Chapter 4: The Tissue Level of Organization Flashcards
stratified epithelium
several layers of cells
epithelial tissue
covers the surfaces of the body, inside and out; produce glandular secretions
functions of epithelial cells
- physical protection
- permeability
- sensation
- specialized secretions
connective tissue
-support for the body
-connects all of its parts (mouth to anus)
-fill internal space
-store energy
muscle tissue
contracts to produce movement
neural tissue
conducts electrical impulses, carries information
exocrine secretions
discharged onto the surface of the epithelium
endocrine secretions
released into the surrounding tissue fluid and blood
three types of cellular junctions
tight, gap, desmosomes
tight junctions
-lipid layers of adjacent cell membranes are tightly bound together by interlocking membrane proteins
-prevent passage of water and solutes between cells
gap junction
-two cells are held together by embedded membrane proteins
-allow passage of small molecules and ions between cells
desmosome
locking of cells by intercellular cement and membrane proteins; more durable
those that resemble small discs are called “button desmosomes”; “hemidesmosomes” are half circles that attach cell to basement membrane
basement membrane
network of protein fibers which lies between epithelium and underlying tissues
simple epithelium
composed of a single layer of cells
simple squamous epithelium
single layer of flattened cells
reduces friction, controls permeability/absorption/secretion
found in: ventral body cavities, lining of heart/blood vessels, alveoli
simple cuboidal epithelium
single layer of cube shaped cells
limited protection, secretion/absorption
found in: glands/ducts, portions of kidney tubules
simple columnar epithelium
single layer of tall cells that fit closely together
secretion/absorption
found in: lining of GI tract
transitional epithelium
stretches readily
found in: ureters, urinary bladder, and part of the urethra
pseudostratified columnar epithelium
single layer of irregularly shaped and sized cells that give the appearance of multiple layers
found in: ducts of certain glands and the upper respiratory tract, portions of the male reproductive tract
stratified squamous epithelium
protects underlying tissues in areas subjected to high mechanical stress
found in: skin, lining of mouth, throat, rectum
goblet cells
-unicellular glands
-secrete mucous which protect and line intestinal tract
merocrine secretion
release of a substance from a gland via exocytosis; cell remains wholly intact
saliva from salivary glands, mucus in digestive and respiratory tracts, perspiration, milk
apocrine secretion
release of a substance along with the apical portion of the cell; cell remains partially intact
milk in breasts, viscous underarm perspiration
holocrine secretion
release of a substance caused by the complete rupture of a gland cell
skin oils and waxy coating of hair
serous secretion
watery solution containing enzymes
three basic components of connective tissue
cells, protein fibers, ground substance
functions of connective tissue
*support and protection
*transportation of materials
*storage of energy reserves
*defense of the body
connective tissue proper
tissue underlying skin, fatty tissue, tendons, ligaments
may be loose (adipose tissue) or dense (tendons and ligaments)
fluid connective tissue
blood and lymph
supporting connective tissues
cartilage and bone
fibroblasts
responsible for producing and maintaining the connective tissue fibers and ground substance
macrophages
engulf damaged cells or pathogens that enter tissue, release chemicals which mobilize the immune system
fat cells
adipocytes
mast cells
release heparin and histamine to begin body’s defense activities after an injury or infection
collagen fibers
long, straight, and unbranched; strong and flexible
elastic fibers
contain elastin; branched and wavy and return to original length after stretching
reticular fibers
least common; thinner than collagen fibers, form a branching, interwoven framework in various organs
ground substance
unstructured material that fills the space between the cells and contains fibers
loose connective tissue
pads and supports surrounding tissue
dense connective tissue
may be regular or irregular; mostly collagen fibers; tendons and ligaments
Chondrocytes
cartilage cells
hyaline cartilage
Most common type of cartilage; stiff but somewhat flexible
Where synovial fluid is present
ends of long bones, ribs, and nose
elastic cartilage
cartilage with abundant elastic fibers; tolerates distortion without damage, returns to original shape
outer ear, epiglottis, and middle ear
fibrocartilage
little ground substance, matrix is dominated by collagen fibers; resist compression and shock
vertebral column, pelvis, and around joints (medial/lateral epicondyles)
Osteocytes
mature bone cells
periosteum
fibrous (outer) and cellular (inner) layers covering bone
mucous membranes
coated with secretions of mucous glands
line the digestive, respiratory, urinary and reproductive tracts
serous membranes
line the ventral body cavities (peritoneal, pleural, pericardial)
cutaneous membrane
skin
synovial membranes
line joint cavities and produce fluid within the joint
skeletal muscle
large, multiple nuclei, prominent striations, unbranched arrangement
cardiac muscle
small, branch, single central nucleus, striated, interconnected by intercalated discs
smooth muscle
small and spindle-shaped, central nucleus, no branches or striations
Respiratory, circulatory, digestive, reproductive tracts
intercalated discs
specialized connections between myocardial cells containing gap junctions and desmosomes
neuroglia
-physical support for neural tissue
-maintain the chemical composition of the tissue fluids
-supply nutrients to neurons
-defend the tissue from infection
three parts of neuron
cell body, dendrites, axon
dendrites
receive messages from other cells
axon
send messages to other cells; end in synaptic terminals
fibrosis
replacement of damaged cells with scar tissue
characteristics of epithelial cells
*closely bound together
*free surface exposed to environment
*attachment to underlying basement membrane
*absence of blood vessels
*continually replaced/regenerated
