Chapter 4: Histology Flashcards
histology
study of the structure of tissues
tissue
composed of cells and surrounding extracellular matrix (ECM)
extracellular matrix composition (ECM)
is composed of the substances surrounding the cells in a tissue
ECM has 2 main components: ground substance and protein fibers
4 classes of tissues
epithelial, connective, muscle, and nervous tissue
function of ECM
provides tissue with strength, regulates cell activity, and anchors cells in place
3 types of protein fibers
collagen, elastic, and reticular fibers
collagen fibers
most abundant protein in body; composed of multiple subunits of fibrous protein
- very resistant to tension/pressure (STRONG)
elastic fibers
- composed of the protein “elastin”, that’s surrounded by glycoproteins
- very STRETCHY and does NOT break, returns to original length
reticular fibers
a type of collagen fiber
thinner and shorter than collagen fibers, and they interweave to form a meshwork (reticul- = “netlike”) that supports cells and the ground substance of many tissues.
cell junctions
intercellular connections between the plasma membranes of adjacent cells of tissues
tight junctions
make the space between adjacent cells impermeable to macromolecules (sealed tight)
desmosomes
anchor neighboring cells together to increase the strength of a tissue with respect to mechanical stress
gap junctions
small pores in the plasma membranes of two adjacent cells that allow small substances to pass from the cytosol of one cell to that of another
functions of epithelial tissues
function in protection, immune defenses, secretion, transport, and sensation
what cell junctions does epithelial cells have?
epithelial cells are joined by tight junctions and desmosomes
basement membrane
thin, dense layer of ECM that anchors epithelia to underlying tissues
is Epithelia vascular or avascular?
avascular (no blood vessels)
simple epithelia
only one cell layer
stratified epithelia
have 2 or more cell layers
squamous epithelia
FLAT cell layer(s)
cuboidal epithelia
CUBED cell layer(s)
columnar epithelia
COLUMN shaped (long) cell layer(s)
describe transport across simple epithelia
only 1 thin cell layer, substances are able to cross them rapidly
2 types of transport across epithelia
paracellular transport and transcellular transport
paracellular transport
substances can leak between the cracks of the epithelial cells
transcellular transport
process where substances cross epithelia directly
substance enters cell’s the phospholipid bilayer, diffuses through cytosol, and exits through other cell surface.
list of simple epithelia
simple squamous, simple cuboidal, and simple columnar epithelium
ciliated pseudostratified columnar epithelium
a type of simple epithelium that appears stratified but consists of only a single layer of cells
list of stratified epithelium
stratified squamous (may or may have keratinized layer)
stratified cuboidal and columnar epithelia (both rare in body)
transitional epithelium (found in urinary system)
2 types of glands in the body
exocrine, and endocrine glands
exocrine glands
release their product through a duct to an epithelial surface. Most of their products have local actions
endocrine glands
release their product into the bloodstream
their products can have actions on distant target cells in the body
structure of multicellular glands
vary in shape and complexity
3 ways exocrine glands release their products:
merocrine, holocrine, and apocrine secretion
merocrine secretion
the product is released by exocytosis
holocrine secretion
the cell ruptures (breaks), releasing the product
apocrine secretion
a portion of the cytoplasm is pinched off and released with the product
connective tissues functions
include connecting and binding, support, protection, and transport
2 basic types of connective tissue:
connective tissue proper and specialized connective tissue
cells of connective tissue proper
may be resident cells or migrant cells.
Resident cells: fibroblasts, adipocytes, mast cells, and phagocytes
Migrant: Leukocytes (white blood cells)
4 types of connective tissue proper
Loose (areolar) and dense connective tissue, reticular tissue, and adipose tissue
Loose connective tissue
- has all 3 fiber types (collagen, elastic, reticular)
- primary element = ground substance
- part of the SKIN and lines body CAVITIES and hollow organs
functions of dense connective tissue
supports, protects, and holds bones, muscles, and other tissues and organs in place
Dense irregular connective tissue
contains bundles of collagen fibers arranged at various angles (RANDOM) to one another
Dense regular collagenous connective tissue
contains parallel bundles of collagen fibers
dense regular elastic connective tissue
contains parallel bundles of elastic fibers
reticular tissue
contains numerous reticular fibers in its ECM that form weblike networks in the SPLEEN and LYMPH NODES
adipose tissue
contains adipocytes (fat storage cells) as its primary element
adipocyte
a cell specialized for the storage of fat, found in connective tissue
The 3 specialized connective tissues:
cartilage, bone, and blood
cartilage
a tough but flexible tissue that absorbs shock and is resistant to tension and compression
3 types of cartilage
hyaline cartilage, fibrocartilage, and elastic cartilage
hyaline cartilage
found on the ends of bones in joints, in the nose, in certain respiratory passages, and where the ribs meet the sternum
fibrocartilage
contains many bundles of collagen fibers in its ECM
is found in certain joints and the INTERVERTEBRAL discs
elastic cartilage
contains elastic fibers in its ECM and is found in the EAR and in parts of the LARYNX
bone (osseous tissue) composition
contains collagen fibers, ground substance, and calcium phosphate crystals
osteoblasts
make (BUILD) the organic component of the ECM
osteoclasts
break down bone (clasts = clash/destroy)
blood
a fluid connective tissue
ECM is plasma and the main cell types are erythrocytes and leukocytes
erythrocytes
red blood cells
leukocytes
white blood cells
describe how muscle tissue cells function
cells contract by turning the chemical energy of ATP into the mechanical energy of movement
muscle cells
excitable cells that respond to electrical or chemical stimulation
They may be striated or smooth
3 types of muscle tissue:
skeletal, cardiac, and smooth muscle tissue
skeletal muscle tissue
voluntary
consists of long, striated, multinucleated muscle fibers
cardiac muscle tissue
involuntary
found in the heart. cells are striated, short, wide, and uni-nucleated
united by intercalated discs.
smooth muscle tissue
involuntary
uninucleate smooth muscle cells
found in the eye, lining most hollow organs, in the ducts of certain glands
nervous tissue makes up most of…
the brain, spinal cord, and nerves
neurons
excitable cells that send and receive messages in the form of NERVE IMPULSES to other neurons, muscle cells, and/or glands
axon
SINGLE neuron arm
carries nerve impulses AWAY from the CELL BODY
dendrites
one or more neuron arms
bring impulses from other neurons INTO the CELL BODY
neuroglial cells
the supporting cells of nervous tissue. Small dots in that float around it.
organs
made up of several different types of tissues that function together
membranes
thin sheets of one or more tissues that anchor organs in place, create barriers, function in immunity, and secrete substances
serous membranes
true membranes that secrete serous fluid
form the pleural, pericardial, and peritoneal body cavities
serous fluid
fills the interior of the membrane (lubricant)
synovial membranes
true membranes that secrete synovial fluid
line the cavities surrounding freely moveable joints
mucous membranes
membrane-like structures that SECRETE MUCOUS and line body passages and hollow organs that open to the outside of the body
cutaneous membranes
the skin, a membrane-like structure, and it consists of the superficial epidermis and the deeper dermis
regeneration
damaged cells are replaced with cells of the same type
fibrosis
fibroblasts fill in the defect with dense irregular connective tissue, forming scar tissue
tissues that undergo regeneration
Epithelial, most connective, and smooth muscle tissues
tissues that undergo fibrosis
Cartilage, skeletal muscle, and cardiac muscle tissues
