The Tissue Levels of Organization (Exam 1 - Chapter 4)

Tissues

collections of specialized cells in cell products that carry out a limited number of functions

Histology

The study of tissues

Epithelial tissue

Covers exposed structures, lines internal pathways and chambers, and forms glands

connective tissue

fills internal spaces, provide structural support for other tissues, transports materials within the body, and stores energy

Muscle tissue

specialized for contraction and includes the skeletal muscles of the body, the muscle of the heart, and the muscular walls of hollow organs

Nervous tissue

carries information from one part of the body to another in the form of electrical impulses

Epithelia

singular layers of cells that cover the external or line internal surfaces

What are the characteristics of epithelial tissue?

polarity, cellularity, attachment, vascularity, and regeneration

Polarity (characteristics of epithelial tissue)

Refers to the presence of structural and functional differences between the exposed and attached surfaces. (apical)

Give an example of How polarity is evident in the epithelium

the atypical and basal surface are attached to each other. They have different structure and function. Apical surfaces have microvilli and sometimes cilia. Polarity is important when it comes to the distribution of organelles between exposed surfaces and the basement membrane.

Cellularity (characteristics of epithelial tissues)

cells bound closely together by interconnections known as cell junctions

Attachment (characteristics of epithelial tissue)

Refers to how different parts of the epithelium adhere to each other. For example, the basement membrane is formed from the fusion of several layers such as the Basil Lamina and the reticular lamina

Basement membrane

The base of the epithelium that is noncellular

Avascularity (characteristics of epithelial tissue)

refers to the lack of blood vessels in epithelial tissue

Regeneration (characteristics of epithelial tissue)

Refers to the process of cell division and replacement of epithelial cells that are damaged or lost at the exposed surfaces.

What are the two functional regions that the epithelial cell is divided into?

apical surface and Basil surface

Microvilli

lines internal pathways abundant on epithelial surfaces where absorption and secretion take place

Ciliated epithelium (motile cilia)

Move substances over the epithelial surface. An example of cilia being an epithelial surface could be in the lungs because cilia move dust and bacteria from getting into the lungs

What are intercellular connections?

Based on cellularity, how epithelium cells firmly attach to one another through specialized active sites

Cell junctions

Specialized areas of the plasma membrane that attach A cell to another cell or to extracellular materials

Gap Junctions

Two cells are held together by two embedded interlocking transmembrane proteins called connexons

What are the three types of cell junctions?

junctions, tight junctions, and desmosomes

Gap junctions

Allows neighboring cells to exchange small molecules such as ions (movement of ions)

Tight junctions

Two membranes that are tightly bonded together by interlocking membrane proteins.

Adhesion belt

A band that encircles or surrounds the cell and binds them to adjacent cells.

What is the role of tight junctions?

prevents water and saw use from passing between the cells

Desmosomes

Structures that are very strong and can resist stretching and twisting or in general any mechanical stretches

What are the two types of desmosomes?

spot desmosomes and hemi-desmosomes

Spot desmosomes

small disk connected to the bands (ties adjacent cells together) of the intermediate filaments which stabilize the shape of the cell

Hemi desmosomes

Half of a spot desmosome, attaches a cell to extracellular filaments in the basement membrane which helps stabilize the position of the epithelial cell

What makes up the basement membrane?

The basil Lamina and reticular lamina

What is the function of the basal lamina?

Restricts the movement of proteins and other large molecules comes from connective tissue from getting in into the epithelium.

Reticular lamina

Deeper portion of the basement membrane that consists of reticular fibers and ground substance

What is the function of reticular lamina?

Gives the basement its strength

What are the three basic shapes of epithelial cells?

Squamous, cuboidal, and columnar

Squamous epithelium

Then, flat, irregular in shape, and very similar to a jigsaw puzzle

Cuboidal

Hexagonal shaped boxes from their apical surfaces

Columnar

Tall, slender rectangular cells

Simple epithelium

singular layer that is thin and fragile. They line internal compartments and pathways. Because they are so thin they don’t provide machinal protection

What regions are simple epithelia found in?

Regions in which secretion and absorption occurs

Stratified epithelium

Several layers of cells that cover the basement membrane and can be packed with keratin

What region is stratified epithelia usually found in?

areas that are exposed to mechanical or chemical stresses such as the lining of the mouth and the surface of the skin.

Mesothelium

a simple squamous epithelium that lines body cavities for example the lungs the heart and abdominal organs

Endothelium

Simple squamous epithelium lining the inner surface of the heart in all blood vessels

What areas can simple squamous be found in?

the lining of the thoracic in abdominal pelvic cavities and lining of blood vessels

Where can stratified squamous non characterized be found?

