Tissues Flashcards
Define the term tissue.
A tissue is a group of similar cells that usually have a similar embryological origin and are specialized for a particular function.
Name the four primary adult tissue types, and give a brief description of each.
Depending on their function and structure, the various tissues of the body are classified as the following four principal types:
- Epithelial tissue covers body surfaces; lines hollow organs, body cavities, and ducts; and forms glands. Epithelial tissue provides external protection for underlying tissue.
- Connective tissue protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity.
- Muscle tissue is responsible for movement and generation of force.
- Nervous tissue initiates and transmits action potentials (nerve impulses) that help coordinate body activities, monitors the external environment, and contribute to homeostasis.
What is the function of Epithelial Tissue?
- Epithelial tissue covers body surfaces;
- lines hollow organs, body cavities, and ducts
- forms glands.
- Epithelial tissue provides external protection for underlying tissue.
What is the function of Connective Tissue?
Connective tissue protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity.
What is the function of Nervous tissue?
Nervous tissue initiates and transmits action potentials (nerve impulses) that help coordinate body activities, monitors the external environment, and contribute to homeostasis.
Describe the features of epithelial tissue.
- arranged in sheets, in either single or multiple layers.
- consists mostly of packed cells with little extracellular material. In epithelial tissues, many cell junctions are present, providing secure attachments among cells.
- has an apical surface and a basal surface attached to a base membrane.
- Epithelia adhere firmly to nearby connective tissue through a thin extracellular layer called the basement membrane. Epithelia have a nerve supply and a high capacity for renewal (a high mitotic rate).
- The basement membrane is made up of a cellular layer of collagen and glycoproteins called the basal lamina; often, it is underlain with a layer of reticular fibres and glycoproteins called the reticular lamina.
- Epithelial tissue is avascular; the exchange of materials between epithelium and adjacent connective tissue is by diffusion.
- Functions of epithelia include protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory reception, and reproduction.
What are the different types of simple epithelial tissues?
Simple Squamous Epithelium Simple Cuboidal Epithelium Simple Columnar Epithelium (non-ciliated and ciliated) Pseudostratified columnar Epithelium (non-ciliated and ciliated)
What are the different types of stratified epithelium?
Stratified squamous Epithelium Stratified cuboidal Epithelium Stratified columnar Epithelium Transitional Epithelium
Discuss the classification scheme for epithelia.
The covering and lining of the epithelia can be classified as a combination of layers and shapes of cells. The name of the specific type of stratified epithelium depends on the shape of the surface cells.
Layers are arranged as simple (one layer), stratified (several layers), or pseudostratified (one layer that appears as several).
Cell shapes include squamous (flat), cuboidal (cube-like), columnar (rectangular), and transitional (variable).
Provide a structural description of simple squamous epithelium
The simple squamous epithelium consists of a single layer of flat, scale-like cells.
Provide a structural description of the Simple Cuboidal Epithelium.
- consists of a single layer of cube-shaped cells,
- round
- centrally located nucleus.
Provide the structural description of Nonciliated simple columnar epithelium.
- single layer of non-ciliated column-shaped cells
- nuclei near the base of the cell
- contains cells with microvilli
- Contains goblet cells..
Provide a structural description of Ciliated Simple Columnar Epithelium.
- single layer of ciliated column-like cells with nuclei near bases
- contains cilia
- contains goblet cells in some locations.
what are microvilli?
microscopic finger-like projections, which increase the surface area of the plasma membrane increasing the absorption rate.
What are goblet cells?
modified columnar cells that secrete mucus at their apical surface.
Provide a structural description of Nonciliated Pseudostratified Columnar Epithelium.
- Appear to have several layers due to the nuclei being at different levels
- All cells attach to the basement cell
- not all cells extend to the apical level of the cell.
- It does not have goblet cells
- does not have cilia or mircovilli.
Provide a structural description of Ciliated Pseudostratified columnar epithelium.
- Appear to have several layers because the nuclei are at different levels.
- All cells attach to the basement cell
- not all cells extend to the apical level of the cell.
- It contains cells that extend to the surface and either contain cilia or secrete mucus (goblet cells)
Provide a structural description of stratified squamous epithelium
- Consists of several layers.
- The apical and several deeper layers are squamous.
