidermis and nervous system
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endoderm
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innermost layer that gives rise to the mucous membranes of the digestive and respiratory tracts and to the digestive glands
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mesoderm
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a layer of more loosely organized cells
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mesenchyme
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gelatinous layer that is composed of fine, wispy collagen fibers and branching mesenchymal cells embossed in a gelatinous ground substance
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histological sections
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thin slices of histology under a microscope
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fixative
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a chemical that prevents decay
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stains
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artificially colored histological cells to help enhance detail
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longitudinal section
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a tissue cut on its long axis
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cross section
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one cut perpendicular
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oblique sections
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cross section
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smears
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tissue is rubbed or spread across the slide
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spreads
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tissue is laid out on the slide
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epithelial tissue
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consists of a sheet of closely adhering cells, one or more cells thick, with the upper surface usually exposed to the environment or to an internal space in the body
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protection
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epithelia protect deeper tissues from invasion and injury
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secretion
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epithelia produce mucus, sweat, enzymes, hormones, and most of body’s other secretions
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excretion
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epithelia void wastes from the tissues across the pulmonary epithelium and bile from the epithelium of the liver
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absorption
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epithelia absorb chemicals form the adjacent medium
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filtration
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all substances leaving the blood are selectively filtered through the epithelium that lines the blood vessels
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sensation
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epithelia are provided with nerve endings that sense stimulation ranging from a touch on the skin to irritation of the stomach
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avascular
without blood vessels
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basement membrane
between an epithelium and the underlying connective tissue
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basal surface
the surface of an epithelial cell that faces the basement membrane
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simple epithelium
every cell is anchored to the basement membrane
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stratified epithelium
some cells rest on top of other cells and do not contact the basement membrane
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simple squamous
thin scaly cells
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simple cuboidal
squarish or round cells
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simple columnar
tall narrow cells
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pseudostratified columnar
not all cells reach the surface, the shorter cells are covered by the taller ones
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goblet cells
wingless-shaped cells that produce protective mucous coatings over the mucous membranes
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stratified squamous
deepest layer of cells are cuboidal to columnar and include mitotically active stem cells
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stratified columnar epithelia
seen only in places where other two epithelial types meet (larynx, pharynx, anal canal, and male urethra)
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transitional epithelia
only found in urinary tract
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umbrella cells
the domed surface cells of transitional epithelium
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lipid rafts
dense patches
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uroplakins
embedded proteins
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connective tissues
most abundant, widely distributed, and histologically variable of the primary tissues
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fibroblasts
large, fusiform or stellate cells that often show slender, wispy branches (they form the fibers and ground substance that form the matrix of the tissue
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macrophages
large phagocytic cells that wander through the connective tissues, where they engulf and destroy bacteria
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anitgens
activate the immune system when they sense foreign matter
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monocytes
arise from WBC or from the stem cells that produce monocytes
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leukocytes or WBCs
travel briefly in the bloodstream, then crawl out through the walls of small blood vessels and spend most of their time in the connective tissue
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neutrophils
wander about attacking bacteria
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lymphocytes
react against bacteria, toxins, and other foreign agents
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plasma cells
certain lymphocytes turn into plasma cells when they detect foreign agents
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antibodies
disease-fighting proteins
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mast cells
found along blood vessels that secrete heparin
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histamine
increases blood flow by dilating blood vessels
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adipocytes or fat cells
appear in small clusters in some fibrous connective tissues
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collagenous fibers
fibers made of collagen are tough and flexible and resist stretching
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white fibers
some collagenous fibers have a glistening white appearance
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reticular fibers
thin collagen fibers coated with glycoprotein
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reticular fibers
thin collagen fibers coated with glycoprotein
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elastic fibers
thinner than collagenous fibers, and they branch, and rejoin each other along their course (made of protein called elastin that is coated with glycoprotein or fibrillin)
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ground substance
gelatinous to rubbery consistency, absorbs compressive forces and protects the more delicate cells from mechanical injury
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glycoaminoglycan (GAG)
a long polysaccharide composed of unusual disaccharides called amino sugars and uronic acid
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chondroitin sulfate
most common GAG that is abundant in blood vessels and bones and gives cartilage its relative stiffness
