Advertisement Upgrade to remove ads

tissue

A group of similar cells and cell products that arise from the same region of the embryo and work together to form a specific structural or physiological role in an organ

four primary tissues

Epithelia, connective, nervous, and muscular tissue

organ

structure with discrete boundaries that is composed of two or more tissue types

fertilization

Human life begins at WHAT egg, which soon divides to produce scores of identical, smaller cells. The first tissues appear when these cells start to organize themselves into layers-first two, and soon three strata called the primary germ layers, which give rise to all of the body's mature tissues.

primary germ layers

The first tissues appear when these cells start to organize themselves into layers-first two, and soon three strata called the WHAT, which give rise to all of the body's mature tissues.

ectoderm, mesoderm, and endoderm

The three layers are called WHAT?

ectoderm

The WHAT is an outer layer that gives rise to the epidermis and nervous system.

endoderm

The inner layer, the WHAT, gives rise to the mucous membranes of the digestive and respiratory tracts and to the digestive glands

mesoderm

Between these two (ectoderm and endoderm) is the WHAT, a layer of more loosely organized cells. It eventually turns to a gelatinous tissue called mesenchyme

mesenchyme

Mesoderm eventually turns to a gelatinous tissue called WHAT? It gives rise to muscle, bone, an blood, among other tissues.

stem cells

The growth and differentiation of tissues depends upon a supply of reserve WHAT? These are undifferentiated cells that are not yet performing any specialized function, but they have the potential to differentiate into one or more types of mature functional cells, such as liver, brain, cartilage, or skin cells.

developmental plasticity

Stem cells are elastic in its development- it gives rise to many different mature cell types. Plasticity=flexible. It hasn't developed yet, but as it changes it can become something else

embryonic stem cells

A type of stem cells that compose the early human embryo. Stages: totipotent and pluripotent

totipotent

Embryonic stem cell. In the early stages of development, WHAT have the potential to develop into any type of fully differentiated human cell

pluripotent

Cels of the inner cell mass are called WHAT stem cells; they can still develop into any cell type of the embryo, but not into the accessory organs of pregnancy.

adult stem cells

Undifferentiated cells in tissues of adults. (Undifferentiated- not yet performing any specialized function, but have the potential to).

multipotent

Adult stem cell. Able to develop into two or more different cell lines. Ex.) Certain WHAT bone marrow stem cells can give rise to red blood cells.

unipotent

Adult stem cell. They have the most limited plasticity, as they can produce only one mature cell type. Ex.) The cells that give rise to sperm and eggs

intercellular junctions

Most cells must be anchored to each other and to the matrix if they are to grow and divide normally. The connections between one cell and another are called WHAT? These attachments enable the cells to resist stress and communicate with each other.

tight junctions

A type of junction that is impossible for something to pass between cells. It is a region in which adjacent cells are bound together by fusion of the outer phospholipid layer of their plasma membranes. It is important for stomach and intestines. WHAT prevent digestive juices from seeping between epithelial cells.

desmosome

(anchoring) WHAT are not continuous and therefore cannot prevent substances from passing between cells. They serve to keep cells from pulling apart and thus enable a tissue to resist mechanical stress.

gap junction

(communicating) communication and transport of molecules. Ions, glucose, amino acids, and other small solutes can pass directly from the cytoplasm of one cell into the next through these pores. In the embryo, nutrients pass from cell to cell through THIS junctions.

connective tissue

A type of tissue in which cells usually occupy less space than the extracellular material, and that serves in most cases to bind organs to each other. Ex.) The way a tendon connects muscle to bone or to support and protect organs

extracellular material

Most cells of a connective tissue are not in direct contact with each other, but are well separated by WHAT. Most kinds of connective tissues are highly vascular- richly, supplied with blood vessels

functions of connective tissue

functions of connective tissue: Binding of organs, support, physical protection, immune protection, movement, storage of fat, heat production, transport of nutrients, wastes, hormones, and blood cells

epithelial tissue

covers the body surface, lines body cavities, forms the external and internal linings of many organs, and constitutes most gland tissue.

basement membrane

Between an epithelium and the underlying connective tissue is a layer called the WHAT? It contains collagen and glycogen. It serves to anchor an epithelium to the connective tissue below it.

simple and stratified

Epithelia are classified into two broad categories- WHAT and WHAT?

simple epithelium

Type of Epithelial tissue- every cell touches the membrane basement

stratified epithelium

Type of Epithelial tissue- Some cells rest on top of other cells and do not contact the basement membrane

fibroblasts

Component of fibrous connective tissue: They produce the fibers and ground substance that form the matrix of the tissue.

macrophages

Component of fibrous connective tissue: They engulf and destroy bacteria, other foreign particles, and dead or dying cells of our own body. They also activate the immune system when they sense foreign matter called antigens. They arise from certain white blood cells called monocytes

Leukocytes

Component of fibrous connective tissue: or white blood cells. They travel in the blood stream. Most of them are neutrophils, which wander about attacking bacteria. The mucous membranes often exhibit dense patches of tiny WBCs called lymphocytes, which react against bacteria, toxins, and other foreign agents.