- The deeper layers beyond that vary from cuboidal or columnar.
- Basal (deepest) cells continually undergo cell division.
- New cells push the old cells closer to the top.
- Skin closer to the top keratinizes
what is keratinization of the cell?
when a tough layer of skin develops in the apical layer of skin. Helps protect skin and underlying tissues from microbes, heat and chemicals.
Provide a structural description of Stratified cuboidal epithelium
- 2 or more layers of cells
- the apical layer are cube-shaped
- fairly rare type.
Provide a structural description of stratified columnar epithelium
- basal layer consists of shortened
- irregularly shaped cells
- the apical layer has columnar cells.
Provide a structural description of Transitional Epithelium.
- Appearance is variable.
- An unstretched or relaxed state looks like a stratified cuboidal epithelium.
- The apical layer tend to be large and rounded.
- A stretched state the cells become flatter, look like stratified squamous epithelium.
Define gland, and differentiate between exocrine and endocrine.
Is a single cell or a group of epithelial cells adapted for secretion.
Endocrine glands secrete hormones into interstitial fluid then the blood
Exocrine glands (mucous, sweat, oil, and digestive glands), secrete into ducts or directly onto a free surface.
Describe the general characteristics of connective tissues (CTs), and discuss their major structural differences from epithelial tissue.
- consists of 2 basic elements: cells and extracellular matrix. (material between widely spaced cells)
- extracellular matrix consists of protein fibres and ground substance (material between cells and fibres)
- The extracellular matrix is secreted by the cells of the connective tissue and determines the tissue’s qualities.
- for example, in bone, the extracellular matrix is firm and not pliable, in cartilage, it’s firm but pliable.
- Unlike epithelial tissue, connective tissues do not occur on free surfaces.
- Unlike epithelium, connective tissue is highly vascular (except for cartilage and tendons).
- like epithelium, has a nerve supply (cartilage does not)
Describe matrix and ground substance; list the three CT fibre types, and name the types of cells of which CT can be composed
Extracellular matrix
- The properties of the connective tissue is based on the extracellular materials between the cells. This matrix consists of a fluid, gel, or solid ground substance + protein fibres.
- Ground substance can take the form many forms; fluid, semifluid, gelatinous, fibrous or calcified. This usually secreted by the connective tissue cells and adjacent cells. They determine the qualities of tissues.
- Cells found in connective tissue include;
- fibroblasts (which secrete fibres and matrix),
- macrophages (perform phagocytosis)
- plasma cells (secrete antibodies)
- mast cells (produce histamines)
- adipocytes or fat cells (which store energy in the form of fat).
- The three types of fibres embedded in the matrix between the cells of connective tissues are the following:
- Collagen fibres, composed of the protein collagen, are very tough and resistant to stretching, yet allow some flexibility in the tissue; they are found in bone, cartilage, tendons, and ligaments.
- Elastic fibres, composed of the protein elastin, fibrillin and other glycoproteins. Provide strength and stretching capacity and are found in the skin, blood vessels, and lungs.
- Reticular fibres, consisting of collagen and glycoprotein, provide support in the walls of the blood vessels and form a strong, supporting network around fat cells, nerve fibres, and skeletal and smooth muscle fibres.
What is the function of ground Substance?
- supports cells
- binds cells together
- provides a medium through which substances are exchanged between the blood and cells.
- Influences tissue development, migrate, proliferate, change shape, and perform metabolic function.
List the different classifications of connective tissue.
Five types of CT include:
- Loose connective tissues
- areolar
- adipose
- reticular
- Dense connective tissues
- dense regular
- dense irregular
- elastic
- Supporting Connective Tissues
- Cartilage
- Hyaline Cartilage
- Fibrocartilage
- Elastic Cartilage
- Bone
- Liquid
- blood
- lymph
- Cartilage
Describe the structure of areolar Connective Tissue
- Consists of randomly arranged fibres (collagen, reticular, elastic)
- several kinds of cells, (fibroblasts, macrophages, plasma cells, adipocytes, mast cells)
- has a few white blood cells
- forms the subcutaneous layer of skin along with adipose tissue.
What are the subclassifications of loose connection tissue?
- Areolar Connective Tissue
- Adipose Connective Tissue
- Reticular Connective Tissue
What are the subclassifications of Dense Connective Tissue
- Dense Regular
- Dense Irregular
- Elastic
What are the subclassifications of Supporting Connective Tissue?
