what is tissue
collections of cells and cell products that preform specific limited function
what are the four types of tissue
epithelial
connective
muscle
neural
what differentiates the different types
structure and function
what is the purpose of epithelial tissue and where is it found?
covers exposed surfaces and lines internal passageways
what does epithelial tissue form
glands
what does connective tissue do
fill internal space
supports other tissue
transport materials
stores energy
what is the specialty of muscle tissue
contraction
what are the three types of muscle tissue
skeletal tissue
cardiac muscle
smooth muscle ( walls of hollow organs
what does neural tissue do
carry electrical signals from one part of the body to another
what is epithelia
layers of cells covering internal or external surfaces
what are glands
structures that produce sereations
what are characteristics of epithelia
cellularity (cell junctions)
polarity (apical and basal surfaces)
attachment (basement membrane or basal lamina)
avascularity
regeneration
how does epithelia get its nutrients
it diffuses in from the basolateral
what can epithelia do faster than any other type of tissue
reproduce and regrow
are all epithelia ciliated ?
no
what are the functons of epithelial tissue
provide physical protection
control permeability
provide sensation
produce specialized secretions (glandular epithelium )
what are three specializations of epithelial cells
1. move fluids over the epithelium (protection)
2. move fluids through the epithelium (permeability)
3. produce secretions (protection and messengers)
what increases absorption or secretion of apical sufaces
microvilli
what moves fluid on the apical surface
cilia
what three things help maintain the physical integrity of an epithelium
intercellular connections
attachment to the basement membrane
epithelial maintenance and repair
what are CAMs (cell adhesion molecules)
transmembrane proteins that bind to each other and to extracellular material
what is the intercellular cement
protoglycans
what is hyaluronan (hyaluronic acid)
a glycosaminoglycan that bond a thin layer of proteoglycans
what are cell junctions and what are the three types
specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials. the three types:
tight junctions
gap junctions
desmosomes
what is a tight junctions
when lipid portion of the two plasma membrane are tightly bound together by interlocking membrane proteins. they are so tight they cant prevent passage of water and can isolate wastes in the lumen
where is an adhesion belt and what does it do
inferior to the tight junction and it forms a band that encircles cells and binds them to their neighbors. they are attached to the microfilaments of the terminal web
what are gap junctions
holds two cells together by interlocking transmembrane proteins called connexons. form narrow passageway that lets small molecules and ions pass from cell to cell
where are gap junctions common
among epithelial cells and other tissues
what do gap junctions do in the heart
coordinate contractions in heart muscle
what are desmosomes
here CAMs and proteoglycans link the opposing plasma membranes. they are strong and can resist stretching and twisting
describe the typical desmosome
formed by two cells, ad within each cell is a dense area which is connected to the cytoskeleton and this gives it its strength.
where are desmosomes abundant
between cells in the superficial layers of the skin (that is why damaged skin is lost in sheets)
what are the two types of desmosomes
spot desmosomes
hemidesmosomes
what are spot desmosomes
small discs connected to bans of intermediate filaments. stabilize the shape of the cell
what are the hemidesmosomes
attach a cell to extracellular filaments in the basement membrane. helps stabilize position of epithelial cell and anchor it to underlying tissues
what are the two parts of the basement membrane
clear layer and the dense layer
describe the clear layer
closer to the epithelium, contains glycoprotiens and a network of fine protein filaments. secreted by epithelia. barrier to protein (thin)
describe the dense layer
contains bundles of coarse protein fibers produced by connective tissue cells. thick fibers , produced by connected tissue, strength and filtration
how are epithelia are replaced
by division of germinative cells (stems cells) -located near the basement membrane
how are epthelia classified
by shape and layers
what are the three shapes of epithelia
squamous
cubodial
columnar
what are the two layer types of epithelia
simple
stratified
what are the four types of squamous epithelia
-simple squamous epithelium
-mesothelium
-endothelium
stratified squamous epithelium
what does simple squamous epithelia do
absorb and diffuse
what does mesothelium do and where is it
lines body cavities and it is in the middle and does not communicate with the outside world
what is the endothelium
it lines heart and blood vessels and does not communicate with the outside world
what is stratified squamous epithelium
generally located where mechanical stresses are severe and they form several layers. they protect against attacks. keratin protein adds strength and water resistance (keratinized) . non keratinized resist abrasion but will dry out and deteriorate unless kept moist.
