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Define tissue.

A tissue is a group of cells with similar structure and function that have similar extracellular substances located between them.


What is the name of the microscopic study of tissues.



There are four basic types of tissue. Name them.

1. Epithelial
2. Connective
3. Muscle
4. Nervous


Where in the body can you find epithelial tissue?

Epithelium covers external and internal surfaces throughout the body. Surfaces on the body include the outer layer of the skin and the lining of cavities. It also forms most glands.


There are two surfaces to epithelial tissue.

The free surface, which is not in contact with other cells, and the basal surface which is adjacent to a basement membrane.


What is the basement membrane?

It consist of a meshwork of protein molecules with other molecules bound to them.


What produces the basement membrane.

Usually both the epithelium and the underlying tissues.


What is the function of the basement membrane?

It can function as a filter and as a barrier to the movement of cells. Blood vessels also do not cross this membrane.


What are the major functions of epithelia?

1. Protecting underlying structures.
2. Acting as a barrier
3. Permitting the passage of substances
4. Secreting substances
5. Absorbing substances.


One of the functions of epithelia is Protecting underlying structures. , elaborate.

Examples include the outer layer of the skin and the epithelium of the oral cavity, which protects the underlying structures from abrasion.


One of the functions of epithelia is Acting as a barrier , elaborate.

Epithelium prevents many substances from moving through it. For example, the epithelium of the skin acts as a barrier to water and reduces water loss from the body. The epithelium of the skin also prevents many toxic molecules and microorganisms to enter the body.


One of the functions of epithelia is Permitting the passage of substances , elaborate.

Epithelium also allows many substances to move through it. For example oxygen and carbon dioxide are exchanged between the air and blood by diffusion through the epithelium in the lungs.


One of the functions of epithelia is Secreting substances , elaborate.

Sweat glands, mucous glands, and the enzyme-secreting portion of the pancreas are all composed of epithelial cells.


One of the functions of epithelia is Absorbing substances. , elaborate.

The cell membranes of certain epithelial tissues contain carrier proteins that regulate the absorption of materials. For example, the epithelial cells of the intestines absorb digested food molecules, vitamins, and ions.


How is epithelia classified?

Epithelia are classified according to the number of cell layers and the shape of the cells.


Which different layer types of epithelium are there?

1. Simple (single layer of cells)
2. Stratified (more than one layer)
3. Pseudostratified (modification of simple epithelium)
4. Transitional (modification of stratified epithelium)


Simple epithelium can have different cell shapes. Which?

Squamous, cuboidal or columnar.


Stratified epithelium can have different cell shapes. Which?

Squamous (nonkeratinized or keratinized), cuboidal (rare) or columnar (rare).


Pseudostratified epithelium can have different cell shapes. Which?

Only columnar. You'll see: pseudostratified columnar epithelium.


Transitional epithelium can have different cell shapes. Which?

Roughly cuboidal to columnar when not stretched, and squamouslike when stretched.


A squamous cell has a .... shape



A duboidal cell has a .... shape



A columnar cell has a ... shape

tall and thin, columnar...


What is the structure of simple squamous epithelium?

Single layer of flat, often hexagonal cells; the nuclei appear as bumps when viewed in cross section because the cells are so flat.


What is the function of simple squamous epithelium?

Diffusion, filtration, some secretion, and some protection against friction.


What is the location of simple squamous epithelium?

Lining of blood vessels and the heart, lymphatic vessels, alveoli of the lungs, portions of the kidney tubules, lining of serous membrane of body cavities.


What is the structure of simple cuboidal epithelium?

Single layer of cube-shaped cells; some cells have microvili (kidney tubules) or cilia (terminal bronchioles of the lungs).


What is the function of simple cuboidal epithelium?

Secretion and absorption by cells of the kiney tubules; secretion by cells of glands and choroid plexuses; movement of particles embedded in mucus out of the terminal bronchioles by ciliated cells.


What is the location of simple cuboidal epithelium?