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proteoglycan
shaped somewhat like a bottle brush with a central core of protein and bristle-like outgrowths composed of GAGs
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adhesive glycoproteins
protein-carbohydrate complexes that bind plasma membrane proteins to extracellular collagen and proteoglycans
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loose connective tissue
much of the space is occupied by ground substance, which dissolves out of the tissue during histological fixation and leaves empty space in prepared tissue
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dense connective tissue
fiber occupies more space than the cells and ground substance, and appears closely packed in tissue sections
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areolar tissue
exhibits loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space
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reticular tissue
a mesh of reticular fibers and fibroblasts
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dense regular connective tissue
collagen fibers are closely packed and leave relatively little open space and the fibers are parallel to each other
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elastic tissue
the vocal cords and some spinal ligaments are made of a dense regular connective tissue
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dense irregular connective tissue
thick bundles of collagen and relatively little room for cells and ground substance, but the collagen bundles run in seemingly random directions
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adipose tissue (fat)
tissue in which adipocytes are the dominant cell type
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white fat
more abundant and is the most significant adipose tissue of the adult body
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brown fat
found mainly in fetuses, infants, and children, but adults also have small deposits of brown fat, it accounts for up to 6% of an infant's weight and is concentrated especially in fat pads in the shoulders, upper back, and around the kidneys
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cartilage
a relatively stiff connective tissue with a flexible rubbery matrix
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thyroid cartilage
adam's apple
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chondroblasts
produces cartilage cells
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lacunae
little cavities
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chondrocytes
cells enclosed in lacunae
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hyaline cartilage
clear, glassy appearance, which stems from the usually invisible fineness of its collagen fibers
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elastic cartilage
conspicuous elastic fibers
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fibrocartilage
coarse, readily visible bundles of collagen
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perichondrium
sheath of dense irregular connective tissue
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bone (osseous tissue)
hard, calcified connective tissue that composes the skeleton
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spongy bone
fills the heads of the long bones and forms the middle layer of flat bones
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compact (dense) bone
denser calcified tissue with no spaces visible to the naked eye
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central (haversian or osteonic) canals
run longitudinally through the shafts of long bones
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concentric lamellae
onionlike layers around each canal
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osteocytes
bone cells
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canaliculi
delicate channels that radiate from each lacuna to its neighbors and allow the osteocytes to contact each other
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periosteum
tough fibrous similar to the perichondrium of cartilage
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blood
a fluid connective tissue that travels through tubular blood vessels
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blood plasma
blood's ground substance
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formed elements
its cellular components
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erythrocytes
red blood cells (most abundant)
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leukocytes (WBC)
serve various roles in defense against infection and other diseases
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platelets
small cell fragments scattered amid the blood cells
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excitable tissues
the highest degree in nervous and muscular tissues
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membrane potential
the basis for their excitation is an electrical charge difference
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nervous tissue
specialized for communication by means of electrical and chemical signals
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neurons
nerve cells
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neuroglia (glial cells)
protect and assist the neurons
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neurosoma (cell body)
houses the nucleus and most other organelles
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dendrites
multiple, short branched processes receives signals from other cells and conduct messages to the neurosoma
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axon (nerve fiber)
sends outgoing signals to other cells
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muscular tissue
specialized to contract when stimulated and thus to exert a physical force on other tissues, organs, or fluids
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skeletal muscle
consists of long threadlike cells that have muscle fibers
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muscle fibers
long threadlike cells
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sphincter
muscular rings or cuffs that open and close body passages
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striations
alternating light and dark bands, created by the overlapping pattern of cytoplasmic protein filaments that cause muscle contraction
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cardiac muscle
striated, cells are shorter
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cardiomyocytes
shorter cells that are exclusive to the heart, branched and notched at the ends
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intercalated discs
cardiomyocytes are joined end to end by junctions
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smooth muscle
lacks striations and is involuntary
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myocytes
smooth muscle cells that are fusiform and relatively short
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visceral muscle
forms layers in the walls of the digestive, respiratory and urinary tracts
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cell junctions
the connections between one cell and another, they enable the cells to resist stress, communicate with each other, and control the movement of substances through tissues
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tight junction
encircles an epithelial cell near its apical surface and joins it tightly to the neighboring cells
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desmosome
a patch that holds cells together somewhat like the snap on a pair of jeans
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hemidesmosomes
half desmosomes
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gap (communicating) junction
formed by a connexon surrounding a water-filled channel
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connexon
consists of 6 transmembrane protein arranged in a ring
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gland
a cell or organ that secretes substances for use elsewhere in the body or for elimination as waste
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secretion
removed from the tissues
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excretion