- Cartilage
- -hyaline -fibrocartilage -elastic
- Bone Tissue
- Liquid Connective Tissue
- -blood -lymph
Describe the structure of Adipose Tissue
Structure:
- It has cells called Adipocytes (specialized for fat storage)
- When the cell fills up with a single, large triglyceride droplet, the cytoplasm and nucleus are pushed to the periphery of the cell.
- The more adipose tissue a person has the more blood vesicles that form
Describe the structure of Reticular Connective Tissue.
Structure:
- fine interlacing network of reticular fibres (thin form of collagen fibre)
- reticular cells.
Describe the structure of Dense Regular Connective Tissue.
Structure:
- The extracellular matrix looks shiny white
- Composed of mainly collagen fibres regularly arranged in bundles
- fibroblasts present in rows btw the bundles.
Describe the structure Dense Irregular Connective Tissue
Structure:
- mostly collagen fibres randomly arranged
- have a few fibroblasts
Describe the structure of Elastic Connective Tissue.
Structure:
- Mostly elastic fibres
- fibroblasts presents in spaces btw fibres
- unstained tissue is yellowish
Describe the structure of Hyaline Cartilage
Structure:
- contains a resilient gel as ground substance which appears bluish-white.
- fine collagen fibres are not visible
- Chondrocytes are found in lacunae surrounded by perichondrium.
- most abundant cartilage in the body
Describe the structure of Fibrocartilage
- contains chondrocytes scattered among clearly visible thick bundles of collagen fibres within the extracellular matrix
- it lacks perichondrium.
Describe the structure of elastic cartilage
Structure:
- contains chondrocytes located in a threadlike network of elastic fibres within the extracellular matrix
- the perichondrium is present.
Locations:
- lid on top of larynx (epiglottis)
- part of external ear (auricle)
- auditory tubes
Function:
- provides strength and elasticity
- maintains the shape of certain structures
What is the epithelial membrane? What are the different types of membranes and what is their general function?
The epithelial Membrane is the combination of an epithelial layer and an underlying connective tissue layer.
- Mucous Membranes: line entire digestive tract, respiratory, the reproductive and urinary systems
- Serous Membrane (lines body cavities)
- cutaneous membrane (skin)
- Synovial membrane (lines joints)
Identify the major cell of nervous tissue; denote the location of nervous tissue in the body, and discuss its function.
consists of neurons and neuroglia
Neurons: sensitive to stimuli converting them into nerve impulses and conduct them to other neurons, muscle fibres, or to glands
Neuroglia: do not transmit nerve impulses they have other protective and supportive functions
Define the term mucous membrane, and discuss the structure, location, and function of mucous membrane
- Lines the body cavities that open to the outside of a cell. It secretes mucus from goblet cells
- found lining the digestive tract, respiratory, reproductive, and urinary systems.
- prevents cavities from drying out, traps particles in the respiratory tract, lubricates and absorbs food, secretes digestive enzymes.
Define the term serous membrane, and discuss the structure, location, and function of serous membrane
- lines body cavities that do not open directly to the exterior. covers organs that lie within the cavity.
- Composed of a visceral layer (attaches to organs inside the cavity) and Parietal layer (attached to the cavity wall)
- each layer consists of areolar connective tissue covered by mesothelium.
- the mesothelium secretes serous fluid which lubricates the organs to glide over one another or slide against the walls.
Define the term Synovial membranes, and discuss the structure, location, and function of Synovial membranes
line the cavities of some joints.
composed of a areolar connective tissue and adipose tissue with collagen fibres. they do not have an epithelial layer.
synoviocytes secrete synovial fluid
lubricates the ends of bones as they move at joints. nourishes cartilage covering the bones and removes microbes and debris from the joint cavity.
Define what an endocrine gland is and its function.
Endocrine glands enter the interstitial fluid and then diffuse into the bloodstream without flowing through a duct. (these secretions are called hormones.) Include the pituitary, thyroid, and adrenal.
Define what an exocrine gland is and what it does.
Exocrine Glands secrete their products into ducts that empty at surface epithelium such as the skin or the lumen of a hollow organ. include; mucus, perspiration, oil, earwax, milk, saliva, and digestive enzymes.