Oral cavity, vagina, esophagus and pharynx

Where can stratified squamous keratinized epithelium be found?

the surface of the skin

Where can simple cuboidal epithelia be located?

along the ducks of sweat glands and in the larger ducts of memory glands

Transitional epithelium

can change between being squamous and cuboidal in shape

Where can transitional epithelium be found? And why?

In areas like the urinary system because that region stretches and compresses when the blotter is full versus when the bladder is empty

Where are simple columnar epithelium usually found?

in the small and large intestines

Pseudostratified alumni epithelium

Cells with varying shapes and functions they appeared to be layered but are not

Where are pseudostratified columnar epithelial cells located?

in the trachea (windpipe), the bronchi, and mal reproductive tract.

Granular epithelial

Epithelia that contain gland cells that are specialized for secretion

What are the two main types of glands?

endocrine glands and exocrine glands

Endocrine glands

Secret hormones in the bloodstream through ductless glands

What are some examples of endocrine glands?

thyroid glands and pituitary glands

Exocrine glands

Secret discharge onto the epithelial surface through ducts

Unicellular glands

independent scattered gland cells, the individual secretory cells

What are the single cells in unicellular glands?

Goblet cells

What do goblet cells secrete?

mucin

In Goblet cells, when mucin is produced what is the sticky lubricant that is formed when mixed with water?

mucus

What type of epithelium that is found in the small and large intestines would also have goblet cells scatter along the absorptive cells?

Columnar epithelium

Multicellular glands

Aggregations of glands cells that produce exocrine or endocrine secretions

Multicellular exocrine gland

Gland cells form an epithelium that releases secretions into an inner compartment

What are the characteristics for multicellular exocrine glands?

The structure of the duct, the shape of the sensory portion of the gland, the relationship between the ducts and the Glandular areas

What is the two types of duct structures?

simple and compound

simple (duct structure)

a single duct that doesn’t divide on its way to the gland cells

compound (duct structure)

a duct that divides one or more times on its way to the gland cells

What are the two types of shapes of the secretory portion of the gland?

Tubular and acinar

Tubular

glands whose glandular cells form tubes. these tubes can be straight or coiled

Acinar or Alveolar

Blind pockets that are formed (looks like a tear drop)

What is the relation between the ducts and glandular area?

whether there are several secretory areas (branched)

What are the three methods of secretion?

merocrine, apocrine, and holocrine

Merocrine secretions

the product is released from an exocrine cell by secretory vesicle through exocytosis

What is the most common method of secretion?

merocrine

What is an example of merocrine secretion?

the secretion of mucous in the salivary glands

Apocrine secretion

An exocrine cell involves the loss of cytoplasm as well as the secretory product

The combination of what secretion is involved in milk production in the mammary glands?

merocrine and apocrine

Holocrine secretion

Destroys the glance cell (superior glands cells burst)

What is an example of Holocrine secretion?

gland cells were destroyed, and cell division occurs and is associated with the hair follicle.

What are the different types of sections?

serous glands (salivary glands), mucous glands (mucins), and mixed exocrine glands (different type of exocrine secretions)

Epithelial tissue is always attached to which other major tissue type?

connective tissue

The combination of fibers and ground substance in supporting connective tissues is known as

matrix

The three categories of connective tissues are

connective tissue proper, fluid connective tissue, and supporting connective tissue

Which tissue is correctly paired with its category of connective tissue?

lymph—fluid connective tissue

Which of the following tissues are classified as "connective tissue proper"?

areolar connective tissue, adipose tissue, and dense irregular connective tissue

Blood is which type of tissue

connective tissue

Which of the following connective tissue cells produces collagen?

fibroblasts

Cells that store fat are called

adipocytes

Cells that respond to injury by dividing to assist in connective tissue repair are

mesenchymal cells.

Cells that engulf bacteria or cell debris within loose connective tissue are

macrophages

In areolar connective tissue, ________ cells release histamine to stimulate inflammation.

mast

Antibodies are produced by

plasma cells

Two types of microphages include

neutrophils and eosinophils.

The three types of protein fibers in connective tissue are

collagen, reticular, and elastic

The viscous component of connective tissue matrix is called

ground substance.

Loose connective tissue functions in all of the following ways except

providing strong connections between muscles and bones

Wharton's jelly is a form of

mucous connective tissue.

The color distinction between white fat and brown fat exists because brown fat

is highly vascular.