A&P Chapter 4: Flashcards
groups of cells similar in structure that perform common or related function
tissues
study of tissues
histology
four basic tissue types of histology:
1.) epithelial
2.) connective
3.) muscle
4.) nervous tissue
internal communication
- brain, spinal cord, and nerves
Nervous tissue
contracts to cause movement
muscle tissue
forms boundaries between different environments, protects, secretes, absorbs, filters
- lining of digestive tract organs and other hollow organs, glands, skin surface
epthelial tissue
supports, protects, binds other tissues together
- bones, tendons, fat and other soft padding tissue
connective tissue
tissue is preserved with solvent
fixed
cut into slices thin enough to transmit ligh or electrons
sectioned
to enhance contrast, although artifacts ( distortions) detract from what the sample looks like in living tissues
stained
is a sheet of cells that cover body surfaces or cavities
epitheial tissue (epithelium)
two main forms of the epithelial tissue
1.) covering and lining epithelia
- on external and internal surfaces (ex: skin)
2.) glandular epitheia
- secretory tissue in glands (ex: salivary glands)
main functions of epithelial tissue
protection, absorption, filtration, excretion, secretion, and sensory reception
epithelial tissue five distinguishing characteristics:
polarity, specialized contacts, supported by connective tissues, avascular, but innervated, and regeneration
cells have polarity (top and bottom)
polarity
upper free side, is exposed to surface or cavity
apical surface
decribe apical surface
most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli
lower attached side, faces inwards toward body
basal surface
describe basal surface
attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells
- epithelial tissues need to fit closely together
specialized contacts
supported by connective tissues
recticular lamina and basement membrane
- No blood vessels are found in epithelial tissue
- Epithelia are supplied by nerve fibers
avascular, but innervated
Stimulated by loss of apical-basal polarity and broken lateral contacts
regeneration
what cells have a high regenrative capacities
epithelial cells
all epithelial tissues have two names
1.) indicates number of cell layers
- simple epithelia and stratified epthelia
2.) indicates shape of cells
- squamous, cuboidial, and columnar
simple epithelia
are a single layer thick
stratified epithelia
are two or more layers thick and involved in protection (skin)
sqaumous
flattened and scale like
cuboidial
box-like, cube
columnar
tall, column-like
Involved in absorption, secretion, or filtration processes
simple epithelia
- Cells are flattened laterally, and cytoplasm is sparse
- Function where rapid diffusion is priority
- ex: kidney and lungs
simple sqaumous epithelium
Two special simple squamous epithelia are based on locations:
– Endothelium: lining of lymphatic vessels, blood vessels, and heart
– Mesothelium: serous membranes in the ventral body cavity
- Single layer of cells
– Involved in secretion and absorption
– Forms walls of smallest ducts of glands and many kidney tubules
simple cuboidial epithelium
- Single layer of tall, closely packed cells
- Involved in absorption and secretion of mucus, enzymes, and other substances
- Found in digestive tract, gallbladder, ducts of some glands, bronchi, and uterine
tubes
simple columnar epithelium
Cells vary in height and appear to be multi-layered and stratified, but tissue is in
fact single-layered simple epithelium
Pseudostratified columnar epithelium
- Involve two or more layers of cells
– New cells regenerate from below
stratified epithelial tissues
*Most widespread of stratified epithelia
▪ Free surface is squamous, with deeper cuboidal or columnar layers
▪ Located in areas of high wear and tear (example: skin)
▪ Keratinized cells found in skin; nonkeratinized cells are found in moist linings
stratified squamous epithelium
*Quite rare
▪ Found in some sweat and mammary glands
▪ Typically only two cell layers thick
stratified cuboidal epithelium
*Also very limited distribution in body
▪ Small amounts found in pharynx, in male urethra, and lining some glandular
ducts
▪ Usually occurs at transition areas between two other types of epithelia
stratified columnar epithelium
*Forms lining of hollow urinary organs
– Found in bladder, ureters, and urethra
▪ Basal layer cells are cuboidal or columnar