Kidney tubules, glands and their ducts, choroid plexuses of the brain, lining of terminal bronchioles of the lungs, and surfaces of the ovaries.


What is the structure of simple columnar epithelium?

Single layer of tall, narrow cells; some cells have cilia (bronchioles of lungs, auditory tubes, uterine tubes, and uterus) or microvili (intestines).


What is the function of simple columnar epithelium?

Movement of particles out of the bronchioles of the lungs by ciliated cells; partially responsible for the movement of oocytes through the uterine tubes by ciliated cells; secretion by cells of the glands, the stomach and the intestine; absorption by cells of the intestine.


What is the location of simple columnar epithelium?

Glands and some ducts, brochioles of the lungs, auditory tubes, uterus, uterine tubes, stomach, intestines, gallbladder, bile ducts, and ventricles of the brain.


What is the structure of pseudostratified columnar epithelium?

Single layer of cells; some cell are tall and thin and reach the free surface, and oither do not; the nuclei of these cells are at different levels and appear stratified; the cells are almost always ciliated and are associated with goblet cells that secrete mucus onto the free surface.


What is the function of pseudostratified columnar epithelium?

Synthesize and secrete mucus onto the free surface and move mucus (or fluid) that contains foreign particles over the surface of the free surface and from passages.


What is the location of pseudostratified columnar epithelium?

Lining of the nasal cavity, nasal sinuses, auditory tubes, pharynx, trachea, and bronchi of the lungs.


What is the structure of stratified squamous epithelium?

Sever layers of cells that are cuboidal in the basal layer and progressively flattened toward the surface; the epithelium can be nonkeratinized (moist) or keratinized; in nonkeratinized stratified squamous epithelium, the surface cells retain a nucleus and cytoplasm; in keratinized stratified epithelium, the cytoplasm of cells at the surface is replaced by a protein called keratin, and the cells are dead.


What is the function of stratified squamous epithelium?

Protects against abrasion, forms a barrier against infection, and reduces loss of water from the body.


What is the location of stratified squamous epithelium?

Keratinized - outer layer of the skin; nonkeratinized - mouth, throat, larynx, esophagus, anus, vagina, inferior urethra, and corneas.


What is the structure of transitional epithelium?

Stratified cells that appear cuboidal when the organ or tube is not stretched and squamous when the organ or tube is stretched by fluid.


What is the function of transitional epithelium?

Accomodates fluctuations in the volume of fluid in an organ or a tube; protects against the caustic effects of urine.


What is the location of transitional epithelium?

Lining of the urinary bladder, ureters, and superior urethra.


Cells with the major function of diffusion are usually..



Cells with the major function of secretion or absorption are usually

cuboidal or columnar.


Why, most likely, are the cells with the major function of secretion or absorption usually cuboidal or columnar?

Because these tissue types have bigger cells that can hold more organelles - this makes them able to hold such functions.


What is the difference between microvili and cilia?

Microvili are cylindrical extensions of the cell membrane that increases the free surface area. Cilia propel materials along the free surface of cells.


What are tight junctions?

Epithelial cells are connected to one another in several ways, one of these is through tight junctions. They bind adjacent cells together and form permeability barriers. In this way, materials that pass through the epithelial layer must pass through the cells.


What are gap junctions?

Small channels that allow small molecules and ions to pass from one epithelial cell to an adjacent one.


What is a gland?

A gland is a structure that secretes substances onto a surface, into a cavity, or into the blood. Most glands are composed primarily of epithelium and are multicellular.


Two categories of glands exist. Which?

Exocrine and endocrine


What are exocrine glands?

Exocrine cells have ducts for secretion.


Exocrine glands can also be classified according to how products leave the cell. Which types?

1. Merocrine secretion
2. Apocrine secretion
3. Holocrine secretion


What is merocrene secretion?

In merocrene secretion, products are released, but no actual cellular material is lost. Secretions are either actively transported or packaged in vesicles and then released . Sweat and digestive enzymes produced by the pancreas are released by merocrene secretion.


What is apocrine secretion?