waste product that is released
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exocrine glands
usually maintain their contact with the surface by way of a duct
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duct
an epithelial tissue that conveys their secretion to the surface
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endocrine glands
lose contact with the surface and have no ducts, have a high density of blood capillaries and secrete their products directly into the blood
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hormones
chemical messengers that are secreted by endocrine glands
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unicellular glands
secretory cells found in an epithelium that is predominantly nonsecretory
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septa (singular, septum)
extensions
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trabeculae
divides the interior of the gland into compartments called lobes
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lobules
finer connective tissue septa may further subdivide each lobe into microscopic lobules
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stroma
connective tissue framework that supports and organized the glandular tissue
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parenchyma
the cells that perform the tasks of synthesis and secretion are collectively
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simple
single unbranched duct
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compound
branched duct
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tubular
the duct and secretory portion are of uniform diameter
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acinus
if the secretory cells form a dilated sac, the gland is called acinar and the sac is an acinus or alveolus
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tubuloacinar gland
a gland with secretory cells in both the tubular and acinar portions
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serous glands
produce relatively thin, watery fluids
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mucous glands
secrete a glycoprotein called mucin in the oral and nasal cavities
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mixed glands
contain both serous and mucous cells and produce a mixture of the two types of secretions
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merocrine (eccrine) glands
release their products by means of exocytosis
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holocrine glands
cells accumulate a product and then the entire cell disintegrates
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cutaneous membrane
largest membrane of the body, consists of a stratified squamous epithelium resting on a layer of connective tissue
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mucous membrane (mucosa)
lines passages that open to the exterior environment
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lamina propria
an areolar connective tissue
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muscularis mucosae
a layer of smooth muscle
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serous membrane (serosa)
composed of a simple squamous epithelium resting on a thin layer of areolar connective tissue
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serous fluid
produced by the serous membranes that arises from the blood and derives its name from the fact that it is similar to blood serum in composition
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mesothelium
epithelial component for of serous membrane
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endothelium (derived from mesoderm)
a simple squamous epithelium lining
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periosteum
covering of each bone
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hyperplasia
tissue growth through cell multiplication
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hypertrophy
the enlargement of preexisting cells
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neoplasia
the development of a tumor composed of abnormal, nonfunctional tissue
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differentiation
development of a more specialized form and function
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metaplasia
a change from one type of mature tissue to another
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stem cells
undifferentiated cells that are not yet performing any specialized function, but have the potential to differentiate into one or more types of mature functional cells
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developmental plasticity
diversity of mature cell types to which they can give rise
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embryonic stem cells
compose the early human embryo
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totipotent stem cells
they have the potential to develop into any type of fully differentiated human cell
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blastocyst
a hollow ball with an outer cell mass that helps form the placenta and other accessory organs of pregnancy, and an inner cell mass (embryoblast) that becomes the embryo itself
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pluripotent stem cells
cells of the inner cell mass that can still develop into any cell type of the embryo but not into the accessory organs of pregnancy
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adult stem cells
occur in small numbers in mature organs and tissues throughout a person's life
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multipotent
able to develop into two or more cell lines
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unipotent
stem cells have the most limited plasticity as they can produce only one mature cell type
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regeneration
the replacement of dead or damaged cells by the same type of cells
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fibrosis
the replacement of damaged tissue with scar tissue, composed mainly of collagen produced by fibroblasts
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granulation tissue
a soft mass with deeper portions of a clot that becomes infiltrated by capillaries and fibroblasts
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fibroblastic (reconstructive) phase
repair begins 3-4 days after the injury and lasts up to 2 weeks
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atrophy
shrinkage of a tissue through a loss in cell size or number
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senile atrophy
atrophy from normal aging
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disuse atrophy
lack of use of an organ
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necrosis
premature, pathological tissue death due to trauma, toxins, infection, and so forth
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infarction
the sudden death of tissue
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gangrene
any tissue necrosis resulting from an insufficient blood supply
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dry gangrene
often occurs in diabetes, especially in the feet
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decubitus ulcer (bed sore or pressure sore)
a form of dry gangrene that occurs when immobilized persons
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wet gangrene
occurs in internal organs and involves neutrophil invasion, liquefaction of the tissue, pus, and a foul odor
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gas gangrene
necrosis of a wound resulting from infection with a wound is contaminated with soil
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blebbing
bubbling
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apoptosis (programmed cell death)
normal death of cells
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fas
an extracellular suicide signal binds to a receptor protein in the plasma membrane
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endonuclease
chops up DNA
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protease
destroys cellular proteins
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nerve growth factor
those that make connections with target cells survive