▪ Ability of cells to change shape when stretched allows for increased flow of
urine and, in the case of bladder, more storage space
transitional epithelium
One or more cells that makes and secretes an aqueous fluid called a secretion
gland
- internally secreting (example: hormones)
- Secrete (by exocytosis) hormones, messenger chemicals that travel through
lymph or blood to their specific target organs
– Target organs respond in some characteristic way - ductless glands
endocrine
- externally secreting (example: sweat)
- More numerous than endocrine glands
– Secrete products into ducts
exocrine
- Found in epithelial linings of intestinal and respiratory tracts
– All produce mucin, a sugar-protein that can dissolve in water to form mucus, a
slimy protective, lubricating coating - are only mucous cells and goblet cells
unicellular exocrine glands
Usually surrounded by supportive connective tissue that supplies blood and nerve
fibers to gland
▪ composed of a duct and a secretory unit
multicellular exocrine gland
multicellular exocrine glands structure
*Simple exocrine glands have unbranched ducts, but compound glands have
branched ducts
▪ In a tubular gland, secretory cells form a duct, whereas in alveolar glands,
secretory cells form sacs
multicellular exocrine glands mode of secretion
Merocrine: most secrete products by exocytosis as secretions are produced
(sweat, pancreas)
▪ Holocrine: accumulate products within, then rupture (sebaceous oil glands)
▪ Apocrine: accumulate products within, but only apex ruptures (maybe mammary cells
is the most abundant and widely distributed of primary tissues
connective tissue
four main classes of connective tissue:
connective tissue proper, cartilage, bone, and blood
characteristics make connective tissues different from other primary tissues
– Have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized)
– Cells are suspended/embedded in extracellular matrix (ECM) (protein-sugar
mesh)
all connective tissue have three main elements:
ground substance, fibers, cells
Unstructured gel-like material that fills space between cells
ground substance
connective tissue fibers
collagen, elastic fibers, recticular
- Strongest and most abundant type
▪ Tough; provides high tensile strength
collagen
▪ Networks of long, thin, allow for stretch and recoil
elastic fibers
- Short, fine, highly branched collagenous fibers (different chemistry and form
from collagen fibers)
▪ Branching forms networks that offer more “give”
recticular
Immature form of cell that actively secretes ground substance and ECM fibers
“blast” cell
found in connective tissue proper
fibroblast
found in cartilage
chondroblast
found in bone
osteoblast
Mature, less active form of “blast” cell that now becomes part of and helps maintain health of matrix
“cyte” cells
stores nutrients
fat cells
- Neutrophils, eosinophils, lymphocytes
▪ Tissue response to injury
white blood cells
Initiate local inflammatory response against foreign microorganisms they detect
mast cells
Phagocytic cells that “eat” dead cells, microorganisms; function in immune
system
macrophages
Consists of all connective tissues except bone, cartilage, and blood
connective tissue proper
two subclasses for connective tissue proper:
1.) CT proper: loose connective tissues
2.) CT proper: dense connective tissues
CT proper: loose connective tissues
areolar, adipose, and recticular
CT proper: dense connective tissues
dense regular, dense irregular, and elastic
areolar connective tissue
- Most widely distributed CT
▪ Supports and binds other tissues
▪ Universal packing material between other tissues
adipose tissue
white fat: Similar to areolar tissue but greater nutrient storage, richly vascularized, and functions in shock absorption, insulation, and energy storage
brown fat: Use lipid fuels to heat bloodstream rather than to produce ATP
recticular connective tissue
▪ Resembles areolar tissue, but fibers are thinner reticular fibers
* fibers form a mesh-like stroma that acts as a support for blood cells
in lymph nodes, spleen, and bone marrow
dense regular connective tissue
- Very high tensile strength;
▪ Closely packed bundles of thick collagen fibers run parallel to direction of pull
ex: tendons and ligaments
dense irregular connective tissue
- bundles of collagen are thicker
▪ Forms sheets rather than bundles
▪ Resists tension from many directions - found in dermis, fiberous joint capsules, fiberous coverings of some organs