In apocrene secretion, the secretory products are released as fragments of the gland cell. Milk secretion by the mammary glands utilizes some apocrine secretion.


What is holocrene secretion?

Holocrine secretion involved the shedding of entire cells. Sebaceous (oil) glands of the skin utilize holocrine secretion.


What is the prime characteristic of connective tissue?

It consists of large amounts of extracellular material that separates cells from one another. This extracellular material is called the extracellular matrix.


The extracellular matrix of connective tissue has three major components. Which?

1. Protein fibers
2. Ground substance consisting of nonfibrous protein and other molecules
3. fluid


Three types of protein fibers help form most connective tissues. Which?

1. Collagen fibers
2. Reticular fibers
3. Elastic fibers


Short: how do collagens fibers look?

They resemble microscopic ropes.


Short: how do reticular fibers look?

Reticular fibers are very fine, short collagen fibers that branch to form a supporting network.


Short: how do elastic fibers look?

Elastic fibers have a structure similar to that of coiled metal springs; after being stretched they can recoil to their original shape.


What is the ground substance of the extracellular matrix in connective tissue?

Ground substance is the shapeless background against which cells and collagen fibers can be seen when using a light microscope. Although ground substance appears shapeless, the molecules within it are highly structured. Proteoglycans resemble the limbs of pine trees, with proteins forming the branches and polysaccharides forming the pine needles. This structure enables proteoglycans to trap large quantities of water between the polysaccharides.


Connective tissue cells are named according to their functions. They are given suffixes that can tell you a lot about their function. Which suffixes are normal?

- blast, -cyte and -clast.


Looking at the suffix, what does a fibroblast do?

Cells ending with -blast (germ) produce the matrix. In this case, fibroblasts are cells that form fibers and ground substance in the extracellular matrix.


Looking at the suffix, what does a osteocyte do?

Cells ending with -cyte (cell) maintain connective tissue. In this case, osteocytes maintain bone.


Looking at the suffix, what does a osteoclast do?

Cells ending with -clast (break) break tissue down for remodeling. Osteoclasts break down bone.


What are the seven function of connective tissue?

1. Enclosing and separating other tissues
2. Connecting tissues to one another
3. Supporting and moving parts of the body
4. Storing compounds
5. Cushioning and insulating
6. Transporting
7. Protecting


A function of connective tissue is enclosing and separating other tissues. Elaborate.

Sheets of connective tissue form capsules around organs, such as the liver and the kidneys. Connective tissue also forms layers that separate tissues and organs. For example, connective tissues separate muscles, arteries, veins, and nerves from one another.


A function of connective tissue is connecting tissues to one another. Elaborate.

Tendons are strong cables, or bands, of connective tissue that attach muscles to bone, and ligaments are connective tissue bands that hold bones together.


A function of connective tissue is supporting and moving parts of the body. Elaborate.

Bones of the skeletal system provide rigid support for the body, and semirigid cartilage supports structures, such as the nose, the ears, and the surfaces of joints. Joints between bones allow one part of the body to move relative to other parts.


A function of connective tissue is storing compounds. Elaborate.

Adipose tissue (fat) stores high-energy molecules, and bones store minerals, such as calcium and phosphate.


A function of connective tissue is cushioning and insulating. Elaborate.

Adipose tissue (fat) cushions and protects the tissues it surrounds and provides an insulating layer beneath the skin that helps conserve heat.


A function of connective tissue is transporting. Elaborate.

Blood transports gases, nutrients, enzymes, hormones, and cells of the immune system throughout the body.


A function of connective tissue is protecting. Elaborate.

Cells of the immune system and blood provide protection against toxins and tissue injury, as well as against microorganisms. Bones protect underlying structures from injury.


What is problematic with connective tissue classification?

Connective tissue types blend into one another, and the transition points cannot be precisely identified. As a result, connective tissue is somewhat arbitrarily classified.


Which types of connective tissue are there?

