BIO 141 Lab 2: tissues

9f. Connective tissue proper

- Consisting of areolar (loose), reticular, dense connective tissue

9a. Connective tissue9

-A diverse group of tissues that are the most abundant and widely distributed tissue type in the body. -CT is the bony skeleton, it is blood, it encapsulates organs, it is an organ's structural framework that supports other cells, it stores fat, and it is involved in defense and protection because it contains immune cells. -Because it contains blood vessels, its aqueous component of its ground substance functions as a medium through which nutrients and wastes are exchanged between the blood and cells of the body. -Even though CTs differs greatly in their forms, they are similar because they all contain cells, fibers, and ground substance. -The extracellular matrix (fibers and ground substance) is the major component of CTs.

9e. Ground substance

-A gel like amorphous substance mostly consisting of water, it surrounds and permeates a fibrous matrix. -The fimness of the ground substance along with which fiber type is most prevalent, dictates the functional properties of the tissues. -An example , are tendons contain a large amount of type I collagen, which allows the tendon to resist strong pulling forces, while hyaline cartilage contains a more firm ground substance, which allows the tissue to resist compressive forces.

4m. Tight junction

-A specialized cell junction that prevents membrane proteins from mixing between the apical domain and the basal lateral domain. -Seals the spaces between adjacent cellsto prevent substances from being exchanged between the lumen/cavity and the underlying connective tissue and vice versa.

7c. Goblet cells

-A type of exocrine glandular cell -May be present in columnar epithelium. -An individual mucous-secreting cell. -Unicellular exocrine glands that secrete mucin into a lumen, which when mixed with water, forms mucus. -They are present among epithelial cells forming sheets in areas of the respiratory tract and gastrointestinal tract.

14g. Fibrocartilage

-A unique type of cartilage that is a mix between a dense type of connective tissue and cartilage. -The predominant fiber type of the matrix is type I collagen, which allows it to resist tensile forces

6h. Pseudostratified columnar epithelium

-A unique type of simple columnar epithelium because it is composed of cells that vary in height. It consists of tall columnar cells alongside short basal cells. -Both the tall and short cells are in contact with the underlying supportive connective tissue, but only the tall cells are in contact with the cavity/lumen the tissue lines. -It is called pseudostratified (pseudo means fake) because the nuclei in the tissue are not in a single row as is present in a simple columnar epithelium, but instead they are at different levels in the tissue giving it the appearance that it is composed of multiple cell layers.

6i. Columnar cells (In pseudostratified epithelium)

-Are in contact with both the cavity/lumen and the underlying basal lamina.

6j. Basal cells (In pseudostratified epithelium)

-Are not in contact with the cavity/lumen, but are in contact with the basal lamina. -It is thought that the basal cells are stem cells that are capable of dividing and ultimately become tall columnar cells.

3a. Epithelial tissue

-Black arrows indicates this tissue -These tissues form sheets that line cavities in the body and the external surface of the body. -Epithelial tissues also form glands, which produce secretions.

14a. Chondrocytes

-Cartilage maintaining cells that reside in lacunae

4g. Renewal

-Cells of epithelial tissues constantly undergo this process. -Different types of tissues do this at different rates. -All epithelial tissues are capable of regenerating new cells when damaged.

11a. Areolar (loose) connective tissue

-Composed of a loosely woven extracellular matrix consisting of collagen fibers, elastic fibers, and reticular fibers that is loosely woven among a considerable amount of ground substance. -Loose connective tissue contains more cells than dense types of connective tissue. -Is the most abundant and widespread of the connective tissues. -Areloar tissues underlie and support the many miles of epithelial tissues in the body. -It contains the blood supply for the overlying avascular epithelial tissues, areolar tissue is the medium through which blood gases, nutrients, and wastes must diffuse to be exhcanged between capillaries and epithelial cells.

9c. Reticular fibers

-Consist of fibrils formed by type III collagen molecules. -The fibers are extremely thin, form a flexible mesh-like network in certain organs (spleen), and don't bundle to form thick fibers. -They are not visible microscopically by H and E staining, but can be viewed when stained with silver stain.

