Anatomy Mid 1 - Epithelial Tissues

mucus

a lubricant to reduce wear & tear; also traps debris( dust, bacteria) and contains a group of enzymes called lysozymes- digest bacterial cell walls ( respiratory,GI, urinary & repro tracts)

surface of modification

cilia- composed of microtubles, have a sweeping action in one direction - cilia move in concert, move fluids over surface of cells, do not move big things, in trachea & fallopian tubes, not GI Microvilli- also called brush borders, modification of cell membranes to enhance absorption are present in places body needs to take up materials( small intestine) Flagella - similar to cilia but single, longer, for locomotion: sperm

What type of intercellular junction provides resistance to mechanical stress at a single point?

desmosomes

what is intercellular junction?

epithelial cells are strongly bound together by specialized connections in the plasma membranes of their lateral surfaces called intercellular junctions..

nervous tissue

excitable, provides communication,initiates and transmits nerve impulses

Where is simple columnar epithelium found?

inner lining of digestive tract stomach, small intestine, large intestine, rectum, fallopian tubes, endometrium, and respiratory bronchioles

Where is transitional epithelium found?

inner lining of urinary bladder and linings of ureters and part of urethra

adhering junction ( #5 in pic)

this type of junction occurs when extensive zones of mircrofilaments extend from cytoplasm into plasma membrane, forming a supporting and strengthening belt within the plasma membrane, that completely encircles the cell immediately adjacent to all of its neighbors. ....thus, the function affords a passageway between cells for materials that have already passed through the apical surface of the epithelial cell and can then exit through the membranes on the lateral surface and continue their journey toward the basement membrane.

gap junctions

provide a direct passageway for small molecules traveling between neighboring cells.Ions, glucose , amino acids, and other small solutes can pass directly from the cytoplasm of one cell into the neighboring cell through these channels. the flow of ions between cells coordinates such a cellular activities as the beating of cilia.

multicellular glands

duct- can be simple or compound secretory unit- can be tubular or alveolar ( acinar) simple: *tubular- coiled or branched *alveolar-simple or branched compound: *tubular *alveolar *tubulalveolar

stratified columnar

rare, for protection & secretion, pharnyx, larynx, male urethra

stratified cuboidal

rare, for protection, ducts of sweat glands

basement membrane is composed off..?

three layers: -lamina lucida -lamina densa -reticular lamina

which intercellular junction ensures that epithelial cells act as gatekeepers

tight junction

transitional

tissue is stratified; cells rand from Squamous to cuboidal in appearance; this tissue permits distension, has ability to expand w/out tearing only found in urinary system, bladder, portions of ureter, urethra

exocrine glands

release substances via duct to a free surface or lining eg mucous, sweat, oil, saliva, enzymes

endocrine

releases hormone into blood

number of layers

simple- one layer of cells over basement layer stratified- several layers of cells over basement membrane

cell shape

squamous - flattened, scale- like cells, very thin, irregular shape, so thin nucleus causes a buldge cuboidal- like a cube columnar - much longer than wider, rectangle set on ends ,nucleus in lower ( basal ) end

stratified squamous

strongest epithelium in body, placed in areas of great wear & tear, too thick for absorption mouth, esophagus, vagina, anus; kertinized in skin

SPECIALIZED structures of epithelial tissue

the four types of epithelial cell junctions are -tight junctions -adhering junctions -desmosomes -gap junction

epithelial tissue covers?......... and forms .....?

the surface of the body, lines body cavities, and forms secretory structure called glands ( exocrine and endocrine glands)

What are the three secretion methods of exocrine glands, and how does erach method mowrk?

(1) Merocrine secretion - occurs when small secretory vesicles move to the apical surface of the cell and release their contents by exocytosis. (2) Holocrine secretion - occurs when cells fill with an accumulated product and then the entire cell disintegrates releasing both product and cell fragments. (3) Apocrine secretion - occurs when the apical region of the cell 'pinches off' releasing some cellular fragments and product.

What are the similarities and differences between skeletal muscle, cardiac muscle and smooth muscle?