Plasma cells

Component of fibrous connective tissue: They synthesize disease-fighting proteins called antibodies

Mast cells

Component of fibrous connective tissue: These cells, found especially alongside blood vessels, secrete a chemical called heparin that inhibits blood clotting, and histamine that increases blood flow by dilating blood vessels.

Adpiocytes

Each cell is filled mainly by a globule of triglycerides (fat molecules)

collagenous fibers

One of the 3 Fiber types: Most abundant of the body's proteins. It is the base of such animal products as gelatin, leather, and glue. In fresh tissue, collagenous fibers have a glistening white appearance, as seen in tendons and some cuts of meat (called white fibers). Tendons, ligaments, and the deep layer of the skin are made mainly of collagen.

reticular fibers

One of the 3 Fiber types: These are thin collagen fibers coated with glycoprotein. They form a spongelike framework for such organs as the spleen and lymph nodes.

elastic fibers

One of the 3 Fiber types: These are thinner than collagenous fibers, and they branch and rejoin each other along their course. They are made of protein called ELASTIN, whose coiled structure allowed it to stretch and recoil like a rubber band. Elastic fibers account for the ability of the skin, lungs, and arteries to spring back after they are stretched. Fresh elastic fibers are yellowish and therefore often called yellow fibers.

loose and dense connective tissue

Fibrous connective tissue is divided into two broad categories according to the relative abundance of fiber: WHAT and WHAT?

loose connective tissue

Type of fibrous connective tissue. Much of the space is occupied by ground substance which is dissolved out of the tissue during histological fixation and leaves empty space in prepared tissue sections. The WHAT connective tissue we will discuss are areolar and reticular tissue.

dense connective tissue

Type of fibrous connective tissue. Fiber occupies more space than the cells and ground substance, and appears closely packed in tissue sections. The two WHAT connective tissues are dense regular and dense irregular connective tissue

areolar tissue

A type of loose connective tissue. Exhibits loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space. It is found in tissue sections from almost every part of the body. It surrounds blood vessels and nerves and penetrates with them even into the small spaces of muscle, tendon, and other tissues. Nearly every epithelium rests on a layer of areolar tissue.

reticular tissue

A type of loose connective tissue. A mesh of reticular fibers and fibroblasts. It forms the structural stroma (framework) of such organs as the lymph nodes, spleen, thymus, and bone marrow. If you imagine a kitchen sponge soaked with blood, the sponge fibers are analogous to this tissue stroma.

dense regular connective tissue

A type of dense connective tissue. It is named for two properties: 1. The collagen fibers are closely packed and leave relatively little open space 2. The fibers are parallel to each other. It is found especially in tendons (attach muscles to bones) and ligaments (hold bones together). The parallel arrangement of fivers is an adaptation to the fact that tendons and ligaments are pulled in PREDICTABLE directions. **This type of tissue has few blood vessels, so injured tendons and ligaments are slow to heal. How does it get nutrients in there? Fluid through diffusion

dense irregular connective tissue

A type of dense connective tissue. Also has thick bundles of collagen and relatively little room for cells and ground substances, but the collagen bundles run in random directions. This arrangement enables the tissue to resist UNPREDICTABLE stresses. This tissue consists most of the dermis, where it binds the skin to the underlying muscle and connective tissue. It forms a protective capsule around organs

adipose tissue

(fat) adipocytes are the dominant cell type. This tissue provides thermal insulation, anchors and cushions such organs as the eyeballs and kidneys. Women have more fat relative to body weight than men do. Female body fat helps to meet the caloric needs of pregnancy and nursing an infant, and having too little fat can reduce female fertility. Most adipose tissue is a type called white fat, but fetuses, infants, and children also have a heat-generating tissue called brown fat. Brown fat has numerous mitochondria, but their oxidation pathway is not linked to ATP synthesis. Therefore, when these cells oxidize fats, they release all of the energy as heat. Hibernating animals accumulate brown fat in preparation for winter.

cartilage

A supportive connective tissue with a flexible rubbery matrix. It gives shape to the external ear, the tip of the nose, and the larynx.

hyaline cartilage, elastic cartilage, and fibrocartilage

Differences in the fibers provide a basis for classifying cartilage into three types:

hyaline cartilage

It is named for its clear, glassy microscopic appearance, which stems from the usually invisible fineness of its collagen fibers. Locations: articular (where bones meet) cartilage, costal (ribs) cartilage, trachea, larynx, fetal (where baby is developed in womb) skeleton. Eases joint movements, holds airways open, moves to vocal chords.

elastic cartilage

Named for its conspicuous elastic fibers. Covered with perichondrium. Provides flexible, elastic support. External ear and epiglottis.

fibrocartilage

cartilage containing large, coarse bundles of collagen fibers. Never has perichondrium. Resists compression and absorbs shock. Pubic symphysis, menisci, and intervertebral discs.