6e. Simple cuboidal epithelia

-Consist of one layer of cells that are as tall as they are wide and appear square in histological sections. -Nuclei of these cells are often round and located in the middle of the cell.

6f. Simple columnar epithelia

-Consist of one layer of cells that are taller than they are wide and appear rectangular in histological sections. -Nuclei of these cells are often oblong and located near the middle of the cell.

9g. Specialized connective tissue

-Consisting of adipose, cartilage, bone, blood

6m. Stratified squamous epithelium

-Consists of many layers of cells and the most superficial cells are flattened squamous cells.

6l. Stratified epithelial tissues

-Consists of more than one layer of cells

11e. Blood vessels in areolar tissues

-Contains many blood vessels as it is a supporting tissue for epithelial tissue. -Capillaries are numerous in areolar tissue, for the exchange of blood gases, nutrients, and wastes between the blood and the overlying epithelial tissue.

4f. Avascular

-Distinction of all epithelial cells -Blood vessels do not run through the tissue, so cells of epithelial tissues rely upon diffusion to and from blood vessels in supporting connective tissue for the exchange of blood gases, nutrients, and wastes.

14d. Collagen type II

-Dominant fiber in hyaline cartilage -Not visible under a light microscope -The lack of visible fibers is a key feature in identifying this type of cartilage in lab. -

5a. Cilia

-Elongated, motile projections of the cytoplasm that are covered by plasma membrane. -They project from the apical surface of some epithelial cells that function to move substances across the surface of the epithelium. -An example is cilia in the trachea that function to move mucus away from the lungs toward the throat.

4. List the general characteristics of epithelial tissues and explain how the characteristics relate to the function of epithelial tissues

-Epithelial tissues are organized into two groups: sheets and glands. -Epithelial tissues classified as sheets, consist of contiguous cells that cover exposed surfaces (skin), line internal body passages, and line body cavities. -Throughout the body, sheets of epithelial cells play an important role in forming a barrier between tissues containing blood vessels and a cavity or lumen. -The cells of epithelial tissues function as gatekeepers determining what substances cross the epithelium.

7a. Endocrine cells

-Form an endocrine glandular epithelium that release secretions, called hormones, into underlying connective tissue where they can affect adjacent cells or diffuse into the bloodstream to affect cells in distant regions of the body. -Endocrine cells are in many different forms throughout the body.

1. Explain which structures of a histological specimen are stained by hematoxylin and eosin and why this staining process occurs

-Hematoxylin stains acidic structures blue -Eosin stain basic structures pink -Use of different stains is neccesary for differentiation between cell structures and so the cells will be visible.

11c. Lymphocytes

-Immune cells, present in areolar tissue that differentiate into antibody producing cells (plasma cells, which are identified as small cells with dark blue nuclei). -These cells are important for immunity.

14f. Elastic cartilage

-Like hyaline cartilage, has collagen type II -Has the addition of elastic fibers -Results in a cartilage that offers great flexibility and the ability to recoil to its original shape after deformation

11f. Reticular fibers (reticular connective tissue)

-Linked to each other forming a network of fibers. -Composed of type III collagen, which is a more delicate and thinner type of collagen as compared to type I collagen. -This type of connective tissue forms the structural framework of organs such as the spleen, liver, wall of blood vessels, and lymph nodes.

7b. Exocrine cells

-Makes up exocrine glandular epithelium, that produce secretions that are released into a lumen across the apical membrane.

6g. Goblet cell

-May be present in columnar epithelium. -An individual mucous-secreting cell. -Unicellular exocrine glands that secrete mucin into a lumen, which when mixed with water, forms mucus. -They are present among epithelial cells forming sheets in areas of the respiratory tract and gastrointestinal tract.

4h. Polar

-Most epithelial tissues consist of cells that are polar. -Epithelial cells can exhibit polarity in more than one way. -The membrane on one side of the cell consists of membrane proteins that are different from the proteins in the membrane on the other side of the cell. - The different membrane regions are structurally and functionally different from each other.