(1) Skeletal muscle tissue is composed of long, cylindrical thin muscle cells called muscle fibers, have more than one nucleus, are striated, attached to the skeleton, and are voluntary. (2) Cardiac muscle tissue is confined to the heart wall; its cells are often shorter than skeletal muscle cells, but they are striated like skeletal muscle cells; cardiac muscle cells usually are branched and they contain only one or two, centrally-located nuclei. Cardiac muscle cells are connected together by intercalated discs, which are strong gap junctions between the cells. (3) Smooth muscle tissue lacks the striations seen in the other two types of muscle tissue. It is involuntary and called visceral muscle because it is found in the walls of most viscera (organs), such as the stomach, urinary bladder, and blood vessels. Its contraction helps propel material.

List the epithelian type that is found (a) lining the lumen of the stoomach (b) lining the oral cavity (c) lining the urinary bladder (d) lining the tiny air sacs of the lungs

(a) simple columnar epithelium. (b) stratified squamous epithelium. (c) transitional epithelium. (d) simple squamous epithelium.

In what regions of the body would you expect to find hyakunbe cartilage, fibocartilage, and elastic cartilage, and why would thee supporting connective tissues be located in thee regions

*Hyaline cartilage is found in: - nose - trachea - larynx (voice box) - costal cartilage (the cartilage attached to the ribs) - articular ends of long bones - the fetal skeleton. *Hyaline cartilage functions primarily to support soft tissue: it also forms most of the fetal skeleton and in so doing it forms a model for future bone growth. Fibrocartilage is found: - in the intervertebral discs - the pubic symphysis - the menisci of the knee joint. *Fibrocartilage resists compression and is a good shock absorber. *Elastic cartilage is found: - within the epiglottis - and in the external earis *Elastic cartilage is extremely resilient and flexible.

basement membrane functions

- provide physical support for the epithelium - anchoring the epithelium to the connective tissue - acting as a barrier to regulate the movement of large molecules between the epithelium and the underlying connective tissue

what are the characteristics of epithelial tissue

-cellularity -polarity -attachment to basement membrane -avascularity -innervation -high regeneration capacity * epithelial cells have apical (free) surface, junctions on lateral membranes that bind neighboring cells, and a basal surface, which is closest to the basement membrane,

four tissue types in the body

-epithelial tissue -connective tissue -muscle tissue -nervous tissue

functions of epithelial tissue

-physical protection -selective permeability -secretions -sensations

what are the four types of epithelial cell junctions ?

-tight junctions -adhering junctions -desmosomes -gap junction

Classification of epithelial tissue

1. Number of layers of cells 2. Shape of cells

Identify the three types of protein fibers in connective tissue proper.

Collagen fibers, elastic fibers, and reticular fibers make up connective tissue proper.

Why is one epithelium referred to as "pseudostratified"?

A pseudostratified epithelium looks multilayered, or stratified, because the cells' nuclei are distributed at different levels between the apical and basal surfaces. However, although all of these epithelial cells are attached to the basement membrane, some of the cells do not reach its apical surface.

What type of intercellular junction provides resistance to mechanical stress at a single point?

Desmosomes provide resistance to mechanical stress at a single point.

connective tissue characteristics

Diverse types; all contain cells, protein fibers, and ground substance

What characteristics are common to all connective tissues?

All connective tissue share a similar structural plan that includes: the presence of specific connective tissue cells that produce an extracellular matrix contain protein fibers to strengthen and support the connective tissue and an amorphous ground substance within which the cells and fibers reside.

What are some common characteristics of all types of epithelium?

All epithelia exhibit cellularity, polarity, attachment to underlying connective tissue, avascularity, innervation, and high regeneration capacity.

Why is epithelial cell regeneration important to the continues functioning of a holocrine gland?

Because each secretory cell is destroyed during holocrine secretion, the ruptured, dead cells are replaced by regeneration.

What two main characteristics are used to classify epithelial tissues?

Epithelial tissues are classified according to the number of cell layers and the shape of the cell at the apical surface.

Where is stratified squamous epithelium found?