what does simple cubodial epithelia provide
limited protection and occurs where secretion or absorption take place
where is stratified cubodial epithelia founded
along the ducts of sweat glands and in the larger ducts of mammary glands
what is transitional epithelia
an unusual stratified epithelium because, unlike most epithelia, it tolerates repeated cycles of stretching and recoiling without damage. the appearance changes as stretching occurs. (in urinary system)
where is simple columnar epithelium chemical stress typically found
where absorption and secretion occurs (like in the small intestine) and can protect against
what is pseudostratified columnar epithelium and what does it typically have?
a columnar epithelium that includes several types of cells with varying shapes and functions. they nucleus are not aligned giving the appearance of being stratified but they are not. they typically have cilia (ex:trachea)
what does stratified columnar epithelia do an where?
provides protection along potions of pharynx, epiglottis, anus, and urethra and a few large excretory ducts?
what do endocrine glands do
release their secretions into the interstitial fluid (no ducts)
what do exocrine glands do
release their secretions into ducts that open onto an epithelial surface
what are the three modes of secretions for glandular epithelia
merocrine
apocrine
holocrine
what is merocrine secretion and where is it produced? what is an example
product is released from secretory vesicles by exocytosis so nothing is lost. it is produced in the Golgi apparatus. an example are sweat glands
what is apocrine secretion and where is it produced? what is an example
involves the loss of cytoplasm as well as the secretory product when the apical portion of the cytoplasm becomes packed with secretory vesicles and is then shed. it is produced in the Golgi apparatus and an example are mammary glands
how are holocrine secretion released and how are they replaced? what is an example
the entire cell becomes packed with secretory products. they are released by cell bursting killing glands which are replaced my stem cells. an example is sebaceous glands
modes of glandular secreation diagram
how is mucus formed
mucin mixed with water
what are the three types of secretions
serous glands
mucous glands
mixed exocrine glands
what do serous glands secrete
watery solution that contain enzymes
what do mucous glands secrete
mucins that hydrate to form mucus
what do mixed exocrine glands contain
both serous and mucous glands
what is an unicellular gland and what is an example
one cell that secretes everything. the only example is the Mucous (goblet) cells which are scattered among epithelia. an example is in intestinal lining
what is the simplest multicellular exocrine gland
the a secretory sheet in which gland cells form an epithelium that released cretions into an inner compartment
what three things describe the structure of multicellular exocrine glands
the structure of the duct
the shape of the secretory portion of the gland
the relationship between the ducts and the glandular areas
what are the two structure types a duct can have
it can be simple if it has a single duct that does not divide on its way to the gland cell or it can be compound if the duct divides one or more times on its way to the gland cells
what are the two shapes the secretory portion of a gland can have/
they can be tubular (tube shaped) or alveolar / acinar if they form blind pockets
what are glands whose secretory cells form both tubes and pockets called
tubuoalveolar and tubuloacinar
what kind of a relationship can a duct and a glandular area have
they can be branched where several secretory areas share one duct
mulitcellular glands diagram
...
what does connective tissues do for epithelial tissue
connect it to the rest of the body
what three basic components of connective tissue
specialized cells
extracellular protein fibers
fluid extracellular ground substance
what makes up the matrix? what does the the matrix for connective tissue
the extracellular fibers and ground substance together. it makes up the majority of the volume and determines specialized functions
what are 6 functions of connective tissue
- establishing a structural framework for the body
- transporting fluid and dissolved materials
- protecting delicate organs
- supporting, surrounding, and interconnecting other types of tissue
- storing energy reserves, esecially in the form of triglycerides
what are the three general categories of connective tissue
- connective tissue proper
- fluid connective tissue
- supporting connective tissue
what does connective tissue include and what does it do
includes connective tissues with many types of cells and extracellular fibers in a syrupy ground substance. it connects and protects
what does fluid connective tissue have and what does it do
distinctive populations of cells suspended in a watery matrix that contains dissolved proteins. they transport
how do supporting connective tissues differ from connective tissue proper and what do they do
because they have a less diverse ell population and a matrix containing much more densely packed fibers. they give structural support
what are the two types of connective tissue proper?
loose connective tissue and dense connective tissue
what is loose connective tissue
packing materials of the body. they fill spaces between organs, cushion and stabilize specialized cells in many organs and support epithelia. they have more ground substance and fewer fibers
an example is fat (adipose tissue)
what is dense connective tissue?