5b. Microvilli

-Nonmotile, slender, cylindrical projections of the cytoplasm covered by plasma membrane that emanate from the apical surface of epithelial cells in places such as the gastrointestinal tract and kidney tubules. -They function to increase the surface area of cell membrane exposed to the lumen. -The increased surface area allows more space for proteins that function as transporters to move substances across the epithelium.

6a. Simple squamous epithelia

-One layer of flattened cells.

11d. Mast cells

-Present in areolar tissue -Function in the promotion of inflammation by secreting substances such as histamine and heparin. -Identified as cells that containmany large, red secretory vesicles in the cell's cytoplasm.

11b. Fibroblasts

-Produce all the components of extracellular matrix in areolar tissue.

7d. Pancreatic acinar cells

-Pyramidal in shape (like pyramids or slices of a pie) and together form glands called acini that are spherical clusters. -Their secretions are secreted into the lumen of the spherical acinus. -

6b. Endothelium

-Simple squamous epithelium that forms the layer that lines the lumen of all blood vessels and lymphatic vessels.

6d. Mesothelium

-Simple squamous epithelium that forms the outer lining of some organs in the ventral body cavity and lines the walls of the ventral cavity. -This epithelium is responsible for the production of serous fluid that coats its apical surface surface. -Serous fluid is a slippery fluid that functions to prevent friction as organ surfaces rub against each other and as they rub against the wall of the cavity in which the organ resides.

14b. Lacunae

-Spaces surrounded on all sides by the extracellular matrix that is produced by the chondrocytes. -The extracellular matrix of cartilage is more firm than the extracellular matrix of connective tissue proper. -The firm, gel-like extracellular matrix of cartilage allows cartilage to resist compressive forces but also maintain some flexibility. -There are three different types of cartilage whose functional properties reflect the predominant fiber type in the extracellular matrix.

12a. Adipose tissue

-Specialized connective tissue consisting of cells called adipocytes

6o. Transitional epithelium

-Stratified epithelium composed of irregularly shaped cuboidal/columnar cells when the epithelium is not distended. -It is named transitional because the epithelium takes on a different appearance depending upon whether it is relaxed or distended. -When it is relaxed the surface cells have a dome-shaped appearance. -You will view a virtual slide of transitional epithelium in its relaxed state, so lood for the dome-shaped cells to identify this tissue. -This type of epithelium is only found in the urinary system, so sometimes it is called urothelium.

6p. Keratinized stratified squamous epithelium

-Stratified squamous epithelium that contains a superficial layer of dead cells. -This layer of dead cells is easily recognized because the cells lack nuclei. -This type of tissue is only found forming the epidermis of the skin. -The keratinized layer offers excellent protection against abrasion and dessication.

6n. Nonkeratinized stratified squamous epthelium

-Stratified squamous epithelium that does not contain a superficial layer of dead cells. -All layers including the most superficial layer of cells contain nuclei. -This tissue is good at resisting abrasion, but lacks the ability to resist desiccation, so it is found in places where the surface is covered by a layer of mucus.

11h. Fibroblast

-The cell responsible for producing all the extracellular matrix components, which includes fibers and ground substance. -Creates this ground matrix in dense connective tissue

6c. Endothelium cells

-The cells forming endothelial tissues.

9b. Type I collagen

-The most abundant type of collagen in the body. It forms fibers consisting of densely packed thick fibrils, which results in a fiber with a wide diameter relative to the other collagen types. -In many areas of the body (dermis of skin), the collagen fibers are parallel to each other forming collagen bundles. -Type I collagen functions to resist tensile (pulling) forces and stains pink in H and E staining procedures.

14c. Hyaline cartilage

-The most prevalent cartilage type in the body -Collagen type II is the dominant fiber type of the matrix, however it is not visible with the light microscope. -The extracellular matrix is also an excellent shock absorber because it consists of molecules that allow the cartilage to attract and hold water. (This is an important function that covers bone that are in contact with each other at joints)

14e. Difference between hyaline cartilage and elastic cartilage

-The only difference is the addition of elastic fibers in the the extracellular matrix of elastic cartilage. -Elastic fibers can be observed with easily with the light microscope

12. Identify adipose and adipocytes on a virtual slide and/or photomicrograph

-There are special types of connective tissue with properties that are different from connective tissue proper. Adipose is an example of a specialized connective tissue

3b. Connective tissue

-This tissue indicated by the blue arrows -These tissues are the structural framework of organs and the skeleton. -Fills internal spaces. -Supports overlying epithelial tissue. -Stores fat. -Plays a role in nutrient diffusion and defense and protection.