elastic connective tissue
- Some ligaments are very elastic
– Example: ligaments connecting adjacent vertebrae must be very elastic
▪ Also found in walls of many large arteries
– Arteries need to stretch when blood enters and recoil to push blood out
Matrix secreted from chondroblasts (during growth) and chondrocytes (adults)
cartilage
receives nutrients from membrane surrounding it (perichondrium)
avascular
three types of cartilage:
hyaline cartilage, elastic cartilage, and fibrocartilage
hyaline cartilage
- Most abundant; “gristle”
▪ Appears as shiny bluish glass
▪ Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs
elastic cartilage
- Similar to hyaline but with more elastic fibers
▪ Found in ears and epiglottis
fibrocartilage
- Properties between hyaline and dense regular tissue
▪ Strong, so found in areas such as intervertebral discs and knee
bone
_ Also called osseous tissue
– Supports and protects body structures
– Stores fat and synthesizes blood cells in cavities
– Has more collagen compared to cartilage
– Has inorganic calcium salts
– Osteoblasts produce matrix
maintain the matrix
osteocytes
- Most atypical connective tissue because it is fluid
- Functions in transport and in carrying nutrients, wastes, gases, and other
substances
blood
- Highly vascularized
- Responsible for most types of movement
muscle tissue
three types of muscle tissue
skeletal muscle, cardiac muscle, and smooth muscle
skeletal muscle tissue
- Attached to and causes movement of bones
– Also called voluntary muscle
– Cells are called muscle fibers
cardiac muscle tissue
- Found only in walls of heart
– Involuntary muscle
– Like skeletal muscle, contains striations; but cells have only one nucleus
– Cells can have many branches that join branches of other cardiac cells
smooth muscle tissue
- Found mainly in walls of hollow organs (other than heart)
– Involuntary muscle
– Has no visible striations
– Spindle-shaped cells with one nucleus
Main component of nervous system (brain, spinal cord, nerves)
nervous tissue
specialized nerve cells that generate and conduct nerve impulses
neurons
three types of covering and lining membranes
Cutaneous membranes, mucous membranes, and serous membranes
cutaneous membranes
_ Another name for skin
* Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of
connective tissue (dermis)
* Unlike other membranes, skin is a dry membrane
mucous membranes
- Mucosa indicates location, not cell composition
- Also called mucosae
- Moist membranes bathed by secretions (or urine)
- Epithelial sheet lies over layer of loose connective tissue called lamina propria
- May secrete mucus
serous membranes
- Also called serosae
- Found in closed ventral body cavities
- Constructed from simple squamous epithelium (called mesothelium) resting on thin
areolar connective tissue
- Repair starts very quickly
- Repair is the function of the inflammatory process
tissue repair
repair can occur in two major ways:
- Regeneration: same kind of tissue replaces destroyed tissue, so original function
is restored
– Fibrosis: connective tissue replaces destroyed tissue, and original function lost
The steps in tissue repair:
1.) Inflammation sets stage
2.) Organization restores blood supply
3.) Regeneration and fibrosis effect permanent repair
Inflammation sets stage
Release of inflammatory chemicals causes:
▪ Dilation of blood vessels
▪ Increase in blood vessel permeability
– Clotting of blood occurs
organization restores blood supply
- begins as the blood clot is replaced with granulation tissue (new
capillary-enriched tissue)
– Epithelium begins to regenerate
– Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete
– Any debris in area is phagocytized
Regeneration and fibrosis effect permanent repair
- The scab detaches
– Fibrous tissue matures
– Epithelium thickens and begins to resemble adjacent tissue
– Results in a fully regenerated epithelium with underlying scar tissue, which may or
may not be visible
Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue
Tissues that regenerate extremely
Tissue with moderate regenerating capacity
smooth muscle and dense regular connective tissue
Tissues with virtually no functional regenerative capacity
- Cardiac muscle and nervous tissue of brain and spinal cord
– New research shows cell division does occur, and efforts are underway to coax
them to regenerate better
primary germs layer
- Superficial to deep: ectoderm, mesoderm, and endoderm