1. Connective tissue proper (loose, dense)
2. Supporting connective tissue (cartilage, bone)
3. Fluid connective tissue (blood, hemopoietic tissue)

Score: you don't need to mention the ( ---).


Which types of connective tissue proper are there?

Loose and dense connective tissue.


Which types of loose connective tissue proper are there?

1. Areolar
2. Adipose
3. Reticular


Which types of dense connective tissue proper are there?

Dense, regular collagenous
Dense, regular elastic
Dense, irregular collagenous
Dense, irregular elastic


Which types of supporting connective tissues are there?

1. Cartilage (Hyaline, Fibrocartilage, Elastic)
2. Bone (Spongy, Compact)


Which types of cartilage are there?

1. Hyaline
2. Fibrocartilage
3. Elastic


Which types of bone are there?

1. Spongy
2. Compact


Which types of fluid connective tissues are there?

1. Blood
2. Hemopoietic tissue (red marrow, yellow marrow)


Which types of Hemopoietic tissues are there?

1. Red marrow
2. Yellow marrow


What is the structure of areolar connective tissue?

A fine network of fibers (mostly collagen fibers with a few elastic fibers) with spaces between the fibers; fibroblasts, macrophages, and lymphocytes are located in the spaces.


What is the function of areolar connective tissue?

Loose packing, support and nourishment for the structures with which it is associated.


What are the locations of areolar connective tissue?

Widely distributed throughout the body; substance on which epithelial basement membranes rest; packing between glands, muscles, and nerves; attaches the skin to underlying tissues.


What is the structure of adipose tissue?

Little extracellular matrix surrounding the cells; the adipocytes, or fat cells, are so full of lipid that the cytoplasm is pushed to the periphery of the cell.


What is the function of adipose tissue?

Packing material, thermal insulator, energy storage, and protection of organs against injury from being bumped or jarred.


What are the locations of adipose tissue?

Predominantly is subcutaneous areas, mesenteries, renal pelves, around kidneys, attached to the surface of the colon, mammary glands, and in loose connective tissue that penetrates into spaces and crevices.


What is the structure of reticular tissue?

Fine network of reticular fibers irregularly arranged.


What is the function of reticular tissue?

Provides a superstructure for lymphatic and hemopoietic tussues.


What are the locations of reticular tissue?

Within the lymph nodes, spleen, bone marrow.


What is the structure of dense regular collagenous connective tissue?

Matrix composed of collagen fibers running in somewhat the same direction in tendons and ligaments; collagen fibers run in several directions in the dermis of the skin and organ capsules.


What is the function of dense regular collagenous connective tissue?

Withstanding great pulling forces exerted in the direction of the fiber orientation due to great tensile strength and stretch resistance.


What are the locations of dense regular collagenous connective tissue?

Tendons (attach muscle to bone) and ligaments (attach bones to each other); also found in the dermis of the skin, organ capsules, and the outer layer of many blood vessels.


What is the structure of dense regular elastic connective tissue?

Matrix composed of collagen fibers and elastin fibers running in somewhat the same direction in elastic ligaments; elastic fibers run in connective tissue of blood vessel walls.


What is the function of dense regular elastic connective tissue?

Capable of stretching and recoiling like a rubber band with strength in the direction of fiber orientation.


What are the locations of dense regular elastic connective tissue?

Elastic ligaments between the vertebrae and along the dorsal aspect of the neck (nucha) and in the vocal cords; also found in elastic connective tissue of blood vessel walls.


What is the structure of hyaline cartilage?

Collagen fibers are small and evenly dispersed in the matrix, making the matrix appear transparent; the chondrocytes are found in spaces, or lacunae, within the firm but flexible matrix


What is the function of hyaline cartilage?

Allows growth of long bones; provides rigidity with some flexibility in the trachea, bronchi, ribs, and nose; forms strong, smooth, yet somewhat flexible articulating surfaces; forms the embryonic skeleton.


What is the location of hyaline cartilage?

Growing long bones, cartilage rings of the respiratory system, costal cartilage of ribs, nasal cartilages, articulating surface of bones, and the embryonic skeleton.