3d. Muscle tissue

-This tissue indicated by the red arrow -These tissues consist of muscle cells that contain proteins that interact with each other to cause contraction. -Contractions of muscle tissue results in the alterationof the shape of organs and the movement of the bony skeleton. -There are three types of muscle: 1. Skeletal muscle 2. Smooth muscle 3. Cardiac muscle -All of these types of muscle will be explored in greater detail in a future lab dedicated to muscle.

3c. Nervous tissue

-This tissue indicated by the yellow arrows -These tissues consist of neurons and supporting cells. -The function of neurons is communication. -They transmit signals in the form of potentials (graded and action) from one place in the body to another.

11g. Type I collagen fibers (Dense connective tissue)

-Tightly packed -Little space for ground substance to occupy

11j. Type I collagen fibers (Dense irregular connective tissue)

-Tightly packed -Oriented in various directions throughout the tissue. -The disorganized arrangement allows the tissue to resist pulling forces in multiple directions.

11i. Type I collagen fibers (Dense regular connective tissue)

-Tightly packed -Oriented side-by-side in a parallel arrangement -Resists tensile (pulling) forces that occur at the ends of the fibers

9d. Elastic fibers

-Typically thinner than type I collagen fibers and are composed of the protein elastin. -Elastic fibers can stretch and then recoil back to its orginal state

12b. Adipocytes

-specialized connective tissue cell -Stores lipids (triglycerides) -As lipid accumulates, the cell takes on a spherical shape and the nucleus and cytoplasm are displaced to the periphery of the accumulating lipid droplet. -**( In histology, the fat is dissolved away in the preparation process, sothe site of lipid storage in the living specimen will appear as a white empty space on the slide

10. Identify the connective tissues in the connective tissue proper classification on virtual slides and/or photomicrographs and describe how the structure of each connective tissue relates to its function.

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11. Identify The listed cells and extracellular matrix components that comprise the conective tissues in the connective tissue proper classification on photomicrographs and /or virtual slides.

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13. Identify the three different types of cartilage and describe thow the structure of each type of cartilage relates to its function

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14. Identify listed cells and extracellular matrix components that comprise the different types of cartilage

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6.Identify the listed epithelial tissues, cells, and apical specializations on a picture and /or a virtual slide.

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7. Describe and distinguish histologically between an example of endocrine tissue and exocrine tissue

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8. List the general characteristics of connective tissues and explain how each characteristic relates to the function of the tissue.

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9. Contrast the characteristics of connective tissue to epithelium tissues

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4b. Exocrine gland

A gland whose products are secreted into a lumen

4c. Endocrine gland

A gland whose products are secreted into the underlying connective tissue and/or bloodstream

4a. Gland

An epithelial tissue that is primarily involved in secretion.

5c. Brushborder

Areas where the microvilli are so densely packed that individual microvilli can't be resolved with the light microscope, but collectively they look like the bristles of a brush.

2d. Nucleus

Blue arrow

2b. Plasma membrane

Green arrows

2c. Cytoplasm

Red circle

4e. Cellularity

Refers to epithelial tissues consisting of tightly packed cells with very little extracellular matrix (non living layer between cells) between the cells

4l. Basolateral membrane domain

Refers to how to the lateral membrane domain and the basal membrane domain together are continuous without interruption.

4d. Hormones

Secretions of endocrine glands into the bloodstream

4j. Lateral domain

The portion of the cell membrane that faces adjacent cells.

4i. Apical membrane domain

The portion of the cell membrane that forms the edge of the lumen

4k. Basal membrane domain

The portion of the cell membrane that is in contact with underlying connective tissue.

2e. Nucleolus

Yellow arrow

2a. Cell

red arrows indicate the plasma membrane and the shape of the cell