Esophagus, mouth, and vagina, epidermis of the skin, and dry membranes.

What is the extracellular matrix? What are its main components?

Extracellular matrix is a nonliving material produced by and surrounding connective tissue cells. Protein fibers and ground substance are the components of the extracellular matrix.

simple cuboidal epithelium

Function: secretion and absorption Location: Kidney tubules; ducts and secretory portions of small glands, ovary surface.

simple columnar

Functions in active transport, secretion, stronger than cuboidal, ducts of some glands, stomach cilated: Fallopian tube, small bronchi brush border ( microvilli): for absorption; intestines

What general name is applied to the supporting cells in nervous tissue?

Glial cells are the supporting cells in nervous tissue.

single cells

Goblet cells- are single cell glands, secrete mucus to t Mucus- a lubricant to reduce wear & tear ; also traps debris ( dust, bacteria) and contains a group of enzymes called lysozmes- digest bacterial cells walls ( respiratory, GI, urinary & repro tracts)

What are the main structural differences between dense regular and dense irregular connective tissue?

In dense regular connective tissue, collagen fibers are packed tightly, and aligned parallel to applied forces. In dense irregular connective tissue collagen fibers form a scattered meshwork array in which individual bundles of fibers extend in all directions.

What are Intercalated discs?

Intercalated discs are strong gap junctions between neighboring cardiac muscle cells. They permit the rapid transport of an electrical stimulus (nerve impulse) through many cardiac muscle cells at once, allowing the entire muscle wall to contract as a unit.

Compare loose connective tissue to dense connective tissue with respect to fiber density and distribution and amount of ground substance.

Loose connective tissue has a scattered distribution of fibers that are in relatively low concentration; it is primarily ground substance. Dense connective tissue has extensively distributed fibers, which are its primary component. Ground substance is sparse in dense connective tissue.

tight junctions ( #3 in pic)

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid * the tight junction forces almost all materials to move through, rather than between, the epithelial cells in order to cross the epithelial.Thus, epithelial cells control whatever enters and leaves the body by moving across the epithelium. for example, in the small intestine, tight junctions prevent digestive enzymes that degrade molecules from moving between epithelial cells into underlying connective tissue.

What is the function of mucus membranes?

Mucous membranes function in absorption, protection, and secretion.

What are the two basic parts of a multicellular exocrine gland?

Multicellular exocrine glands contain both a secretory portion and a conducting portion.

classification of ET

Number of layers, cell shape, surface modification

Fuctions of Epithelial Tissue

Protection- from physical and chemical trauma transport- filtration,secretion, excretion, absorption, glands - secretion miscellaneous- digestion, sensory reception, reproduction, lubrication, temperature regulation

rules for naming epithelium tissue

Sequence is - number of layers, cell type, modification *cilia are never on squamous or cuboidal cells, only columnar *microvilli are never on squamous cells pseudostratified - appear stratified but is simple, all cells touch basement membrane transitional - always stratified, cells are cuboid al in shape

What type of muscle tissue has long, cylindrical, multinucleated cells with obvious striations?

Skeletal muscle tissue has long, cylindrical, multinucleated cells with obvious striations.

Describe the basement membrane, its origins, and its functions

The basement membrane is a three layered, protein and carbohydrate structure secreted by the overlying epithelium and the underlying connective tissue. The basement membrane provides physical support for the epithelium, anchors the epithelium to the connective tissue, and acts as a barrier to regulate the movement of large molecules between the epithelium and the underlying connective tissue.

Distinguish between the parietal and visceral layers of the serious membrane.

The parietal layer of a serous membrane lines the body cavity, and the visceral layer covers organs.

What three categories are used to classify connective tissue types?

The three categories of connective tissue are connective tissue proper, supporting connective tissue, and fluid connective tissue.

Which intercellular junction ensures that epithelial cells act as "gatekeepers"?

The tight junction (zonula occludens) ensures that epithelial cells act as "gatekeepers."