What is the structure of fibrocartilage?

Collagen fibers similar to those in hyaline cartilage; the fibers are more numerous than in other cartilages and are arranged in thick bundles.


What is the function of fibrocartilage?

Somewhat flexible and capable of withstanding considerable pressure; connects structures subjected to great pressure.


What are the locations of of fibrocartilage?

Invertebral disks, pubic symphysis and articular disks (e.g. knees and temporomandibular [jaw] joints)


What is the structure of elastic cartilage?

Similar to hyaline cartilage, but matrix also contains elastin fibers.


What is the function of elastic cartilage?

Provides rigidity with even more flexibility than hyaline cartilage because elastic fibers return to their original shape after being stretched.


What are the locations of elastic cartilage?

External ears, epiglottis, and auditory tubes.


What is the structure of bone?

Hardy, bony matrix predominates; many osteocytes are located within lacunae; the matrix is organized into layers called lamellae.


What is the function of bone?

Provides great strength and support and protects internal organs, such as the brain; bone also provides attachment sites for muscles and ligaments; the joints of bones allow movements.


What are the locations of bone?

All bones of the body... duh


What is the structure of blood?

Blood cells and fluid matrix.


What are the functions of blood?

Transports oxygen, carbon dioxide, hormones, nutrients, waste products, and other substances; protects the body from infections and is involved in temperature regulation.


What is the structure of skeletal muscles?

Skeletal muscle cells or fibers appear striated (banded); cells are large, long and cylindrical, with many nuclei.


What is the funciton of skeletal muscles?

Movement of the body; under voluntary control.


What are the locations of skeletal muscles?

Attached to bone or other connective tissue.


What is the structure of cardiac muscles?

Cardiac muscle cells are cylindrical and striated and have a single nucleus; they are branched and connected to one another by intercalated disks, which contain gap junctions.


What is the function of cardiac muscles?

Pumps the blood; under involuntary control.


What is the structure of smooth muscle?

Smooth muscle cells are tapered at each end, are not striated, and have a single nucleus.


What is the function of smooth muscle?

Regulates the size of organs, forces fluid through tubes, controls the amount of light entering the eye, and produces "goose bumps" in the skin; under involuntary control.


What is the location of smooth muscle?

In hollow organs, such as the stomach and intestine; skin and eyes.


What is a membrane?

A membrane is a thin sheet or layer of tissue that covers a structure or lines a cavity. Most membranes consist of epithelium and the connective tissue on which the epithelium rests.


What are the three major categories of internal membranes?

1. Mucous membranes
2. Serous membranes
3. Synovial membranes


What are mucous membranes?

Mucous membranes consist of varous kinds of epithelium resting on a thick layer of loose connective tissue. The line cavities that open to the outside of the body. Many, but not all, mucous membrane have mucous glands.


What are serous membranes?

Serous membranes consist of simple squamous epithelium resting on a delicate layer of loose connective tissue. Serous membranes line the trunk cavities and cover the organs within these cavities. Serous membranes secrete fluid that cover these membranes.


What are synovial membranes?

Synovial membranes are made up of only connective tissue. They line the inside of joint cavities (the space where bones come together within a movable joint). Synovial membranes produce synovial fluid, which reduces friction in the joint.


Following an injury to a tissue, substances called chemical mediators are released or activated in the injured tissues and adjacent blood vessels. Name two such mediators.

1. Histamine
2. Prostaglandins.


What is an edema, and what causes it?

Chemical mediators of inflammation also increase the permeability of blood vessels, allowing materials and blood cells to move out of the vessels and into the tissue, where they can deal directly with the injury. Edema, or swelling, of the tissue results when water, proteins and other substances from the blood move into the tissues.


Tissue repair can occur by ...... or by ......
also say something about those two.

By regeneration, which is the replacement of dead cells for cells of the same type. Or by fibrosis, which is replacement by a new tissue type (scarring).


What is necessary for regeneration of tissues?

Stem cells.