most of the volume occupied by fibers and often contain collagenous tissues because fibers are the dominant type f fiber in the. ( less ground substance) an example is tendons
what are the 9 connective tissue proper ell populations
fibroblast
fibrocytes
adipocytes
mesenchymal cells
macrophages
mast cells
lymphocytes
microphages
melanocytes
what is the most abundant cell type and where is it found? whats it secrete? what does it help make
fibroblast
in all connective tissue proper
secrete proteins and hyaluronan
they help make ground substance gel
what is the second most abundant cell type and where is it found? whats does it do
fibrocytes
found in all c.t proper.
maintain fibers of connective tissue
what are adipocytes? where is it found?
fat cells. each cell stores a single large fat droplet. only found in loose c.t. proper
what are mesenchymal cells? where are they found and what do they differentiate into?
stem cells that respond to injury or infection. they are found in embryonic cells and stem cells so they can turn into anything. it is found in all c.t. proper. they differentiate into fibroblast and macophages
What do melanocytes do?
Synthesize and store the brown pigment melanin
What are the three types of connective tissue fibers?
Collagen, reticular, and elastic. They are all secreted by fibroblast and are specialized proteins
What is the most common fiber in connective tissue proper?
Collagen fibers
Describe collagen fibers.
Long straight and unbranched, strong and flexible, and resist force in one direction. They are thick and durable
What is an example of collagen fibers?
Tendons and ligaments
What is a network of interwoven fibers?
Reticular fibers
Describe reticular fibers.
Strong and flexible, resist force in many directions, stabilize functional cells and structures
What is an example of reticular fibers?
Sheaths around organs
Describe elastic fibers
Contain elastin, branched and wavy, and they return to original length after stretching. It is protein made by fibroblast. It is like a rubber band and it is very durable.
What is the ground substance of connective tissue?
A clear colorless and viscous thing that fills space between cells and slows pathogen movement and also protects
Is embryonic connective tissue found in adults?
No the cells are but Wharton’s jelly is not. we have the cells so we can heal when needed by we don’t have the jelly because we do not need to regenerate
What is the first connective tissue found in embryos?
Mesenchyme (embryonic stem cells)
What is the loose embryonic tissue called?
Mucous connective tissue
What is the “packing material” of the body?
Loose connective tissue
What are the three types of loose connective tissue found in adults?
Areolar, adipose, and reticular
What is the least specialized of the three loose connective tissues?
Areolar
Describe areolar c.t.:
open framework, viscous ground substance, elastic fibers, and holds blood vessels and capillary beds. They are not very complex
What is an example of areolar c.t.?
Under the skin
Describe adipose tissue.
Contains many adipocytes (fat cells)
What are the two types of adipose tissue?
White fat and brown fat.
Describe white fat.
Most common, stress fat, absorbs shocks, and slows heat loss
Describe brown fat.
More vascularized, adipocytes have many mitochondria, when stimulated by nervous system fat breakdown accelerates, releasing energy. It also absorbs energy from surrounding tissues
Which of the two types of adipose tissue is primarily found in adults? Which is found in infants?
White. Brown and it has more fat cells
Adipocytes do not divide. Instead what do they do?
They expand to store fat and shrink as fats are released.
What cells can divide and differentiate and why do they do it?
Mesenchymal cells. They do it to produce more fat cells when more storage is needed
Describe reticular fibers.
They provide support, they are complex and three- dimensional networks, they have supportive fibers and reticular organs.
What do the supportive fibers (stoma) support?
Functional cells (parenchyma)
What are the reticular organs?
Spleen, liver, lymph nodes, and bone marrow
What is dense connective tissue?
Connective tissue proper that is tightly packed with high numbers of collagen elastic fibers
What are the three types of dense connective tissues?
Dense regular, dense irregular, and elastic
Describe dense regular.
Tightly packed, parallel collagen fibers
What are three types of dense regular connective tissues and what do they connect?
Tendons- attach muscle to bone, ligaments- connect bone to bone and stabilize organs, and aponeuroses- attach in sheets to large, flat muscle
Describe dense irregular connective tissue.
Interwoven networks of collagen fibers. They are layered in skin, around cartilage, around bones, and form capsules around some organs
What is elastic tissue made of?
Elastic fibers
What does supporting connective tissue do?
Support soft tissue and body weight
What is cartilage and what is it for? A gel-type ground substance and it is for shock absorption and protection
A gel-type ground substance and it is for shock absorption and protection