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