perichondrium

Elastic cartilage and most hyaline cartilage are surrounded by a sheath of dense irregular connective tissue. There is NONE of this around fibrocartilage.

bone

Two meanings: 1. An organ of the body 2. bone tissue, or osseous tissue, which makes up most of the mass of bones.

spongy bone

Fills the heads of the long bones and forms the middle layer of the flat bones such as the sternum (breastbone). Although it is calcified and hard, its slivers and plates give it a spongy appearance.

compact bone

(dense bone) A denser calcified tissue with no spaces visible to the naked eye. It forms the external surfaces of all bones, so spongy bone, when present, is always covered by compact bone.

blood

A fluid connective tissue that travels through tubular vessels. Its primary function is to transport cells and dissolve matter from place to place.

plasma

Blood consists of a ground substance called WHAT?

formed elements

cells and cell fragments in blood

erythrocytes

Red blood cells. The most abundant formed elements. They transport oxygen and carbon dioxide.

leukocytes

White blood cells. Serve various roles in defense against infection and other diseases.

Platelets

Small cell fragments scattered amid the blood cells. They are involved in clotting and other mechanisms for minimizing blood loos, and in secreting growth factors that promote blood vessel growth and maintenance.

nervous tissue

It is specialized for communication by means of electrical and chemical signals. It consists of neurons, or nerve cells, and a much greater number of neuroglia, or glial cells, which protect and assist the neurons

neurons

nerve cells. Detect stimuli, respond quickly, and transmit coded information rapidly to other cells.

neuroglia

(glial cels) which protect and assist the neutrons. "housekeepers of nervous system"

neurosoma

Part of neuron. cell body in nervous tissue that houses the nucleus and most other organelles.

dendrites

Part of neuron. Extending from the neurosoma, there are usually multiple short, branched processes called WHAT which receive signals from other cells and transmit messages tot he neurosoma.

axon

Part of neuron. A single, much longer WHAT, or nerve fiber, which sends outgoing signals to other cells.

muscular tissue

Consists of elongated cells that are specialized to contract in response to stimulation; thus, its primary job is to exert physical force on other tissues and organs. Ex.) When a skeletal muscle pulls on a bone. Not only do movements of the body and its limbs depend on muscle, but so do such processes as digestion, waste elimination, breathing, speech, and blood circulation. The muscles are also an important source of body heat- generates heat through cellular respiration

skeletal, cardiac, and smooth

There are three histological types of muscle:

skeletal muscle

consists of long threadlike cells called muscle fibers. Most of it is attached to bones.

cardiac muscles

It is limited to the heart. Its cells are much shorter, so they are commonly called mycocytes or cardiocytes rather than fibers.

smooth muscles

WHAT lacks striations and is involuntary (it is not usually under conscious control). WHAT muscles are fusiform (thick in the middle and tapered at the ends) and relatively short.

tissue growth

WHAT is caused because their cells increase in number or because the existing cells grow larger.

hyperplasia

Most embryonic and childhood growth occurs by WHAT? Tissue growth through cell multiplication.

hypertrophy

Exercised muscles grow through WHAT, the enlargement of preexisting cells.

neoplasia

WHAT is the development of a tumor composed of abnormal, nonfunctional tissue

differentiation

Unspecialized tissues of the embryo develop into more diverse and specialized types of mature tissue- ex.) mesenchyme to muscle

metaplasia

A change from one type of mature tissue to another. Ex.) The vagina of a young girl is lined with a simple cuboidal epithelium. At puberty, it changes to the stratified squamous epithelium, better adapted to the future demands of intercourse and childbirth.

regeneration and fibrosis

Damaged tissues can be repaired in WHAT and WHAT two ways:

regeneration

Tissue repair. The replacement of dead or damaged cells by the same type of cells as before. Most skin injuries (cuts, scrapes) heal by regeneration.

fibrosis

Tissue repair. The replacement of damaged tissue with scar tissue. Scar tissue helps to hold an organ together, but it does not restore normal function. Ex.) The healing of severe cuts and burns, the healing of muscle injuries, and scarring the lungs in tuberculosis.

Atrophy

The shrinkage of a tissue through a loss in cell size or number. It results from both normal aging and lack of use of an organ.

necrosis

The premature, pathological death of tissue due to trauma, toxins, infection, and so forth.

apoptosis

programmed cell death is the normal death of cells that have completed their function and best serve the body by dying and getting out of the way.

skin grafting video

skin grafting video: Tissue engineering is the artificial production of tissues and organs in the laboratory for implantation in the human body. The process commonly begins with building a scaffold (framework) of collagen in the shape of a desired organ such as an ear. The scaffold is seeded with human cells and put in a "bioreactor" to grow. The bioreactor supplies nutrients, oxygen, and growth factors. When a lab-grown tissue reaches a certain point, it is implanted into the patient. Some patients have been successfully treated for defective urinary bladders by growing new bladders from the patients' own cells and replacing all but the basal region where the ureters join the bladder.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set