Name the four types of body membranes

The types of body membranes include: (1) mucous membrane: lines body passageways. *digestive *respiratory *reproductive *urinary (2) serous membrane: *lines body cavities - the parietal layer and *covers organs - the visceral layer (3) cutaneous membrane: *the skin - both epidermis and dermis (4) synovial membrane: *lines some joints of the skeletal system

Describe the types of intercellular junctions between epithelial cells and where each is located

There are four types of intercellular junctions in the lateral surfaces of epithelial cell membranes. (1) tight junctions - encircle the cells near their apical surfaces and completely attach each cell to its neighbors. (2) adhering junctions - deep to the tight junctions and form a supporting and strengthening belt of protein fibers inserted into the plasma membrane. (3) desmosomes - a small region of protein fibers that hold cells together and provide resistance to mechanical stress at a single point. (4) gap junctions - provide a direct passageway through protein pores between cells for small molecules to communicate between neighboring cells.

Why is smooth muscle referred to as involuntary?

We do not have voluntary control over smooth muscle.

desmos=

a band

pseudostratified

appears stratified, but is simple, all cells touch basement membrane strongest among simple types; almost always ciliated & has goblet cells good for protection, not for absorption, found in nasal cavity, trachea bronchi thin to allow warming & humidification of air, mucus captures debris & bacteria in air, cilia move the mucus to pharynx - can be removed via mouth or sent to stomach via esophagus

goblet cells

are single cell glands. secrete mucus to lubricate surfaces

Where is hyaline cartilage found?

articular cartilage, costal cartilage, trachea, larynx, fetal skeleton

connective tissue functions

binds structures together, forms a framework, provides metabolic and physical support

where is fluid connective tissue found ?

blood

soma=

body

muscle tissue characteristics

contractile, receives stimulation from nervous system and/ or endocrine system

functions of epithelial tissue

covers body & organ surfaces, lines cavities & hollow organs, forms glands ( there are exocrine and endocrine glands); ET provides protection, transport * text def -epithelial tissues provide physical protection, control permeability, produces secretory products, and contain nerve cells that detect sensation. gland cells are derived from epithelial cells and produce secretions.

muscle tissue functions

facilitates movement of skeleton or organ walls specialized for movement, contraction; is also excitable

glandular epithelium

function of glands is to secrete, tissue is modified & specialized for secretion glands can be endocrine or exocrine

structural classification of exocreine glands

glands can be single cells or multicellular

simple cuboidal w/ brush border ( microvilli)

goods for absorbing material from a fluid, very fragile; kidney tubules

desmosomes

is like a button or snap between adjacent epithelial cells. each cell contributes half of the complete desmosome. it is a small region that holds cells together and provides resistance to mechanical stress at a single point, but it does not totally encircle the cell. in contrast to tight junctions.which encircle the cell to secure it to its neighbors everywhere around its periphery, the desmosome attaches a cell to its neighbors only at potential stress points

where is smooth muscle found ?

muscle layer in digestive tract

where is cardiac muscle tissue found?

muscle layer in heart

Desmosomes is also known as

macula adherens

Basal Lamina

made of collagen and proteins & carbohydrates secreted by epithelium

Reticular Lamina

made of reticular fibers and proteins & carbohydrates secreted by CT cells

functional classification of exocrine glands

merocrine - cells release product by exocytosis ( pancreas) apocrine - apical portion of cell pinches off w/ product (mammary) holocrine- whole cells are released w/ their contents ( sebaceous glands)

where is skeletal muscle tissue found?

muscle attached to bones

general features, characteristics of ET

two major types: epithelial & glands celularity: tightly packed cells, many anchoring junctions, arranged in sheets. polarity: cells have an apical & a basal surface avascular: nutrients supplied via diffusion from CT below regenerative: high mitotic rate- many cells are lost due to wear and tear ( cancer possibly)

simple squamous epithelium

very thin, for diffusion, osmosis, filtration,glomerular capsule, lung alveoli endothelium- a type of SS; lines blood bessels, lymph vessles, heart mesothelium- a type of SS: part of serous membranes; covers organs, lines all body cavities

adhering junctions is also called ?

zonula adherens ( "adjesion belt")

tight junction is also called ?

zonula occludents